After review, I at least somewhat agree with you. FH and the Block-1 SLS are comparable, so FH is a substitute in that range of payloads. SLS is a decent derivation of the DIRECT philosophy of scalable designs, tho it starts a bit too high up the payload curve IMO, and is as always a bit too platinum-plated. NASA of course has a history of doing that, but I expect budgetary considerations over the next decade to knock off some of that chrome - drop the total payload a bit and switch to cheaper main engines, most probably. Assuming of course that SLS survives taxmageddon and the next six months.93143 wrote:[*facepalm*]
You know, on NSF, people who criticize SLS usually have half a clue what they're talking about...
Falcon Heavy is not and never will be a substitute for SLS. Especially after reusability has taken its toll on the payload capacity, assuming they get reusability to work at all (which isn't a given)...
50 Years of Progress in Launcher Design
Vae Victis
I cant wait to see where SpaceX will take the future of human spaceflight. NASA has disappointed me for more than 30 years with empty promises and political decisions over rational decisions. Time to let the private industry take over. I hope SpaceX and CCDev will be so successful that NASA will finance everything the same way in the future. ATK, Boeing, Lockheed and co are only interested in sole source cost plus contracts. They dont want to innovate or take risks with development. Dinosaurs!
I hope we will see less of them and more of the likes of SpaceX in the future.
I hope we will see less of them and more of the likes of SpaceX in the future.
Not really. SLS Block 1 can throw Orion (or a similar-mass module) to the vicinity of the moon. Falcon Heavy in fully-expendable mode may be able to do the same with Dragon, but Dragon is significantly smaller and has much less delta-V of its own.djolds1 wrote:FH and the Block-1 SLS are comparable, so FH is a substitute in that range of payloads.
Even without the ICPS, SLS Block 1 should be able to heave well over 90 tonnes into LEO. The 70-ton figure is legalspeak, a minimum requirement that even Block 0 would have met. Not that LEO performance is terribly important for a gateway-based architecture...
I agree that it's a bit large, but with the 5-seg nearly ready and the 4-seg unavailable it didn't make much sense to build a J-130, and the core stretch and extra engine followed from that - not inevitably, but reasonably given the circumstances and legal requirements. If they can fully utilize the vehicle's capacity (which is, of course, the catch), it should be cheaper than Jupiter per kg...
Well, Block 1B seems to be leaning in that direction already; it keeps the 5-seg boosters and just adds the full-up CPS, rather than moving to advanced boosters first. I don't think an official decision has been made yet...I expect budgetary considerations over the next decade to knock off some of that chrome
I doubt that. The thermal environment under the vehicle requires regenerative nozzle cooling, which means that unless you want to spend a billion dollars or so redesigning the RS-68 (assuming the Air Force will let you), the RS-25 is the only option. The changes to get to the RS-25E are mostly the SSME Block III mods without the advanced internal diagnostics, so it's a low-risk program to get a cheaper and more robust engine. The cost difference between RS-68R and RS-25E isn't all that large, particularly considering the RS-25E's superior performance...switch to cheaper main engines, most probably.
They've already replaced the eyelid-and-dome engine heat shield with a flexible blanket design, saving money, effort, time, and about 700 pounds of weight.
Yeah, the government has made a royal mess of the budget, hasn't it? And their spastic attempts at repair may well fail to take into account the fact that NASA's budget hasn't been bloating with the rest of the government and is not much higher than the agency's baseline structural cost...Assuming of course that SLS survives taxmageddon and the next six months.
@DeltaV: That is an epic video.
No, it's time to fully fund NASA and try to shake some of the politics out. (Not necessarily in that order...) I bet there are tons of engineers there who would love to take a crack at, say, a triprop rSSTO using Aerojet's thrust-augmented nozzle technology, but of course there are no funds for something like that...Skipjack wrote:NASA has disappointed me for more than 30 years with empty promises and political decisions over rational decisions. Time to let the private industry take over.
We should never have shut down the SLI. Though it appears Boeing was good enough to rescue the RL-60, partnering with Mitsubishi to produce the MB-60...
The Aeronautics budget needs to at least double to get back up near its historical level. Apparently their green aviation program is getting to the point where they need to make some major spends...
Everything? Really?I hope SpaceX and CCDev will be so successful that NASA will finance everything the same way in the future.
You must have a very fuzzy notion of what all NASA does...
