Jim, do you think VentureStar was possible?
Quote from: Eerie on 12/20/2008 04:40 pmJim, do you think VentureStar was possible?In particular, was the BF Goodrich TPS workable? I wonder if it would have done the job for an SSX-like vehicle...
Just as the shuttle was, but will it be economical?
Quote from: Jim on 12/20/2008 06:17 pmJust as the shuttle was, but will it be economical?Well, it had no boosters and no ET, a true SSTO, so the only question is how expensive its maintenance would be...
Quote from: Eerie on 12/20/2008 06:47 pmQuote from: Jim on 12/20/2008 06:17 pmJust as the shuttle was, but will it be economical?Well, it had no boosters and no ET, a true SSTO, so the only question is how expensive its maintenance would be...and the size of the payload may have been small
Quote from: mlorrey on 12/20/2008 04:44 amThus, you can blame Walter Mondale for the failure of STS (and the loss of one if not both shuttle crews).No, you can blame a NASA management that made safety decisions (if you want to call them that) in a lackadaisical fashion, and in both cases against the advise of the sme’s on the teams. In the case of Challenger, they even disregarded an ATK Technical Bulletin that specifically told them not to fly the SRB’s below a certain temperature. They just flat ignored it, as if to say “Huh, who do they think they are? We’re NASA. They can’t tell us what to do.” NASA management quite simply *chose* to ignore the people who actually knew what they were talking about as if, because they were NASA, and for no other reason what-so-ever, they knew best. The laws of physics wouldn’t dare contradict them. The CAIB was *very* clear in it's condemnation of NASA management in this regard.
Thus, you can blame Walter Mondale for the failure of STS (and the loss of one if not both shuttle crews).
Quote from: mlorrey on 12/20/2008 05:05 am… NASA should use its funds to stimulate private industry to make these things happen with both prizes and contracts once one or more parties achieve the goals set. NASA cannot use its funding for anything except what the Congress specifically authorizes. It has absolutely no wiggle room in that regard.
… NASA should use its funds to stimulate private industry to make these things happen with both prizes and contracts once one or more parties achieve the goals set.
QuoteBoth prizes and contract competitions stimulate private capital to invest in ventures at a much higher level than currently.That takes much deeper pockets than most venture capitalist have available. There are probably only a small handful of such people in the world. Even the conglomerates with much more funding available won’t do it because they have stockholders to answer to who insist on a relatively secured return on investment. Stockholders are not in the habit of authorizing the expenditure of, for example, $5,000,000 to win a $500,000 prize, with no guaranteed $10,000,000 contracts for the winner. It’s a nice idea, but it is not a money-maker. If it doesn’t make money for the investor, the investments don’t happen.
Both prizes and contract competitions stimulate private capital to invest in ventures at a much higher level than currently.
QuoteAs for Obama, I do not expect his team to have this level of vision. Obama wrt the wider economy, seems more New Deal oriented, so the old NASA-as-jobs-program paradigm will IMHO be retained.There is no such thing, except in the minds of a few detractors, as “the old NASA-as-jobs-program”. There is the current condition where because of idiotic lack of real planning and ideological goals rather than goals of excellence and common sense, where we stand to decimate the only highly trained space workforce we have. We did that once, back when Saturn was shutdown. NASA, stupidly, fired them all believing that they could just rehire them when Shuttle was ready. That was stupid, really stupid, because not even one on ten came back. They had other priorities, like food, mortgages, families, so they went elsewhere, to more secure jobs. It took NASA over twenty years to rebuild the majority of the skill sets it lost by that move, and to this very day there are still things we did routinely back in the day that NASA still has no clue how to do.
As for Obama, I do not expect his team to have this level of vision. Obama wrt the wider economy, seems more New Deal oriented, so the old NASA-as-jobs-program paradigm will IMHO be retained.
<snip> a competent engineering team will document everything they do, and a competent management team will preserve that stored knowledge as hard won intellectual capital.
