Which Orion is better? A (smallSM) "CorkScrew-Orion" or a (bigSM) "SwissKnife-Orion"?

[gaetanomarano]

.

After the first article and the SM thread here, I've written a new article about the Orion Service Module to compare the two SM options.

Also, I start a poll about this argument, but, if you want to vote, PLEASE read the new article about the smallSM/bigSM comparison, thank you.

.

[Doodler]

You start off with a false comparison. The SM has squat to do with mission capability, which is a function of the lander, so you've already dismantled the credibility of the argument.

[gaetanomarano]

You start off with a false comparison.

instead of post insults, you can (simply) explain here HOW a TEI-only SM can perform tha SAME missions/operations of my comparison list

[Bob B.]

Gaetanomarano, you are still insisting the small SM weighs only 10 mT and has only 7 mT of propellant. The equations indicate this is impossible, which I have attempted to show you on more than one occasion in another thread. Orion simply cannot produce the published delta-v out of only 7 mT of propellant. You are certainly entitled to your opinion and are free to write as many articles as you want, but please stop repeating figures that demonstrably wrong. Doing so only make you look dishonest. A more reasonable estimate is 13 mT total mass with 10 mT propellant.

[gaetanomarano]

...you are still insisting the small SM weighs only 10 mT and has only 7 mT of propellant. The equations indicate this is impossible, which I have attempted to show you on more than one occasion in another thread. Orion simply cannot produce the published delta-v out of only 7 mT of propellant. You are certainly entitled to your opinion and are free to write as many articles as you want, but please stop repeating figures that demonstrably wrong. A more reasonable estimate is 13 mT total mass with 10 mT propellant.

no, it's only my evaluation, that has the same value of every other evaluation, since LM don't give yet any official data about the SM/propellant weights
however, the point of my comparison is NOT between 7 mT or 10 mT of propellant, but between "TEI-only propellant SM" (the "corks screw Orion") and "TEI+LOI propellant SM" (the "swiss knife Orion")
then, also if I accept your evaluation (10 mT of SM propellant) that doesn't change nothing of the question explained in my article (smallSM or bigSM?)

[Bob B.]

no, it's only my evaluation, that has the same value of every other evaluation, since LM don't give yet any official data about the SM/propellant weights

If we don’t know official data, then why do you insist on given any figures at all in your article? You seem to have no problem telling people the SM will have “less than 7 mT of propellant” as if it is fact, yet when some one tries to provide you with a more accurate estimate you scorn them and say they can’t possibly know because the data is unavailable.

Based on the most recent information published by NASA, we know the following:

CM dry mass: 7,891 kg
CM launch mass: 8,485 kg
SM propellant: N2O4/MMH
SM delta-v: 1,855 m/s

This is enough information to make a fairly good estimate of the SM propellant load, which Mark Wade and I have already done. Those calculations show that 9.5 to 10 mT is a reasonable estimate. Your figure of 7 mT is simply not creditable.

then, also if I accept your evaluation (10 mT of SM propellant) that doesn't change nothing of the question explained in my article (smallSM or bigSM?)

If the argument presented in your article is not changed by accepting the 9.5-10 mT propellant figure, then why not change it? I can assure you that 13 mT total and 10 mT propellant mass is much closer to the real figures than your 10 mT and 7 mT numbers. Wouldn’t you want your article to be as close to reality as possible rather than containing clearly flawed information?

[gaetanomarano]

If the argument presented in your article is not changed by accepting the 9.5-10 mT propellant figure, then why not change it? I can assure you that 13 mT total and 10 mT propellant mass is much closer to the real figures than your 10 mT and 7 mT numbers. Wouldn’t you want your article to be as close to reality as possible rather than containing clearly flawed information?

despite I (still) don't agree with your evaluation, I've changed the SM and propellant data in my article (to 13 mT and 10 mT) to exclude this (secondary) argument from the discussion (since both propellant weight are near HALF the weight of the Apollo CSM propellant...) and I post here the main specs of "my" SwissKnife Orion SM that must have the propellant for...

- LOI of the Orion+SM alone
- LOI of the Orion+SM+LSAM
- TEI of the Orion+SM
- earth/lunar orbit maneuvering
- ISS/LSS orbital reboost
- earth/lunar orbit change
- earth reentry speed braking (optional)

.