Besides which, NASA financing stuff that way is a far cry from "let the private industry take over". It basically boils down to contract types and regulatory regimes. And SAA vs. FAR and FFP vs. cost plus are not anywhere near as clear-cut as the angry-blogger types make out. They all have their place. Though I do concur with the sentiment, to a degree...
Explain CST-100. (Or Liberty, for that matter, though the spacecraft was a bit dubious.) Also, ATK offered NASA a very reasonably-priced FFP contract for the SLS boosters at the first hint of competition... speaking of which, there's an interesting lineup of proposals for the SLS advanced booster program...ATK, Boeing, Lockheed and co are only interested in sole source cost plus contracts.
Have you ever heard of ACES/IVF? NGE? RBS? TAN? ACES/IVF in particular has been progressing without apparent government support for some years now, and it looks like it's going ahead. Personally I think the idea of a piston ICE on a rocket (inline 6, if you must know; it runs on fuel-rich hydrolox) is hilarious, but apparently it makes the most sense out of the various options...They dont want to innovate or take risks with development. Dinosaurs!
SpaceX's aggressive low-cost approach has required that they restrict technical innovation to leveraging well-understood technology (such as gas-generator kerolox engines) rather than pushing boundaries. Their main claim to fame in terms of technical innovation is their attempt to come up with an RLV, which hasn't really gotten off the ground yet. It's also not the first time this style of RLV has been attempted, and the market conditions required to support an RLV are such that even if technically successful it's a bit of a gamble. SpaceX is an unusual company; it's not fair to criticize normal companies for being more risk-averse than SpaceX...
That's actually what I dislike most about NASA, and conversely like most about SpaceX and the new startups. The observation has been made since the first Apollo successors were contemplated - NASA designs embody an engineer's technonerd-joy with maximum possible theoretical performance, not a producer's priorities of good-enough at least-cost. My personal preferences are maximum launch rate at least cost, to get the maximum number of homo sapiens sapiens into space at the highest possible rate. But pushing boundaries down the diminishing returns curve hikes costs per Pareto rules - 80/20. If NASA were pursuing the LCLV philosophy necessary to make "a rocket a day" happen, SLS would resemble a scaled-down Truax Sea Dragon, not DIRECT. Who cares about favorable mass fractions and upper-edge propellant performance if the lower cost more than compensates? But an intentionally... crude... design is an offense to the mentality of a rightfully proud engineer. Its also probably an offense to the mentality of a government bureaucracy.93143 wrote:SpaceX's aggressive low-cost approach has required that they restrict technical innovation to leveraging well-understood technology (such as gas-generator kerolox engines) rather than pushing boundaries. Their main claim to fame in terms of technical innovation is their attempt to come up with an RLV, which hasn't really gotten off the ground yet. It's also not the first time this style of RLV has been attempted, and the market conditions required to support an RLV are such that even if technically successful it's a bit of a gamble. SpaceX is an unusual company; it's not fair to criticize normal companies for being more risk-averse than SpaceX...
Vae Victis
I'm not criticizing them for it. It's good that someone's started from a clean sheet and done it. There have been attempts before, but European politics killed OTRAG, and Sea Dragon just never got traction (and may have been too big in any case). DIRECT P2 seems to have... well, I won't comment on that.
Now, SpaceX's designs are not truly MCD. They're a compromise. Those engines, for instance, are very efficient for their class and very powerful for their size. But the mass-production thing seems to be working for them, and they seem to have done good work keeping their operations lean.
...
When you consider what NASA's history has been with launch vehicles, I'm not sure the story is as consistent as you make out. Before STS, it was all fairly unfamiliar, and Apollo had to do what it had to do. It is notable that significant cost reductions were in the pipeline for Saturn V before it was cancelled...
Shuttle was the world's first attempt at an RLV. Given the constraints they were under, and their total lack of hindsight, I'd say they did pretty well. NLS was an attempt to make Shuttle technology cheaper for expendability. The STME program gave us the RS-68, which is very cheap for such a high-thrust hydrolox engine, largely because it is simple.
VentureStar was an attempt at a reusable SSTO. MCD doesn't work very well in that scenario, but there is a case for rSSTO being ultimately the best way to do affordable launch, provided you can make it work.
SLI tried to come up with a number of low-cost reusable engines for use in two-stage RLVs. The Fastrac program produced a low-cost engine design that was actually simpler than the current Merlin engines, comparable to the 1a (it seems Merlin has a fair bit of indirect design and concept heritage from Fastrac). If this line of work had been continued, NASA would have been doing approximately what SpaceX is doing now, at least regarding RLV development.
