NASA may use only expendable SRBs (as suggested on ghostNASA)

[gaetanomarano]

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three months after my suggestion on ghostNASA (http://ghostnasa.blogspot.com/2006/09/decision-006-use-only-expendable-srbs.html) (only a coincidence, of course) NASA appears close to adopt only expendable SRBs (http://www.spaceref.com/news/viewnews.html?id=1177)for (both) Ares_I and Ares _V

as explained in my ghostNASA's post, this is a very good news for NASA budget since the saving of a refurbished SRB is only (about) 10% of the price of a new motor, while, retrieve the SRBs from ocean has a fixed cost of $500M per year

another good news is that an expendable SRB (without parachutes and retrieval systems) may increase the Ares_I payload of an extra 10-12 mT, and, since the definitive (fueled) Orion+SM mass will be around 10-15% less than planned (then, under 18 mT) that NASA choice may be due to one of these reasons (or both):

a) the new 5-seg.SRB Ares_I has not sufficient power to lift the Orion, as evaluated in my SRB article (http://www.gaetanomarano.it/articles/011srb5.html)(and as rumored latest weeks) or...

b) they want more payload to launch an ISS/lunar "CorkScrew" Orion AND a powerful "SwissKnife Orion (http://www.gaetanomarano.it/articles/014swissCEV.html)"...

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[NEOWatcher]

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three months after my suggestion on ghostNASA (http://ghostnasa.blogspot.com/2006/09/decision-006-use-only-expendable-srbs.html) (only a coincidence, of course) NASA appears close to adopt only expendable SRBs (http://www.spaceref.com/news/viewnews.html?id=1177)for (both) Ares_I and Ares _V

But their reasoning and your reasoning are not the same.
You state "The ONLY fast, cheap and safe way to build a shuttle-derived rocket with the SRB is to use the standard 4sSRB of the Shuttle WITHOUT ANY (little or big) CHANGES to avoid new tests, re-certification, extra-costs, etc. (with all the navigation system, electronics, attitude controls, energy, etc. built inside the core stage, like with the Shuttle).
In other words no changes make it cheaper
Nasa is saying
In making this recommendation, this requirements change request cites the fact that somewhere between 20,000 and 25,000 pounds of weight could be saved in the design of the first stage by removing the systems needed to allow it to be recovered after it has been used.
In other words changing it to make it cheaper.

[gaetanomarano]

But their reasoning and your reasoning are not the same.

in all my articles and posts I suggest to use only the 4-seg.SRB to save 3+ years of time and $3+ billion of R&D costs and that's the reason of my "virtual decisions" in my "virtual NASA" about the SRB

however, the main point of my "decision #006" at ghostNASA is the giant saving of money that may come from deleting the fixed costs per year to retrieve the burned SRB from ocean

the very good news is that an expendable SRB may give a weight saving of up to 12 mT with a big increase of the max payload mass

that figure was completely unexpected to me (and to other peoples I've read on blogs an forums) since I've never imagined that the SRB's recovery system was so heavy!

but in my ghostNASA's post (at point 2 of advantages) I've suggested to build a non-segmented expendable SRB to save weight and increase the rocket's payload that is (exactly) one of the main NASA targets

the sum of both lists of (my and NASA) "good reasons" clearly demonstrate that use ONLY expendable SRBs is a VERY GOOD choice!

(and use ONLY the 4-segments version is BETTER)

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[Cugel]

Scott Horowitz:

"Its is very important that we recover the first stage of the Ares I so we can inspect it and assure quality of performance."

If that same Scott Horowitz now drops this requirement 'just like that', it appears to me like a rather desperate action and only proves that the Ares-I is underpowered. I think they started designing at the wrong end of the stack, with the CEV. That thing is simply way too big to be lifted by a single SRB. If they would reduce the size and mass of the CEV all the Ares-I problems would disappear overnight. The fact that this is politically unthinkable demonstrates the real problems of the program.

[gaetanomarano]

Scott Horowitz:
"Its is very important that we recover the first stage of the Ares I so we can inspect it and assure quality of performance."

recover the Ares' SRBs to "inspect it and assure quality of performance" is a minor problem

if they MUST recover the SRBs (that are the simplest, best tested and "inspected" part of the entire ESAS hardware) then, they MUST recover (to "inspect them and assure quality of performance") ALL other (more complex and untested) ESAS hardware... like... the Ares_V 1st and 2nd stages, the Ares_I 2nd stage/EDS, the LSAM descent and ascent stages, the Orion's SM, the LAS, the Orion's thermal shield, the lunar spacesuits, rovers, etc. etc. etc...

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[SpaceNutNewmars]

First off the quality goes into the product (SRB) as you build it, not from review of why it does not work via a recovery process, that is how you fix the quality control of build, you do this from the recovery information. You can only fix why it is unsafe by identifing what failed in the process of build by inspection of what gets recovered.

Not recovering them causes no change in safety since the unit if it were unsafe after inspection via the recovery process and having this knowledge will not change the fact that the SRB has already been used.

Adding a batch of sensors to the segments would give a better picture of performance.

[Mellow]

First off the quality goes into the product (SRB) as you build it, not from review of why it does not work via a recovery process, that is how you fix the quality control of build, you do this from the recovery information. You can only fix why it is unsafe by identifing what failed in the process of build by inspection of what gets recovered.

Not recovering them causes no change in safety since the unit if it were unsafe after inspection via the recovery process and having this knowledge will not change the fact that the SRB has already been used.

Adding a batch of sensors to the segments would give a better picture of performance.

Agreed, you design quality in, not tinker it in after the fact. I am interested in Cugels point about designing the stack back to front, starting with Orion.

I wonder, would the best design of Orion be the hardest/most critical part to get right? perhaps I underestimate the challenge involved in getting launcher capacity/performance designed correctly.

[Cugel]

Agreed, you design quality in, not tinker it in after the fact. I am interested in Cugels point about designing the stack back to front, starting with Orion.

I wonder, would the best design of Orion be the hardest/most critical part to get right? perhaps I underestimate the challenge involved in getting launcher capacity/performance designed correctly.

Interesting remark. There are 2 parts to the equation: the booster (Ares-I) on the left and the payload (Orion) on the right. Of course, the sides have to match and preferably with some margin. Currently they don't match, so you have to change one of the 2 sides. So, what would you change:

1) a non-existing, fully in its design phase, from scratch new to build capsule.
2) existing booster hardware, man-rated, tested and 'debugged' in over more than 100 flights.

And remember that the main selling point of the Ares-I was its commonality with the existing shuttle hardware. By chosing option 2) you completely dump that. Apparently the requirements of the Orion are cast in solid rock.

[gaetanomarano]

...existing booster hardware, man-rated, tested and 'debugged' in over more than 100 flights...

true, but only for the standard SRB (with 231 successful flights, if we consider two per launch, less one SRB failed with Challenger) but NOT for the 5-seg. version (that, in fact, needs 3+ years of research and tests)

that is the main reason I suggest (from months) to use ONLY the standard SRB

about the payload weight, the solution is simple, build a (4.5 m.) capsule for THREE

it will be not like Apollo, since, this time, all astronauts will land on the moon

also, a moon missions for "three" needs a smaller LSAM and Ares_V with 4-seg.SRB and only four RS-68

last, a 10 days 3x moon mission will give the same results of a 7 days 4x mission (with less costs!)

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[ToSeek]

That seems to assume that a short-duration Moon landing mission is the only kind of mission we want to do.

[gaetanomarano]

That seems to assume that a short-duration Moon landing mission is the only kind of mission we want to do.

the "plan" already IS for SHORT missions...

2006-2019: no moon

2020-2025: just a dozen of short missions

2026-UP: lunar outpost and long missions

since long missions need many cargoLSAMs and habitat modules, nothing change with a 3x capsule

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[cjl]

Umm...

Are we going to get into this again?

Gaetano: how many times do we have to tell you that the 5 sement version is an easy (minor) change from the 4 segment, and is NOT the same as an entirely new design? The construction techniques and propellant formulation are identical (with the exception of a minor change in the binder used), and because of this, the 5 segment is already well characterized. It will NOT require all of the additional testing that you seem to think is necessary.

[gaetanomarano]

...the 5 sement version is an easy (minor) change from the 4 segment...

3+ years and $3+ billion appear too much for a so "easy (minor) change"...

however (both) time and money lost with the 5-seg.SRB can be saved using the standard version

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[stutefish]

3+ years and $3+ billion appear too much for a so "easy (minor) change"...

"appear too much" TO YOU.

How about some evidence that it IS too much? That would be a lot more convincing than your opinion.

[gaetanomarano]

"appear too much" TO YOU.
How about some evidence that it IS too much? That would be a lot more convincing than your opinion.

the best answer to your question is:

"because only (about) twice the time for that "easy (minor) change" was sufficient to NASA (with "primitive" '60s technology) to go from zero to Armstrong's moonwalk..."

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[Nicolas]

And you are arguing that Apollo's safety standard is acceptable for what we're going to build now? This time, we're not in a hurry.

Agreed, the only thing that separates man from animals is Duct Tape, but still I think we should allow ourselves to iterate the design more, in order to come with safer concepts. I'm not saying Apollo was suicide, nor that we can't accept any risks now. It's just that tomorrow there's another day, and we'd better be safe than sorry this time. If it takes 3 years to develop good boosters, so be it.

[gaetanomarano]

And you are arguing that Apollo's safety standard is acceptable for what we're going to build now? This time, we're not in a hurry.

1. the comparison is between 3 years to add a segment to the SRB and 7 years to start (from zero) and build Mercury, Gemini, Apollo, Saturn, LEM, learn (again, from zero) how to fly in space, how to rendez-vous, etc... then, land safely on the moon and come back to earth!!!

2. the 3 years delays will be NOT used to increase the "safety standard" of the (already safe, reliable, tested and man-rated) 4-segments SRB but (only) to add a further segment to have a 5-segments SRB with unknown safety and reliability since we can know (and be sure) that it is safer only after 231 successful flights!!!

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[Nicolas]

from zero

The word zero in bold should be read as "lots of previous knowledge on V2's and other missiles, and an engineering effort of unseen proportions".


2. the 3 years delays will be NOT used to increase the "safety standard" of the (already safe, reliable, tested and man-rated) 4-segments SRB but (only) to add a further segment to have a 5-segments SRB with unknown safety and reliability since we can know (and be sure) that it is safer only after 231 successful flights!!!

Of course they are not adding a 5th segment for safety. I have this gut feeling there might be a different, very very subtle reason for adding a 5th segment...

[gaetanomarano]

..."lots of previous knowledge on V2's and other missiles, and an engineering effort of unseen proportions"...

all experiences are important (of course) but, compare the V2 with the SaturnV, is like compare a WWI biplane with the Concorde

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[stutefish]

I'm sorry, Gaetano, but I'm still not convinced.

Do you have any details about the costs of the Apollo program, and how they relate to the costs of the Orion program?

I'm also especially interested in any technical details you might have, that would explain why the two programs are comparable on a technical level, to the point where their respective costs are also comparable.

[gaetanomarano]

Do you have any details about the costs of the Apollo program, and how they relate to the costs of the Orion program?

if you consider that 90% of the technology and experience (now used to come back on the moon) was developed with Apollo, the costs of the ESAS plan quickly appears very very high (5+ times higher than necessary)

then, you must ADD the Apollo costs to the ESAS costs to have the REAL "price"


I'm also especially interested in any technical details you might have, that would explain why the two programs are comparable on a technical level, to the point where their respective costs are also comparable.

the two programs are not comparable, in fact, I've not compared them here

I've only said that 3+ years to add an SRB segment appears too much (to me) since in (only) twice that time NASA had lauched all capsules from Mercury to Apollo!!!

exactly, this thread is only about the advantages of use expendable SRBs

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[djellison]

Guys - I thought we had all seen very obviously that gaetanomarano has his opinions, and regardless of any data, facts, or laws of physics to the contrary he doesn't change them. Debating the issue is like urinating into the wind.

Doug

[cjl]

Of course they are not adding a 5th segment for safety. I have this gut feeling there might be a different, very very subtle reason for adding a 5th segment...
You mean like adding more thrust and total impulse so that the rocket could lift more payload?

No, it couldn't be that...

[gaetanomarano]

...has his opinions...
I've "my" opinion exactly like all other users have "their" opinions (and, so far, I've not seen they change them)


...regardless of any data, facts...
we are talking of SRB and "data+facts" clearly say that a standard SRB is cheaper than a new 5-seg.SRB since it doesn't need any additional R&D time and money
also, an expendable SRB is better than reusable saving fixed costs

however, I don't think forums are places where we must "change opinions" but only a place where we can "expose opinions" and debate of them remaining with our respective (and respectable) opinions

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[Bob B.]

but in my ghostNASA's post (at point 2 of advantages) I've suggested to build a non-segmented expendable SRB to save weight and increase the rocket's payload that is (exactly) one of the main NASA targets
If you want to use a non-segmented SRB then you had better start looking for a new SRB manufacturer, which will of course cost you considerable time and money. ATK, the current manufacturer, is located in Utah. The only way to get the SRBs to the Cape is by rail, which means they must be segmented. A non-segmented design means you have to switch to a manufacturer on the coast who can ship the SRBs by barge.

[cjl]

I've "my" opinion exactly like all other users have "their" opinions (and, so far, I've not seen they change them)


we are talking of SRB and "data+facts" clearly say that a standard SRB is cheaper than a new 5-seg.SRB since it doesn't need any additional R&D time and money
also, an expendable SRB is better than reusable saving fixed costs

however, I don't think forums are places where we must "change opinions" but only a place where we can "expose opinions" and debate of them remaining with our respective (and respectable) opinions

.
You, however, are ignoring the fact that the 5 segment has more thrust and total impulse, and would therefore lift more payload than the 4 segment version. Because of this, it is very likely that the 5 segment is cheaper than the 4, just because it reduces the number of launches necessary to get the same payload to orbit, and also allows for a larger, more capable capsule to be put into orbit.

[gaetanomarano]

ATK, the current manufacturer, is located in Utah
ATK can assemble the new SRB in a new factory near KSC
the money saved with the non-segmented SRBs and the time and money saved without SRB travels from Utah will be much higher than build the new SRB factory
also, have the SRB factory near the KSC may give great logistic advantages when the Ares launches per year will increase
however, have a 2nd (and 3rd) SRB manufacturer is be very good for quality and prices (that, thanks to competition, may fall under $10M per SRB)

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[gaetanomarano]

You, however, are ignoring the fact that the 5 segment has more thrust and total impulse, and would therefore lift more payload than the 4 segment version.
it's true, but latest rumors say that a 5-seg. Ares still remains underpowered for the planned Orion, then, a smaller Orion or a new Ares design (with two 4-seg. SRB) will soon become a necessity
also, in my articles I suggest to build a Single Launch Vehicle that uses ONLY (two or three) 4-seg.SRBs

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[Bob B.]

ATK can assemble the new SRB in a new factory near KSC.
In a factory that does not exist and will have to by built at great cost.


the money saved with the non-segmented SRBs
There currently is no non-segmented SRB; it will have to be designed, developed, tested, and evaluated.


and the time and money saved without SRB travels from Utah will be much higher than build the new SRB factory
Hogwash, shipping cost is minimal compared to the cost of a new factory. Furthermore, a skilled workforce already exists in Utah. If you think it is so easy to move operations to Florida, then why don't you be the one to layoff all the workers in Utah and devastate the lives of those families.

[gaetanomarano]

In a factory that does not exist and will have to by built at great cost.
not so great

...shipping cost is minimal compared to the cost of a new factory...
ok, then ship them!
I'm sure it's not a so complex job for to-day's tecnology!
however, use non-segmented SRBs is only a further (useful) option... the two most important choices are:
- use ONLY expendable SRBs, and...
- use ONLY standard 4-segments SRBs

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[gaetanomarano]

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to moderators:

two minutes ago I've tried to start a new thread but I've receied this error message:

Fatal error: Allowed memory size of 20971520 bytes exhausted (tried to allocate 1024 bytes in /home/baut/domains/bautforum.com/public_html/includes/functions_search.php on line 196

can you explain me how I can solve/avoid this problem?

thank you

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[cjl]

Another problem is that going to a single monolithic grain VASTLY changes propellant geometry to the extent that basically, a full redesign would be necessary to achieve proper characteristics for thrust and chamber pressure.

You keep going on and on about the horrible money that would have to be spent to redesign it and retest a 5 segment, but then you turn around and propose a MUCH larger change that would require far more time and money than the simple addition of an extra segment.

[gaetanomarano]

You keep going on and on about the horrible money that would have to be spent to redesign it and retest a 5 segment, but then you turn around and propose a MUCH larger change that would require far more time and money than the simple addition of an extra segment.
the main problem for high costs is due to the SINGLE source (without any competition)
I'm sure that with two-three competing sources the new (4 or 5 seg., segmented or not) SRB may be ready to fly in less time and at lower price (maybe, under $10m each!)

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[Dave J]

Is there, or has there ever been, a SRB of the scale of the STS SRB built as a single, non-segmented unit? I can only think of the old Titan IV SRBs, they too were segmented. What challenges would there be in such a big propellant pour? You can't just "upscale" a smaller, monolithic Atlas or Delta SRB, I suspect.
As for using the 4 seg standard SRB, it probably doesn't have the total impulse to do the job for the envisioned CEV. Spending capital now in designing a more robust SRB makes sense...designing a smaller interim CEV is expensive. As is moving SRB manufacture to Florida.
And Apollo vs Aires1 is a poor comparison, we are so very early in the Aires process, and the dollars used in Apollo aren't the same as what they are today. The time frame and sense of "urgency" is also non-comparable.

[Bob B.]

the main problem for high costs is due to the SINGLE source (without any competition)
I'm sure that with two-three competing sources the new (4 or 5 seg., segmented or not) SRB may be ready to fly in less time and at lower price (maybe, under $10m each!).
ATK/Thiokol already had to compete against other contractors to win the original Shuttle SRB contract. They now have a leg up on the competition because they have design already in full-scale production. A competing contractor would have to start from scratch with its own design. Starting over with a new contractor would probably result in lengthy and unsatisfactory delays.

[Bob B.]

Is there, or has there ever been, a SRB of the scale of the STS SRB built as a single, non-segmented unit?
No, the Shuttle SRBs are the largest solid rocket motors ever built and they are obviously segmented. I don't know what the largest single segment SRM is, however I seem to recall hearing that proposals were submitted for the Shuttle SRBs that would have used a non-segmented casing, but they were rejected in favor of the Thiokol proposal. I may be misremembering though and I cannot confirm this.

[cjl]

I believe you are correct. However, I am not sure if the propellant would have been a single monolithic grain, or if they would have still used segmented propellant grains within a single casing.

[gaetanomarano]

ATK/Thiokol already had to compete against other contractors to win the original Shuttle SRB contract. They now have a leg up on the competition because they have design already in full-scale production. A competing contractor would have to start from scratch with its own design. Starting over with a new contractor would probably result in lengthy and unsatisfactory delays.

strange (political?) positions...

America IS the place of competion!

everything (from cellphones to airplanes) costs LESS when there is a competition!

when the SRB contract was assigned there was the big AT&T but antithrust authority has sliced it in many (more efficient) companies

I'm SURE that, if NASA gives new-SRB contracts to MANY aerospace companies ALL the "problems" you quote will never happen and (without a monopoly) the new-SRB price will FALL every year!

do you want more space exploration per $ or (only) more ATK profits?

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[gaetanomarano]

Is there, or has there ever been, a SRB of the scale of the STS SRB built as a single, non-segmented unit?
probably (but I'm not sure) some ICBM rockets
however, build a single-piece rocket is not too complex for to-day's technology

As for using the 4 seg standard SRB, it probably doesn't have the total impulse to do the job for the envisioned CEV.
latest news say that not even the 5-seg. Ares-I will have the power to lift the Orion, so, a NEW Ares-I design will be soon necessary

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[Bob B.]

everything (from cellphones to airplanes) costs LESS when there is a competition!
That works when there is a large market and a large number of units being produced because multiple companies can each reap a share of the market and sell enough units to remain viable. It doesn't necessarily work for a highly specialized product with only a limited number of units being produced.

