This rocket won't die...

[cjameshuff]

A LEO human payload will not include solids; but a trip to Mars should. The debate has gone round and round these threads about the virtues of each family. IMOHO the multiple launches likely necessary for an all liquid system will prove cost ineffective comoared with a liquid core strapped to a gang of high density solids. Now that Liberty is out of the way, the designers should move towards the most cost effective heavy launch system.

Where the heck does this conclusion come from? To achieve more, we must take a step back and use inferior solid rockets?

Liquids do not need more launches, quite the opposite. The highest-capacity Atlas V variants are completely liquid fueled. It'd take six Liberty launches to equal one Saturn V launch. The Liberty first stage is big enough that there have been major problems with actually implementing it, in spite of deriving from an existing, only slightly smaller system, while the competing all-liquid systems have plenty of room for growth and have proven far more flexible overall. Contrast the expense and difficulty of reworking Shuttle SRBs to the reuse of engines between Falcon 1 and Falcon 9, the extended tanks of the v1.1 Falcon 9, the concepts for future upgrades with a Merlin 2 engine, etc. If solids aren't even a part of manned LEO launches, there's no reason to think they'll have anything to do with Mars.

[cjl]

The three heaviest flown or planned vehicles of all time ( Saturn V, Buran and Falcon Heavy ) have not a single solid motor between them.

Why do you work under the assumption that heavy lift requires solids?

To be entirely fair, the Shuttle pretty solidly beats the Falcon Heavy in mass-to-orbit, and it's even slightly higher than the Energia (which is what actually launched the Buran spacecraft), putting it behind only the Saturn V. Also, if you're including planned vehicles, several of the SLS variants also get up into that same rough payload range (100-130 tons). Of course, the SLS is very much a paper rocket at this point, while the Falcon Heavy is much more likely to actually fly. Still, the Shuttle, which is fairly indisputably in the top 3 (and arguably in the top 2) rockets ever in mass to orbit uses solids, so there is some precedent in their use in large rockets.

cjames: About the Atlas... I'm not sure I'd say that the highest-capacity Atlas V variants are liquid fueled. Yes, the Heavy exists on paper, but the highest capacity anyone has used or plans to use for the moment is the 551, which uses 5 solid boosters. Anything too heavy for that rocket currently uses the Delta IV heavy, since the development costs of the Atlas V heavy are too high at the moment for its relatively small benefit. Of course, the Delta IV heavy is also all liquid.

Honestly, where solids really excel is in two areas: increasing the payload of an existing rocket without substantially changing either its pad footprint or its ground support needs, and in allowing a rocket family to have a large range of possible payloads and performances, while maintaining a fairly constant pad footprint and ground support. Given a single mission, all liquid is usually better, but given a wide range of possible missions, solids can be used to increase flexibility.

[cjl]

Very good. HTPBs can hold up to ~95% bimodal solids; and then the net gain depends upon what solids you load the polymer with.

I hate to repeat myself, but I'd still be curious to see a citation for that (your statement here is not a citation - it's an assertion). I know this isn't in ATM or anything, so I'm not demanding you back this up. I'm just having a very hard time believing a 95% solids figure, given that the GEM-60 motors used on the Delta IV (which are very modern, composite-case HTPB based APCP solids) have around 87% solids (interestingly enough, this is very nearly identical to the solids loading of the Shuttle SRBs, which use PBAN), along with a very impressive 275s vacuum ISP (which is very slightly better than the shuttle - possibly due to propellant formulation, possibly due to something else [nozzle expansion ratio?]). I would think that if 95% were achievable, these motors would have well over 90%, given how recently they were designed.

[cjameshuff]

cjames: About the Atlas... I'm not sure I'd say that the highest-capacity Atlas V variants are liquid fueled. Yes, the Heavy exists on paper, but the highest capacity anyone has used or plans to use for the moment is the 551, which uses 5 solid boosters. Anything too heavy for that rocket currently uses the Delta IV heavy, since the development costs of the Atlas V heavy are too high at the moment for its relatively small benefit. Of course, the Delta IV heavy is also all liquid.