[Doodler]

You seem to have no problem telling people the SM will have “less than 7 mT of propellant” as if it is fact, yet when some one tries to provide you with a more accurate estimate you scorn them and say they can’t possibly know because the data is unavailable.

1) I'm always right.
2) I'm never wrong.
3) In case of doubt, read my article where it says I'm right in #1.

[Count Zero]

I prefer this Orion.

[captain swoop]

and where are G's similar numbers?

[Bob B.]

and where are G's similar numbers?

The ESAS report doesn't give G's for the LSAM, or at least not that I've seen, but we can easily calculate it. The report says the descent stage will have four 66.7-kN (15,000 lbf) engines. That's a total thrust of 266.8 kN, or 27,200 kgf.

For LOI the mass varies from 66,000 kg to 51,480 kg (my numbers), therefore

G @ start of burn = 27,200/66,000 = 0.41 g

G @ end of burn = 27,200/51,480 = 0.53 g

During descent the mass varies from 30,480 kg to 19,845 kg, therefore

G @ start of burn = 27,200/30,480 = 0.89 g

G @ end of burn = 27,200/19,845 = 1.37 g (100% thrust)

Of course the engines won't be firing at 100% thrust near the end of the descent burn because they need only to counteract gravity so the LSAM can hover and set down gently. The "weight" of the LSAM in lunar gravity at touchdown will probably not be less than about 33 kN (unless we use gaetanomarano's downsized LSAM). Hovering will therefore require 1/8th thrust, or two engines at 25% thrust.

[Bob B.]

Okay, who voted for the BigSM? Gaetanomarano?

[gaetanomarano]

Okay, who voted for the BigSM? Gaetanomarano?

I'll be happy if other users will vote PRO my bigOrion proposal, however, I've published my bigOrion's articles before the this thread/poll and my first target MUST be to demontrate that my proposals can (really) work ...that's the thing I've done (with a single shot) for (both) the bigOrion and the ArianeCEV...

[Doodler]

Launchwindow. So sayeth the pollin' thing.

And somehow, Wolf-S voted small twice.

[Bob B.]

since the full Apollo SM propellants' mass was 18,4 mT (less the LOI/TEI mass) the residual propellants' mass was 2.9 mT but only (about) 0.8 mT was used "for other" since the propellants' mass after TEI was 2.1 mT

maybe, part of this (2.1 mT) residual propellants was used to correct the CSM trajectory in the moon-earth flight, but great part of it was (probably) only an extra-mass loaded to give some redundancy.

The linked data appears to be for the Apollo 11 mission. It is true some of the SPS propellant was a reserve; however Apollo 11 was atypical in some ways. The amount of maneuvering the CSM had to perform while in lunar orbit increased on later missions.

For example, one of the maneuvers was a plane change prior to LM ascent. This was necessary because, as the Moon rotated, the LM’s landing site would slowly move out of the plane of the CSM’s orbit. The CSM had to adjust its orbital plane so that its flight path once again passed over the landing site. The LM could then insert itself into the same orbital plane, which was required for rendezvous. The longer the LM was on the surface the more it moved out the CSM’s path, thus the greater the plane change. Plane changes require a lot of propellant; therefore the longer missions required more propellant.

[gaetanomarano]

The amount of maneuvering the CSM had to perform while in lunar orbit increased on later missions.

like the Apollo, I've added 2 mT of "redundancy and maneuverings" extra-fuel in my latest evaluations of the Orion's mass

[Bob B.]

you have calculated the TEI propellants' mass at 9.5-10 mT here

No, I did not. Please read carefully what I wrote …

This is enough information to make a fairly good estimate of the SM propellant load, which Mark Wade and I have already done. Those calculations show that 9.5 to 10 mT is a reasonable estimate. Your figure of 7 mT is simply not creditable.