Then the Constellation program took over and Griffin got hold of it, and the objective was to repurpose existing systems to produce a BEO launch capability as quickly and cheaply as possible. This was botched, of course, and modified into SLS, and here we are...
...
When you think about it, it really isn't NASA's job to reduce costs by mass production and lean operations. That's the private sector's job. NASA's job is to push the technical boundaries so that the private sector has that data and experience and technology to draw on when doing commercial stuff.
SpaceX would be nothing without NASA. They themselves have said so repeatedly.
Now, SpaceX's designs are not truly MCD. They're a compromise. Those engines, for instance, are very efficient for their class and very powerful for their size. But the mass-production thing seems to be working for them, and they seem to have done good work keeping their operations lean.
...
When you consider what NASA's history has been with launch vehicles, I'm not sure the story is as consistent as you make out. Before STS, it was all fairly unfamiliar, and Apollo had to do what it had to do. It is notable that significant cost reductions were in the pipeline for Saturn V before it was cancelled...
Shuttle was the world's first attempt at an RLV. Given the constraints they were under, and their total lack of hindsight, I'd say they did pretty well. NLS was an attempt to make Shuttle technology cheaper for expendability. The STME program gave us the RS-68, which is very cheap for such a high-thrust hydrolox engine, largely because it is simple.
VentureStar was an attempt at a reusable SSTO. MCD doesn't work very well in that scenario, but there is a case for rSSTO being ultimately the best way to do affordable launch, provided you can make it work.
SLI tried to come up with a number of low-cost reusable engines for use in two-stage RLVs. The Fastrac program produced a low-cost engine design that was actually simpler than the current Merlin engines, comparable to the 1a (it seems Merlin has a fair bit of indirect design and concept heritage from Fastrac). If this line of work had been continued, NASA would have been doing approximately what SpaceX is doing now, at least regarding RLV development.
Then the Constellation program took over and Griffin got hold of it, and the objective was to repurpose existing systems to produce a BEO launch capability as quickly and cheaply as possible. This was botched, of course, and modified into SLS, and here we are...
...
When you think about it, it really isn't NASA's job to reduce costs by mass production and lean operations. That's the private sector's job. NASA's job is to push the technical boundaries so that the private sector has that data and experience and technology to draw on when doing commercial stuff.
SpaceX would be nothing without NASA. They themselves have said so repeatedly.
SLS isn't about lowering launch costs. It's about scientific study of the moon, asteroids, and Mars, and risk retirement for private-sector BEO operations. NASA isn't pursuing any launch vehicle philosophy; they just want something that works and is fundable. A clean-sheet design - any clean-sheet design - would take considerably longer than SLS, and would lose a lot of political support. Furthermore, while Shuttle-derived technology is well understood, a clean-sheet MCD rocket might not support high-confidence reliability. Not good for a manned launch system...If NASA were pursuing the LCLV philosophy necessary to make "a rocket a day" happen, SLS would resemble a scaled-down Truax Sea Dragon, not DIRECT.
Yeah, where Boeing has indicated that they will not continue the CST 100 development if NASA does not commit to at least a certain about of launches (with them) a year.Explain CST-100. (Or Liberty, for that matter, though the spacecraft was a bit dubious.) Also, ATK offered NASA a very reasonably-priced FFP contract for the SLS boosters at the first hint of competition... speaking of which, there's an interesting lineup of proposals for the SLS advanced booster program...
And Liberty was dead the moment NASA did not give them any CCDev funding this round. This was actually hillarious to see how ATK made total asses out of themselves, when they first boldly proclaimed that they would continue the development of the Liberty even without NASAs money but then emmediately let it die when that trick did not result in any funding. I am glad they did not get any money. They dont deserve it!
What does "fully fund" mean? I am all for more money for science and NASA in particular, but I am for spending it well.No, it's time to fully fund NASA and try to shake some of the politics out.
I think they should have never shut down the DC-X/Y Delta Clipper whatever you want to call it project. Instead they wasted a fortune on another politically motivated design, the X33...We should never have shut down the SLI.
You must have a very fuzzy notion of what all NASA does...
You should have known how I meant that...
Well take the JWST for instance. I think that they should have done a CCDev like contract for that. The project might have not turned into the desaster that it is now. They could have had several different approaches to a telescope with simillar capabilities for a much lower price...Besides which, NASA financing stuff that way is a far cry from "let the private industry take over". It basically boils down to contract types and regulatory regimes. And SAA vs. FAR and FFP vs. cost plus are not anywhere near as clear-cut as the angry-blogger types make out. They all have their place.