You can evidently order the Atlas V Heavy, just nobody actually has done so. There's a 30 month wait time, presumably for them to do the engineering work for integrating 3 CCBs that they haven't seen the need to perform without customers, but it's an available configuration. So I stand by my original statement: the heaviest Atlas V configuration (the two heaviest configurations, actually) is all-liquid.

[Garrison]

To be entirely fair, the Shuttle pretty solidly beats the Falcon Heavy in mass-to-orbit, and it's even slightly higher than the Energia (which is what actually launched the Buran spacecraft), putting it behind only the Saturn V.

But if you take the figures for maximum payload rather than total mass then you get:

STS: 24,400 kg

Falcon Heavy: 53,000 kg

Very clear which one is the real HLV.

[Garrison]

Very good. HTPBs can hold up to ~95% bimodal solids; and then the net gain depends upon what solids you load the polymer with.

A LEO human payload will not include solids; but a trip to Mars should.

Which is not what you said a few posts back:

I will be surprised if the next manned vehicle does not have solid boosters of some kind

You made no distinction about destinations.

Now that Liberty is out of the way, the designers should move towards the most cost effective heavy launch system.

I'm sure they will; the Falcon Heavy has by far the lowest projected costs and could flying within a couple of years. Especially if they dropped the pork barrel that is SLS.

[djellison]

Very clear which one is the real HLV.

Exactly.

[cjameshuff]

Even looking at total mass, the Shuttle's a bad example for solids. Although they never flew, an upgrade to dense liquid boosters was considered at various times which would have raised total mass and thus payload by 8000-9000 kg.

[cjl]

But if you take the figures for maximum payload rather than total mass then you get:

STS: 24,400 kg

Falcon Heavy: 53,000 kg

Very clear which one is the real HLV.

I would make the case that the shuttle is the true HLV between the two, since it put twice as much mass in orbit. Yes, if you're looking at useful payload, the Falcon is the better choice, but if you're trying to make a point about whether large rockets use solids, the fact is the shuttle is a larger rocket than the Heavy, and it uses solids.

(I'm really not trying to argue against liquids here - as I said, I agree that liquids are the best choice for an optimized launcher designed for a single payload class. I just think that they can stand on their own merits, without needing help from questionably broad or sweeping statements about large rockets never using solids)


Cjames: out of curiosity, would you happen to have a link to those upgrade studies? I'd be interested to see what configuration and propellants they considered, since it would be difficult to change out the boosters without dramatically increasing the pad footprint (assuming similar thrust levels to the solids).
EDIT: never mind, I found the LRB studies myself after a bit of searching. It's quite interesting, actually. They studied both LH2 and RP1 powered LRBs - I'm surprised that they would have considered the LOX/LH2 version. The resulting LRBs are enormous (though actually lower mass than the SRBs) - apparently, they didn't have very much of a pad footprint concern. I would have expected that they would have gone with LRBs in the first place in that case though, so I'm a bit puzzled by the design decision to go with solids. Of course, a fair number of things about the Shuttle design puzzle me - it really didn't seem like a very good choice overall, so this is just another thing to add to that list...

[Grashtel]

EDIT: never mind, I found the LRB studies myself after a bit of searching. It's quite interesting, actually. They studied both LH2 and RP1 powered LRBs - I'm surprised that they would have considered the LOX/LH2 version. The resulting LRBs are enormous (though actually lower mass than the SRBs) - apparently, they didn't have very much of a pad footprint concern. I would have expected that they would have gone with LRBs in the first place in that case though, so I'm a bit puzzled by the design decision to go with solids. Of course, a fair number of things about the Shuttle design puzzle me - it really didn't seem like a very good choice overall, so this is just another thing to add to that list...