For the large SRBs there is only one consumer, NASA, and they'll be buying, what, maybe a dozen units a year. That is simply not enough units to keep more than one company in business producing them. Do you really think it will be cheaper to have two or three companies each maintaining a factory to produce only a few units per year? Do you think it is better for NASA to buy from multiple sources, each with its own design and specifications, or to standardize on one consistently manufactured product?

When there is an extremely limited and specialized market, as is usually the case in aerospace, the competition is held up front when the various contractors submit their proposals. After a company's bid is accepted, they typically become the one and only supplier. I agree that holding a new competition and accepting new bids may ultimately result in a lower price, but to suggest there can be simultaneous multiple producers from which NASA can shop around every time they want to buy a SRB I believe is naive.

There are many benefits that come from staying with the current contractor who has a known track record, extensive experience, existing production facilities, and an in-place workforce. Switching to a new contractor will move us into unknown territory and would almost certainly result in delays. Cost is often not the only consideration in the decision-making.

[gaetanomarano]

...For the large SRBs there is only one consumer, NASA, and they'll be buying, what, maybe a dozen units a year...
again, it's strange...

ESAS is a NEW plan and EVERYTHING in this (new) plan will be assigned to a contractor after a competition!

ALL parts... excluding the SRB...

the use of SRB was decided BEFORE the Jan 2004 Bush's press conference about VSE (I've read that CLV was a NASA idea from years) and adopted without an Orion-like competition...

probably it's a political (but not rational) decision

since the Ares-I must be ready to launch in 2015, I'm sure that half dozen companies (like Boeing and LockMart) are PERFECTLY able to design something better (and in time for the launch) ...if someone will ask them to do that, of course...

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[gaetanomarano]

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to moderators:

I've tried again to start a new thread but, again, I've receied this error message:

Fatal error: Allowed memory size of 20971520 bytes exhausted (tried to allocate 1024 bytes in /home/baut/domains/bautforum.com/public_html/includes/functions_search.php on line 196

can you help me?

thank you

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[Bob B.]

since the Ares-I must be ready to launch in 2015, I'm sure that half dozen companies (like Boeing and LockMart) are PERFECTLY able to design something better (and in time for the launch) ...if someone will ask them to do that, of course...
I find this hilarious, gaetanomarano. In the past you've argued against the 5-segment SRB because of the time it would take to make the modification from the 4-segment version. Yet here you say another contractor can start from scratch and produce a wholly new booster design without any delay whatsoever. This is not the first time you've argued both sides of the fence depending on the point you are trying to make at the moment. You are not being honest with yourself, gaetanomarano. You continually exaggerate the problems of your competition while downplaying the problems with your own concepts to the point of being irrational. I believe your judgment and objectivity is extremely clouded, gaetanomarano.

[gaetanomarano]

I find this hilarious...

my answers depends of your questions

I still suggest to use ONLY ready available SRB and engines (then, no 5-seg.SRB and no J-2x) ...and this is "my choice" all my articles and all "my decisions" at ghostNASA, but, if you say that build a non-segmented booster is "too complex" or "impossible", my answer (to this specific point) is that your claim is not true since a new, better and cheaper SRB can be made, especially with companies' competition

the most rational choice/decision may be: use the standard SRB now and, in the long term, search new sources and develop better models (don't forget that all ESAS hardware will be used in the next 30+ years, so, every cent saved must be multiplied by hundreds units!)

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[DOOMMaster]

I find this hilarious, gaetanomarano. In the past you've argued against the 5-segment SRB because of the time it would take to make the modification from the 4-segment version. Yet here you say another contractor can start from scratch and produce a wholly new booster design without any delay whatsoever. This is not the first time you've argued both sides of the fence depending on the point you are trying to make at the moment. You are not being honest with yourself, gaetanomarano. You continually exaggerate the problems of your competition while downplaying the problems with your own concepts to the point of being irrational. I believe your judgment and objectivity is extremely clouded, gaetanomarano.

After this new set of posts, I'd don't believe his judgement and objectivity to be extremely clouded, I KNOW it is. The argument against the 5 segment booster and making a proposal to the building of an entirely new factory in Florida or shipping of a non-segment across the country is ludacris at best. I don't even want to get into what it would be at worse.

gaetanomarano do you have ANY idea at all how much time and money it would cost to build a new factory in Florida? Far more than the $3 billion and 3 years it is going to take to test and start production of a 5 segment booster. Building a factory is not cheap, and for far more reasons than just the building of the factory itself. You have to take into consideration the cost of the land to build on (land in Florida is FAR more expensive than in Utah, both due to fact that large areas of Florida are unsuitable for building as well as the larger population density of people and endangered species that prevent building), the taxes of the area, not to mention the cost to pay the contractors and labor force to build the factory.

As for shipping a non-segmented booster, sure it would be possible to develop a mention to do this from Utah to Florida. It could be flown in if you want to spend the money and time to develop a system to do this. But the cost would be far more and the time far greater than what it would be to build the factory in Florida (I'm ignoring all the technical changes that would have to be made to the booster than also makes this idea entire ridiculous, not to again mention the cost in money and time).

Ship a completed booster across the road system? Forget it. Aside from the fact that it probably wouldn't fit under the overpasses of our national Interstate system and have to be shipped by backroads, there is no way a completed booster would be under the weight limit for these roadways. According to a quick Google search, 1,300,000 pounds (590,000 kg) is the completed launch weight to the SRB, with 1,100,000 of it the propellant. There isn't a roadway in the US, nor anywhere else in the world for that matter, that could handle that much weight.

Ship it across the ocean? Well, first you'd have to get it there (Utah isn't located on the coast, after all). Again, this would cost far more money and time than the current system of shipping segmented parts across the country by rail. And if they can only ship 2 completed segments by rail at a time (again, a quick Google search), its very unlikely the rail system could handle the entire assembly SRB. Unless you want to build a dedicated rail system that could, again costing more time and money than it's worth.

You clearly have no knowledge about what is involved in the building a new factory, nor of the limitations and costs of transportation. You have just about the same amount of knowledge when it comes to the SRB boosters and the NASA plans for the moon. You only have your "opinions," which you are willing to go to ridiculous means to try to defend, as has been demonstrated in this thread. If you fail to see why it's a good idea to spend $3 billion and 3 years on a 5-segmented booster with clear advantages over the 4-segmented one but are willing to waste billions of dollars and years worth of time to build a new factory/new shipping system/entirely new design of SRB, your judgement is clearly suspect.

[gaetanomarano]

...do you have ANY idea at all how much time and money it would cost to build a new factory...
nothing is fast and cheap in a 20y/$230B plan!
however, build a new factory is not so dramatic as you say here!
no more than thousands new factories built in the world every year!
also, my short term suggestion is to use ONLY standard (and expendable) SRBs and engines
build a new factory to manufacture a non-segmented SRB is NOT my "first choice" but, don't forget that the ESAS hardware will be used for 30+ years, then, in the long term, a non-segmented SRB will be more reliable (and a factory located in Florida may have great logistic advantages)
again, the keyword is "competition" since high costs comes (first) from MONOPOLIES
I'm sure that many (competing) companies will be able to solve all problems with new technologies and smart solutions
one possible solution (but not the only) may be to ship the (63 mT only) empty non-segmented SRBs from Utah (or from another State/Company) and fill them in a smaller factory near KSC
about the detailed solutions (for every small problem) you want from me... I can find some of them (instead of give only "opinions") but I'm NOT involved in the ESAS plan, so, I don't need (nor want) to do the the work other peoples are paid to do

.

[cjl]

Most factories that are built are nowhere near as specialized as the ones required to build SRB's. Also, note that the SRB's WERE built after a competition, and the reason for the monopoly is that it is CHEAPER to have only one manuf. when there is such a limited market. You seem to have a very short memory, as quite recently, you were advocating a completely opposite strategy from what you are now.

[gaetanomarano]

.

solution found!

since an empty SRB is smaller and weigh less than an empty Orbiter, one empty (non-segmented) SRB can be moved (from everywhere in the USA) to KSC with the same Boeing 747-100 SCA used to move the Shuttle

.

[gaetanomarano]

...the SRB's WERE built after a competition...
a competition made 35 years ago!
then, if an US public office had made a competition in '30s for some cars, to-day they must use their same, dear, old, Ford-T.....

...and the reason for the monopoly is that it is CHEAPER to have only one manuf. when there is such a limited market.
not true
to have the best product at the best prices is sufficient a competition with two-three companies
look at the Orion... only two competitors and only a few of capsules to build
and, since a solid rocket is simpler (and will be built in dozens units!) NASA can find many competitors

...you were advocating a completely opposite strategy...
which "strategy" you refer to?
if you refer to the "use of standard SRBs" I still suggest to use them

.

[DOOMMaster]

.

solution found!

since an empty SRB is smaller and weigh less than an empty Orbiter, one empty (non-segmented) SRB can be moved (from everywhere in the USA) to KSC with the same Boeing 747-100 SCA used to move the Shuttle

.

Oh, wow. Do you have ANY idea how much it costs to move the shuttle via the 747 and why NASA always tries to land the shuttle in Florida just to avoid this? Its costs approximately $1 million to transport the shuttle via the 747, which is pretty much how much it would cost to transport a SRB each time. Not to mention what it would cost to modify the 747 to carry the SRB. Do you do any research into something before you bother to propose it, or is random idea all you go off of? And you wonder why no one takes any of your ideas seriously.

[DOOMMaster]

nothing is fast and cheap in a 20y/$230B plan!
however, build a new factory is not so dramatic as you say here!
no more than thousands new factories built in the world every year!
also, my short term suggestion is to use ONLY standard (and expendable) SRBs and engines
build a new factory to manufacture a non-segmented SRB is NOT my "first choice" but, don't forget that the ESAS hardware will be used for 30+ years, then, in the long term, a non-segmented SRB will be more reliable (and a factory located in Florida may have great logistic advantages)
again, the keyword is "competition" since high costs comes (first) from MONOPOLIES
I'm sure that many (competing) companies will be able to solve all problems with new technologies and smart solutions
one possible solution (but not the only) may be to ship the (63 mT only) empty non-segmented SRBs from Utah (or from another State/Company) and fill them in a smaller factory near KSC
about the detailed solutions (for every small problem) you want from me... I can find some of them (instead of give only "opinions") but I'm NOT involved in the ESAS plan, so, I don't need (nor want) to do the the work other peoples are paid to do

.

Yes, every year thousands of factories are produced that are capable of building very large, highly complex, and very expensive limited use items such as SRBs. Oh, wait, no there aren't. You seem to think that a factory producing clothing or other simple consumer goods are comparable to the gigantic factory that must assemble a SRB. You seem to need a lesson in the difference between the two, not to mention a lesson in economics.

An SRB is not a cell phone. It's not even a car. It's a very complex and highly specialised piece of equipment. The factory that builds them now has been building such things for the space program as well as the US military for decades. They have the workforce with the knowledge of how to build them as well as the equipment and factory in place to build them. This wasn't built overnight, as you seem to assume. It took many years and large amounts of money. The cost it would take to build such a facility in Florida would be billions of dollars, probably in excess of $10 billion and more than 5 years of construction (an educated guess based on the size or the current Utah factory size). Not to mention the fact that you would lose many of those people in the workforce in that move (sure, some would go to not lose their jobs, but many would not leave their home area due to family, friends, etc.). This is foolish when you have a perfectly fine factory and mention of shipping the current boosters, as well as the future boosters to be used.

As for your next idea of shipping your new non-segmented booster without it being full of propellant, can you even show this is possible? The booster is long and the rail train will have to make turns on the way to Florida. Weight is not the only limiting factor in shipping the booster, length is also. But, again, you've not bothered to do research as to whether your idea is feasible, you just suggest something at random that seems like it might support your position.

Not to mention the fact that you now want to build yet ANOTHER factory in Florida to fill the non-segmented booster when it arrives. Aside from more waste in money and time to build this new factory when there is no good reason to, you have yet to show that a non-segmented booster is even possible. Let alone that it would be more reliable, cheaper, and easier to construct, or whether the propellant can even be filled in a non-segmented booster.

Once again, you have shown exactly why no one takes your ideas seriously. They have absolutely no solid reasoning behind them, just simple guessing and little thought into whether they would be feasible or not. You seem to think you don't have to provide any details because "you aren't part of the ESAS plan," but you have no problem with proclaiming that what NASA is doing is wrong while proporting that every "opinion" you have is the correct one (especially in the face of overwhelming evidence that your "opinions" are incorrect). Sorry, but if you are going to make these proposals, you might want to actually try doing some research into them, because people here are going to expect it. And if you actually did, you might end up seeing why everyone here disagrees with you.

[djellison]

Once again, you have shown exactly why no one takes your ideas seriously. .

It's the bold letters and red text that makes it so good though - don't you think. The guys website actually gives me a headache.

Doug

[gaetanomarano]

.

DOOMMaster, I give you a global answer to your two posts:

as I've explained in ALL my posts here, in my articles and in my "decisions" at ghostNASA, in the short term I suggest to use ONLY ready available (and expendable) SRBs and engines... again, I repeat, "ONLY READY AVAILABLE SRBs AND ENGINES" (then, I've not changed my opinion)

however, in the long term (and the ESAS plan needs a VERY long time!) move to non-segmented SRB has (at least) three BIG advantages:

1. a lower price per unit... now an SRB costs $40M but the price of a simpler (expendable) version without the structure to refurbish and test the segments (for possible leaks) may fall under $20M (or less with a second source that compete with the first) and, with the launches planned in the next 20 years (12 lunar with three SRB each and two dozens of orbital with one SRB each) the money saved will be over one billion (the price to build a small factory near KSC to fill the empty SRBs) while (at $1M per flight) the costs to move ALL empty SRBs will be only $60M

2. as reported by NASA, the expendable (segmented) SRB give a 10-12 mT saving of weight... a, simpler, non-segmented version may increase the weight saved of many mT increasing the payload the Ares_I and V can lift... I can't predict the total weight saved and how much the payload will be increased, so, for the payload, I give a conservative figure of 2 extra-mT of paylod with the Ares_I and 4 extra-mT for the Ares_V... well, you know that every kg. launched in orbit is very very very expensive... I've evaluated that each mT send in orbit with an Ares_I will cost (including shared R&D costs) over $15M... 60 "SRB-light" will increase the total payloads launched (in the next 20 years) of 120+ mT... then, 120 x 15 = $1800M saved!

3. the last (and most important!) reasons to use the non-segmented SRBs is the increase of rockets RELIABILITY and the astronauts' safety... the Ares_V is a cargo-only vehicle and the Ares_I is safer than Shuttles (it can't explode like the Challenger) but (both) will be incredibly expensive!!! I've evaluated that EACH Ares_I orbital launch will cost over $1 billion (including shared R&D costs) while EACH moon mission (of the 12 planned in the next 20 years) will cost between $9 billion (from latest NASA global VSE evaluation of costs) and $17 billion (from GAO evaluation) then (CLEARLY) a leak in one or more segmented-SRB will result in many LOSS OF MISSIONS (and more risks for the astronauts) with extra costs for NASA in the order of many billion$$$ or tens of billion$$$

compared with these advantages, the price to build a small factory near KSC (to fill the non-segmented SRBs) and the 747 flights appears only MINOR (and RIDICULOUS) costs!!!

.

[SpaceNutNewmars]

One of the items of concern is how much the booster will flex at the segment joints as it goes thou the launch profile since it has never had the weight of the rocket placed at its top. This will lead to compression of the joint seals.

This will have answers in the coming launch demonstator.

As for a non segmented, I believe the ESA Vega first stage is a new SRB but I think it is not in the same class.

[gaetanomarano]

One of the items of concern is how much the booster will flex at the segment joints as it goes thou the launch profile since it has never had the weight of the rocket placed at its top. This will lead to compression of the joint seals.

you're right!

this is an excellent 4th good reason to use non-segmented SRBs

the 5-seg.SRB will have 20% more thrust, an higher acceleration (since, with the same burning time, it will be jettisoned at 60-65 km.) and OVER 300 mT ON THE TOP (2nd stage, Orion and LAS)

the combination of these forces may result in an incredible extra-pressure on the segments with many possible leaks and/or some SRB broken-in-flight (a giant risk for astronauts and many launches/missions loss/aborted)

.

[Nicolas]

Is 20% more segments 20% more thrust for the SRB, or rather 20% longer burn time?

[Bob B.]

Is 20% more segments 20% more thrust for the SRB, or rather 20% longer burn time?
I think you mean a 25%, 5/4 = 1.25.

It appears there will be a combination of both greater thrust and longer burn time. Based on demonstration tests from a few years ago and literature released in the last year or so, it looks like the 5-segment SRB will have a burn time about 5 seconds longer than the 4-segment booster. Since we know the addition of the fifth segment will add approximately 25% to the total impulse, the average thrust will be about 20% greater considering the slightly longer burn time. The demonstration tests achieved a peak thrust of 3.6 million pounds versus 3.3 million for the 4-segment version.

[Dave J]

Where are you getting your cost savings figures from?
Leaking SRBs...last I knew, this problem was solved with the redesign.
20% more thrust from 5 seg SRB, higher (to the point of overstressing?) accelleration, but still can't produce enough thrust to lift the Aires? Am I missing something here?
The engineers working in the program know what they're doing. I'll trust the designs that they come up with.

[gaetanomarano]

Is 20% more segments 20% more thrust for the SRB, or rather 20% longer burn time?

as evaluated in my SRB article (http://www.gaetanomarano.it/articles/011srb5.html)and confirmed in this Michael Cabbage's Blog Ares-I article (http://blogs.orlandosentinel.com/news_space_thewritestuff/2006/08/new_details_on_.html#comments)(about a NASA press conference) and also in a very interesting NASA report (http://www.nasa.gov/centers/marshall/news/news/releases/2003/03-186.html)(about a REAL 5-segments SRB test with a small increase of the nozzle's diameter) the 5-seg.SRB burning time was (in the 2003 test) and is expected to be (in the final version) only 5 seconds more than a standard 4-seg.SRB since the new SRB will have the same diameter and propellent's geometry of the standard version

the 5-seg.SRB extra-thrust was only +9% in the 2003 (real) test adìnd is planned to be +25% in the final version while the increase of weight may be around 20-22% (we must add only the weight of the 5th segment since both SRBs have some parts in common)

however, a +25% increase of thrust is not sure (only the future tests can say a final word) so I've evaluated/posted a (more prudent and realistic) +20% then, I agree with Bob B. evaluation


.

[NEOWatcher]

as evaluated in my SRB article (http://www.gaetanomarano.it/articles/011srb5.html)and confirmed in this Michael Cabbage's Blog Ares-I article (http://blogs.orlandosentinel.com/news_space_thewritestuff/2006/08/new_details_on_.html#comments)(about a NASA press conference)
Since there is no data to back up the blog, all it confirms is that someone agrees with you.
Yes; fuel is dangerous in a rocket. It's also dangerous in the cryo tank being transported to the rocket. I see no appreciable risk differences.

and also in a very interesting NASA report (http://www.nasa.gov/centers/marshall/news/news/releases/2003/03-186.html)(about a REAL 5-segments SRB test with a small increase of the nozzle's diameter)
You might want to re-read that. According to the article. The shuttle 4 segment produces 2.6 million pounds and this 5 segment test produced 3.6 that's 38%.

[gaetanomarano]

Leaking SRBs...last I knew, this problem was solved with the redesign.
true, but the problem can happen again, especially in the Ares-I (with 300+ mT on the top of the segments...)

...but still can't produce enough thrust to lift the Aires...
recent news (you can find Googling) say the Ares-I is expected to be "underpowered"
however (if that will be true) I think that problem may come also from an underpowered 2nd stage/engine

.