Well they are certainly innovating in a lot of ways. They are not making huge leaps in technology, but they are still innovating.SpaceX's aggressive low-cost approach has required that they restrict technical innovation to leveraging well-understood technology (such as gas-generator kerolox engines) rather than pushing boundaries.
Well their RLV tech got further than anything NASA has ever attempted (with maybe the exception of the DC-XA which was a DOD project initially anyway and was hated and subsequently killed at NASA).Their main claim to fame in terms of technical innovation is their attempt to come up with an RLV, which hasn't really gotten off the ground yet.
It's also not the first time this style of RLV has been attempted, and the market conditions required to support an RLV are such that even if technically successful it's a bit of a gamble. SpaceX is an unusual company; it's not fair to criticize normal companies for being more risk-averse than SpaceX...
The whole myth of the launch rate required to make an RLV pay of is of course a myth too. The launch rate is needed to get a return on the initial developent cost which is naturally higher for an RLV. That however is of course much more relevant for a multi billion government programme with a giant development effort (full of fancy new technology) and a huge standing army to support it), than a slick and comparably low cost, efficient private development effort and operations like the one SpaceX is doing. SpaceX already is profitable with the launch rate that they have, being able to reuse at least part of the vehicle will only make that margin better, not worse. It is also pretty clear from the way the suborbital market has clearly developed that the market for space launches does increase when the prices come down far enough.
Agree with most of what you said here. People are so concerned about mass fractions, when the fuel only makes a completely negligible part of the cost of a rocket launch, e.g. 200,000 out of 50 million for the F9).That's actually what I dislike most about NASA, and conversely like most about SpaceX and the new startups. The observation has been made since the first Apollo successors were contemplated - NASA designs embody an engineer's technonerd-joy with maximum possible theoretical performance, not a producer's priorities of good-enough at least-cost. My personal preferences are maximum launch rate at least cost, to get the maximum number of homo sapiens sapiens into space at the highest possible rate. But pushing boundaries down the diminishing returns curve hikes costs per Pareto rules - 80/20. If NASA were pursuing the LCLV philosophy necessary to make "a rocket a day" happen, SLS would resemble a scaled-down Truax Sea Dragon, not DIRECT. Who cares about favorable mass fractions and upper-edge propellant performance if the lower cost more than compensates? But an intentionally... crude... design is an offense to the mentality of a rightfully proud engineer. Its also probably an offense to the mentality of a government bureaucracy.
Make the cost of the fuel 400,000 and it will barely make a dent in the whole calculation.
SLS is about fueling money to ATK. Shameless Shelby even bragged how he managed to insert the language into the NASA bill to make sure that they have to use ATK for the development of the SLS.SLS isn't about lowering launch costs. It's about scientific study of the moon, asteroids, and Mars, and risk retirement for private-sector BEO operations.
The administrations plan originally wanted a superheavy lifter, but much later and it would have looked much different, probably based on a competition like CCDev.
Waaayy to ambitious. NASA chose the technologically most challenging design of all proposals, because "it would allow them to develop the most new technologies along the way". It was bound to fail.VentureStar was an attempt at a reusable SSTO.
They cancelled the much more promising (and already flying) DC-X for the X33 which was (just like the DC-XA) only a suborbital demonstrator, yet never flew, even after massive cost overruns and delays.
Total joke. Personally I am annoyed with NASA after 30 years of broken promises I have come to the conclusion that they simply can not do it and I think it is time to try something else.
This is all of course BS.A clean-sheet design - any clean-sheet design - would take considerably longer than SLS, and would lose a lot of political support. Furthermore, a clean-sheet MCD rocket would not have the technical history of Shuttle-derived, and thus not as much confidence in its reliability
1. the shuttle was never save to begin with.
2. Constellation was never fast to develop and the SLS is not either.
3. SpaceX clearly shows that a clean sheet design can be done faster than anything NASA has ever attempted.
4. The EELVs have a pretty decent flight history. You can launch crew on them and launch the cargo separately. That is what should be done anyway. It simplyfies operations enormously, since you dont have to worry about failures as much for the pure cargo flights. That makes everything cheaper.
5. The EELVs would actually be capable of doing a BEO mission. There are several studies about this, both by NASA and Boeing. They were held back for political reasons, but some senators like Rohrabacher got really annoyed about this and have been making some noise. Look it up!