The shuttle was designed by several different groups with different requirements, its pretty much a classic example of why design by committee sucks

[Garrison]

I would make the case that the shuttle is the true HLV between the two, since it put twice as much mass in orbit. Yes, if you're looking at useful payload, the Falcon is the better choice, but if you're trying to make a point about whether large rockets use solids, the fact is the shuttle is a larger rocket than the Heavy, and it uses solids.

Sorry but how on earth can you ignore useful payload? The shuttle hauling a great deal of dead weight into orbit on every mission was one of the reasons why it was so expensive. It was a lousy advert for solid rockets.

[publiusr]

The orbiter itself was the dead weight--now omitted. Its not just mass--but payload shroud diameter that is of import. Now Shuttle C was to have very wide side mount aerobrake disks according to some drawings from way back. Here is an example of a rigid aerobrake: http://www.wired.com/wiredscience/20...n-1983/aaaotv/ Top mount has its advantages too however. What I really wanted to see myself was Athena III: http://www.b14643.de/Spacerockets_2/...tion/Frame.htm

Falcon Heavy has by far the lowest projected costs and could flying within a couple of years. Especially if they dropped the pork barrel that is SLS.

Falcon Heavy, using dense kerosene--isn't as wide as SLS--which also limits shroud diameter, which HLV experts understand and its critics don't. Musk for LEO, SLS for BEO. It's ULA that is finally on the outside looking in for a change, instead of HLV advocates.

Now, with Liberty out of the picture--what does this mean for ATK? Or Ariane 5's future? The Germans want to keep it--and others want a smaller Ariane 6. Liberty might have been a way to keep something of Ariane 5 itself alive.

[cjl]

Sorry but how on earth can you ignore useful payload? The shuttle hauling a great deal of dead weight into orbit on every mission was one of the reasons why it was so expensive. It was a lousy advert for solid rockets.

I agree that the Shuttle hauling a great deal of dead weight into orbit on every mission was part of why it was expensive. I don't see how you go from that to "lousy advert for solid rockets" though - the rockets don't care whether what they're hauling to orbit is useful or not. If you took the Shuttle off, and replaced it with a giant cargo container with 3 SSMEs on the bottom, the solids would perform just as well, and the rocket would now have a useful payload in the range of a hundred metric tons or so. As such, I judge rocket motor performance (and booster design) based on mass-to-orbit. The fact that the shuttle is spectacularly inefficient in terms of payload mass relative to structure mass doesn't change the fact that 2 SRBs and 3 SSMEs manage to haul over a hundred tons of stuff to LEO (and given a slightly different design, using the same amount of fuel and same boosters/engines, you could absolutely design a ~100 ton class expendable launcher).

[djellison]

2 SRBs and 3 SSMEs manage to haul over a hundred tons of stuff to LEO

Subtract the mass of the SSME's, their thrust structure and aft avionics bay plumbing etc etc. You're not comparing like with like.

Note - in the '90s a study was done to replace the SRB's with LFFB's to try and help cut down on the ludicrous operation costs of the SRB's.

The ASRM's were an utter disaster.

And I quote "NASA believes that the LFBB would cost $4 to $5 billion to develop but would improve safety, reduce long-term operational costs, enable a higher flight rate, and increase the shuttle's payload capacity" - http://www.nap.edu/openbook.php?record_id=6384&page=8

Even NASA didn't want them on the Shuttle.

[Garrison]

The orbiter itself was the dead weight--now omitted. Its not just mass--but payload shroud diameter that is of import. Now Shuttle C was to have very wide side mount aerobrake disks according to some drawings from way back. Here is an example of a rigid aerobrake: http://www.wired.com/wiredscience/20...n-1983/aaaotv/ Top mount has its advantages too however. What I really wanted to see myself was Athena III: http://www.b14643.de/Spacerockets_2/...tion/Frame.htm

Falcon Heavy, using dense kerosene--isn't as wide as SLS--which also limits shroud diameter, which HLV experts understand and its critics don't. Musk for LEO, SLS for BEO. It's ULA that is finally on the outside looking in for a change, instead of HLV advocates.

