Quote from: truth is life on 02/09/2015 10:16 pm....From a purely technical standpoint, a perfectly reasonable system that could have achieved all of the principle goals of both sides was surely achievable...and such a vehicle could surely have been designed to have been more economical and safer than STS proved to be...In hindsight there is limited credible basis this was practically achievable. In fact the core problem was the pervasive assumption that "surely a reusable winged vehicle is the way forward". This mindset was deeply ingrained from the 1950s onward. Von Braun's associate Walter Dornberger may have coined the term space shuttle, and described it as "an economical space plane capable of putting a fresh egg, every morning, on the table of every crew member of a space station circling the globe".When you combine this compelling, seemingly plausible vision with success of the X-15 and Dyna-Soar (even thought it never flew), it's understandable how this led to a superficial, optimistic viewpoint that a large winged LV can be made with airliner-like turnaround and operating costs.In retrospect you can almost rekindle the reasoning: X-15 was turned around in two days, there were plans for orbital versions, shuttle will be like that only bigger. Obvious problems like TPS, engines and turnaround had facile solutions. TPS would use "new technology", the J-2 engine actually has a long lifetime, how hard could the SSME be? George Mueller's solution for turnaround was "automated checkout", which he said would make it possible for a small ground crew to carry out the preflight checks, achieving true aircraft-like simplicity. In his vision each major system would have built-in health and trend monitoring as a fundamental core element. This would facilitate targeted servicing, especially attractive in an era of clipboards and visual inspection of gauges and pen plotters.Unfortunately the devil is in the details. IF this was achievable (which is unclear), it would have required a dogged, persistent focus on how every design decision along the way affected serviceability and turnaround goals. From the smallest access panel, to cable routing, to subcomponent selection, to overall vehicle architecture.
....From a purely technical standpoint, a perfectly reasonable system that could have achieved all of the principle goals of both sides was surely achievable...and such a vehicle could surely have been designed to have been more economical and safer than STS proved to be...
So, I think we've established there was little chance of there being a joint NASA/USAF launch system in the early 70's, but assuming the two -could- play nice, what might a joint LV have looked like?
Quote from: Lobo on 02/10/2015 11:03 pmSo, I think we've established there was little chance of there being a joint NASA/USAF launch system in the early 70's, but assuming the two -could- play nice, what might a joint LV have looked like?It seems to me we're then looking at something like the low-cost expendables that I mentioned a few posts back. I think we can be confident such a thing would have saved money, because, unlike the Shuttle, its development would not have entailed much technological risk. Maybe NASA could have built a re-usable crew vehicle to ride on such a thing, as an X-vechicle for a reusable shuttle, if nothing else.
OK then something both could use.Atlas V like-Core plus US able to lift ~30,000 lb to LEO. ( No SRB's for crew safety, add bells and whistles for crew launch )US most likely Centaur V1 or V2.New crew capsule. Three minimum seating or more if NASA wanted more crew within the mass limit of the two stage lifter.( Land-landed reusable capsule ) Add Atlas V like SRB's for added lift. ( That would be 70's tech )NASA has it's own launch pad and USAF has it's own pad.Manufacture takes orders from both NASA and USAF.Latter if greater payload mass was needed they could add in the tri-core option with cross feed.