It is ridiculous to go to Mars, the moon or an asteroid, if there is no space architecture in place that allows us to do so repeatedly and at a reasonable cost. A one shot stunt mission to the moon was fun the first time arround. There is no need to do it again. If we go to the moon again, we should do it to stay there and never leave. For this we need to have the cost low enough that it stays underneath the political radar. Otherwise it will get cancelled like Apollo did.
Mars is the same issue.
For an architecture like that, the most crucial thing is to make access to LEO affordable and routine. The SLS is not contributing anything to that and thus is worthless, at least at this point in time (though I think it is generally worthless).
Yeah, where Boeing has indicated that they will not continue the CST 100 development if NASA does not commit to at least a certain about of launches (with them) a year.Explain CST-100. (Or Liberty, for that matter, though the spacecraft was a bit dubious.) Also, ATK offered NASA a very reasonably-priced FFP contract for the SLS boosters at the first hint of competition... speaking of which, there's an interesting lineup of proposals for the SLS advanced booster program...
And Liberty was dead the moment NASA did not give them any CCDev funding this round. This was actually hillarious to see how ATK made total asses out of themselves, when they first boldly proclaimed that they would continue the development of the Liberty even without NASAs money but then emmediately let it die when that trick did not result in any funding. I am glad they did not get any money. They dont deserve it!
What does "fully fund" mean? I am all for more money for science and NASA in particular, but I am for spending it well.No, it's time to fully fund NASA and try to shake some of the politics out.
I think they should have never shut down the DC-X/Y Delta Clipper whatever you want to call it project. Instead they wasted a fortune on another politically motivated design, the X33...We should never have shut down the SLI.
You must have a very fuzzy notion of what all NASA does...
You should have known how I meant that...
Well take the JWST for instance. I think that they should have done a CCDev like contract for that. The project might have not turned into the desaster that it is now. They could have had several different approaches to a telescope with simillar capabilities for a much lower price...Besides which, NASA financing stuff that way is a far cry from "let the private industry take over". It basically boils down to contract types and regulatory regimes. And SAA vs. FAR and FFP vs. cost plus are not anywhere near as clear-cut as the angry-blogger types make out. They all have their place.
Well they are certainly innovating in a lot of ways. They are not making huge leaps in technology, but they are still innovating.SpaceX's aggressive low-cost approach has required that they restrict technical innovation to leveraging well-understood technology (such as gas-generator kerolox engines) rather than pushing boundaries.
Well their RLV tech got further than anything NASA has ever attempted (with maybe the exception of the DC-XA which was a DOD project initially anyway and was hated and subsequently killed at NASA).Their main claim to fame in terms of technical innovation is their attempt to come up with an RLV, which hasn't really gotten off the ground yet.
It's also not the first time this style of RLV has been attempted, and the market conditions required to support an RLV are such that even if technically successful it's a bit of a gamble. SpaceX is an unusual company; it's not fair to criticize normal companies for being more risk-averse than SpaceX...
The whole myth of the launch rate required to make an RLV pay of is of course a myth too. The launch rate is needed to get a return on the initial developent cost which is naturally higher for an RLV. That however is of course much more relevant for a multi billion government programme with a giant development effort (full of fancy new technology) and a huge standing army to support it), than a slick and comparably low cost, efficient private development effort and operations like the one SpaceX is doing. SpaceX already is profitable with the launch rate that they have, being able to reuse at least part of the vehicle will only make that margin better, not worse. It is also pretty clear from the way the suborbital market has clearly developed that the market for space launches does increase when the prices come down far enough.
Agree with most of what you said here. People are so concerned about mass fractions, when the fuel only makes a completely negligible part of the cost of a rocket launch, e.g. 200,000 out of 50 million for the F9).That's actually what I dislike most about NASA, and conversely like most about SpaceX and the new startups. The observation has been made since the first Apollo successors were contemplated - NASA designs embody an engineer's technonerd-joy with maximum possible theoretical performance, not a producer's priorities of good-enough at least-cost. My personal preferences are maximum launch rate at least cost, to get the maximum number of homo sapiens sapiens into space at the highest possible rate. But pushing boundaries down the diminishing returns curve hikes costs per Pareto rules - 80/20. If NASA were pursuing the LCLV philosophy necessary to make "a rocket a day" happen, SLS would resemble a scaled-down Truax Sea Dragon, not DIRECT. Who cares about favorable mass fractions and upper-edge propellant performance if the lower cost more than compensates? But an intentionally... crude... design is an offense to the mentality of a rightfully proud engineer. Its also probably an offense to the mentality of a government bureaucracy.
Make the cost of the fuel 400,000 and it will barely make a dent in the whole calculation.