SLS for cancellation in a couple of years when there's new senate and the costs have spiralled and the schedule has slipped. The SLS won't get any nearer flying than Liberty because it exists for much the same reasons; to milk NASA for cash and protect jobs.

Now, with Liberty out of the picture--what does this mean for ATK? Or Ariane 5's future? The Germans want to keep it--and others want a smaller Ariane 6. Liberty might have been a way to keep something of Ariane 5 itself alive.

Ariane 6 is nothing but a proposal ATM, the Ariane 5 has a lot of life left in it. As for what what this means for ATK; well they still have their cut of the SLS and their involved with the Antares so they'll keep the bucks rolling in rockets that haven't flown.

[Jerry]

Which is not what you said a few posts back:

...
You made no distinction about destinations.

That's because you read what I wrote, not what I was thinking What I think will drive solid strap-ons for interplanetary flight is the smaller launchpad footprint, not politics.

I hate to repeat myself, but I'd still be curious to see a citation for that (your statement here is not a citation - it's an assertion). I know this isn't in ATM or anything, so I'm not demanding you back this up. I'm just having a very hard time believing a 95% solids figure, given that the GEM-60 motors used on the Delta IV (which are very modern, composite-case HTPB based APCP solids) have around 87% solids (interestingly enough, this is very nearly identical to the solids loading of the Shuttle SRBs, which use PBAN), along with a very impressive 275s vacuum ISP (which is very slightly better than the shuttle - possibly due to propellant formulation, possibly due to something else [nozzle expansion ratio?]). I would think that if 95% were achievable, these motors would have well over 90%, given how recently they were designed.

Higher solids are used in some tactical, military and decoy compositions.

These are the best internet source I can find, but you have to read a little between the lines:

http://www.freepatentsonline.com/2926613.pdf

http://www.yang.ae.gatech.edu/public...ropellants.pdf

also

http://www.imemg.org/res/IMEMTS%2020...010-Papers.pdf

Not all formulations are publicly available.

[publiusr]

The SLS won't get any nearer flying than Liberty because it exists for much the same reasons; to milk NASA for cash and protect jobs.

Not so fast--folks have advocated for larger systems before: http://adsabs.harvard.edu/abs/2002AcAau..51..779W DIRECT, etc.
A couple other folks on SLS--Carolyn Porco of the Cassini mission
http://forum.nasaspaceflight.com/ind...8485#msg848485

So, yes, the capability of the rocket DOES come before the mission design and the payload determination.

http://forum.nasaspaceflight.com/ind...8427#msg848427

John Grunsfeld
http://www.nature.com/news/an-astron...ientist-1.9835

"The other is the size of the SLS. If down the road we wanted to launch a telescope that could, for instance, study the entire energy balance of Earth with pixel sizes smaller than clouds, it would take a big telescope. With a big rocket, you can think start to think about launching big optical systems. We think of the SLS as the human spaceflight programme, but it could be hugely enabling for science."

Anti-SLS arguements are wrong for the same reason anti-Curiosity arguements would be wrong. For two billion--you could have had a lot of MER rovers too. But an increase in capability is a good thing.

They are going to need huge aeroshells for anything larger than to go to Mars:
http://www.universetoday.com/96119/i...sions-to-mars/

This earlier article I found to be funny:
http://www.universetoday.com/7024/th...he-red-planet/

Rob Manning the Chief Engineer for the Mars Exploration Directorate says that: “the problem is that right now the heat shield diameter for a human-capable spacecraft overwhelms any possibility of launching that vehicle from Earth....The structure would need to be about thirty to forty meters in diameter. The problem here is that large, flexible structures are notoriously difficult to control. At this point in time there are also several other unknowns of developing and using a Hypercone."

