AHC: Tortoise Vs Rabbit. (X15 instead of Mercury. )

[DougM]

So the X15 was slowly increasing the technology/ability to fly higher and faster. So much so that it was nosing up to being a spacecraft or space plane.
When Nasa and the Kennedy administration got into the space race it became evident that a capsule design would be (arguably) faster and easier to develop. And being as NASA was as much a political/propaganda tool as it was anything else Whatever got the job done sonnest was the preferred choice

So my question is… If we avoid the We chose to this this because it it is hard political retoric. Would it have been possible to use a different approach to get into orbit/space such as a next generation X15? Would it have been possible to develope a system to go to the moon using this space plane to get into orbit. Presumably a Earth orbit rendezvous . Using some sort of luner orbit transfer vehicle or some such.
If so would this have resulted in a more usefull and longer lasting technology? Because ultimatly the US has developed 3 families of space craft. The Mercury/Gemini/Apollo family of capsules , The shuttle, and the disaster that is whatever we will get from Boeing. And once we moved on the the next we tossed the previous tech out the window.

I know this evolution would take longer and require more hardware to be created but ultimately would it have been more sustainable?
The Apollo concept of Lunar Orbit rendezvous was a bit like building a ship to cross. the Atlantic that carries a truck to cross Panama and the truck carries another ship to cross the Pacific, Nothing is ideal for the job it is doing. And it is all scraped when its job is done.

Note I understand that for quick and dirty get the job done this is probably best. But ultimatly. A ship for the Atlantic, a port in NY, a train train to California, a port in California and another ship for the Pacific is going. yo work better. Last longer. and move more people. Even though the build cost will be a LOT more and take longer.

Although that brings up the point that if we didn't rush it would the cost savings from not rushing everything help offset the cost? And would we have develouped new technology that we could exploit elsewhere? Perhaps avoiding the Space Shuttle issues, The mess with X33 and now the Orion disaster.

So what do we think could have been if somehow the USSR doesn't embarrass the US with Sputnik and its early successes in space?

 

[Polish Eagle]

X-15 and X-20, despite looking like spacecraft, were really more hypersonic research testbeds, and not well-suited for the rigors of orbital flight. To a large extent, that's why X-20 got canned down the line. When the USAF did capability studies, they found that modified Gemini capsules would be able to do the work orbital X-20 was supposed to, but better--and X-20's original reason for existence, "boost-glide," was rendered obsolete by missile development.

The other thing that drove Mercury into existence was the very real question in the 1950s of whether humans could function at all in microgravity. The USAF would have looked like Grade A jerks if they got their ultra-high-performance aerospace fighter onto the runway, flew it to orbit, and promptly killed the pilot because the human heart won't beat in microgravity or something.

If the US beat the USSR into orbit with both machine and man, you would see Mercury develop into Block I Apollo, and a space station of some sort by 1970. Whether the US reaches the Moon at all afterward is an open question--stagflation and the changing culture of the early 1970s will both kneecap the US space effort in the 1970s.

 

[DougM]

Yes the X-15 was not perfect, and would not do the job of Mercury. That is kind of my point. But NASA was created and went with Mercury and Gemini and Apolo not because it was the best design nor the best long term option. It was chosen because it was the fastest option to get there. (Wherever there was).
Attempting to build a a better long term solution was going to take longer, which would not be good for propaganda or politics.
Mercury was built (to a degree) on the ICBM projects, Gemini was built from Mercury(sort of) and Apollo from that. But once we landed on the moon we basically tossed the baby out with the bath water and what did we do? We went back to the space plane. But not having developed that much in the last decade or so it was to complicated and we didn’t know enough to get it done then the mess with the Air Force and we get the Shuttle. When we looked for a Shuttle replacement we looked for a spaceplan again but once again we try for to big a leap. So when that bombed we fell back on the “simpler” capsule concept that is “Orion” But by this time we have a program that doesn’t know what it is doing. Which is mot a surprise as they (NASA and its suppliers) had never really ran a successful program that had long term goals it was always either a crash program with almost no limits on cost or it was an over blown project that tried to do to much on to small of a budget.