SLS is about fueling money to ATK. Shameless Shelby even bragged how he managed to insert the language into the NASA bill to make sure that they have to use ATK for the development of the SLS.SLS isn't about lowering launch costs. It's about scientific study of the moon, asteroids, and Mars, and risk retirement for private-sector BEO operations.
The administrations plan originally wanted a superheavy lifter, but much later and it would have looked much different, probably based on a competition like CCDev.
Waaayy to ambitious. NASA chose the technologically most challenging design of all proposals, because "it would allow them to develop the most new technologies along the way". It was bound to fail.VentureStar was an attempt at a reusable SSTO.
They cancelled the much more promising (and already flying) DC-X for the X33 which was (just like the DC-XA) only a suborbital demonstrator, yet never flew, even after massive cost overruns and delays.
Total joke. Personally I am annoyed with NASA after 30 years of broken promises I have come to the conclusion that they simply can not do it and I think it is time to try something else.
This is all of course BS.A clean-sheet design - any clean-sheet design - would take considerably longer than SLS, and would lose a lot of political support. Furthermore, a clean-sheet MCD rocket would not have the technical history of Shuttle-derived, and thus not as much confidence in its reliability
1. the shuttle was never save to begin with.
2. Constellation was never fast to develop and the SLS is not either.
3. SpaceX clearly shows that a clean sheet design can be done faster than anything NASA has ever attempted.
4. The EELVs have a pretty decent flight history. You can launch crew on them and launch the cargo separately. That is what should be done anyway. It simplyfies operations enormously, since you dont have to worry about failures as much for the pure cargo flights. That makes everything cheaper.
5. The EELVs would actually be capable of doing a BEO mission. There are several studies about this, both by NASA and Boeing. They were held back for political reasons, but some senators like Rohrabacher got really annoyed about this and have been making some noise. Look it up!
It is ridiculous to go to Mars, the moon or an asteroid, if there is no space architecture in place that allows us to do so repeatedly and at a reasonable cost. A one shot stunt mission to the moon was fun the first time arround. There is no need to do it again. If we go to the moon again, we should do it to stay there and never leave. For this we need to have the cost low enough that it stays underneath the political radar. Otherwise it will get cancelled like Apollo did.
Mars is the same issue.
For an architecture like that, the most crucial thing is to make access to LEO affordable and routine. The SLS is not contributing anything to that and thus is worthless, at least at this point in time (though I think it is generally worthless).
The Cold War killed OTRAG, and Sea Dragon was aiming for Nova class payloads (500 tonnes to LEO) - waaaaaay too big. A small company named Beal Aerospace tried for a modest pressure-fed design similar to Sea Dragon in the late '90s, but the entrepreneur pushing it did not have Musk's wad of cash to finance his dreams. SpaceX ended up buying some of the bankrupt Beal capital plant early on.93143 wrote:I'm not criticizing them for it. It's good that someone's started from a clean sheet and done it. There have been attempts before, but European politics killed OTRAG, and Sea Dragon just never got traction (and may have been too big in any case). DIRECT P2 seems to have... well, I won't comment on that.
Musk & Co. decided to split the difference between mechanical simplicity and proven track record - the later IMO to inspire confidence in potential clients. Essentially, SpaceX is flying a robust/quality R-7/Soyuz, the most reliable rocket family in human history.93143 wrote:Now, SpaceX's designs are not truly MCD. They're a compromise. Those engines, for instance, are very efficient for their class and very powerful for their size. But the mass-production thing seems to be working for them, and they seem to have done good work keeping their operations lean.
LCLV was proposed as far back as '65 or so - NASA opted for Nova, a "breakthrough/banner project." Can't blame NASA for wanting to top Apollo, but the mentality of their leadership seems to always been ten years behind the spirit of the times.93143 wrote:When you consider what NASA's history has been with launch vehicles, I'm not sure the story is as consistent as you make out. Before STS, it was all fairly unfamiliar, and Apollo had to do what it had to do. It is notable that significant cost reductions were in the pipeline for Saturn V before it was cancelled...
Shuttle was an attempt at an RLV, but it became obvious pretty fast that it had failed. Every flight essentially required near-remanufacture of the SSMEs and SRBs. If anything, I'm saddened NASA didn't quietly dump the orbiters and shift to Shuttle-C plus a capsule after Challenger. But they just couldn't give up on that "reusable" cachet.93143 wrote:Shuttle was the world's first attempt at an RLV. Given the constraints they were under, and their total lack of hindsight, I'd say they did pretty well. NLS was an attempt to make Shuttle technology cheaper for expendability. The STME program gave us the RS-68, which is very cheap for such a high-thrust hydrolox engine, largely because it is simple.