But then he goes on to say: “Mars is really begging for a space elevator,” said Manning. “I think it has great potential. That would solve a lot of problems, and Mars would be an excellent platform to try it.”

So let me get this straight. He has already dismissed future HLLVs out of hand, but then in the same breath talks about a space elevator tens of thousands of miles tall, dwarfing any HLLV. That anti-heavy-lift mindset is what is hobbling us. An HLLV is just a water tower. The best thing is to just build an SLS replacement launcher in about 30-50 years time that is itself 30 meters across and just launch the aeroshell in one piece. Now if you think that sounds large, it is--but not compared to other things we build, like the Troll platform or Very Large Crude Carriers (supertankers)

Heck a reusable HLLV like NEXUS has a bulkhead very broad and shallow--very like a Mars aeroshell would need to be:
http://en.wikipedia.org/wiki/NEXUS_%28rocket%29

Certain Shuttle-C designs had rigid aeroshells the width of an orbiter.
www.astronautix.com/craft/otv.htm
http://adsabs.harvard.edu/full/1992lbsa.conf...17L
http://www.astronautix.com/craft/rideport.htm
http://pdf.aiaa.org/preview/CDReadyM...V2004_3734.pdf


And there are other LV designs that allow for very wide structures as payloads--at least potentially:
www.astronautix.com/craft/bonaucer.htm

More do-able: OTRAG
http://www.astronautix.com/lvs/otrag.htm

Parallel staging allowed very large payload diameters up to 30 m and thrust acceleration to be limited to a maximum of 3 g to allow lighter payload and space vehicle structures. The low cost was mainly achieved by simple design, lack of moving components, cheap commercial materials and components, and large volume production of tens of thousands CRPU's per year.

Getting rid of SLS is the waste. As it stands it is a force driver for new uses of friction stir welding--allowing larger diameters of LV for manned Mars missions to come.
http://www.ncamlp.org/technology/fsw-history.html

Keeping Infrastructure and expertise is NOT pork--no matter how many times that old lie is bandied about. The Chinese know that--and that is why they are building a wider HLV than we are at 9 meters. The Former Soviets are going backwards--if anything: http://www.nasaspaceflight.com/2012/...er-soyuz-2-1v/ Our LV progress has been impressive: http://www.nasa.gov/exploration/systems/sls/

As for what what this means for ATK; well they still have their cut of the SLS and their involved with the Antares so they'll keep the bucks rolling in rockets that haven't flown.

Now that is a reason to worry. With LFBs being talked about--ATKs reason to support for SLS will wane over time. They are looking after themselves to be sure--but so is everyone else in the game. I wonder what Aerojets plans are. They are big solid providers too. I doubt they will have anything like the Stick--but Antares is their baby too, remember. I am happy at the money spent on rocketry development myself.

More on the fallout of ATK's loss: http://thespacereview.com/article/2132/1

[Noclevername]

Now, the OTRAG idea seems like a worthy one to me; I started a thread about it some time back, but it never really went anywhere. Apparently the fact that it's been mocked for so many years is enough to prevent anyone from taking it seriously, despite the fact that it was successful up until it was killed by politics.

[cjl]

That's because you read what I wrote, not what I was thinking What I think will drive solid strap-ons for interplanetary flight is the smaller launchpad footprint, not politics.



Higher solids are used in some tactical, military and decoy compositions.

These are the best internet source I can find, but you have to read a little between the lines:

http://www.freepatentsonline.com/2926613.pdf

http://www.yang.ae.gatech.edu/public...ropellants.pdf

also

http://www.imemg.org/res/IMEMTS%2020...010-Papers.pdf

Not all formulations are publicly available.