[gaetanomarano]

...all it confirms is that someone agrees with you...
if "someone" are NASA (in the press conference) and ATK (with the test) that is sufficient for me!

Yes; fuel is dangerous in a rocket. It's also dangerous in the cryo tank being transported to the rocket. I see no appreciable risk differences.
I've not posted any opinion here about liquid vs. solid engines, however, I agree with you on that point

The shuttle 4 segment produces 2.6 million pounds and this 5 segment test produced 3.6 that's 38%.
as you can read in the Bob B. post (and in the full SRB specs) the peak thrust of the 4-seg.SRB is 3.3 million pound while the 5-seg. test has evidenced a peak thrust of 3.6 million pound, +9%, not +38% (a value that is clearly impossible to have adding only ONE extra-segment and with the small increase of the nozzle's diameter used in the test)

[Bob B.]

You might want to re-read that. According to the article. The shuttle 4 segment produces 2.6 million pounds and this 5 segment test produced 3.6 that's 38%.
2.6 Mlbf is the 4-segment's average thrust, while 3.6 Mlbf is the 5-segment's maximum thrust. The maximum thrust of the 4-segment is 3.3 Mlbf, and based on total impulse and burn time, the average thrust of the 5-segment should be around 3.1 Mlbf.

[Nicolas]

true, but the problem can happen again, especially in the Ares-I (with 300+ mT on the top of the segments...)

That thing's got up to 1600 metric tons of force compressing it, due to the thrust.
300 tons compression from the load might be handled as well then. Have you got good reasons to assume it won't?

Oh wait, the compressive force of this top load onto the boaster depends on the acceleration of the stack, right. That's quite some force then, at say 5 G's. Still I can't just say from my chair whether they could engineer that or not.

Thinking about it, also the requirements on say the engine frames of Saturn V and the compressive axial loads on its (empty) fuel tanks are quite impressive.

[Bob B.]

recent news (you can find Googling) say the Ares-I is expected to be "underpowered"
however (if that will be true) I think that problem may come also from an underpowered 2nd stage/engine.
I actually have to agree with part of what you say here. So far I’ve only heard rumblings about the Ares I being underpowered and haven’t really looked into the details. I’m having a hard time seeing why there would be any problem with the first stage SRM because the last data I saw placed the vehicle launch weight at around 2 million pounds, while the first stage’s peak thrust is about 3.6 Mlbf and the average thrust about 3.1 Mlbf. The first stage SRM seems to be plenty powerful enough; I fail to see a problem. If anything is underpowered I think it has to be the second stage.

Since the second stage is a completely new design it can be engineered with as much impulse (i.e. propellant) as necessary, however the J-2X engine seems to me like it might be a bit underpowered. The thrust-to-weight ratio at second stage ignition (a little over 2 minutes after launch) seems awfully low to me. As you may recall, the second stage engine was originally going to be an SSME with about 70% more thrust than a J-2X. I don’t know what other people are saying, but if there is a problem my guess is the second stage thrust may be too low.

I’m not going to worry about it though; NASA has top-notch engineers working on the problem and they’ll figure it out. Overcoming problems like this is all part of the normal design process; I think the naysayers need to just chill and let things play out. Problems become mistakes only when they carry over into the final product. So far no mistakes have been made, so just let the engineers finish doing their job.

[Nicolas]

Overcoming problems like this is all part of the normal design process

Designing truly new things that push the enveloppe often is basically finding for 99% of the time that it will not work, and the last 1% is finding your final, working design.

[gaetanomarano]

...300 tons compression from the load might be handled as well...

do you think that, under the very high stress of a launch, it's easier to break the object a) (close to the Ares-I design) or the obiect b) ???

4247

[gaetanomarano]

A:

Since the second stage is a completely new design it can be engineered with as much impulse (i.e. propellant) as necessary, however the J-2X engine seems to me like it might be a bit underpowered. The thrust-to-weight ratio at second stage ignition (a little over 2 minutes after launch) seems awfully low to me. As you may recall, the second stage engine was originally going to be an SSME with about 70% more thrust than a J-2X. I don’t know what other people are saying, but if there is a problem my guess is the second stage thrust may be too low.

B:

I’m not going to worry about it though; NASA has top-notch engineers working on the problem and they’ll figure it out. Overcoming problems like this is all part of the normal design process; I think the naysayers need to just chill and let things play out. Problems become mistakes only when they care over into the final product. So far no mistakes have been made, so just let the engineers finish doing their job.

your claim "B" contradicts your claim "A" since the 2nd stage design described in the claim "A" (inlcuding the -70% underpowered engine) was made (about one year ago) by the SAME "top-notch engineers" of your claim "B" and NEVER CHANGED (so far)

also, the contract of the (-70% underpowered) J-2x engine was already assigned many months ago (and its design/test will need seven years!)

then, where do you see the "changes" needed to avoid these (serious) design "mistakes"?


a further doubt... if the J-2x is -70% underpowered to lift the small Ares-I 2nd stage and Orion... how much it will be underpowered to lift (as single engine) the 3+ times heavier AresV 2nd stage/EDS and the 45 mT LSAM ??? -270% ???


.

[Doodler]

This again? More of the "they didn't get it right the first time, it'll NEVER work" ranting with all the obnoxiously colored text, capslocks, and bolding?

Plus c'est la meme chose, plus ça change, indeed...

[NEOWatcher]

then, where do you see the "changes" needed to avoid these (serious) design "mistakes"?
.
A change is not a mistake. It is not a mistake until they actually make the hardware. Until then it is only new knowledge.

[Nicolas]

do you think that, under the very high stress of a launch, it's easier to break the object a) (close to the Ares-I design) or the obiect b) ???

Thank you so much, the phenomenon of buckling was totally new to me.

How about the phenomenon "air resistance"?

[gaetanomarano]

.

to Doodler and NEOWatcher

you're both right, but...

1. a good engineer doesn't make so big mistakes (not even "on paper") and...

2. despite the Ares-I (clear) problems, they STILL don't make any design change, but insist to develop the current design (with the J-2x, etc.) and assign the contracts of its main parts...

then...

.

[Nicolas]

And obviously you have full Unagi on the whole design tradeoff table, design options tree, etcetc.

[gaetanomarano]

How about the phenomenon "air resistance"?
in my post/drawing I wish to refer to the fragility of a structure so thin compared with its lenght

.

[gaetanomarano]

...design options tree...
I don't see any "design option tree" in the already assigned contracts of the 5-seg.SRB and J-2x
where do you see the possible changes that, with the same engines, may give the right power?

.

[Doodler]

.

to Doodler and NEOWatcher

you're both right, but...

1. a good engineer doesn't make so big mistakes (not even "on paper") and...

2. despite the Ares-I (clear) problems, they STILL don't make any design change, but insist to develop the current design (with the J-2x, etc.) and asign the contracts of its parts...

then...

.

Ehm, Gaetano, Engineers have been known to make legendary mistakes on paper that often get right to the point of almost being fabricated before being found.

If Engineers didn't make mistakes on paper, then we'd never see a machine fail because of design defects.

If Engineers can screw up to the point of building bad machines (N-1, etc), then it stands to reason they can make some serious screw ups on paper. Given the law of averages and cross checking, for every mistake that makes it into production, you can easily assume ten major mistakes were corrected in the design process.

Also, be wary of what you call a mistake. A completely reasonable solution to one problem may not immediately work for another application which requires a certain amount of rethinking, retooling, trial, and error. This is what is seen in the Ares project in the current phase. They're in the process of taking an idea that looks good scrawled on the back of an envelope and going through the motions of developing a working design that will likely face constant revision right up through the tooling and assembly process. This is nothing new in any design/build field.

[Bob B.]

your claim "B" contradicts your claim "A" since the 2nd stage design described in the claim "A" (inlcuding the -70% underpowered engine) was made (about one year ago) by the SAME "top-notch engineers" of your claim "B" and NEVER CHANGED (so far)

also, the contract of the (-70% underpowered) J-2x engine was already assigned many months ago (and its design/test will need seven years!)

then, where do you see the "changes" needed to avoid these (serious) design "mistakes"?
I’ve only speculated about what the problem might be if there is indeed a problem, which I’ve seen no evidence of. You want to second guess something that is an ongoing and evolving process. Why don’t you let the engineers finish their work before you before you critique them? Yes, they switched to the J-2X a year ago and they may switch to something else before the design is finalized. Evaluating design trades is all part of the process and changes are commonplace. It is way too early to characterize the selection of certain trades as mistakes because at this point things are still fluid.

[Nicolas]

I don't see any "design option tree" in the already assigned contracts of the 5-seg.SRB and J-2x
where to you see the possible changes that, with the same engines, may give the right power?

.

That 's exactly what I mean. You don't see everything. I don't see everything. If you're no part of the design team, you don't know what are all the options, what are all the specific advantages and disadvantages of these options on every level, how they interact, etcetcetc. Even when you're in the design team you only know about a part of it.

You see the already assigned contracts. You don't see all internals preceding that. And that's just one example.

[Nicolas]

in my post/drawing I wish to refer to the fragility of a structure so thin compared with its lenght

.

I know, man, I'm an aerospace engineer. I learned about buckling already in high school.

I raised air resistance as one simple illustration of how different criteria result in different outcomes, and the wonder of design is to find something that fulfills all criteria. A rocket designed for buckling strength alone will look totally different from one designed for aeronautics alone will look totally different for one having maximum internal volume will look totally different from a maximal stearable rocket will look totally different from the lightest rocket will look totally different from the cheapest rocket will look totally different from the most powerful rocket etcetcetc. You have to find an equilibrium.

[Bob B.]

1. a good engineer doesn't make so big mistakes (not even "on paper") and...
What mistake has been made?


2. despite the Ares-I (clear) problems
What clear problems? Do you have any hard evidence beyond rumor and speculation?


they STILL don't make any design change, but insist to develop the current design (with the J-2x, etc.) and assign the contracts of its main parts...
How do you know they haven’t been making changes? You opened this thread by calling attention to a design change that is rumored to be under consideration (i.e. changing to an expendable SRB), yet you now say they are refusing to make changes. So what is it, are they making changes or aren’t they, and what evidence do you have either way?

[Nicolas]

NASA must hire Gaetan. He has more overview of the design process than any lead engineer and manager in any large design process ever done on this planet.

Gaetan, it's perfectly fine to have ideas or remarks on designs, but you must realize that you, nor I, know all arguments made thus far in the design process and all its facets.

[gaetanomarano]

...legendary mistakes on paper...
agree on that... but the Ares-I already is something more (much more) than a "piece of paper" ...with the SRB, J-2x and Orion contracts assigned and (most important) their specs already DECIDED, the Ares-I/Orion system already is in the design phase where a bad choice IS a mistake

.

[gaetanomarano]

I’ve only speculated about what the problem might be if there is indeed a problem, which I’ve seen no evidence of.
I think you've speculated correctly and that some problems exists
after all, how a smaller J-2x engine can lift a payload that (only one years ago) was planned to need an SSME ?
and... how a single J-2x can lift the (3+ times bigger) EDS/LSAM payload if it is not sufficient to lift the small Orion?

...they switched to the J-2X a year ago and they may switch to something else...
I don't see them switching to "something else" (and I don't think they want/can "switch" since they have already assigned the J-2x contract) but, if they'll change again the Ares' engines, all the time/money they've spent so far will be LOST and the first Orion launch will shift to 2018-up (thanks to: one year already lost + one year to admit the wrong choice + one year to change the Ares' design, search the right engines and assign the new contracts...)

.

[gaetanomarano]

...You don't see everything. I don't see everything...
that's true, but some key decisions/data are already known and we (I, you and thousands other peoples around the world, on space forums, blogs, websites, magazines, universities, etc.) discuss/evaluate them starting from these (well known) FACTS
maybe, there are (or will be) some changes... but the Ares-I NEVER can become a SaturnV and the J-2x NEVER can become an F-1

.

[gaetanomarano]

...I'm an aerospace engineer...
then you already know these problems (and the forces that a "toothpick-rocket" like the Ares-I must face in real flights)

.

[djellison]

how a single J-2x can lift the (3+ times bigger) EDS/LSAM payload if it is not sufficient to lift the small Orion?


Upper stages don't have to 'lift' - they have to accelerate - deliver a total impulse. You can do it quickly with a powerfull engine, or more slowly with a less powerfull engine. Indeed the lighter J2-X probably delivers better upper stage performance than the heavier (and more expensive) SSME given that the engine itself is dead weight.

Doug

[gaetanomarano]

What mistake has been made?
exactly those you quote in your post

...have any hard evidence beyond rumor...
many rumors read in last year had become true after a few days/weeks

How do you know they haven’t been making changes?
they HAVE made many changes... some in the right direction (and I admit that when I see one of these changes) but (also) some (crucial) changes/decisions in the wrong direction (like 5-seg.SRB and the J-2x)
this is only my opinion, of course

.

[gaetanomarano]

Upper stages don't have to 'lift' - they have to accelerate - deliver a total impulse.
true, but (both) are 2nd stages... so, if the Ares-I's J-2x has no sufficient power to lift/accelerate its 2nd stage/payload, how the same (underpowered) engine can lift/accelerate the (3+ times heavier) EDS/LSAM without fall in the ocean?
I feel we will (soon) see some (radical) design changes...

.

[gaetanomarano]

...more overview of the design process than any lead engineer and manager in any large design process ever done on this planet...
you can give your opinions (or post critics about my opinions) also without use tons of sarcasm against me

.

[cjl]

true, but (both) are 2nd stages... so, if the Ares-I's J-2x has no sufficient power to lift/accelerate its 2nd stage/payload, how the same (underpowered) engine can lift/accelerate the (3+ times heavier) EDS/LSAM without fall in the ocean?
I feel we will (soon) see some (radical) design changes...

.
And I feel you are wrong.

The upper stage engines do NOT need to have huge thrust. Efficiency is far more important. It is IRRELEVANT how much thrust they have (well, OK, not completely, but within a certain range it is), all that really matters is total impulse. Rockets cannot just fall into the ocean if they've been accelerated to several thousand mph by the booster stage.

Basically, you are wrong, and it can be shown by math.
Now PLEASE, leave the design work to those qualified to do it :wall:

[Bob B.]

I think you've speculated correctly and that some problems exists
after all, how a smaller J-2x engine can lift a payload that (only one years ago) was planned to need an SSME ?
The obvious answer is that when the first stage was changed from a 4-segment SRM to a 5-segment SRM, the impulse requirement of the second stage decreased significantly. With a smaller second stage, a smaller engine could be used.


and... how a single J-2x can lift the (3+ times bigger) EDS/LSAM payload if it is not sufficient to lift the small Orion?
Firstly, it is by no means established that the J-2X can't lift Orion. I just expressed the opinion that the thrust seems a little lower than I'm use to seeing. (I'll explain more about this in my next post.)

Secondly, the Ares V EDS does its work late in the launch when the vehicle is at high altitude and traveling essentially horizontally. At this point in the launch there is little need for the engine to fight gravity, its job is to accelerate the stack to its final orbital velocity. This can be done with a fairly low power engine. Don’t forget that a single J-2 (which is less powerful than the J-2X) performed the same job launching Apollo with no problem.



What mistake has been made?
exactly those you quote in your post
I haven’t quoted any mistakes.

[Bob B.]

The upper stage engines do NOT need to have huge thrust. Efficiency is far more important. It is IRRELEVANT how much thrust they have (well, OK, not completely, but within a certain range it is), all that really matters is total impulse. Rockets cannot just fall into the ocean if they've been accelerated to several thousand mph by the booster stage.
For the most part I agree with you, cjl, particularly in the case of the Ares V EDS. For the Ares I however, I think the thrust of the second stage is an important consideration since the vehicle drops its booster so early in the flight (just a little over minutes after launch). There is still a lot of gravity to overcome at that point, so the second stage can’t be too underpowered or it might struggle getting the vehicle to altitude. The losses due to gravity will be less with a higher thrust engine, but the thrust can’t be too great or the acceleration loads at burnout will be too high. This is one of those areas where the designers have to start making trades.

For Ares I the thrust-to-weight ratio at stage 2 ignition is only about 0.9. This seems low to me for the T+2 minute point in the launch, which is why I mentioned it early. This does not mean it won’t work however; the problem is far too complex to make a quick judgment like that. We just need to let the engineers finish doing their job to see what the come up with.

[cjl]

You're right, that does seem low, which is part of the reason I did not completely say thrust was irrelevant. However, it should still be able to work, as long as there is sufficient fuel in the second stage - it would just slow down a bit until it had burned enough fuel to reach a T:W ratio >1:1.

Also, that make the staging much less violent, a definite plus for any passengers...

[Dave J]

I've been reading a good account of the 747 development. When it rolled off the assembly line for test flight, it was overweight and underpowered. The engines were horrifically unreliable.
As flight test proceeded, they learned about the engine problems and inefficiencies, and solved them. They put the airframe through a weight reduction program and soon enough, the ship was performing as advertised. The MD-11 went through the same process, as did the LM and Saturn V.

Sure, the basic technology of the new program is Shuttle based. There will be big changes, refinements, and improvements along the way. The engineers have just opened the book here, and are two steps into the long process. I doubt they will end up with a badly designed, underpowered launch system. They know the minutia of the systems they are designing and working with. They know the aerodynamic and propulsive challenges.

It's like griping about NASA's Apollo program while the first model of the Saturn 1 was still in engineering. The SRBs are understood technology, well understood, having been flown and refined over decades. The joints are very strong, the cases are overengineered (spelled "man rated"), the J-2 is a well known and robust man rated system as well. They will determine how to make the system work. If they run into a show stopper, then they will adjust course as required. So much depends on the payload as well, still in it's infancy in design.

It is really too early in the project to be second guessing things. It seems that until some real coherent test data on the systems starts being produced, it's just guessing. Until then, I'll be watching, and I'm sure the engineers and developers will be hard at it...they're not stupid, they understand what they have to work with far better than us.

[cjl]

I've been reading a good account of the 747 development. When it rolled off the assembly line for test flight, it was overweight and underpowered. The engines were horrifically unreliable.
As flight test proceeded, they learned about the engine problems and inefficiencies, and solved them. They put the airframe through a weight reduction program and soon enough, the ship was performing as advertised. The MD-11 went through the same process, as did the LM and Saturn V.

Sure, the basic technology of the new program is Shuttle based. There will be big changes, refinements, and improvements along the way. The engineers have just opened the book here, and are two steps into the long process. I doubt they will end up with a badly designed, underpowered launch system. They know the minutia of the systems they are designing and working with. They know the aerodynamic and propulsive challenges.

It's like griping about NASA's Apollo program while the first model of the Saturn 1 was still in engineering. The SRBs are understood technology, well understood, having been flown and refined over decades. The joints are very strong, the cases are overengineered (spelled "man rated"), the J-2 is a well known and robust man rated system as well. They will determine how to make the system work. If they run into a show stopper, then they will adjust course as required. So much depends on the payload as well, still in it's infancy in design.

It is really too early in the project to be second guessing things. It seems that until some real coherent test data on the systems starts being produced, it's just guessing. Until then, I'll be watching, and I'm sure the engineers and developers will be hard at it...they're not stupid, they understand what they have to work with far better than us.

:clap::clap::clap:

[Bob B.]

It is really too early in the project to be second guessing things. It seems that until some real coherent test data on the systems starts being produced, it's just guessing. Until then, I'll be watching, and I'm sure the engineers and developers will be hard at it...they're not stupid, they understand what they have to work with far better than us.
Agreed.

[SpaceNutNewmars]

I am not sure quite how I should feel about this gaetanomarano;
DISCOVERY'S RING OF FIRE (http://cosmiclog.msnbc.msn.com/archive/2006/12/11/19898.aspx) Comment area for the STS116 launch descriptions where you post about this expendable SRB and ect... from this thread there.

First if you check out the newmars threads on SRB for use in cev you will find that I posted on Tue Sep 14, 2004 that an EELV is expendable in that we do not care what happens with it and even though An SRB is reusuable should we care about that feature, probably not.