I wrote “SM propellant load”, there is no mention of “TEI propellants' mass”. This calculation has been repeated several times and I have always maintained it is the total SM propellant mass based on the delta-v requirement of 1,855 m/s. I have never claimed it to be TEI only. In fact, four days ago I specifically explained this to you in another of your threads…

if the propellant for TEI-only is (e.g.) 9 mT, the extra propellant for an (autonomous) LOI must be MORE than 9 mT (since, at LOI, the engine must brake the Orion + the TEI-fuel mass)

Herein lies the crux of the problem. The 9-10 mT of CEV propellant is for more than just TEI. The CEV is probably going to have to perform several maneuvers, similar to what Apollo did. Apollo had to perform altitude changes, plane changes, course corrections, etc. TEI itself required only about 1,000 m/s delta-v. The CEV has a delta-v of 1,855 m/s. …

I clearly explained that TEI is only a portion of the delta-v/propellant budget, and I even told you that TEI on an Apollo-like mission is about 1,000 m/s. This 1,000 m/s number is exactly the same delta-v I used to calculate the TEI propellant mass of 4.5 mT (post #63). I didn’t perform the calculation four days ago because it wasn’t pertinent to the discussion at that time, but I clearly set forth the parameter upon which it is based. I calculated it today only because this is the first time it came up in the conversation.

and the total Orion+SM mass at 21-21.5 mT here

Yes, and I still stand by that calculation.

[gaetanomarano]

wrote “SM propellant load”, there is no mention of “TEI propellants' mass”...

only a "linguistic trick"... for over a week (on this thread and on the "giant mistake Orion" thread) we have discussed ONLY (as everyone can read) of the propellants' mass the Orion SM needs for TEI or LOI+TEI and (absolutely) NOT of any extra-propellants "loaded" (maybe) to help Orion play Baseball around the Moon...

...I calculated it today only because this is the first time it came up in the conversation.

and (exactly) 30 minutes after the NEOWatcher post...

I still stand by that calculation.

the ONLY reason to add 5 mT of (useless and unused) propellants' mass in the SM tanks is to support the 5-segments SRB for the Ares-I (so it can lift 5 mT of dead-weight)

[Bob B.]

So sayeth the pollin' thing.

Huh... I just learned something new; I didn't know you could see the results. I never tried clicking on the numbers before.

[Doodler]

Huh... I just learned something new; I didn't know you could see the results. I never tried clicking on the numbers before.

Could be an option set when you set up the poll.

[stutefish]

I have thought for some time now that these threads should all be in "against the mainstream".

As far as I can tell, the only thing keeping them out of "conspiracy theories" is that Gaetano has never actually addressed the fact that if NASA really were as incompetent and ignorant as he implies, there would pretty much have to be a conspiracy of epic proportions to keep it quiet.

[gaetanomarano]

..."conspiracy theories"...

there is NOTHING about any "conspiracy theories" in my articles/threads/posts... ONLY good (and, maybe, a little "alternative") ideas about spacecrafts

[stutefish]

there is NOTHING about any "conspiracy theories" in my articles/threads/posts... ONLY good (and, maybe, a little "alternative") ideas about spacecrafts

Exactly my point. There's nothing about conspiracy theories in your article, which is why they don't belong into the "conspiracy theories" section of the board.

On the other hand, it seems to me that your positions strongly imply that NASA is staffed by people who are incompetent and ignorant on a grand scale--so grand, in fact, that a conspiracy would be necessary to cover it up. But you never address this implication. Which is what keeps these threads out of the "conspiracy theories" section. Q.E.D.

[gaetanomarano]

...it seems to me that your positions strongly imply that NASA is staffed by people who are incompetent and ignorant on a grand scale...

absolutely not true... the ESAS plan (with some changes) can work "as is" with the 5-segments SRB, the small Orion, etc.
my articles are only suggestions to make a BETTER plan and to accomplish more and better missions

[Doodler]

I dunno about against the mainstream, you'd actually have to be swimming to pull that off, he's been flopping like foundered flounder through every thread on the Orion he's started.

[3rdvogon]

OK I am not in the same class as some of you guys - in that I can't to the math for propellant and thrust calculations. However if it were deemed necessary would it not be possible to develop a "stretched" Service Module for use on specific missions (where the lander could be eliminated). Surely most of the same components (engines, control systems, connections to the CM etc) could be re-used so surely an enlarged SM would not need to be designed from scratch were the need to arise, that after all should be the benefit of a modular design structure.