Those papers support what I remembered though - the first one is talking about solid fuel for a ramjet, which isn't really all that similar to solid propellant (since the oxidizer is the majority of the volume of a solid propellant, while a ramjet needs no oxidizer), and I didn't see a solids loading mentioned in it anyways (though I'll admit that I just skimmed it once I saw that it was for a ramjet rather than a rocket). The second paper talks about solids in the 88-90% range being possible, and no higher. The third one is actually talking about a different kind of propellant entirely - one with solids down as low as 70% or so, but with a so-called energetic binder, such that the binder itself contributes a substantial amount of energy to the propellant. In this case, the binder is no longer pure HTPB, so it's not really comparable anyways, and as I said, the solids fraction is actually fairly poor to allow for a larger portion of the energetic binder to be used. None of them discuss solid propellant with a higher than 90 percent solids loading.

[Jerry]

My point is was, not every propellant developed is well characterized in publicly available literature. I have personally worked with HTPB propellants with 94+% solid loading.

[R.A.F.]

My point is was, not every propellant developed is well characterized in publicly available literature.

How is it relevant that the "public" know about ALL propellents?

Your statement makes no sense.

[Jerry]

How is it relevant that the "public" know about ALL propellents?

Your statement makes no sense.

It isn't. Many formulas are classified. To say that PBAN and HTPB propellants have the same solid limits based upon publicly available data is not necessarily accurate. In both cases, the limits are not absolute - small motors can be packed with very high solid ratios and still maintain the necessary physical properties. If energetic, cross-linking binders are used, the line between solids and polymers is also blurred - certain 'solids' can be dissolved in polymers just as sugar is desolved in water. (Even ammonium perchlorate goes into partial solution in some cases).

[publiusr]

It isn't. Many formulas are classified.

Probably why the Soviets kept liquid ICBMs for so long--they didn't have the right recipe.

[Jerry]

Probably why the Soviets kept liquid ICBMs for so long--they didn't have the right recipe.

Likely. They were further advanced that we thought; and also unique - we were expecting their solid program to be more or less copies of our own, but they were not; and it is fair to say we learned as much in the technical exchange at the end of the cold war as they did; if not more.

One area that we advanced in tremendously after the exchange is in the choices of fuels for airbags.

[Doodler]

http://www.space.com/17489-nasa-spac...ty-system.html

Maybe it will die now.

[Garrison]

http://www.space.com/17489-nasa-spac...ty-system.html

Maybe it will die now.

For some reason The Who classic 'Won't Get Fooled Again' comes to mind...

[Noclevername]

For some reason The Who classic 'Won't Get Fooled Again' comes to mind...

Meet the new boost, same as the old boost.

[Jerry]

Where the heck does this conclusion come from? To achieve more, we must take a step back and use inferior solid rockets?.... If solids aren't even a part of manned LEO launches, there's no reason to think they'll have anything to do with Mars.

If and only if Mitt wins the presidency (which is a very unlikely scenario) will we see the solid revival I championed and many of you despise...in the US. The US solid industry is gutted - virtually all of the RSRM scientists and engineers are plowing other fields.

[Disclaimer: this is not a Mitt indorsment, I don't want to see it that bad.)

China is a much more likely go to Mars, but frankly, I think the dream of interplanetary human spaceflight is now beyond the horizon of most of us living today.

That said, solid strapons are still the most efficient way to boost the payload of manned or unmanned flights. They reduce both the size and complexity of the launch pad configuration: Solids rarely delay launches; while getting 8-16 turbo driven liquid systems all on the same page at launch time; and making a pad large enought to handle the workload is problematic.

[djellison]

while getting 8-16 turbo driven liquid systems all on the same page at launch time; and making a pad large enought to handle the workload is problematic.

The four active Soyuz vehicles still currently flying include 750 instances of not finding it especially problematic.

[MaDeR]

"Solids are branch of fireworks, not rocketry."
More seriously, about one good thing where solids are useful is ICBM and similar toys (there IS reason for "minute" in Minuteman). Any use in other fields are simply moving partially costs of R&D and operations of solids for military (as if they have little money) on other areas.