[SpaceNutNewmars]

Then further into it I posted
Do less design and more building of the stick. Review design after prototype launch, sensor the cramp out of it to get the most info that you can for later rehash of the design.

Well guess what gaetanomarano thats about the direction Nasa has chosen.

That does not make me a rocket design just a go gut feeling guesser....

[Nicolas]

you can give your opinions (or post critics about my opinions) also without use tons of sarcasm against me

.

You could give your critics against everything engineers do with some reservations, given you nor anyone outside of the team knows all details. You come over very arrogant to me, presenting all your ideas as if these engineers haven't got a clue as to what awful mistakes they're making, and you know it all better. I say wait and see what their final design is; they're good and experienced engineers and must have their reasons for the choices they made, are making and still have to make.

Yes there is a lot of sarcasm in that reply, but it points to exactly how you come across to me: a person seemingly having a complete overview of something he nor anyone outside of the team cannot know more than those details given in the media. I have given that critique in the past without sarcasm as well, but I don't see changes in your attitude nor justifications for it.

[Nicolas]

then you already know these problems (and the forces that a "toothpick-rocket" like the Ares-I must face in real flights)

.

Yes and I also know that I cannot tell, simply by the height/diameter ratio, whether they will or won't be able to make it handle the forces, and whether it is the best design when looking at all variables in the design decision table.

[Nicolas]

If they run into a show stopper, then they will adjust course as required. So much depends on the payload as well, still in it's infancy in design.

Show stoppers as I learned it were defined as having no solution, contrary to the various levels of design problems challenges ;) that may occur during the design process but can be solved or worked around. I know what you meant, and I fully agree with your post. Give them some slack. Look into any advanced design in its early stages, and you only see loads of things that will not work or will turn out not to work. That's engineering life.

[gaetanomarano]

...leave the design work to those...
I've accepted their choice as correct, but exactly from the same sources come changes and doubts, including doubts about the Ares-I flight's stability (see the Cabbage's article)

.

[gaetanomarano]

Firstly, it is by no means established that the J-2X can't lift Orion.
latest news seem to go in that direction
about the AresV... you're right, but consider that they have outlined the AresV around the same J-2x specs, then, if it will result underpowered for the Ares-I, also the AresV design must be revised

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[djellison]

:wall:

The 'power' of the J2-X doesn't matter. It is simply the downselection option for the most efficient

You could deliver that impulse with an F1 engine from a Saturn V, the upper stage from an Atlas V, a Delta IV, a J2-X ...it doesn't (within reason) actually matter.

The parameter that changes is the total impulse required - do you understand that?

[gaetanomarano]

The parameter that changes is the total impulse required.
when I (and other) talk of engine's "power" I/we (simply) refer to the fact that its specs (Thrust and Isp) matches (or not) the rocket's needs

.

[djellison]

The answer to my question is no then - you do not understand the requirements and deisgn trades around an upper stage...please stop pretending that you do.

[gaetanomarano]

...you do not understand the requirements and deisgn trades around an upper stage...
this thread was (only) about "expendable SRBs" and shifted (first) to the non-segmented SRBs and (now) to the question if Ares-I has the "power" to launch the Orion (or not) but this is NOT an "invention" of mine, since it is an argument you can read (these days) on many space news, forums and blogs (and we can talk of it without any special permission)

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[djellison]

In this ('your') thread on expendable SRB's - you said

and... how a single J-2x can lift the (3+ times bigger) EDS/LSAM payload if it is not sufficient to lift the small Orion?

The reply being that the fact you even ask the question demonstrates zero understanding of upper stages. Your understanding the SRB first stage was demonstrated to be zero some time ago when you were convinced a 5 segment motor would destory itself.

The point is that you simply do not understand the basic principle behind this stuff - you are not in an intellectual position to make the claims that you do. Stop pretending that you know what you are talking about - you do not and the more you speak, the more gratuitous the chasm between what you are saying, and the truth.

Doug

[Nicolas]

For the most part I agree with you, cjl, particularly in the case of the Ares V EDS. For the Ares I however, I think the thrust of the second stage is an important consideration since the vehicle drops its booster so early in the flight (just a little over minutes after launch). There is still a lot of gravity to overcome at that point, so the second stage can’t be too underpowered or it might struggle getting the vehicle to altitude.

You mean that Ares V EDS is used, roughly speaking, to finish off the intended orbit. At the time it is ignited, the 'orbital' velocity already compensates a large part of gravity, so there's no need for a large against-gravity thrust vector. While the Ares I second stage is still used to get it to *a* more or less orbitlike state in the first place; the 'orbital' velocity does not compensate gravity to a large extent yet at that point, so apart from accelerating one also needs to do a lot of work in making sure it doesn't drop too much due to the large uncompensated gravity part. Is that what you meant?

When going from LEO to GEO, it is quite clear that a small thrust force could do it, as gravity is already compensated for so only delta V is of importance. But indeed, going from close to LEO towards LEO also doesn't require T>W. The transient behaviour of a rocket dropping from close to LEO is so slow, that T being "a lot" smaller than W can also accelerate the rocket enough to go closer to GEO, as long as T is not so small that gravity has pulled us further away from orbital conditions after the burn. A simple example: your first stage puts you on a vertical parabola with your intended orbital altitude as highest point. No more gravity to compensate after first stage in that case. The second stage can be used exclusively to increase orbital velocity. The only requirement on this is that it accelerates the rocket so much that the intended orbital velocity is reached by the time the highest point of the parabola is reached. Of course this is a simplified model, as the changing orbital velocity will continuously change the parabola you're flying (due to changing gravity compensation), but anyway that's the idea why you don't need T>W for an upper stage. The interaction on the parabola will even further reduce the required T/W fraction.

Feel free to correct any mistakes.

There are also some nice results on the best trajectory towards orbit with and without atmosphere, but I don't know them by heart.

[gaetanomarano]

In this ('your') thread on expendable SRB's - you said
I've explained why in latest posts since both rockets was designed around the same J-2x specs

about your second point:

1. since I/we am/are not living in North Korea, I/we am/are free to talk of the arguments I/we want

2. many (disliked) arguments/opinions/critics I've posted in last year+ on my website and some space forums come true after a few weeks/months

3. my arguments/threads/posts give a furher opportunity to a genius like you to expose your "expert" opinions

.

[Bob B.]

You mean that Ares V EDS is used, roughly speaking, to finish off the intended orbit. At the time it is ignited, the 'orbital' velocity already compensates a large part of gravity, so there's no need for a large against-gravity thrust vector. While the Ares I second stage is still used to get it to *a* more or less orbitlike state in the first place; the 'orbital' velocity does not compensate gravity to a large extent yet at that point, so apart from accelerating one also needs to do a lot of work in making sure it doesn't drop too much due to the large uncompensated gravity part. Is that what you meant?
Yes, that is exactly what I meant, though you said it much better than I. Thank you for clarifying.

[gaetanomarano]

...It's like griping about NASA's Apollo program while the first model of the Saturn 1 was still in engineering...It is really too early in the project to be second guessing things...
I agree about Apollo/Saturn (since they was in the early years of space exploration with low experience) but not about to-day's vehicles that born (after 50 years of experience and launches) from well known hardware
the ESAS hardware was not designed "one year ago" (that already is too much for to-day's standards) but (minimum) three years ago (before Bush's press conference) and some concepts was much older
to-day (with decades of experience, math models, computers, etc.) the design of cars, airplanes, ships, rockets, etc. MUST be 99% right at the "first shot"
how do you think of a car engineer that designs a vehicle, and, after (only) a few weeks changes the engine, after a few months changes the brakes, more weeks and changes the number of wheels, last months changes the number of seats, next week will change the weight of the car, another month and the car will be longer and larger, etc. etc. etc.

.

[gaetanomarano]

I am not sure quite how I should feel about this gaetanomarano...
I'm used to acknowledge the (good) ideas' authors and I don't propose as mine (like other peoples do) STUMPYid or inDIRECT versions of ideas found on internet...

.

[gaetanomarano]

...Well guess what gaetanomarano thats about the direction Nasa has chosen...
as (I think) is clear reading my posts and my website, I'm not critics only about Ares-I details but (most important) about some fundamental choices of the entire ESAS plan (and I'm NOT alone on that)
...the 1.5 launch architecture, both Ares, the use of 5-seg.SRB, the too big capsule, its shape, the small SM, etc. etc. etc.
then, I don't suggest (only) to change an engine (or make it better) but to change the full plan (and, again, I'm NOT alone on that)

.

[gaetanomarano]

...your critics against everything...
(you know) the web is FULL of different ideas, critics, insults (and cospiracy theories) against EVERYTHING (space and non space) and EVERYONE including hundreds peoples that has different (good or bad) ideas about the space programs
I never posts insults but ONLY my opinions
why do you think I must be the only person in the world that can't do that?

.

[gaetanomarano]

...I cannot tell, simply by the height/diameter ratio, whether they will or won't be able to make it handle the forces...
true, but consider that the Ares-I 1st stage is not a single piece but has 5 segments and 6+ junctions (that makes it less resistant)

.

[gaetanomarano]

...but can be solved or worked around...
that's true for small problems, not if the Ares needs (as I think) a complete design change (and I'm NOT alone in that opinion, please read other forums and blogs about space)

.

[Bob B.]

Firstly, it is by no means established that the J-2X can't lift Orion.
latest news seem to go in that direction
Has the news specifically singled out the J-2X as the culprit? I’ve read rumors that the “Ares I” may be underpowered but no specifics as to the reason.


about the AresV... you're right, but consider that they have outlined the AresV around the same J-2x specs, then, if it will result underpowered for the Ares-I, also the AresV design must be revised
No, a problem in one application does not mean there will be a problem in the other. The Ares V application is very different than that in Ares I.


this thread was (only) about "expendable SRBs" and shifted (first) to the non-segmented SRBs
If you are complaining about the change of topic, let me remind you that you brought up the non-segmented SRB issue in Post #3. I then commented on it in post #25 only to point out that the current SRBs must be segmented because they are shipped via rail. Rather than simply saying something like, “Thank you, I’ll take that information under advisement”, you turned it into a major debate topic.


and (now) to the question if Ares-I has the "power" to launch the Orion (or not)
Let me again point out that you brought up the issue of whether or not Ares I has sufficient power in your opening post when you wrote, “the new 5-seg.SRB Ares_I has not sufficient power to lift the Orion.” You then expanded the topic to include discussion of the second stage and J-2X engine in Post #61 when you wrote, “I think that problem may come also from an underpowered 2nd stage/engine.”

[Doodler]

I've been reading a good account of the 747 development. When it rolled off the assembly line for test flight, it was overweight and underpowered. The engines were horrifically unreliable.
As flight test proceeded, they learned about the engine problems and inefficiencies, and solved them. They put the airframe through a weight reduction program and soon enough, the ship was performing as advertised. The MD-11 went through the same process, as did the LM and Saturn V.

And sometimes, you start with a ship that barely fits the profile, then improve the next version having seen one fly.

Consider, because of generational improvements, the shuttles that followed Columbia were actually substantially lighter because of better materials and trade offs in structural mass because of what the first ship taught them.

That doesn't mean there were mistakes in Columbia's design, just that the Challenger and those that followed were dramatically improved.

[gaetanomarano]

Has the news specifically singled out the J-2X as the culprit? I’ve read rumors that the “Ares I” may be underpowered but no specifics as to the reason.
true, but, if you say that the 1st stage has sufficient "power", my logic (and your logic) say that the problem must come from the 2nd stage

...a problem in one application does not mean there will be a problem in the other...
true, but since they have designed both rockets the same days with the same engines (that has the same specs) if the J-2x will result "underpowered" for the Ares-I they must change something also on the AresV design

...saying something like, “Thank you, I’ll take that information under advisement”
you can agree that it is a very important argument (for safety and reliability) to say only "thanks" ...and talk of another argument

.

[Bob B.]

true, but, if you say that the 1st stage has sufficient "power"
That was only my opinion, and I’m working from limited information. The engineers at NASA know a whole lot more about the specifics than I ever will.


my logic (and your logic) say that the problem must come from the 2nd stage
Correct, that is what I reasoned, assuming there even is a problem. I find it interested however that the people spreading the rumors haven’t given more details. That makes me question just how much they really know.


true, but since they have designed both rockets the same days with the same engines (that has the same specs) if the J-2x will result "underpowered" for the Ares-I they must change something also on the AresV design
No, you cannot draw that conclusion. The J-2X “may” be underpowered for Ares I but perfectly suitable for Ares V. The applications are completely different. Your argument is akin to saying the RL-10 engine is too underpowered to use on Ares I, therefore it won’t work on the Centaur stage. The Centaur has been using various versions of the RL-10 since 1963; the engine is perfectly suited for that application. You have to look at the specifics of each individual application and cannot draw sweeping generalizations.

[gaetanomarano]

...was only my opinion...
the fact that they will scrap the retrieval hardware (to save weight) suggests some (possible) problems also for the 1st stage

...that is what I reasoned...
exactly like I have done

...you cannot draw that conclusion...
but there are good probabilities that I'm right
if they have designed both rockets around an engine with a power of "100" and now they have only "70" they must find somewhere the remaining "30" both rockets need
however, we must wait to see the solutions/changes adopted

.

[Bob B.]

the fact that they will scrap the retrieval hardware (to save weight) suggests some (possible) problems also for the 1st stage.
Possibly, but it could also be a remedy for a problem further up the stack. By lightening the first stage, the rocket will be going faster and higher at first stage burnout. This will lessen the impulse requirement of the second stage thus allowing the stage to be made smaller, thereby lessening the burden on the engine. So modifying the first stage doesn’t necessarily mean that is the source of the alleged problem.


but there are good probabilities that I'm right
if they have designed both rockets around an engine with a power of "100" and now they have only "70" they must find somewhere the remaining "30" both rockets need
however, we must wait to see the solutions/changes adopted.
That may be true if the problem is that the J-2X engine is falling short of its expected thrust. However that is not necessarily what is meant by saying the stage is “underpowered”. It could also mean that the mass of the second stage and payload is heavier than originally expected, thus the J-2X may lack the necessary thrust due to mass growth rather than lower than expected thrust. In the later case the J-2X might still be sufficiently powered to meet the Ares V requirements.

If the current expectations for the J-2X is lower than originally anticipated thrust, which I doubt is the case, the solution for the Ares V could simply be two EDS engines rather than one. As you may recall, the concept released in 2005 included two engines but this was later reduced to one when the vehicle was reconfigured using the RS-68 engines.

Let me further add that this is all just guesswork and speculation. We really don’t know for sure that there is a problem, and if so, what it is.

[Dave J]

Gaetano,
I have a question. In your opinion, what difference in performance does a couple/few hundred thousand pounds of max thrust and a few extra seconds of burn time mean to a rocket's peformance like the "stick"?
This is a pointed question for you, there is an answer. (Hint: 1st flight of the Delta IV Heavy). And it has direct bearing on the ability of the SRB5 to do the job.

[gaetanomarano]

Gaetano,
I have a question. In your opinion, what difference in performance does a couple/few hundred thousand pounds of max thrust and a few extra seconds of burn time mean to a rocket's peformance like the "stick"?
near nothing on the 1st stage, very much on the 2nd
but why do you ask me a so obvious question?

.

[stutefish]

Am I right in understanding the following statements to be true?

1. Whereas, at rest, a multistage launch vehicle has a given "at-rest inertia",

2. The first-stage engine of a multistage launch vehicle must produce enough thrust to

- FIRST, overcome the at-rest inertia of the vehicle, and
- SECOND, to impart a certain minimum velocity to the vehicle in a given direction,

3. But the second-, third-, and subsequent stage engines of the launch vehicle do NOT have to overcome the at-rest inertia

4. On account of the vehicle now having a new, "in-motion inertia",

5. Such that the subsequent stage engines of the launch vehicle only need to provide enough thrust to replace velocity lost to air resistance, acceleration due to gravity, etc., in order to preserve the in-motion inertia created by the more powerful first-stage engine.

Please excuse my syntax; a layman is me!

[Nicolas]

Yes, that is exactly what I meant, though you said it much better than I. Thank you for clarifying.

To be honest, I stepped around soome dirty details I couldn't formulate without looking them up, such as what exactly is the criterion for T/W, more specific then "going closer to orbital flight" :).

[Nicolas]

the fact that they will scrap the retrieval hardware (to save weight) suggests some (possible) problems also for the 1st stage

In spaceflight, saving weight does not suggest more than ordinary "problems" occuring in virtually every design, as it is everyday business.


(you know) the web is FULL of different ideas, critics, insults (and cospiracy theories) against EVERYTHING (space and non space) and EVERYONE including hundreds peoples that has different (good or bad) ideas about the space programs
I never posts insults but ONLY my opinions
why do you think I must be the only person in the world that can't do that?

-I never said you can't do that, I state my opinion that I find it bad manners.
-I never said you're the only one.
-YOu are not posting insults in the clearest sense, but when somebody is continuously saying I'm making huge mistakes in my work without knowing the details or giving me time to finish my work, I do find that insulting. There is a difference between suggesting alternatives, posing questions and raising doubts, and continuously stating just how wrong they're doing things, added by a more or less subtle undertone that you know it better and finally they listen to your proposed solution.

Designing is so specific, and every design project truly has its own life, outsiders like us can never know where they're at, how and why they're doing things. It's perfectly fine to give your own ideas and thoughts, but for the n-th time, give the engineers some slack! At the moment, I see nothing happening that points at a bad design process.

Except for maybe a vague statement of the need to go the moon and build a base there, but that's beyond the scope of this discussion.


If I'd give "current state of affairs" of the design we're working at every now and then, you'd be crying when looking at the work presented. HOwever, that is just a current state, the result of exploring ideas, often tangentially, and often while working towards other ideas that aren't made public yet. People who don't know everything that's going on in the design process will look very strange at some choices made. But in light of what is to come and the knowledge gained during the process, it's logical. And just because the current design doesn't work, we can't tell we're doing a bad job. We might be "shooting our last arrow", or we might be doing a final elimination process after which we combine the working alternatives to a magnificent design, everything in between, or learn so much from the non-working designs that we come up with a working one in the end, etcetc. In the meantime, people are more than welcome to help us, give their thoughts, but the last thing we need is people pointing out only how many mistakes we're making and quite arrogantly proposing "better" alternatives while not knowing every detail. The latter results in non-working propositions, propositions that are already being looked at, propositions that have been looked at but are a no-go, etcetc. Very frustrating. And as always, a lot depends on the way in which you bring a message.

[Doodler]

Am I right in understanding the following statements to be true?

1. Whereas, at rest, a multistage launch vehicle has a given "at-rest inertia",

2. The first-stage engine of a multistage launch vehicle must produce enough thrust to

- FIRST, overcome the at-rest inertia of the vehicle, and
- SECOND, to impart a certain minimum velocity to the vehicle in a given direction,

3. But the second-, third-, and subsequent stage engines of the launch vehicle do NOT have to overcome the at-rest inertia

4. On account of the vehicle now having a new, "in-motion inertia",

5. Such that the subsequent stage engines of the launch vehicle only need to provide enough thrust to replace velocity lost to air resistance, acceleration due to gravity, etc., in order to preserve the in-motion inertia created by the more powerful first-stage engine.

Please excuse my syntax; a layman is me!

Just an add to #2, its also got to push it high enough to break through enough atmosphere that the atmospheric resistance against which the second and succeeding stages has to fight with is below a certain level.

This hit me back when John Glenn returned to space in the shuttle after having done capsule flights. He remarked how much faster the shuttle was off the pad. This left me with the impression that the first stage isn't so much about speed as it is lifting power (torque, for lack of a better term, its like a first gear in a transmission). Once out of the denser parts of the atmosphere, the upper stages lay on the speed with less air to punch through.

[cjl]

Yep, and as mentioned before, ONLY the first stage must really fight gravity.