SSTO is a VERY hard needle to thread with chemprop technologies - the mass fractions are just too tight, and have been back to Bono's designs in the '60s. Like the "reusuable" cachet of shuttle or the "horizontal take-off = cheap" delusion of scamjets (NOT sp), SSTO seems obvious. It just doesn't work well enough to justify the huge development cost. Throw-aways are cheaper; this is counter-intuitive, and offends the 'Green/recycle' mentalities in place for decades, but its true.93143 wrote:VentureStar was an attempt at a reusable SSTO. MCD doesn't work very well in that scenario, but there is a case for rSSTO being ultimately the best way to do affordable launch, provided you can make it work.
Yup.93143 wrote:Then the Constellation program took over and Griffin got hold of it, and the objective was to repurpose existing systems to produce a BEO launch capability as quickly and cheaply as possible. This was botched, of course, and modified into SLS, and here we are...
NASA's job is to fly rockets. Pushing boundaries should be the job of the national labs.93143 wrote:When you think about it, it really isn't NASA's job to reduce costs by mass production and lean operations. That's the private sector's job. NASA's job is to push the technical boundaries so that the private sector has that data and experience and technology to draw on when doing commercial stuff.
Disagree. SLS is about GETTING to the Moon and perhaps beyond. Only when we're there can the science happen. The vehicle does not equal the mission. Arctic science using nuclear RTGs can be put in place by dog-sled teams, and you're still doing good science. You just aren't looking sexy while doing it. But NASA hasn't been able to look sexy since Apollo-12. Even back then, the complaint was that NASA made going to the moon look boring. Accept that.93143 wrote:SLS isn't about lowering launch costs. It's about scientific study of the moon, asteroids, and Mars, and risk retirement for private-sector BEO operations.djolds1 wrote:If NASA were pursuing the LCLV philosophy necessary to make "a rocket a day" happen, SLS would resemble a scaled-down Truax Sea Dragon, not DIRECT.
Disagree. NASA has been trying for "knockout-impressive" designs since Apollo, and always disappointing. A decades-long track record of over-promising and under-performing does not impress.93143 wrote:NASA isn't pursuing any launch vehicle philosophy; they just want something that works and is fundable.
I'm conflicted as to whether NASA has or hasn't passed its sell-by date. STS put a lot of vested interests in place, all of which are nurtured by any SDLV design. NACA was retired when justified, and a large part of me thinks its time for NASA to tread that path as well.93143 wrote:A clean-sheet design - any clean-sheet design - would take considerably longer than SLS, and would lose a lot of political support. Furthermore, while Shuttle-derived technology is well understood, a clean-sheet MCD rocket might not support high-confidence reliability. Not good for a manned launch system...
Vae Victis
Yuppers.Skipjack wrote:The whole myth of the launch rate required to make an RLV pay of is of course a myth too. The launch rate is needed to get a return on the initial developent cost which is naturally higher for an RLV. That however is of course much more relevant for a multi billion government programme with a giant development effort (full of fancy new technology) and a huge standing army to support it), than a slick and comparably low cost, efficient private development effort and operations like the one SpaceX is doing.
I actually don't care about profitability for government-program launchers. Least-cost allowing highest-rate-flights is my concern there. But NASA is locked into legacy political patronage obligations it put in place 40 years ago with the early STS program, and has been unwilling to challenge since '80.Skipjack wrote:SpaceX already is profitable with the launch rate that they have, being able to reuse at least part of the vehicle will only make that margin better, not worse. It is also pretty clear from the way the suborbital market has clearly developed that the market for space launches does increase when the prices come down far enough.