[Bob B.]

you can claim that NASA calculations are wrong or the real Ares-I will be different but you can't "change the table".

I’ve made no such claim.

if table's data are correct and close to the real Ares, I've "interpreted" them the right way
the table's data are simple and clear with the estimated NASA specs for the J-2x Ares-I at 22 mT for the payload and 4 mT for the LAS

Correct, I agree with this.

26 mT is the max (total) upperstage mass the J-2x Ares-I can lift from ground, there are no other mass to lift in the table

No it is not. With a liftoff mass of 26 mT the Ares I can deliver 22 mT to orbit, but there is nothing limiting the liftoff mass to 26 mT.

since (now) we know the mass of the (standard) Orion (8.5 mT) interstage (0.6 mT) and LAS (6.2 mT) the SM + propellants' mass must be equal to 10.7 mT or less
you can calculate/evaluate/allocate the mass you want to the SM and the propellants, but the final result must be 10.7 mT and the total upperstage mass must be 26 mT

Your conclusions are incorrect because they are based on a flawed premise; that being your assumption the liftoff mass is limited to 26 mT.

your claim about the "slower 1st stage, faster 2nd stage" is a pure nonsense (or another speculations to match the Ares with your calculations)

My explanation is absolutely correct; your inability to understand it seems to be the problem. But since you say you have no desire or need to learn anything about rocket science, I won’t bother explaining it further.

it's clear that NASA engineers have calculated the J-2x Ares-I max payload with the BEST flight profile
why do they must write in the table that a rocktet can lift "only" 22 mT if (with the same hardware and a different flight profile) can lift more mass???

NASA hasn’t said it can “lift” only 22 mT, they’ve said it can deliver 22 mT to LEO with the 4 mT LAS. Changing to a 6.2 mT LAS increases the Orion’s liftoff mass to about 28 mT with a small reduction in deliverable payload. I estimate that with the heavier ground ignition weight, the deliverable payload will be reduced to about 21.8 mT.

however, the standard SM mass MUST BE in the 3-3.5 mT range to allocate a sufficient mass for the propellants

It MUST be what it needs to be. I can find no precedent to suggest a pressure-fed system of the size required can be fit into such a small package.

true, but you must compare the FULL Apollo CSM mass with the FULL Orion+SM mass

No I don’t. The CM mass has no affect on how big the SM must be to house the required quantity of propellant.

but your specs need an Ares-I able to lift more payload mass than planned and (so far) we have not (real) evidence that it can

I don’t care about the Ares I. You’ve said you want to fly an Apollo-like mission to the Moon using an enlarged Orion SM. I’ve calculated approximately how large Orion needs to be to accomplish that mission. If it is too big to be lifted by the Ares I then that’s your problem.

now LockMart claim the SM will use an "upgraded Shuttle OMS engine"

That could be even worse news for your concept. The Shuttle OMS has an Isp of only 313 seconds.

...starting (everytime!) from the "worst case" (and against my proposals)

We must design for the worst case. If we want to be able to reach a certain site on the Moon with high delta-v requirements, or want to have worst-case abort capability, the system must be designed for those circumstances.

strongly defending your (wrong) point (ignoring the advantages of the concept)

I’m only telling you what the equations say. If the calculations indicate there are problems with your concept, then don’t blame me.

and accepting more reasonable data and results only after a long battle...

If by “accepting more reasonable data” you mean revising the calculations for an Apollo-like mission, then I haven’t accepted that. I’ve performed the calculations but that doesn’t mean I agree the starting parameters are what we should be using. I think Orion/LSAM should be provided with sufficient delta-v to reach the lunar poles, i.e. the worst-case scenario.

I've had not the same impression, so far...

I can find fault in ESAS, I just haven’t found sufficient reasons to favor your concepts.