A rocket could be designed that would be perfectly functional with a first stage t:w ratio of 40:1, and second stage of 0.5:1. It would not be as efficient as other designs for several reasons, but it would work. You need to remember that rockets designed to reach orbit are complex machines, and in many cases are affected by too many factors to simply use "common sense" to determine their flight characteristics and/or possible problems without significant experience in the field. Calculations would be valid, but I have yet to see one calculation from you regarding your complaints about the various "problems" of the new launcher.

[Dave J]

OK, G got me there...he was correct on the first /second stage thing. I still think the higher thrust and slightly longer burn will make a difference.

Now, how much does one more SRB segment weigh? How much does a current segment weigh? I believe each segment has a different weight, as a result of the propellant grain geometry that gives each segment a different propellant shape and load according to it's place in the stack.
So, I am wondering if anyone on this forum can garner a real guess as to what the additional segment will weigh. It all depends on the 5SRB grain geometry, and where the new grain will go.
Also, I've seen the sea level thrust curve for the RSRMs, what does the thrust curve look like actually going uphill in flight? Are the solids also increasing thrust towards the vaccuum?
Does anyone even know what the SRB5's flight weight is? The thrust curve vs the SRB4? Such info would be useful in determining just how capable a lifter it is.
Would love to see the tech specs on the one they burned in October.

But, in the end, it's up to the experts to determine what can or cannot work in the grand plan. We just get to guess with snippets of data.

I'd like to see LockMart secretly developing a capsule for it's Atlas V series...I love that rocket. Just the small matter of "man-rating" it. And the political ramifications of Russian sourced propulsion, unfortunate reality.

[SpaceNutNewmars]

Here are the references that I have found with detail data on the J2-X engine.

Ares I making good progress - Davis (http://www.nasaspaceflight.com/content/?cid=4803)

NASASpaceflight.com: What is the expected performance P&W have been able to assure NASA of (274,500lb thrust, 448s vac Isp?), and do you have any idea what performance figures they are hoping to achieve (295,000lb thrust, 452s vac Isp)?

Davis: NASA engineers and project personnel have worked closely with PWR in designing the concept engine and setting the requirements. We are planning for a 294klbf engine at 448 sec Isp (minimum) / 452 sec (nominal) for the later lunar missions. This could come in the form of a 274klbf capability initially for LEO missions with a later modification for 294klbf or possibly just go directly to 294klbf - design and developmental testing will determine the final approach in the next year.


NASA develops two versions of J-2X engine for Ares boosters I and V (http://www.flightglobal.com/Articles/2006/10/09/Navigation/177/209764/NASA+develops+two+versions+of+J-2X+engine+for+Ares+boosters+I+and.html)

[cjl]

The SRB grain geometry is really interesting.

I believe this is how it is (no guarantees, as I'm going from memory):
Bottom grain, simple, cylindrical, except the core is slightly conical, with the bottom of the core wider than the top
Next 2 grains: simple, cylindrical, with a round, even hole through the middle
Top grain: Finocyl design, which is a cylindrical core in a cylindrical segment, but with slots removed that extend to the outside of the case. Final result has a star shaped cross section. This gives a MASSIVE surface area and a relatively small web thickness, causing the top grain to burn much faster than the rest of the grains. This gives a thrust spike off the pad, and then lowers the thrust (when the top grain is done burning) to reduce the stress on the shuttle for transition through mach (and because it is rapidly lightening because of all the fuel mass lost).

As for increasing towards the vacuum, the specific impulse (and thrust) are increasing relative to a sea-level thrust curve. However, the motor's decreasing thrust for the other reasons explained means that overall thrust is decreasing, though not as quickly as if it were burned entirely at sea level.

I believe the SRB4 has a propellant weight of about 1.1 million pounds, and a flight weight around 1.3 million pounds. It would be logical to assume roughly 25% increase in this mass for the SRB5, meaning roughly 1.375 million pounds propellant in a 1.625 million pound vehicle. If they eliminate the recovery system, the empty mass could be significantly reduced from that.

[gaetanomarano]

...suggesting alternatives, posing questions and raising doubts...
if I think I'm right about a thing, I defend my opinion, of course
however, forums (that are public and can be readed everywhere) are not the right place for personal disputes (that is also a waste of time, forums' space and bandwidth)

...give the engineers some slack!
you give tooooooo much importance to me, my website, my opinions and (in general) to this forum, other space forums and the web!
probably, a few peoples involved in space projects (and some PR men...) read and/or write on websites and forums, but 99.99% of them had no time to follow our discussions
then, don't worry, since you can be sure that, also the strongest critics, don't slow their work, while, the best fanatic support, don't accelerate it!

.

[Nicolas]

you give tooooooo much importance to me, my website, my opinions and (in general) to this forum, other space forums and the web!
probably, a few peoples involved in space projects (and some PR men...) read and/or write on websites and forums, but 99.99% of them had no time to follow our discussions
then, don't worry, since you can be sure that, also the strongest critics, don't slow their work, while, the best fanatic support, don't accelerate it!

I simply think it's impolite. You can bring a message in many different ways.

Let's let this subject rest though.

[gaetanomarano]

...So, I am wondering if anyone on this forum can garner a real guess as to what the additional segment will weigh.
at this point, probably not even NASA and ATK have the right answer (for the reasons you quote) but, since both SRBs have some parts in common, the new SRB may weigh around 20-22% more than a standard SRB, then, around 700-720 mT with an increase of weight around 130 mT

Are the solids also increasing thrust towards the vacuum?
no, it goes down very much a few seconds after launch and never increase (for exact data see the SRB4 table Bob B. posted in my old SRB's thread)

...LockMart secretly developing a capsule for it's Atlas V series...
I've read only that LockMart will man-rate the AtlasV but it's not strange if they will build a small capsule for it (all big companies have some "secret projects/designs" in their drawers...)

.

[gaetanomarano]

...it's impolite...
absoultely NOT since I don't refer to your message in particular but to the use (common in every forum I've seen) to fill pages and pages with personal (light and strong) attacks between members
I think that try to demonstrate that an user is not legitimate to talk about an argument or write on a forum is not the best way to use it

.

[gaetanomarano]

It would be logical to assume roughly 25% increase in this mass for the SRB5, meaning roughly 1.375 million pounds propellant in a 1.625 million pound vehicle. If they eliminate the recovery system, the empty mass could be significantly reduced from that.
if they will use the same segments for the 5th only the propellant increse will be +25% (from 530 mT to 660 mT) while the total increase of weight will be around 120 mT without the recovery system (that weigh around 10-12 mT) with an empty SRB5 mass around 65 mT

.

[Nicolas]

absoultely NOT since I don't refer to your message in particular but to the use (common in every forum I've seen) to fill pages and pages with personal (light and strong) attacks between members
I think that try to demonstrate that an user is not legitimate to talk about an argument or write on a forum is not the best way to use it

.

I honestly do not understand what you're saying here.

For the record, what I was talking about finding impolite in the way you bring your message, was the undertone of the engineers being horribly incompetent in your comments. Nothing more, nothing less.

[gaetanomarano]

I honestly do not understand what you're saying here. For the record, what I was talking about finding impolite in the way you bring your message, was the undertone of the engineers being horribly incompetent in your comments. Nothing more, nothing less.
ok
probably it's a misunderstanding due to my english
however, the web is FULL of critics against ISS, Shuttles, Orion, Ares, engineer's (past and current) designs, space exploration at all, etc.
I don't understand why do you think MY critics are particularly "impolite"

.

[Bob B.]

I believe this is how it is (no guarantees, as I'm going from memory):
Bottom grain, simple, cylindrical, except the core is slightly conical, with the bottom of the core wider than the top
Next 2 grains: simple, cylindrical, with a round, even hole through the middle
Top grain: Finocyl design, which is a cylindrical core in a cylindrical segment, but with slots removed that extend to the outside of the case. Final result has a star shaped cross section. This gives a MASSIVE surface area and a relatively small web thickness, causing the top grain to burn much faster than the rest of the grains. This gives a thrust spike off the pad, and then lowers the thrust (when the top grain is done burning) to reduce the stress on the shuttle for transition through mach (and because it is rapidly lightening because of all the fuel mass lost).
That is my recollection as well.


As for increasing towards the vacuum, the specific impulse (and thrust) are increasing relative to a sea-level thrust curve. However, the motor's decreasing thrust for the other reasons explained means that overall thrust is decreasing, though not as quickly as if it were burned entirely at sea level.
Adding to what cjl said ...

A thrust curve gives the rated thrust (either sea level or vacuum) rather than the actual thrust being produced at any specific moment. The thrust curves I’ve seen for the Space Shuttle SRBs have always been plotted in vacuum thrust rather than sea level thrust. In this case, the actual thrust is a little less at the beginning of the burn because of the ambient air pressure, but the actual and rated thrusts are essentially equal at the end of the burn because the rocket has risen into a virtual vacuum. (Of course the opposite is true if the thrust curve is plotted in sea level thrust. In this case the actual and rated thrusts are equal at the beginning of the burn, while actual exceeds rated at the end of the burn.)

How much thrust is increased or decreased due to differences in atmospheric pressure is simply the pressure difference times the area of the nozzle outlet. The outlet diameter of a Shuttle SRB nozzle is a little under 150-inches, giving it a cross-sectional area of about 17,600 square inches. We can therefore see how thrust is modified at various altitudes due to ambient air pressure:

Altitude … Air Pressure … Thrust Modifier

0 feet … 14.70 PSI … 259,000 lbf
25,000 feet … 5.46 PSI … 96,000 lbf
50,000 feet … 1.69 PSI … 30,000 lbf
75,000 feet … 0.51 PSI … 9,000 lbf
100,000 feet … 0.16 PSI … 3,000 lbf

For example, the maximum thrust of the Shuttle SRB is about 3.3 million pounds @ vacuum. We can see from the above that this SRB would be generating about 259,000 lbf less thrust when burning at sea level, therefore the maximum thrust rated at sea level is about 3.04 Mlbf. The same booster burning at maximum thrust at an altitude of 50,000 feet would be generating an actual thrust of 3.27 Mlbf.

Of course in the case of a solid rocket motor the thrust is also changing due to the changing surface of the propellant grain and the chamber pressure. To know what the actual thrust is at any moment, you need to know both the rated thrust (from the thrust curve) and the rocket’s altitude at that moment. If you had both a thrust curve and a plot of the rocket’s altitude versus time, you could generated a curve showing the motor’s actual thrust output.


I believe the SRB4 has a propellant weight of about 1.1 million pounds, and a flight weight around 1.3 million pounds. It would be logical to assume roughly 25% increase in this mass for the SRB5, meaning roughly 1.375 million pounds propellant in a 1.625 million pound vehicle. If they eliminate the recovery system, the empty mass could be significantly reduced from that.
The CLV (Ares I) and CaLV (Ares V) concept designs released in the 2005 ESAS report gave the following characteristics:

CLV Vehicle Concept Characteristics (later named Ares I)
Propellants: PBAN
Useable Propellant: 1,112,256 lbm
Stage pmf: 0.8554
Burnout Mass: 188,049 lbm
# Boosters/Type: 1 / 4-segment SRM (later changed to a 5-segment)
Booster Thrust (@ 0.7 secs): 3,139,106 lbf @ Vac
Booster Isp (@ 0.7 secs): 268.8 @ Vac

CaLV Vehicle Concept Characteristics (later named Ares V)
Propellants: HTPB
Useable Propellant: 1,434,906 lbm
Stage pmf: 0.8664
Burnout Mass: 221,234 lbm
# Boosters/Type: 2 / 5-segment SRM
Booster Thrust (@ 0.7 secs): 3,480,123 lbf @ Vac
Booster Isp (@ 0.7 secs): 265.4 @ Vac

[Nicolas]

however, the web is FULL of critics against ISS, Shuttles, Orion, Ares, engineer's (past and current) designs, space exploration at all, etc.
I don't understand why do you think MY critics are particularly "impolite"

Because of the undertone, as said. If the web is full of similarly toned commentary, I find that impolite as well. Everyone is equal. It's nothing personal against you, lets be very clear on that. And it's also not a problem with concerns/ideas in general.

Bob B:

Thanks for that clear post. I can use some of that in the office. For some engines, I have only two out of three of the data row vacuum thrust - sea level thrust - nozzle exit area. You gave a simple and in fact quite obvious way of calculating the third one from the other two. Thanks.

The interpretation of this is that the outflow can't expand as much as in vacuum, and therefore produces less thrust, right? Or is this not the physically most correct interpretation of the phenomenon? Air resistance certainly is not the correct interpretation.

[cjl]

There are two explanations:

1) It cannot expand as much against air as it could in a vacuum, and can therefore not produce quite as much thrust
2) It is pushing against an ambient pressure while the exhaust exits the engine. This ambient pressure provides some resistance, and the flow cannot leave the engine as fast. Therefore, less thrust.

And you are correct - air resistance has nothing to do with it.

[gaetanomarano]

I find that impolite as well.
then, to be "polite" (under your criteria) we must avoid critics about space, politics, sport, TV, etc.
you can be sure that, despite no one like critics, all are HAPPY to receive them, because critics are USEFUL (to avoid possible, expensive, mistakes) while applauses are pleasing but USELESS

.

[Doodler]

There are two explanations:

1) It cannot expand as much against air as it could in a vacuum, and can therefore not produce quite as much thrust
2) It is pushing against an ambient pressure while the exhaust exits the engine. This ambient pressure provides some resistance, and the flow cannot leave the engine as fast. Therefore, less thrust.

And you are correct - air resistance has nothing to do with it.

That thud you may have heard was the circuit in my head closing as the differences in rated performance finally made sense and the lightbulb went online.

[cjl]

then, to be "polite" (under your criteria) we must avoid critics about space, politics, sport, TV, etc.
you can be sure that, despite no one like critics, all are HAPPY to receive them, because critics are USEFUL (to avoid possible, expensive, mistakes) while applauses are pleasing but USELESS

.

However, in order to be effective, a critic must be knowledgeable enough in the area of their critique that they can effectively see the REAL problems with a design or idea, and propose valid solutions, rather than ranting on about various imagined problems without a shred of evidence or calculations to back them up.

[Nicolas]

then, to be "polite" (under your criteria) we must avoid critics about space, politics, sport, TV, etc.
you can be sure that, despite no one like critics, all are HAPPY to receive them, because critics are USEFUL (to avoid possible, expensive, mistakes) while applauses are pleasing but USELESS

.

You completely missed the point. THere is nothing wrong with proposing alternative ideas. There is nothing wrong with raising concerns on other people's ideas. However, I find it impolite to immediately present it as if the engineers are incapable, making huge mistakes etcetc, because you are no member of the design team and hence don't know all the details. In that case, IMO it is more suitable to express your concerns in a softer way. (softer as in, not writing "huge mistake" in bold, all caps and bright red, to name just one thing). And on top of that, they haven't finished their job yet.

So do post ideas, do raise concerns, but don't bash the engineers while doing so.

In the root, my point is about the difference between

"Are you sure this is correct, because I think it might not be because of this and that, and from that reasoning it appears to me one could better do this and that because this and that. Can you give more details and your opinion on that?"

and

"You made a HUGE MISTAKE here because it will never work, you MUST do this instead because that is FAR BETTER. Your design is terribly flawed".

You're raising the same concerns, but in the former you keep respect for the engineers, leave room for their side of the story, and express the natural incomplete and hence uncertain character of our outside view on the design process.

[Bob B.]

The interpretation of this is that the outflow can't expand as much as in vacuum, and therefore produces less thrust, right? Or is this not the physically most correct interpretation of the phenomenon? Air resistance certainly is not the correct interpretation.
It all comes back to the basic thrust equation,


F = q*Ve + (Pe - Pa)*Ae

where q is the mass flow rate of the exhaust gases, Ve is the ejection velocity of the exhaust gases, Pe the pressure of the exhaust gases at the nozzle exit, Pa is the pressure of the ambient atmosphere, and Ae is the cross-sectional area of the nozzle exit.

The product qVe is called the momentum thrust and (Pe-Pa)Ae is called the pressure thrust, which is the result of unbalanced pressure forces across the nozzle exit. If we have an engine operating at steady-state conditions, the values of q, Ve, Pe, and Ae are all constants. The momentum component of the thrust is therefore constant but the pressure component is variable depending on the value of Pa, which is a function of altitude. The greater the value of Pa, i.e. the lower the altitude, the lower the total thrust.

The purpose of the nozzle is to accelerate the exhaust gases. The slow-moving, high-temperature, high-pressure gas in the combustion chamber is converted into fast-moving gas of lower temperature and pressure. As the gas moves from the nozzle throat to the nozzle exit, it expands and accelerates. The more the nozzle is extended, the lower the pressure at the nozzle exit (Pe) but the greater the ejection velocity (Ve).

The optimum operating condition for any rocket engine is when Pe=Pa. In this case all the thrust comes from momentum and none from pressure. If the nozzle were extended a little less than optimum, we’d have a positive pressure thrust but Ve wouldn’t be quite so high thus resulting in a lower momentum thrust. The total thrust would be a little lower than optimum. If the reverse where true and we extended the nozzle a little more than optimum, we’d increase Ve and get a higher momentum thrust but we’d have a negative pressure thrust. Again the total thrust would be less than that obtained under the optimum condition of Pe=Pa.

From this we can see that engines/motors are made for the conditions under which they will operate. This is why we have engines with low expansion ratios on the booster stages of a launch vehicle and high expansion ratios on the upper stages. The boosters stages must operate low in the atmosphere where Pa starts out near sea level pressure, thus the nozzles are extended until Pe is at or a little less than one atmosphere. Upper stages, on the other hand, operate in a vacuum therefore the nozzles are extended as much as is practical to reduce Pe as close to zero as possible.

Any engine/motor will produce more thrust in a vacuum than it will at sea level, but that doesn’t mean it is optimized for that condition. Let’s say we have two engines identical in every way except for the expansion ratio. These hypothetical engines might produce thrusts that look something like this:

Engine #1, low expansion ratio
Thrust @ sea level = 250,000 lbf
Thrust @ vacuum = 300,000 lbf

Engine #2, high expansion ratio
Thrust @ sea level = 100,000 lbf
Thrust @ vacuum = 350,000 lbf

Both engines perform better in a vacuum, but Engine #1 outperforms #2 at sea level and Engine #2 outperforms #1 in a vacuum. Engine #1 is optimized for low altitude operation while Engine #2 is optimized for high altitude operation.

[Nicolas]

Thanks for the explanation. What I had in mind came in some aspects close to what you explained, but you gave a far more complete and correct explanation. It's clear to me now. Thanks again. These things sink so fast in my memory when not using them. Luckily, using things more often tends to settle them down a bit, so I won't have to live with a siftlike memory :).

At the moment, hypersonic flow is quite a fortress in my mind :).

[Bob B.]

Thanks for the explanation. What I had in mind came in some aspects close to what you explained, but you gave a far more complete and correct explanation. It's clear to me now. Thanks again. These things sink so fast in my memory when not using them. Luckily, using things more often tends to settle them down a bit, so I won't have to live with a siftlike memory :).
I went with the lengthy explanation even though I'm sure much of what I wrote was already familar to you. I was writing as much for those who are less familiar with the topic as I was for you.

I know full well how one can forget things when they are not being used regularly. My degree is actually in civil engineering, but I work in construction where there is usually little need to do any design work. My interest in rocketry is strictly a hobby, but I've spent far more time studying it than I have keeping up with my civil engineering. I probably couldn't design a simple concrete beam right now if my life depended on it, but I can explain the intricacies of rocket propulsion. If I had know this is where I was going to end up, I probably would have gone into aerospace engineering instead.

[Nicolas]

I went with the lengthy explanation even though I'm sure much of what I wrote was already familar to you.
Well, at a certain moment I had this "oh, I remember that now that you start about it" things, but it was good to read it all again. I take it the value of q compared to Ae and the behaviour of Ve with Pe makes that it is better to have large Ve than Pe? Otherwise, mathematically speaking a large exhaust thrust would be a good thing. The Ve*q needs to increase more than (Pe - Pa)Ae decreases for lower exhaust pressures to be advantageous. On the other hand, apparently Ve increase cannot compensate for the loss of Pe - Pa when the Pe < Pa. I take it that when plotting F, the peak occurs at Pe = Pa.