Quote from: Jim on 12/14/2008 06:35 pmNot a matter of want but what we can afford. RLV to replace EELV's and Shuttle are out of the questionWhile I agree that there isn't enough demand for a Shuttle/EELV sized RLV out there, there's nothing that says RLVs have to be Shuttle or EELV sized. In fact there's a lot to be said for having first generation RLVs be a lot smaller than an EELV. At least as small as 5 tons to orbit, possibly as small as 1 ton.But admittedly it would take some changes in how things are done in order to close the case on a small RLV like that.~Jon
Not a matter of want but what we can afford. RLV to replace EELV's and Shuttle are out of the question
Quote from: jongoff on 12/19/2008 02:10 amQuote from: Jim on 12/14/2008 06:35 pmNot a matter of want but what we can afford. RLV to replace EELV's and Shuttle are out of the questionWhile I agree that there isn't enough demand for a Shuttle/EELV sized RLV out there, there's nothing that says RLVs have to be Shuttle or EELV sized. In fact there's a lot to be said for having first generation RLVs be a lot smaller than an EELV. At least as small as 5 tons to orbit, possibly as small as 1 ton.But admittedly it would take some changes in how things are done in order to close the case on a small RLV like that.~JonDrag losses are much worst with small veichles. A small RLV is even more difficult.
A hot structure would have allowed it to meet its performance objectives. Instead we got an aluminum structure covered with foam and a brick chimney that doubled the maintenance man hours required to turn it around each flight. A 5,000 USD per kg payload cost was turned into 20,000 USD per kg by this fact alone. Doubling the maintenance man hours due to TPS maintenance cuts the sortie rate by half and as a result to revenue to cost models quadruple the per unit price ($/kg payload).Other failures: the SME design was too bleeding edge for a viable 'airline' style operation. Try running a taxi service with Formula 1 engines, it doesnt work. It would have been cheaper to design the engines to be inexpensive single use items. That would cut the shuttle turnaround maintenance costs and time by another 25%.If you redesigned and rebuilt Shuttle with a hot frame and inexpensive single use engines today, you'd have a viable system. IMHO it should have been totally redesigned and rebuilt as such after the Challenger disaster.
Mike:I never indicated that the Shuttle design was optimal. That wasn't part of the equation. I was speaking about the immediate cause of the loss of the two crews. I contend, and the STS workforce will agree with me, that in spite of the suboptimal design, Shuttle *IS* safe to fly - when flown safely!We agree on the Challenger. That is laid directly at the feet of an arrogant NASA management. As for Columbia, I contend the same thing. It wasn't Mondale's fault that NASA management *chose* to NOT image Columbia with the Hubble in spite of the fact that their safety organization officially recommended it after the high speed cameras clearly showed the foam hit. Had they done so, it is likely that the hole in the leading edge would have been seen and the crew would have remained aboard ISS for an extended time, saving their lives.
Drag losses are much worst with small veichles. A small RLV is even more difficult.
Not sure about the hot structure (Titanium tend to be horrendously expensive to manufacture). But (on the subject of cheaper engines) they thought about using J-2S instead of SSME. They called that the Mark 1 / Mark 2 "phased" shuttle. Mark I was to have J-2s and ablative heatshield... Mark II would have been upgraded with reusable heatshield and SSMEs.
Titanium airframe with inconel and such. As I recall reading, cost would have been 2-3 times as much as what we got. They still might have wound up using RCC for the leading edges, however if they had and Columbia still happened (foam airstrike), I doubt the titanium would have had problems standing up to ingress of hot gasses.
Quote from: Jim on 12/20/2008 07:22 pmQuote from: Eerie on 12/20/2008 06:47 pmQuote from: Jim on 12/20/2008 06:17 pmJust as the shuttle was, but will it be economical?Well, it had no boosters and no ET, a true SSTO, so the only question is how expensive its maintenance would be...and the size of the payload may have been smallPayload was 10,000 kg right?
Quote from: mlorrey on 12/22/2008 09:32 amTitanium airframe with inconel and such. As I recall reading, cost would have been 2-3 times as much as what we got. They still might have wound up using RCC for the leading edges, however if they had and Columbia still happened (foam airstrike), I doubt the titanium would have had problems standing up to ingress of hot gasses.Somebody asked, somewhere on the forum, how much longer Columbia would have lasted with a titanium structure rather than Alu. IIRC the answer, from CAIB, was about 15 seconds. Not enough to make any appreciable difference whatsoever to the crew's chances of survival.
Thats debatable, and not that simple. I doubt the 15 second figure. Prior experience people go by for example is the plasma damage X-15 suffered on one flight when a test scramjet cause some serious damage simply from the shock wave plasma at hypersonic speed.