Truax went even farther with Sea Dragon - simple welded steel casings (vs the stir-welded bleeding-edge lithium-aluminum alloys seen today), no/minimum cryogenic fuels, etc. LH/LOX have the Isp, but the costs for cryogenic tanking soar, the lower density of LH requires fatter tanking, creating drag problems. Trying to cut every last excess gram pushes prices waaaaay down the 80/20 cost curve. Problems spiral.Skipjack wrote:Agree with most of what you said here. People are so concerned about mass fractions, when the fuel only makes a completely negligible part of the cost of a rocket launch, e.g. 200,000 out of 50 million for the F9).djolds1 wrote:That's actually what I dislike most about NASA, and conversely like most about SpaceX and the new startups. The observation has been made since the first Apollo successors were contemplated - NASA designs embody an engineer's technonerd-joy with maximum possible theoretical performance, not a producer's priorities of good-enough at least-cost. My personal preferences are maximum launch rate at least cost, to get the maximum number of homo sapiens sapiens into space at the highest possible rate. But pushing boundaries down the diminishing returns curve hikes costs per Pareto rules - 80/20. If NASA were pursuing the LCLV philosophy necessary to make "a rocket a day" happen, SLS would resemble a scaled-down Truax Sea Dragon, not DIRECT. Who cares about favorable mass fractions and upper-edge propellant performance if the lower cost more than compensates? But an intentionally... crude... design is an offense to the mentality of a rightfully proud engineer. Its also probably an offense to the mentality of a government bureaucracy.
Make the cost of the fuel 400,000 and it will barely make a dent in the whole calculation.
I remain convinced that Falcon Heavy is intentionally designed to enable a bare-bones Mars-Direct architecture; not NASA's platinum-plated Design Reference Mission derivatives, but an even more simplified version of Zubrin's baseline mission design.Skipjack wrote:It is ridiculous to go to Mars, the moon or an asteroid, if there is no space architecture in place that allows us to do so repeatedly and at a reasonable cost. A one shot stunt mission to the moon was fun the first time arround. There is no need to do it again. If we go to the moon again, we should do it to stay there and never leave. For this we need to have the cost low enough that it stays underneath the political radar. Otherwise it will get cancelled like Apollo did.
Mars is the same issue.
The interesting question is whether Musk and the people he sends intend to return. Cut out an Earth-Return Stage, and payload-to-Mars allowances become much more generous. Musk definitely intends to return after being the first human to walk on Mars, but after that?
DIRECT is a smarter design philosophy for a government program than was the Ares family. That's probably the best that can be expected out of a partially broken political system.Skipjack wrote:For an architecture like that, the most crucial thing is to make access to LEO affordable and routine. The SLS is not contributing anything to that and thus is worthless, at least at this point in time (though I think it is generally worthless).
Vae Victis
I dont like DIRECT either. It is also too early for my taste. Zubrin is obsessed with getting to Mars ASAP. Guess he wants it to happen in his lifetime. I would love to see humans travel to LEO once a day, or at least once a week in my lifetime. Today even that seems like a distant dream.
And before we have that, we should not even think about Mars or returning to the moon, but people at NASA love the idea of doing Apollo all over again, which I cant help but find incredibly stupid.
And before we have that, we should not even think about Mars or returning to the moon, but people at NASA love the idea of doing Apollo all over again, which I cant help but find incredibly stupid.
At least its a linear development of the shuttle program. HOPEFULLY that will minimize problems and overruns. Essentially the same total mass budget as STS for 3-5x the payload is attractive. Shuttle-C would've been even easier, but would've lacked the financial grease needed to keep the politicians happy, as well as the psychological impact that "we are moving on."Skipjack wrote:I dont like DIRECT either. It is also too early for my taste.
Zubrin - yes. He isn't getting any younger. Musk I think has good odds of pulling it off. And I wasn't joking about Musk doing one-ways using FH and a simplified M-D architecture. The standard objection to that idea is "suicide! Are you insane?" But a one-way once-a-lifetime trip from London to Plymouth c.1625 was hardly suicide. You just weren't going to see the old country or the extended family ever again. The last 130 years have left us spoiled wrt the assumed ease of travel; we think it is a state of nature that we never be more than seven minutes away from a Lifeflight chopper staffed with EMTs, and never be more than 24 hours from anywhere in the human universe. Lastly, remotes have already done the Henry Hudson-style preliminary reconnoitering, so those willing to roll the bones can move straight to colonization.Skipjack wrote:Zubrin is obsessed with getting to Mars ASAP. Guess he wants it to happen in his lifetime. I would love to see humans travel to LEO once a day, or at least once a week in my lifetime. Today even that seems like a distant dream.
The glory days of youth are a strong attraction.Skipjack wrote:And before we have that, we should not even think about Mars or returning to the moon, but people at NASA love the idea of doing Apollo all over again, which I cant help but find incredibly stupid.
Vae Victis
I am not convinced that this is a good thing. I never liked the design of the shuttle much. Lots of reasons for that.At least its a linear development of the shuttle program.
The reason for problems and overruns are usually not (or not only) in the technology, but in the way these sorts of contracts work.HOPEFULLY that will minimize problems and overruns.