The lower sea level thrust at steady state (constant Ve) is clear, mathematically speaking.

[gaetanomarano]

...present it as if the engineers are incapable, making huge mistakes...bold, all caps and bright red...
don't say me that this is my intent since (simply) I can't do that (because engineers have a knowledge I haven't) but ALL peoples (including engineers) make mistakes (often HUGE MISTAKES) and there is nothing bad to give my opinion about (possible) mistakes, also using bold, CAPS and colors (that is only a "style of writing")
last year (and recently) Mr. Griffin said (in press conferences) that (both) the ISS and the Shuttle was "big mistakes"
I think he was wrong, but (despite he haven't used bold and caps talking...) measuring his claims under your criteria, he was "impolite" against last 30 years of NASA engineers and managers... it's correct?

.

[Nicolas]

At least he can be assumed to have [access to] all the relevant data, and spoke out after the engineers, project planners, etc finished their jobs. 2 major differences.


there is nothing bad to give my opinion about (possible) mistakes
Agreed. As said multiple times, it was the way in which you bring it. But let's drop it.

[cjl]

Actually, there is another possible type of nozzle not even touched on in bob's post. The aerospike nozzle is actually something I really like, because it acts as if it were always close to a perfect expansion ratio. It doesn't make quite as much thrust as a fully optimized bell nozzle, but it makes more thrust over a broad range of ambient pressures (and therefore altitudes), allowing for a greater efficiency overall.

The reason for this is that the effective exit area of the nozzle changes with altitude. At high pressure, the flow remains close to the nozzle, resulting in a low expansion ratio close to the optimum for low altitude use.

An example of this is the following diagram of an aerospike nozzle with a pressure ratio of 9:
http://flab.eng.isas.ac.jp/member/ito/web/research/PR9.jpg

At higher elevation and lower pressure, it expands more, causing a larger effective exit area. Here is the same one at a pressure ratio of 71:
http://flab.eng.isas.ac.jp/member/ito/web/research/PR71.jpg

And at extreme altitudes with next to no pressure, the flow expands way out, causing the effective nozzle size to massively increase. Here is a pressure ratio of 500 on the same nozzle:
http://flab.eng.isas.ac.jp/member/ito/web/research/PR500.jpg

I know this is slightly off topic, but it is one area I have always been fascinated with, and is one way to get around that optimization problem with rocket motors that travel through a wide range of altitudes and pressures (primarily first stage motors, as by the time the second stage is lit, the rocket is already essentially in space).

[Nicolas]

It doesn't make quite as much thrust as a fully optimized bell nozzle, but it makes more thrust over a broad range of ambient pressures (and therefore altitudes), allowing for a greater efficiency overall.

...if used over a broad range of ambient pressures.

And of course the "constant" value of thrust of the aerospike needs to be better (in any sense of the word) than the varying thrust of the classical nozzle. As we generally want less thrust near the end (accelerations...), the classic thrust pattern is not optimal. HOwever, if the integrated generated thrust is higher, it still might be advantageous compared to an aerospike, even if it implies having to throttle down at some time.

It all depends on the specifics. But an aerospike certainly is a nice concept, and of course the goal is to be more efficient than a regular nozzle in 1st stage engines.

This concept has been researched since quite some time.

[cjl]

Yes, and the main reason for not implementing it from what I can find is simply that the standard bell nozzle is much more common, and still better understood. The aerospike would almost certainly give an improvement in the average thrust over what a bell would.

As for the "constant" thrust of the aerospike, that isn't quite true. The thrust varies, however, it acts like an almost fully optimal bell at any altitude. So, you could have a motor that both gives 240klbf at sea level, and that gives 340klbf vacuum, as opposed to the options in bob's post.

[Bob B.]

Actually, there is another possible type of nozzle not even touched on in bob's post. The aerospike nozzle is actually something I really like, because it acts as if it were always close to a perfect expansion ratio.
Yeah... the aerospike is a pretty cool concept. I imagine we will probably see it more fully developed if we ever get serious about single-stage-to-orbit technology.

[cjl]

Definitely, as that is its area where it would have the largest advantage.

[Bob B.]

I take it the value of q compared to Ae and the behaviour of Ve with Pe makes that it is better to have large Ve than Pe?
Momentum thrust is always the larger component of thrust, but it is not as simple as saying you want Ve large and Pe small. There is a point where continuing to increase Ve can be detrimental, but that is only true when you are in an atmosphere. To optimize the nozzle for your specific operating conditions, you want to make Pe=Pa. In a vacuum Pa=0, therefore you theoretically what to expand the nozzle to infinity, which of course is impossible. Instead there are practical limits, such as the space available inside the rocket's fairing. There is also a limit whereby the weight added by further increasing the size of the nozzle is more detrimental than the benefit gained by the higher thrust achieved.

If you where to look at a graph of the thrust components versus expansion ratio for a given set of operating conditions, it would look something like this:

* Momentum thrust increases at a diminishing rate as expansion ratio increases.

* Pressure thrust decreases at a fairly steady rate as expansion ratio increases.

* Total thrust initial increases because the momentum thrust initially increases at a faster rate than the pressure thrust decreases.

* Total thrust begins to decline once the rate of increase in momentum thrust drops below the rate of decrease in pressure thrust.

* Total thrust is maximum when the expansion ratio is such that the condition Pe=Pa is satisfied.

The following web page gives a numerical demonstration of the above:
http://www.braeunig.us/space/sup1.htm
_

[gaetanomarano]

...we will probably see it more fully developed...
when?
the X-33 project was deleted, and the next 50 years will turn around the RS-68 and the J-2x... who has the money for advanced researches?
(and, why build a SSTO if a TSTO is more efficient?)

.

[cjl]

Good question.

The answer: it will be developed when it is developed, and not a moment sooner. I would bet that there will be many small independent sounding-type rockets that use it before it is used on any large vehicles.

[gaetanomarano]

.

I've had (and still have) problems to open a new thread, then, I post here my "SAFE Space Shuttle (http://www.gaetanomarano.it/articles/015safeShuttle.html)" article's update with a 2nd animation of a simpler, smaller, lighter, better, safer and cheaper version of my idea!


PS - I'm aware that (safe or not) the Shuttles will be retired in 2010 and that my idea is (and will remains) only a "concept"

.

[cjl]

Umm...

About the new heat shields you're proposing...

You do realize that the reason for the tiles is that they are reusable, right? And that the shields typically used on capsules are ablative and therefore single use only?
Because that kind of eliminates them from consideration as a possibility for the shuttle...

[gaetanomarano]

You do realize that the reason for the tiles is that they are reusable, right? And that the shields typically used on capsules are ablative and therefore single use only?
Because that kind of eliminates them from consideration as a possibility for the shuttle...
I've read (but not searched detailed info) that some new (stronger and lighter) materials have been (or will be) developed
also, the capsule's shield are single use since they are thin
a great progress for Shuttles' maintenance (and costs) may be to have a thermal shield with panels good for 10 flights, so, the Shuttles' fleet will accomplish 30 missions in total without the tiles' problem (+ time + costs + risks)

.

[Dave J]

Another thought on the SafeShuttle...the crew cabin lower deck, where a few of the crew sit for launch, extends down to the wing glove area, so the ejectable capsule would have to include a bug chunk of the forward orbiter.
I'm not sure how feasible this ejection sequence would be.
I don't see how to make shuttle launches survivable, other than make the boosters and tank as safe as possible, which they appear to have done.
It's a hazardous configuration any way you cut it, much as I love Shuttle.

[Bob B.]

...we will probably see it more fully developed...
when?
I have no idea. For going to the Moon and Mars I think expendable launch vehicles are the way to go, at least for the foreseeable future. I see no real future for the aerospike until we need something like an SSTO vehicle for frequent access to low Earth orbit.


and, why build a SSTO if a TSTO is more efficient?
I mentioned SSTO because we were talking specifically about the aerospike engine and SSTO is the perfect application for that technology. TSTO really doesn’t need aerospike technology.

Furthermore, it sounds to me that SSTO can be very efficient with the right technologies, though we have a long way to go to get there. I’m also intrigued by the idea of a reusable spaceplane with a fully recoverable and reusable booster stage. It would be kind of an intermediate step between the Space Shuttle and a full SSTO vehicle.

[Nicolas]

Yeah... the aerospike is a pretty cool concept. I imagine we will probably see it more fully developed if we ever get serious about single-stage-to-orbit technology.

We are very serious about it, but just not capable of doing it at the moment :).

[NEOWatcher]

I've had (and still have) problems to open a new thread, then, I post here my "SAFE Space Shuttle (http://www.gaetanomarano.it/articles/015safeShuttle.html)" article's update with a 2nd animation of a simpler, smaller, lighter, better, safer and cheaper version of my idea!
The suggestions may make sense, but...
1) They only make sense for that type of mission. Not all missions require lots of personel or lots of equipment. Do we know what the percentage of that type of missions is?
2) Your introductory paragraph touts the benefit of the larger crew, then you suggest limiting the crew to 4-5. It may still be a benefit from your logic, but you have negated the argument by contradicting it.
3) The launch cost of "including the very high shared Orion/Ares R&D costs"
Compared to the shuttle cost which has already had that cost absorbed. Add to that, the R&D that the shuttle will need to accomodate your changes, and you end up with completely different comparisons.

[gaetanomarano]

The suggestions may make sense, but...
1) They only make sense for that type of mission. Not all missions require lots of personel or lots of equipment. Do we know what the percentage of that type of missions is?
2) Your introductory paragraph touts the benefit of the larger crew, then you suggest limiting the crew to 4-5. It may still be a benefit from your logic, but you have negated the argument by contradicting it.
3) The launch cost of "including the very high shared Orion/Ares R&D costs"
Compared to the shuttle cost which has already had that cost absorbed. Add to that, the R&D that the shuttle will need to accomodate your changes, and you end up with completely different comparisons.
1) the two more astronauts (generally) are missions' specialists for ISS assembly, but, when the ISS will be finished, 90% of ISS' missions will be for crew rotation, resupply, cargo/experiments return, etc. and only rare missions may need more than 5 astronauts (that can be launched with a Soyuz)

2) same answer of point 1) ...also, consider that some missions may need LESS than 5 astronauts, then, it's only a problem of launch planning

3) NASA launched 3 missions this year (and will launch 13-14 missions within 2010) then, they think the Shuttle ALREADY IS safe!

if the Shuttle is safe for 16+ launches within 2010, then, it is safe for 10-15 more missions between 2011 and 2015 (to fill the Shuttle/Orion gap)

reinstalling the ejectable seats of the first launches, the Shuttle will be very much safer and can fly until 2020 for crew, assembly, resupply and repair orbital missions

if the new Orion (a full interplanetary vehicle) will costs around $4 billion including six capsules, a simple escape module built in three units may cost around $1-1.5 billion, that, shared on 30+ launches, will increase the Shuttles' launch cost from $600M to (only) $650M

.

[Nicolas]

a simple escape module built in three units may cost around $1-1.5 billion

Do you have details on this estimate?

If it only costs 1 billion, why was the detachable crew compartment scrapped from the original design?

[gaetanomarano]

Do you have details on this estimate?
a full, new, advanced, capsule for six astronauts, 15 days life support, interplanetary navigation system, lunar-direct reentry thermal shield, parachutes, airbags, soil/sea landing, service modules, large internals space and six working units costs $3.9 billion
assuming that a much simpler Shuttle escape module (with three working units) costs the SAME price, the extra-price-per-launch (on 30 launches) will be $3900M / 30 = $130M then, each SAFE Shuttle launch will cost $730M instead of $600M, so, each Shuttle launch will cost "only" 1/10th of an equivalent set of Orion launches (1-2 crewOrion + 7-8 cargoOrion to send 5 astronauts and 24 mT of cargo)

.

[Dave J]

1) the two more astronauts (generally) are missions' specialists for ISS assembly, but, when the ISS will be finished, 90% of ISS' missions will be for crew rotation, resupply, cargo/experiments return, etc. and only rare missions may need more than 5 astronauts (that can be launched with a Soyuz)

2) same answer of point 1) ...also, consider that some missions may need LESS than 5 astronauts, then, it's only a problem of launch planning

3) NASA launched 3 missions this year (and will launch 13-14 missions within 2010) then, they think the Shuttle ALREADY IS safe!

if the Shuttle is safe for 16+ launches within 2010, then, it is safe for 10-15 more missions between 2011 and 2015 (to fill the Shuttle/Orion gap)

reinstalling the ejectable seats of the first launches, the Shuttle will be very much safer and can fly until 2020 for crew, assembly, resupply and repair orbital missions

if the new Orion (a full interplanetary vehicle) will costs around $4 billion including six capsules, a simple escape module built in three units may cost around $1-1.5 billion, that, shared on 30+ launches, will increase the Shuttles' launch cost from $600M to (only) $650M

.

There is no "reinstalling" the ejection seats, only Columbia was designed to use them, the rest of the fleet would require major overhaul for such an installation. I too believe that your estimate for the crew escape capsule configuration is way optimistic, considering the huge design, and modification cost, not to mention literally years of design and integration work...and a lot of extra weight. This idea was gone over post-Challenger, and found untenable.

[gaetanomarano]

...only Columbia was designed to use them...
that means the project exists, then, can be adapted to the Shuttles' fleet
the price is not zero, but not so high (especally if compared with the "value" of the astronauts' life, tha is PRICELESS)

.

[NEOWatcher]

that means the project exists, then, can be adapted to the Shuttles' fleet
the price is not zero, but not so high (especally if compared with the "value" of the astronauts' life, tha is PRICELESS)
.
...But high enough to justify designing a new ship.

[gaetanomarano]

...But high enough to justify designing a new ship.
if you refer to the Orion... remember that its first launch is already shifted from 2012 to 2015 in its FIRST year of SEVEN (very long) years (only to develop the Orion) in which EVERYTHING (bad) can happen, then...

.

[NEOWatcher]

if you refer to the Orion... remember that its first launch is already shifted from 2012 to 2015 in its FIRST year of SEVEN (very long) years (only to develop the Orion) in which EVERYTHING (bad) can happen, then...
.
The same can be said of the refitting a shuttle.

[gaetanomarano]

The same can be said of the refitting a shuttle.
true, but the Shuttle already exists and fly, while the Orion may fly in 2018 ...adding only a few (very reasonable) years of delay to the (planned) 2015 first launch...
while one Shuttle is in the "surgery room" the two other Shuttles can accomplish 2+ flights per year

.

[Doodler]

So he's still under the impression this is some kind of race, and he's still fabricating timelines on the fly to make his arguement look good.

I'm half surprised he hasn't resurrected his dead horse of an Arianne arguement yet, considering how much effort he's expending chasing his own tail(tale, could go either way).

[gaetanomarano]

So he's still under the impression this is some kind of race, and he's still fabricating timelines on the fly to make his arguement look good.
the "space-race" DO EXISTS from decades and WILL EXISTS forever!
despite not declared, it is mainly between USA and China and will show its effects in the next decade (now it's too early to see it)
however, the problem is NOT "the race" but the american autonomous access to space
if the Orion will delay 2, 3, 5 + years, can the USA remains (for 5, 7, 8, 10 + years) the only space-country/super-power of the world WITHOUT its own (working) manned spacecrafts?

...Arianne...
why not!
the ATV is better than Progress for that job!

.

[Doodler]

Sorry, there is no race. We get there when we get there, and we do what we need to do. If its 2018, 2020, 2024, 3050, whatever. The mission will fly when its ready.

[gaetanomarano]

Sorry, there is no race.
you can say (and say) that now because you think to have a Jaguar in 2020 while you think that China will use the same Honda Civic of its first flights... but you will change your opinion (and your fair play) when China will reveal (when it will be ready, of course) the true plans and ambitions...
and, without the Shuttle and the Orion, still remains the problem of the access to space

.

[DOOMMaster]

the "space-race" DO EXISTS from decades and WILL EXISTS forever!
despite not declared, it is mainly between USA and China and will show its effects in the next decade (now it's too early to see it)
however, the problem is NOT "the race" but the american autonomous access to space
if the Orion will delay 2, 3, 5 + years, can the USA remains (for 5, 7, 8, 10 + years) the only space-country/super-power of the world WITHOUT its own (working) manned spacecrafts?

why not!
the ATV is better than Progress for that job!

.

You think this. NASA does not. I doubt NASA cares if China beats them to the moon with their current program over Orion. After all, all NASA has to do is point to Apollo and everyone realizes that the US won the moon race decades ago. That you still don't realize this is really not relavant to any arguments regarding Orion.

[gaetanomarano]

You think this. NASA does not. I doubt NASA cares if China beats them to the moon with their current program over Orion. After all, all NASA has to do is point to Apollo and everyone realizes that the US won the moon race decades ago. That you still don't realize this is really not relavant to any arguments regarding Orion.
again, no one is worry of China now looking at its Shenzhou... we (you/they) must wait the next decade...
about the "race"... it will be not another old "military" race to the moon, but a new "commercial" race (do a search on this site, I've already posted many detailed opinions about this point)
the problem of the Orion/Ares is different
it's not a problem of "race"
if you have your office 30 miles away your home, you need a car, so, if you sell/scrap your old car, you need a new car NOW (or, max, in a few weeks)
well, the space is the NASA "office", so, they can't remain 5, 7, 10 years without a space-car!

.

[Nicolas]

They managed to do so in the past. Anf if they really need to be up there, they can always take a taxi.

[gaetanomarano]

They managed to do so in the past. Anf if they really need to be up there, they can always take a taxi.
1. the Shuttle is not a space-car or space-taxi but a space-truck
2. the only space-taxi available (after the Shuttle retirement) will be the Soyuz (and I'm sure that NASA and politics don't like so much to depend 5-10 years from Russia...)
3. the Shuttles don't need to fly dozens times after 2010 since my best suggestion (as explained in another thread I've opened here in the past) is (only) to "save the Shuttles" without send them to a museum, so, if they will NEED them they will HAVE them

.

[cjl]

If it is really such a "space truck," then why is its payload so small?

[gaetanomarano]

If it is really such a "space truck," then why is its payload so small?
small?
the Shuttle's payload mass (up to 28 mT) was incredibly giant in '70s (after the SaturnV retirement) and STILL is UNEQUALLED since all common rockets are in the range of 1/3 to 1/2 its payload!
also, we can't forget that common rockets can launch only "dumb payload" while the payload inside the Shuttle's cargo-bay (thanks to the Shuttle's engines, navigation system, assembly tools, etc.) is a "SMART PAYLOAD" that can go everywere and be assembled, dissassembled, repaired, etc.

.

[DOOMMaster]

(do a search on this site, I've already posted many detailed opinions about this point)

Yes, I know this. Quite well, unfortunately. However, your opinions don't really have anything to back them up, like facts or evidence. It's just random ideas. I yet again fail to see what relevance this brings to any argument against the Orion program. And I'm still waiting for some of the evidence I asked for earlier in this thread about the transportation of the un-segmented SRBs by rail as well as if it is even possible to construct one (not that I actually expect to get any).

[Bob B.]

small?
the Shuttle's payload mass (up to 28 mT) was incredibly giant in '70s (after the SaturnV retirement)
The '70s? The Shuttle didn't start flying until 1981 and the first Shuttle Columbia was rated to carry only 21 mT. The other orbiters, which are lighter than Columbia, are rated for 25 mT; the first of which flew in 1983.


and STILL is UNEQUALLED since all common rockets are in the range of 1/3 to 1/2 its payload!
True, most launchers are smaller because most payloads are smaller. It is good to have a fleet of launchers that can meet a wide variety launch requirements from the small through the large. Today both the Delta IV-Heavy and Atlas V 552 come close to the Space Shuttle with LEO performances of 21.9 mT and 20.5 mT respectively, and are much cheaper to launch.

[gaetanomarano]

...like facts or evidence...
I can't give any "fact or evidence" about China's future space programs... only China can (and, I'm sure, we will be surprised!)