Quote from: RocketmanUS on 02/12/2015 03:29 amOK then something both could use.Atlas V like-Core plus US able to lift ~30,000 lb to LEO. ( No SRB's for crew safety, add bells and whistles for crew launch )US most likely Centaur V1 or V2.New crew capsule. Three minimum seating or more if NASA wanted more crew within the mass limit of the two stage lifter.( Land-landed reusable capsule ) Add Atlas V like SRB's for added lift. ( That would be 70's tech )NASA has it's own launch pad and USAF has it's own pad.Manufacture takes orders from both NASA and USAF.Latter if greater payload mass was needed they could add in the tri-core option with cross feed.On the right track now. In early 70's there were no Atlas like SRB's. There were Titan III segmented SRB's, and Minuteman ICBM small monolithic SRB's. (as I understand).New motors could be made for a new launch system. Basically an EELV 20 years early. It'd be a new development but probably wouldn't have been overly expensive. What core and engines would you use. would this be just two stage? or multi stage? GG kerolox engines and hypergolic engines with relatively low ISP typically had two stages to LEO. Titan III was 2.5 stages to LEO. Atlas and Atlas II used the MA-5 which dropped 2 of it's three nozzles partway up to help performance. Saturn 1 and 1B were two stage to LEO LV's. I believe Proton's first two stages are to get it to LEO. And Saturn V/Skylab LV was basically a 2 stage to LEO LV.Also, it'd have to have good performance to LEO specifically as that's what NASA's needs were. As to where current EELV are more optimized for BLEO than LEO because that was USAF/DoD's primary need. Falcon has better LEO performance compared to it's BLEO performance. If Falcon had a hydrolox 3rd stage on it, it'd have fantastic BLEO performance. Which is why I was thinking something like a large Falcon, with an optional Centaur-D 3rd stage (could be later upgraded to Centaur-T size) for those BLEO payloads for USAF. It'd have great LEO performance for NASA and other LEO payloads. And solids could be omitted entirely and the focus on economics of scale of the liquid engines, with the possibility to have a reusable engine ring.An alternative would be to have a hydrolox core powered by J2S, with Titan III SRB's as sort of a 70's version of Ariane 5. That would satisfy NASA's excitement over hydrolox as the miracle propellant and the core could possibly get all the way to disposal without the need for a whole 2nd stage. But unmanned LEO paylaods would still need a kick stage as there's no big orbiter to do it. But, I think that would be more expensive...and obviously hydrolox is temperamental.If going that route, probably better to make the core kerolox with like 4 or 5 H-1's, and Titan III SRB's, and make it essentially a kerolox version Titan III. Could launch with or without the boosters. Without booster it'd cover the Titan II/III and Atlas-Centaur payloads with more capacity than those. With Titan III SRB's it'd be Titan IV/STS performance. The Titan IIIM UA1207 man rated SRB's would probably need to be developed for this configuration as NASA would need to launch with those SRB's for it's missions. (Could be made reusable if desired).But I still like that SRB-less “Large 1970’s Falcon 9” the best so far. :-)
...although it seems nobody was paying attention, one 1966 study of X-15 operations (attached) concluded that "the present estimates and extrapolations for future reusable boosters and orbital space vehicles appear to be overly optimistic in comparison to the actual X-15 experience, especially in the length of time required for turnaround."...The paper also notes that turn-around costs were about 3% of the cost of a new vehicle. Apply that to the fully-reusable Shuttle that was meant to cost $10 billion (1971 dollars) for a fleet of five, and NASA's projections of $6 million per flight look awfully optimistic.
...More generally on the question of the Shuttle's economics, two RAND studies...indicated that a shuttle did not make economic sense unless the space program were going to be ramped up quite a bit.
In hindsight there is limited credible basis this was practically achievable. In fact the core problem was the pervasive assumption that "surely a reusable winged vehicle is the way forward". This mindset was deeply ingrained from the 1950s onward. Von Braun's associate Walter Dornberger may have coined the term space shuttle, and described it as "an economical space plane capable of putting a fresh egg, every morning, on the table of every crew member of a space station circling the globe".
It implies there was a better alternate design available with the money, knowledge and technology in 1971 which would have achieved the goals. This is by no means clear.
Most of the STS alternatives discussed in this thread have a fatal defect: they LOOK old-fashioned by the standards of the average person in 1969-71. We had all been conditioned by SF artists, Von Braun/Disney animations, and corporate PR departments to expect that ICBM technology would eventually be replaced by sleek winged spaceships. Anything that LOOKED conventional -- couldn't have been sold as advanced technology-- couldn't have been sold as more spectacular than anything the USSR might do-- couldn't have been sold as cheaper than pressing on with Titans and/or Saturns.This is why the program stuck with the "fully reusable" flyback booster until the Phase B sudies showed it to be unbuildable, and why people even today criticise the final STS design as "old-fashioned" or "inferior".Most of these designs also ignore the real unstated goal of the program: preserving the Apollo industrial base during a period of strong anti-technology, anti-space public sentiment. That's why the program was originally intended to last a maximum of 10 years, by which time space would be back in public favor again and the Space Task Group program would finally be funded.