[gaetanomarano]

No it is not. With a liftoff mass of 26 mT the Ares I can deliver 22 mT to orbit, but there is nothing limiting the liftoff mass to 26 mT.

the problem is that you change the reality, interpret the data the way you want, invent new flight profiles, ignore the data you don like, etc. so the reality can match your evaluations
since you have evaluated an heavy standard-Orion, now you need that a J-2x Ares-I can lift it
but you can't change the NASA specs the way you want
LOGIC wants that NASA engineers have (simply) calculated the max upperstage mass at lift-off of every CLV configuration (the original table has six different rockets) and, since the LAS was estimated at 4 mT, they have subtracted that mass to have the max payload value of each configuration
now, with a 6.2 mT LAS, the payload can't remain the same but must have a cut of 2.2 mT + 0.6 mT for the interstage (another mass unknown when the table was made)
you CAN'T add 2, 4, 6, 8, 10 mT or more mass on the same rocket and have the same performances!
maybe, the rocket CAN fly with more upperstage mass, but NOT reach the same (planned) orbit
so, you're correct to say "nothing limiting the liftoff mass to 26 mT" only if you add "but the paylaod can't reach the same orbit"

Your conclusions are incorrect because they are based on a flawed premise; that being your assumption the liftoff mass is limited to 26 mT.

sorry, but my premise/assumption are correct and your evaluations are wrong
if you want to match the Orion with the Ares, you must... reduce the Orion weight OR use a better Ares OR launch and dock the lunar convoy in a lower orbit
since (so far) we don't have any news about orbit change or different Ares' payload+LAS mass, the only way is to reduce the SM mass and/or the propellants' mass

My explanation is absolutely correct; your inability to understand it seems to be the problem.

your explanation is correct, I perfectly understand it and the rocket with 2+ mT extra mass may fly, but NOT reach the same orbit (however, you can ask NASA to change the planned orbit...)

...the deliverable payload will be reduced to about 21.8 mT...

I prefer to see a REAL test and, anyway, the rocket may work with more upperstage mass but not reach the same orbit

...no precedent to suggest a pressure-fed system of the size required can be fit into such a small package...

more SM mass can match the total Orion mass reducing the "extra" propellants' mass

...CM mass has no affect on how big the SM must be to house the required quantity of propellant...

but it has effect on the total mass at TEI that has effect on the propellants' mass for TEI that has effect on the dimensions of the SM tanks that has effect on the SM dimensions that has effect on the SM mass...

Originally Posted by gaetanomarano
but your specs need an Ares-I able to lift more payload mass than planned and (so far) we have not (real) evidence that it can

I don’t care about the Ares I. You’ve said you want to fly an Apollo-like mission to the Moon using an enlarged Orion SM. I’ve calculated approximately how large Orion needs to be to accomplish that mission. If it is too big to be lifted by the Ares I then that’s your problem.

I don't refer to your bigOrion calculations but to your standard-Orion calculations that is too heavy to be launched to the right orbit with the known Ares-I specs

...could be even worse news for your concept. The Shuttle OMS has an Isp of only 313 seconds...

no, it's not, since my bigOrion is the BEST choice at EVERY final weight!
also, we don't know how much "upgrade" LM will put in the SM engine (I suggest to wait for real data about this point instead of guess everyday a new figure)

We must design for the worst case.

true, in fact my SM evaluations have plenty of extra-propellants for maneuverings, emergency, redundancy, etc.
the problem is that your (excessive) evaluations are for the TOO WORST CASE since your goal is to demonstrate that my proposals are flawed

I can find fault in ESAS...

when? in which forum/thread/post?
I've never read any critics from you about ESAS... do you think it's perfect?
.

[gaetanomarano]

However if it were deemed necessary would it not be possible to develop a "stretched" Service Module for use on specific missions (where the lander could be eliminated). Surely most of the same components (engines, control systems, connections to the CM etc) could be re-used so surely an enlarged SM would not need to be designed from scratch were the need to arise, that after all should be the benefit of a modular design structure.

you're right on this point and the extra R&D costs to develop two SMs may be reasonable, but that choice has a big economical problem
launch a bigOrion needs a miniEDS and two (enhanced) Ares-I (or one, bigger, Ares-II)
if the Ares-II will be designed and built now it may have an R&D costs similar to Ares-I and a reasonable hardware price per launch
but, if the only rockets built will be the (too small) Ares-I and the (too big) AresV, the only ways to launch a bigOrion will be:
1. design and build a third rocket (Ares-II) or...
2. launch the bigOrion with the AresV
and, since both options are TOO EXPENSIVE, the bigOrion will never fly!
.