...argument against the Orion program...
I've nothing against the Orion program (if used only for lunar missions) I only say that:

1. it's not good (and incredibly expensive) for orbital missions (then I sugegst to save the Shuttles and modify them to fly safely) and...

2. the planned ESAS hardware and architecture is not the best possible (then I suggest to change in in some points)


...transportation of the un-segmented SRBs by rail...

build a non-segmented SRB is not impossible and I don't suggest to ship it by rail but to send it to KSC empty with the 747-100 SCA (see my previous posts) and fill it in a small factory near KSC (that is also a great idea for logistic)

.

[gaetanomarano]

The '70s? The Shuttle didn't start flying until 1981 and the first Shuttle Columbia was rated to carry only 21 mT. The other orbiters, which are lighter than Columbia, are rated for 25 mT; the first of which flew in 1983.
my post refers to the years (and the technologies) when the Shuttles was developed
NASA announced the first Shuttle flight for 1976, but its first real flight was in 1981 (delays... like the 1st planned Orion flight, shifted from 2012 to 2015...)
about the max Shuttle payload you can read this (http://www.astronautix.com/lvs/shuttle.htm) ("Redesign of the shuttle with reliability in mind after the Challenger disaster reduced maximum payload to low earth orbit from 27,850 kg to 24,400 kg.")


...both the Delta IV-Heavy and Atlas V 552 come close to the Space Shuttle with LEO performances of 21.9 mT and 20.5 mT respectively...
21.9 and 20.5 mT of DUMB payload... no easy moving from orbit to orbit, no assembly, no cargp-return, etc.

.

[stutefish]

DUMB payload...

Which accounts for 99.999% of all payloads, apparently, since that's what pretty much every launch vehicle except the shuttle is built for, both in the private and in the public sector.

no easy moving from orbit to orbit

Name a single payload currently on orbit that requires "easy moving from orbit to orbit" as part of its intended function.

no assembly

This missing feature doesn't seem to bother all the customers of the Delta IV, the Atlas V, the Ariane V, etc.

If on-orbit assembly is so desireable, why isn't the market demanding it?

no cargp (sic)-return

Name a single shuttle mission that used the cargo-return feature.

Again, the Shuttle is the only launch vehicle capable of this, and even its own customers have never found a good reason to use it.

etc.

Et cetera, et cetera, et cetera...

[Doodler]

no easy moving from orbit to orbit

Name a single payload currently on orbit that requires "easy moving from orbit to orbit" as part of its intended function.

The ISS, some KH-11 spysats and their cousins. Not that I agree with him, but those are payloads that can alter their orbital geometry on station.

[stutefish]

The ISS, some KH-11 spysats and their cousins. Not that I agree with him, but those are payloads that can alter their orbital geometry on station.
Interesting.

Thanks for the information!

Do any of these payloads require outside assistance to change their orbits, or were they designed and built to be self-sufficient in this regard?

Has the Shuttle ever been used to change a payload's orbit, as part of that payload's original intended function (as opposed to an "emergency" orbit-change, on account of something unintended happening to the payload)?

[Doodler]

From what I understand, the spy satellites are on their own after launch. They don't alter their altitude, so much, as they do reshape their orbital ellipse to bring different areas along its orbital plane into greater focus, so-called "retasking". This isn't something that's done lightly, apparently.

The station theoretically has the ability to boost itself with one of the Russian modules, the name eludes me at the moment, but has not done so in some time.

[Bob B.]

Has the Shuttle ever been used to change a payload's orbit, as part of that payload's original intended function (as opposed to an "emergency" orbit-change, on account of something unintended happening to the payload)?
I know the Shuttle has been used to reboost the orbits of the ISS and HST. The ISS's orbit is usually reboosted by the Russian Progress ferries. The ISS orbit has to not only be periodically reboosted due to orbit decay, but reboosts are also done prior to Shuttle/Soyuz/Progress launches to get the phasing right so the ISS is in the correct position for docking.

[stutefish]

Thanks, Doodler and Bob!

I did not know that.

Was HST designed to need boosting services from the Shuttle, or have its orbit changes been the result of unforseen contingencies post-design?

[Bob B.]

Was HST designed to need boosting services from the Shuttle, or have its orbit changes been the result of unforseen contingencies post-design?
I have to plead ignorance. I don't know the answer to this though I'm pretty sure HST was designed with servicing missions in mind, so my guess is it was planned but I can't swear to it.

[Dave J]

I have to plead ignorance. I don't know the answer to this though I'm pretty sure HST was designed with servicing missions in mind, so my guess is it was planned but I can't swear to it.

The Shuttle did recover a couple of satellites that had malfunctioned (INTELSATs?) and return them to Earth for refurbishment and a later relaunch. They also did some repair work on orbit with a solar observation satellite. Then they have the Hubble missions.
A lot of capability, but a high cost too.

[DOOMMaster]

I build a non-segmented SRB is not impossible and I don't suggest to ship it by rail but to send it to KSC empty with the 747-100 SCA (see my previous posts) and fill it in a small factory near KSC (that is also a great idea for logistic)

You continue to say this. I'd like to see some evidence for it. I've yet to see ANY information (reliable or otherwise) that says the SRBs can be built un-segmented. Even if they can, your suggestion is ridiculous at best. The current method of shipping segments via rail and then assembling at launch is far more cost effective and already established. Why build another factory at an unknown cost and time to fill un-segmented SRBs that are then flown in via 747 at $1 million each?

But no, they must be able to build an un-segmented SRB, gaetanomarano has said so. It doesn't matter how much time and money in research and development such a thing would take to put into practical use, let alone the cost it would take to modify the factory (or, as he has suggested before, just build another factory, after all, it's not like they don't take years and billions of dollars to build. Oh wait...) to produce them.

I'm not interested in your opinions this time, gaetanomarano. I know what your opinions are. How about backing up some of your opinions with some actual research or data that supports them this time? And if you say "Well, I'm not being paid to be part of NASAs plan, so I'm not going to do the research," just do us all a favor and stop posting your ideas. Your just as bad as all the Against the Mainstream and Conspiracy Theory people with their ideas. You have no evidence to support your position, but your position is right and you don't need to present it. I wish the rules on this part of the forum were the same as the ATM section, I really do.

[Larry Jacks]

Was HST designed to need boosting services from the Shuttle, or have its orbit changes been the result of unforseen contingencies post-design?

Depending on the design lifespan, many low orbiting satellites have propulsion systems to boost their orbits and offset the effects of orbital decay. The HST has no propulsion system because of concern that the thruster firings would contaiminate the optics (a valid concern). It was designed to be launched, serviced, and periodically boosted by the Shuttle. When the Shuttle is approaching the HST, they close the big flap (lense cover) on the HST to prevent contaimination.

As for building large unsegmented SRBs, that presents a lot of problems. First and foremost, you'd have to be very careful to make sure no propellant voids exist anywhere in the SRB except in the intended core geometry. A void exposes more propellant surface area to combustion, resulting in higher pressure and the potential to rupture. You also have to make sure you get the insulation between the casing and the propellant right, or you'll have a case rupture. For that reason, they've built large solid motors with segments for about the last 40 years (since the development of the Titan IIIC at least).

[Dave J]

I would think that the segmented case would actually be stronger as well. Aside from the possible "leak paths", it seems the thicker areas where the segments join would act almost as strengthening "bands" around the case.
There is some weight penalty involved, but it seems the STS SRBs are about the most tested in flight and most durable around....not to mention the biggest and baddest in town.

[gaetanomarano]

DUMB payload...
no easy moving from orbit to orbit
no assembly


I better explain my opinion about "dumb" and "smart" payloads
from the launchers' point of view "smart" and "dumb" is not the payload but the launcher
in other words... I call "dumb" a (dumb or smart) payload simply depolyed in space (like satellites)
while I call "smart" a (dumb or smart) payload that (thanks to it's launcher) can do more
so, a simple (and "dumb") ISS resupply module, become a "smart" payload if launched with the Shuttle
that because the Shuttle can move in space, dock, undock and bring back it to/from ISS or everywhere (an option we can't use only because we haven't a second-third ISS)
the same reason, also ALL Soyuz, Progress, Orion, ATV, etc. payloads are/will be "smart"
I agree that 99% of commercial/military/scientific launches have "dumb" (deployed only) payloads...
but things like Shuttles, Soyuz, ISS, etc. are (less, but) very much different things (that needs more than "deploy")
about "easy moving from orbit to orbit", I refer to all vehicles able to change many times their insertion orbit
a satellite can't go (nor needs to go) "from orbit to orbit" since it is deployed (only) in its right orbit
while, the Shuttles, Soyuz, etc., after their are inserted in a low orbit can go to/from everywere (then, they can go "from orbit to orbit")
also, they can do maneuverings a (smart) vehicle can't do (the planned Hubble repair mission is a good example)
unfortunately we have only one ISS and it is made of a single block
but we can imagine a future with many different objects in many different orbits... and "smart" vehicles (like Shuttle and Orion) that fly from one object to another ("from orbit to orbit" or simply "from one point to another point")
about "assembly"... the ISS already is a BIG object that, without a Shuttle, is very difficult to assemble (and I hope to have, in future, many other things "assembled" in space)

.

[Wolf-S]

The ISS is built using the shuttles not because the shuttle is the best way to build a space station, but because the shuttle had to have a job or the whole program would come to an end. Even Michael Griffin agreed last year that the shuttle and space station was not the right way for space exploration.

If there were no shuttles and if there was even a plan to construct a new space station, it would certainly be possible to do all the work with expendable launchers, much like Mir, which although was cramped inside, lasted for 15 years with numerous expeditions and spacewalks. Or just launch a station with one HLLV, like Skylab.

Most of the satellites have capabilities for maneouvering in orbit to some extent and the only thing shuttle could do better is to bring them back to earth which is not even needed anymore. Besides, with shuttle's OMS engines (delta v of about 300 m/s) it is not possible to play with orbits like that. It is not possible to transfer payloads between stations on, say, 51.6 and 21.8 inclination orbits. With 300 m/s, I think the maximum you could do is change the inclination by 1.5-2.0 degrees or the altitude by 200-300 kilometers. Finally, the risk, the cost and the complexity of the shuttle are substantinal. The benefits of such "smart" payloads are simply not worth it all. The payloads of other vehicles like Soyuz, Progress, ATV and Orion are, however, directly related to their human spaceflight missions and mostly have to do with life support.

[danscope]

Hi, One of the interesting things the Shuttle can do is examine and return an
satelite , if it should fail , mal function as in solar panel deployment failure.
The unit can be returned, and "EXAMINED" so as to LEARN about it's failure mode, and re-design to save the whole program, gauranteeing improved
deployment in future. THIS function of shuttle is surely an excellent, although seldom respected talent, now and in future. In-orbit scrutiny is, at times
illuminating.
Best regards, Dan

[gaetanomarano]

You continue to say this. I'd like to see some evidence for it. I've yet to see ANY information (reliable or otherwise) that says the SRBs can be built un-segmented. Even if they can, your suggestion is ridiculous at best...
as I've explained many times (if you read my posts) build a non-segmented SRB is only a further option to have a SAFER and LIGHTER (standard) 4-seg.SRB, also, I've suggested to adopt this option only in the future (with no rush) while using the standard (segmented) 4-seg.SRB for the first flights

however... (simplified to its max) ...a solid rocket is... "a [special] tube filled with a [special] rubber"

so... claiming (as you do) that NASA and its (expert) contractors (same peoples that have developed and built Mercury, Gemini, Apollo, LEM, SaturnV, Skylab, Shuttle, Hubble, ISS, Mars rovers, etc. etc. etc.) AREN'T ABLE to "fill a tube" (really!) IS ridiculous, exagerated, "handwaving", etc. etc. etc.!

also, your evaluation that, build a (simple) factory near KSC to (only!) FILL the (already built) non-segmented SRB, costs "billions" is absolutely absurd, since, not even the (much bigger, advanced and complex) factories that will build Orion, Ares and LSAM will costs "billions"

.

[djellison]

On what grounds do you state that non-segmented SRBs are safer than segmented SRBs? What quantitative evidence do you have for this claim. Have you gathered statistics to prove this? Or - as with all yourr 'opinions' - is it based on nothing but, yet again, fiction.

You say non-segmented SRB's are safer.

PROVE IT

Doug

[Larry Jacks]

Show us examples of large non-segmented SRBs and their better safety record. Somehow, I doubt you can because they almost certainly don't exist.

[djellison]

I thought adding some bold and red text might make it more at his level :)

[galacsi]

Show us examples of large non-segmented SRBs and their better safety record. Somehow, I doubt you can because they almost certainly don't exist.

New ESA Vega rocket is using a non-segmented SRB as first stage. But as this rocket has still not launched any satellite ,i can say nothing about actual safety.

http://www.physorg.com/news84119945.html

[djellison]

And, compared to the sort of motor required for CEV launch - VEGA is 190 ton's of thrust - the Shuttle SRB's are 1,650 tons of thrust. Not quite, but not far short of an order of magnitude more. Same is true of the SRB's deployed for Delta II's, Delta IV's, Atlas V's etc etc. Even the largest 'not shuttle' SRB's I know of - those from the Titan IV and Ariane V - are segmented motors. One has to wonder what it is that the OP knows, but Boeing, Lo-Mart, Martian Marietta, NASA and Ariane Space doesn't.

Doug

[gaetanomarano]

On what grounds do you state that non-segmented SRBs are safer than segmented SRBs? What quantitative evidence do you have for this claim. Have you gathered statistics to prove this? Or - as with all yourr 'opinions' - is it based on nothing but, yet again, fiction.
You say non-segmented SRB's are safer.
PROVE IT

the non-segmented SRB is SAFER for the (very simple) reason that it can't leak... and the Challenger disaster is the best evidence of that
of course, after Challenger, the SRBs was modifyed and have never leaked again (or, if they have had some leaks, we have not seen them nor had another disaster) but they can leak again in future (since the motor has segments...)
also, don't forget the lower dry mass a non-segmented SRB that may add more (very precious) payload mass to (both) Ares-I and V, especially if the new SRB will be made with with a mix of past and to-day's advanced technologies and materials (like carbon fibers)

.

[gaetanomarano]

Show us examples of large non-segmented SRBs and their better safety record. Somehow, I doubt you can because they almost certainly don't exist.
you're right, but only because the Shuttles' SRBs are the biggest ever solid boosters made
however, that doesn't mean will be impossible to build a non-segmented SRB or a solid booster two, three, ten times bigger!

.

[Larry Jacks]

There are reasons why they built the SRBs with segments. Go educate yourself as to those reasons and you'll learn why your contention is so much nonsense. If it were practical and safer to build the SRBs without segments, they would've done so a long time ago. Just because you say it, it doesn't mean you're right. Quite often, the converse is true.

[djellison]

the non-segmented SRB is SAFER for the (very simple) reason that it can't leak

.

http://youtube.com/watch?v=6K4Ra5Sy5HM

They can - and have.

Clean sheet design for the Ariane V...and they went segmented. (and it was designed with Manned launches via Hermes in mind ) . Titan IV....segmented. All large SRB's are segmented...because the risk trade dictates it the better way to build them.

You really don't know the facts or understand the principles of risk trade - stop pretending that you do...please.

Doug

[gaetanomarano]

...VEGA is 190 ton's of thrust - the Shuttle SRB's are 1,650 tons of thrust...those from the Titan IV and Ariane V - are segmented motors...

VEGA clearly demostrates that bigger non-segmented SRB can be built
the VEGA stage is "only" 1/8th of a Shuttle SRB simply because VEGA is designed for small payloads (around 2.5 mT)
Titan IV and ArianeV don't launch manned vehicles, so, they don't need higher safety standards
about aerospace companies... I'm sure they all are perfectly ABLE to design and build everything they want (including a non-segmented booster 3+ times bigger than Shuttles' SRBs) ...if they receive a contract and sufficient funds, of course...

.

[gaetanomarano]

http://youtube.com/watch?v=6K4Ra5Sy5HM
the video give no evidence that one of the boosters failed (maybe, was the core stage)
also, I've said that a non-segmented SRB is "safer", NOT the "safest"
there are NO "perfect rockets" since all rockets may fail or explode (the non-seg. SRBs can only reduce that risk)

...for the Ariane V...and they went segmented. (and it was designed with Manned launches via Hermes in mind ) ...
it was designed with "Hermes in mind" but NEVER man-rated (I know fron a reliable source that man-rate the ArianeV needs $1.8 billion) and, ALSO the ArianeV (or the Titan or every other rocket), can be ("n" times) SAFER with non-segmented SRBs

...don't know the facts...stop pretending that you do...
I suggest to adopt a simple rule in our discussion:
I don't judge you and you don't judge me... then... I don't dictate you and you don't dictate me

.

[SpaceNutNewmars]

All large SRB's are segmented...because the risk trade dictates it the better way to build them.

You really don't know the facts or understand the principles of risk trade - stop pretending that you do...please.

Doug


Newsgroups: sci.space.shuttle (http://yarchive.net/space/shuttle/srbs.html) from emails, Date: 23 Aug 87




The reason for joints in the first place: When Thiokol was awarded the
contract for the Solid Rocket Motors, there had to be a way to get them
from Utah to Florida. Rail was selected. A combination of diameter
limits (12 feet) and railroad track limits (320,000 lb on one car) set
the size of a segment. It turned out to be 4 segments. The steel case
for each segment comes in 2 pieces, 12 ft long each.

While the delivery was a cause for concern it was other factors of size that drove the decision to make them segmented.

There are no makers at this time that make a monolithic SRB of the shuttle thrust ratings and while it may be possible to do so that was not a requirement for assembly lifting concerns.

Then you have the difficulty of making the tube for the roughly 50 feet with a diameter since it is noted that the way it is done now is not as a complete piece.

Yes it would loss some wieght by not having segments but the difficulty on making and mounting them make it not practicle as other have tried to explain.

[djellison]

the video give no evidence that one of the boosters failed

.

You have got to be kidding me. Do you even research things a tiny tiny ammount?

From http://en.wikipedia.org/wiki/Graphite-Epoxy_Motor
They have had a great success record; however they are not infallible. On 17 January 1997, a Delta II exploded 13 seconds after launch due to a rupture in a graphite-epoxy casing. The failure was a result of the casing having been damaged at some point, either during manufacturing or installation - the investigation could not determine the exact cause of the damage. When the motor ignited, the pressure inside the casing built up until the damaged casing could not hold in the pressure of the burning fuel and exploded, destroying the launch vehicle.

or maybe you should read
http://www.hq.nasa.gov/office/codeq/safety/leadership_vits/12_5_05.pdf
or
http://www.seds.org/spaceviews/9702/features.html
or
http://kevinforsyth.net/delta/news1998.htm

Infact, for someone who makes such bold claims regarding LV's - for someone who seems to speak as an authority - I am utterly utterly AMAZED that you did not know about that LV failure, particularly as it was a GEM failure, the very sort of failure you are saying is impossible.

Again - provide evidence that a non segmented SRB is safer...PROOVE IT. You continue to make the claim without ANY evidence, without ANY facts, without ANY proof, without any CLUE what you are talking about.

You are basically lying your way through your fundamentally flawed understand and knowledge of LV's. You are spreading so much missinformation that the onus is on the rest of us to dictate the facts to you. You may not like them, you may continue to ignore them, but we still have to dictate them.

[NEOWatcher]

VEGA clearly demostrates that bigger non-segmented SRB can be built
the VEGA stage is "only" 1/8th of a Shuttle SRB simply because VEGA is designed for small payloads (around 2.5 mT)

By the same argument I would agree.

I have launched many rockets with Estes C6-7 and other variants of solid rocket motors with various configurations, and have had a very good safety record. :wall:

[djellison]

VEGA clearly demostrates that bigger non-segmented SRB can be built
.

Bigger than what? It's not much bigger than the SRB's fitted to Delta IV's and Atlas V's.

Vega 1st stage - 190 tons
Atlas V SRB's - 130 tons
Delta IV GEM's - 77.4 tons

Then a jump - of nearly half an order of magnitude to the next large SRB's - all made segmented:
Titan IV SRB - 655 tons
Ariane V SRB - 661 tons

and finally the segmented
Shuttle SRB - 1177 tons

Incidentally - the Ariane V SRB is still produced in segments but they are now welded together...not for safety or increased reliability - but to save about 1.9 tonnes of Mass.

However - you claim that a non segmented SRB of 1177 ton thrust is safter and cheaper than the current shuttle SRB.....I ask you, once again, to prove it.

ALL the evidence points at segmentation being the sensible path for large SRBs.

Doug

[gaetanomarano]

...have had a great success record; however they are not infallible...
again... I've NEVER said they are "safest" but only "safer" (like a car with ABS and airbags is SAFER than one without them!)

...due to a rupture in a graphite-epoxy casing. The failure was a result of the casing having been damaged at some point, either during manufacturing or installation...
I don't know the thickness and resistance of the SRB vs. GEM... but I feel that the latter was designed with the payload in mind, while, the SRB was designed and built for a manned vehicle... infact, they have had a better safety standard (one fail on 232 launches) despite they're "segmented"

...GEM failure, the very sort of failure you are saying is impossible...
again... we must see how GEM and SRB are made... also, I've NEVER said that a failure is "impossible"

...PROOVE IT...
I can't PROOOVE IT simply because NO ONE can PROOOOVE that an unexisting motor is safer than an existing one
we can only use our LOGIC and do some evaluations and (those have more data and knowledge) some calculations
not even NASA can PROOOOOVE that a vehicle is safer than another
e.g.: the new Orion/Ares is evaluated/calculated as many times SAFER than Space Shuttles..
comparing both vehicles, that claim may appears true (without PROOOOOOVE IT and without any Orion/Ares launch) because the capsule is mounted on top and has a LAS to escape
but we can be SURE of that, ONLY when the Orion/Ares will fly 116+ times WITHOUT any accident
now we can use only our LOGIC... and, "logic" say us that a capsule with LAS is safer than a Shuttle without escape module... that a car with ABS and airbags is safer than a car without them... and a non-segmented booster is (not perfect!) but SAFER than a segmented version
of course, LOGIC, calculations and evaluations can be contradicted by real launches statistics, so, the Orion can fail more than Shuttle... and the non-segmented can fail more than to-day's SRB

.

[Dave J]

Just as a historical point, after Challenger, the composite SRB was dropped. One reason was the additional joints the design introduced...the joints between the composite segment cylinders and the steel joint assemblies. There are a couple left that have found a home at KSC, in the full size SRB/ET display there.
Were it possible to build a safer, more efficient composite monilithic SRB case, I'm sure they would have headed this direction. The current design is very robust, man rated, and proven in well over 200 burns. You seem to forget, again, the tremendous cost of designing, engineering, and man rating a whole new booster. The current design may not be the most efficient, but it is well proven, one of the most "experienced" boosters out there.

[gaetanomarano]

...of nearly half an order of magnitude to the next large SRB's - all made segmented...
that STILL doesn't appear to me due to manufacturing problems but to "political" problems: build parts in many (and specific) States... assemble in another State... launch it in a further State... etc.
about the "order of magnitude" you claim... it exists but is three-four order of magnitude less than compared with the problems NASA solved with the Apollo project and five-ten orders of magnitude less the problems to solve to land on Mars... then, design a build a non-segmented SRB (simply) ISN'T a problem!

...the Ariane V SRB is still produced in segments but they are now welded together...not for safety or increased reliability - but to save about 1.9 tonnes of Mass...
I think that welded segments' boosters will result safer and much reliable... however, "save mass" is (exactly) one of the (good) reasons I suggest to build (in future) the non-segmented SRB

...on segmented SRB of 1177 ton thrust is safter and cheaper than the current shuttle SRB...
again... since it can't leak, it "may be" safer like a car with ABS and airbags is safer than one without them... it's only LOGIC... no one can "prove" it now (nor the opposite)
also, it can lift more upperstages' mass
the non-segmented SRB is not "cheaper" in a DIRECT way (since it needs some research, tests and a small factory to fill them) but may result cheaper in an INDIRECT way because, with a more reliable SRB, we wil have a safer Ares-I and a much reliable AresV

.

[gaetanomarano]

There are reasons why they built the SRBs with segments. Go educate yourself as to those reasons and you'll learn why your contention is so much nonsense. If it were practical and safer to build the SRBs without segments, they would've done so a long time ago. Just because you say it, it doesn't mean you're right. Quite often, the converse is true.
you know that the main reason of that choice was political (...if they want to build them in UTAH and launch in FLORIDA... "segments" are ONLY a consequence...) and (you may agree with me) a bad choice!

.

[gaetanomarano]

...no makers at this time that make a monolithic SRB of the shuttle thrust ratings and while it may be possible to do so that was not a requirement for assembly lifting concerns...
give contracts to many competing companies... and you will see... they CAN (and dozens of smart solutions to increase safety and reduce weight and costs will be developed!!!)

...difficulty of making the tube for the roughly 50 feet with a diameter since it is noted that the way it is done now is not as a complete piece...
"difficult" ...but not "impossible" to do!

...it would loss some wieght...
consider that NASA has decided (or is forced) to get rid of the SRB recovery system to save (only) 12 mT... so, they may decide (or be forced) to save more weight in future (to launch the payloads they need) and the non-seg.SRB is a good solution to save weight!

.

[gaetanomarano]

Were it possible to build a safer, more efficient composite monilithic SRB case, I'm sure they would have headed this direction. The current design is very robust, man rated, and proven in well over 200 burns. You seem to forget, again, the tremendous cost of designing, engineering, and man rating a whole new booster. The current design may not be the most efficient, but it is well proven, one of the most "experienced" boosters out there.
you're right about the standard SRB "as is" (infact, I've suggested MANY TIMES to use it now to save tim and money!) but you forget that they're going to spend $3 billion to ADD A SEGMENT to the standard SRB and (also) they must man-rate the new rocket since it will be very different than now
then, if thy have money to spend/lose... why don't spend that money in a SMARTER WAY... designing, building and man-rating a new, better, safer and lighter (composite) non-segmented SRB to use it in future?

.

[Larry Jacks]

you know that the main reason of that choice was political (...if they want to build them in UTAH and launch in FLORIDA... "segments" are ONLY a consequence...) and (you may agree with me) a bad choice!

I don't agree with you on much of anything about space hardware because you're consistently wrong. Here's an exercise for you. If you complete it, then you may see why trying to create a truly non-segmented large SRB is such an absurd idea.

In a post on this page, describe the step by step process for putting the propellant into a large SRB and then attaching it to the rest of the booster. Be sure to include the processes necessary to ensure there are no propellant voids or insulation detachment.

Here's a clue: if the casing is truly non-segmented and is in one piece, you'll have to pour the propellant into the casing through nozzle. Keep in mind that the conventional 4 segment Shuttle SRB has a loaded mass of 589,670 kg (1,299,990 lb).

[djellison]

a much reliable AresV


The Shuttle SRB is the most reliable SRB to date.....and you are saying that totally new deisgn would be 'much more reliable' than a derivative ( that has infact already been tested on the ground )

Do you know how crazy that sounds. Honestly - do you?

Doug

[gaetanomarano]

..create a truly non-segmented large SRB is such an absurd idea...
we can discuss if a non-seg. is necessary, but NOT "absurd" since it has many advantages

...if the casing is truly non-segmented and is in one piece, you'll have to pour the propellant into the casing through nozzle...
build a so giant (segmented) booster (and the segments theirself) ALREADY was a BIG challenge... won!
build a non-seg. version is another challenge that can be won with ease thanks to the 30+ years of experience about SRB
about SRB filling... to have a 100% safe booster it must me 100% sealed case but we can accept a compromise to have a (close to 100%) safer SRB: build a composite (and lighter) non-seg. sealed case exculding the nozzle, fill the SRB and weld the nozzle (with an extra external small ring for additional safety)
this is only a proposal... many other solutions may be found by engineers

.

[djellison]

to have a 100% safe booster it must me 100% sealed case

This is an outright lie. Fundamentally, catagorically - a lie. Please please please for your own sake - stop stating things that are nothing more than your guess...as facts.

Doug

[cjl]

Not to mention that even then, it wouldn't be a 100% safe booster...

There is such a thing as a burn through of the case...

Here is an example (http://www.northwestrocketry.com/uploads/Alex%20NUMB%20CD.mov). That was using a SINGLE PIECE casing, and yet it somehow managed to fail nonetheless, and it failed at a location where there was no joint, no attachment, or anything.

Joints do not make the casing inherently unsafe, and in many ways, they actually strengthen it. Please stop your proclamations based on zero actual data, and next time you start stating something, use REAL RESEARCH to back it up.

[gaetanomarano]

...the most reliable SRB to date...
I agree... that is the reason I've suggested (hundreds times) to use ONLY the (ready available, cheap, man-rated and very reliable) standard SRB instead of spend time and money to build a new version that will need many tests, recertification for manned flights and (minimum) 232 launches to know if it is really safe...
but, since NASA is going to spend a GIANT amount of time and money to (simply) ADD A SEGMENT to the old motor... why don't use the same time and money to design and build a brand new (and better) version???
if you have an old car that need very much money to update and "refresh" it... why don't use the SAME money o buy a NEW (better and advanced) car?
why NASA must fly in the next 30+ years with a "refurbished" design, if they can have a NEW design at the same price?
don't forget that in the next 20 years each moon mission (of the 12 planned) may cost over $10 billion (including the shared R&D costs and the fixed "on earth" annual costs) then, this time, a rare (but possible) segmented SRB's leak may destroy a full mission and a giant amount of money... so, why risk?
however, I want to give you ANOTHER very good reason to build a new LIGHTER version of the SRB: "the payload's price-per-ton"
my evaluation is that (in the next 20 years) EACH AresV launch (of 15 tests and missions flights) may costs (around) $400M of hardware + (around) $800M of shared R&D costs + (around) $500M of shared "on earth" fixed costs... a total price per launch (around) $1.7 billion (excluding the payload price)
well, since the AresV can lift to LEO up to 130 mT of payload, EACH mT launched will cost $13 million, then, if a better and LIGHTER booster will increase the payload of (e.g.) 15 mT, each launch will cost up to $200M less than planned... so, the (much expensive) "new SRB" will have a (real) unit price of $0.oo

.

[gaetanomarano]

This is an outright lie.
the "100% sealed case SRB" must STILL have an "hole" called "nozzle", of course...

.

[gaetanomarano]

...Joints do not make the casing inherently unsafe...
true! ...like a car WITHOUT airbags, ABS, etc. is NOT "inherently dangerous" (until it have an accident...)

.

[cjl]

That is not a valid analogy.

The car is very definitely less safe and controllable without ABS and airbags, but the rocket motor is unaffected by the lack of or the presence of joints, assuming they are well designed (and the shuttle joints are).

[gaetanomarano]

That is not a valid analogy. The car is very definitely less safe and controllable without ABS and airbags, but the rocket motor is unaffected by the lack of or the presence of joints, assuming they are well designed (and the shuttle joints are).
we can look at the same analogy in the exactly opposite of your post, since a car travels at 55 mph max (in USA) or 130 kmh max (in Italy) while every rocket is launched at supersonic speed and very close to its limits!
however... how about the BIG advantage of an increased payload mass thanks to lighter SRBs?
launch the BIGGEST possible payload mass IS (or not?) the FINAL TARGET of EVERY rocket?

.

[stutefish]

I'd say the "final target of every rocket" is to consistently launch the most efficient payload.

This may result in something less than the maximum possible payload, as payload capacity is traded for design features that weigh more but contribute to greater efficiency or greater consistency in an extended series of launches.

[gaetanomarano]

...the most efficient payload...
EVERY kg. of mass is the "most efficient possible" in the space industry
then, also a SINGLE "extra-mT" (of exploration and science hardware) landed on the moon (thanks to a more efficient AresV) will be (and will be used) in the "most efficient [way] possible"
also, in the Ares-I, a lighter SRB can solve the "underpowered" problem (if there is one)

.

[Dave J]

Gaetano,
Yoyu state that the "seamless" huge SRB can be engineered, designed, and put into production for the "same money" as adding a segment to the existing RSRM design. Do you really believe this? If so, if your idea os so feasible, why aren't you working at ATK? Why haven't they fallen in love with your proposal?

[cjl]

we can look at the same analogy in the exactly opposite of your post, since a car travels at 55 mph max (in USA) or 130 kmh max (in Italy) while every rocket is launched at supersonic speed and very close to its limits!
however... how about the BIG advantage of an increased payload mass thanks to lighter SRBs?
launch the BIGGEST possible payload mass IS (or not?) the FINAL TARGET of EVERY rocket?

.

Since when is the speed of the rocket the primary cause of failure. I can't recall having ever heard of a failure of a large rocket at liftoff because it couldn't take max Q. Almost every failure is a pressure containment failure, or a burn-through. So speed is IRRELEVANT, and not a valid comparison. As far as the supposed "big advantage", a larger SRB would cost significantly more to produce - it is not an advantage if the additional cost per launch is greater than the cost of just launching a couple more of the slightly heavier ones.

I love how you sit there saying how the tiniest little change is massive, and horrible, and will cost too much, and will take too much time, etc, etc. Yet you then turn around and start advocating changes to the basic designs that would essentially require a redesign from scratch, costing far more and taking far more time than the changes you were just recently proclaiming would cause the end of the world.

Please, make up your mind.
:wall:

[djellison]

the "100% sealed case SRB" must STILL have an "hole" called "nozzle", of course...

.

But for goodness sake - I just proved to you that a sealed SRB is not 100% safe - that Delta II failure was due to a rupture in the side of a single casing SRM - proof positive that your claim that they are 100% safe is a fundamental lie.

You contradict yourself, and the evidence, and common sense, at the same time!!

Oh - and a saving of 1kg in the first stage of an LV does NOT improve to-orbit performance by 1kg as you seem to suggest it does....research the rocket equation.

Doug

[gaetanomarano]

...state that the "seamless" huge SRB can be engineered, designed, and put into production for the "same money" as adding a segment to the existing RSRM design...
design, build, test and launch the big (21 mT payload) Ariane5 have had a total costs of ("only") $8 billion (source: astronautix)
build some new Delta and Atlas versions have had costs in the range of hundreds million$
while, add a 5th segment to the standard SRB, will cost 3 years and $3 billion...
then, is NOT "build a new rocket" SO CHEAP, but "add a 5th segment" TOO EXPENSIVE...
however, since NASA is going to spend that money, I think it's better to spend that billion$$$ (or more) to build a band new booster!
e.g. you've an old Pentium III computer and want to update/upgrade it... your choice are:
a) spend $250 to add new HDD, graphic card, RAM, OS, etc. or...
b) spend $400 to build a brand new PC with dual-core high speed processor, big HDD, Vista, etc.
which choice is better?
I think the latter is the better choice despite it costs more!
NASA faces the same options these day:
a) use in the next 30+ years a "refurbished" design of the old SRB, or...
b) spend more to have a brand new, higher specs, superSRB
which choice is better?

...if your idea os so feasible, why aren't you working at ATK? Why haven't they fallen in love with your proposal?
I doubt that, big aerospace companies, have time to read forums and websites

.

[Bob B.]

Oh - and a saving of 1kg in the first stage of an LV does NOT improve to-orbit performance by 1kg as you seem to suggest it does....research the rocket equation.

Gaetanomarano and I went on for pages about this in this thread (http://www.bautforum.com/showthread.php?t=47006)*. He kept saying that a reduction in the mass of the launch abort system would result in an equal increase in payload mass. I don't think he was ever able to grasp the error in his logic despite great effort on my part to explain it to him.

* Gaetanomarano first mentions the LAS in post #19 and I first respond in post #21.

[gaetanomarano]

...just proved to you that a sealed SRB is not 100% safe...
and I've agreed with you
but the SRBs (build for manned launches) are not the same of GEMs (optimized to launch as much as payload possible)
the non-seg. will be safer since it will be/must be built with same SRB safety standard

...saving of 1kg in the first stage of an LV does NOT improve to-orbit performance by 1kg as you seem to suggest it does...
I know that... infact, launch a rocket is like make a SINGLE toothpick from a big tree...
the "toothpick" of the moon missions will be the, 2 mT only, lunar exploration hardware... so, increase that mass of a further mT or less (thanks to the lighter SRBs) will be a GIANT SUCCESS (and a big advantage)

.

[gaetanomarano]

...a reduction in the mass of the launch abort system would result in an equal increase in payload mass...
you remember that our different evaluations was due to our different guess about the max Ares-I payload: inclusive of LAS (my guess) or exclusive of LAS (your guess) ...however, we can do the right evaluations only when the real Orion/Ares specs will (finally) be available

.

[gaetanomarano]

...recall having ever heard of a failure of a large rocket at liftoff because it couldn't take max Q...
in the past, I've seen some video of rockets that have fallen on theirself (also on the launch pad) due to its low speed... then, that failure can happen

...speed is IRRELEVANT, and not a valid comparison...
you're right... internal pressure is most important... but I'm sure that ATK (or other aerospace companies) are able to design a safe motor

...I love how you sit there saying how the tiniest little change is massive, and horrible, and will cost too much, and will take too much time, etc, etc. Yet you then turn around and start advocating changes to the basic designs that would essentially require a redesign from scratch, costing far more and taking far more time than the changes you were just recently proclaiming would cause the end of the world...
no... if you read all the articles on my website and all posts on ghostNASA you can see that I'm absolutely in favour to use ONLY ready available engines and motors (to save time and money) but... if NASA has DECIDED to spend so much time and money... why spend them to have ONLY some "refurbished" designs, instead of a full line of brand new products?

.

[Dave J]

design, build, test and launch the big (21 mT payload) Ariane5 have had a total costs of ("only") $8 billion (source: astronautix)
build some new Delta and Atlas versions have had costs in the range of hundreds million$
while, add a 5th segment to the standard SRB, will cost 3 years and $3 billion...


.

I think you are confusing launch prices and development costs. From Astronautics, the Atlas V 2002 launch prices were $138m (401 model), $192m (500 series) and estimated $254m (heavy). I am not finding actual development costs, but in Aug 95, the government gave $30m to 4 contractors to do design studies for a new ELV, and in Oct 98, awarded Boeing and LockMart each $500m for development. This does not include $$ the company put forward, or further funding from the government since then. (source: Aerospace America, Mar 2002)
Granted, if the $2B figure for developing the SRB5 are accurate, that is a pile of money. I'm sure it will result in a fine booster.

[gaetanomarano]

I think you are confusing launch prices and development costs...
no, I've not confused "development" with "launch" costs
I don't refer to the costs to design a brand new rocket, but to UPGRADE an existing model (like go, e.g., from Delta IV 5,2 to 5,4, etc.) and I've read (sorry, I don't remember where, nor have a link) that similar upgrades costs in the range of 100s million$$$, not billion$$$
the SRB upgrade will costs $3 billion, that, I think (and many other peoples think) is too much for that work, then, I suggest to:
a) use ONLY ready available motors, or...
b) use that money (or more) to build a brand new motor with lots of better specs and advantages

.

[Larry Jacks]

build a non-seg. version is another challenge that can be won with ease thanks to the 30+ years of experience about SRB about SRB filling... to have a 100% safe booster it must me 100% sealed case but we can accept a compromise to have a (close to 100%) safer SRB: build a composite (and lighter) non-seg. sealed case exculding the nozzle, fill the SRB and weld the nozzle (with an extra external small ring for additional safety)
this is only a proposal... many other solutions may be found by engineers

Once again, you make uninformed sweeping statements without answering anyone's objections. How would you fill up a 1.3 million pound SRB from the nozzle and then flip it pointy end up while ensuring the propellant geometry is correct and there was no insulation delamination. Put up the details or admit you don't know what you're talking about. That would be a first in either case.