If NASA does not go down the Rush/money no object direction it did with Mercury/Gemini/Apollo and continue a slower more methodical method we could have developed a NASA with a corporate culture of getting the job done on a reasonable budget in a realistic time frame and with an incremental improvement of technology. Instead we got one that was running multiple developments without consideration to technology future development and cost. And we got a population with unrealistic expectations. “We went to the mine in 9 years, why is it taking so long to do X”. All of this comes from the way we handle the space program .

As for the X-15. It was not a true spacecraft but it was sneaking up on it. There is a reason it had thrusters to control its flight. Ands there was plans being developed to do a version using a rocket. If we hard started down this road we could have learnt the lessons needed to figure out a long term space. Plane. You cant go from Kittyhawk to XB-70 or B-747. You have to learn incrementaly what does and does not work.
The issues that doomed Challenger and Columbia could have potentially been avoided if we had learned to crawl before we tried to run.

 

[Dr. Hochmeister]

The X-15 was a technological dead end as the "spaceplane" concept relied on scramjet propulsion to lower the fuel load relative to conventional rockets. The aerodynamics of complex hypersonic flows are still problematic to model with modern computing power. The following NASA doc provides some excellent background info on the topic:

https://history.nasa.gov/sp4232.pdf

Now there is a lot to be said for a less frantic NASA push into space producing more economical and robust long-term results than OTL's Apollo/shuttle trajectory, but going down such a path would hinge more on political decisions rather than going with spaceplane tech over rockets.

 

[Workable Goblin]

The X-15 was a technological dead end as the "spaceplane" concept relied on scramjet propulsion to lower the fuel load relative to conventional rockets.

Not precisely. The idea of a "spaceplane" covers a wide range of concepts, some of which did rely on the idea that some form of high-hypersonic propulsion would reduce propellant requirements, others of which did not. Primarily, this can be seen as a divide between HTHL (horizontal takeoff, horizontal landing) proposals, which absolutely require scramjets or another form of high-hypersonic propulsion and VTHL (vertical takeoff, horizontal landing) proposals, which instead use conventional rockets for takeoff and utilize their aerodynamic capabilities only for recovery the way other rockets and vehicles use parachutes or retropropulsion. In fact every actually flown spaceplane has been of the latter type, and there are certain grounds for arguing that this type of spaceplane is good or at least sensible in at least some applications. For example, a winged booster (of the type proposed for use with the Space Shuttle at several points) could be recovered with a lower degree of technical complexity than required for pure retropropulsion and a comparable degree of weight penalty (that is, the weight of wings works out to be similar to the weight of propellant you need for a SpaceX-style approach).

In any case, though, a spaceplane-centric approach to spaceflight, while extremely interesting to contemplate, does not seem likely to occur. The sticky wicket here is that Mercury and Apollo were not crash responses to Kennedy's speech (obviously for Mercury, since the first crewed flights were before the lunar goal was announced!). Instead, they were started earlier, in the late 1950s, as programs to, respectively, do an initial flight into space and check whether humans could actually function and survive in space, and experiment with various "practical" uses of space, including supporting a space station and perhaps venturing around the Moon (that is, with a fly-by) late in the 1960s or in the early 1970s. Apollo was turned into a crash program, but it had actually broadly taken the shape we know today before Kennedy's speech--a capsule, three astronauts, duration long enough to go around the Moon or carry out a Moon landing. In both cases a number of different lifting options were studied and considered, but in both cases it became apparent that they would add cost and complexity without offering a lot of benefit, so these lifting options were dropped (this was particularly serious for Apollo, since wings are just not suitable for lunar return, so at best you can get away with some kind of lifting body). Something similar happened to Gemini, where a number of different approaches to adding some degree of lift capability, particularly the Rogallo wing, were studied, but in the end the benefits didn't seem to be worth the cost and complexity. And even, or maybe especially, if NASA has a more "step-by-step" corporate culture instead of a "giant leap" culture, being cheaper, safer, simpler, and faster to implement is pretty attractive.

Meanwhile, the X-15 was simply not an orbital vehicle. It could get into space as a suborbital vehicle just fine, but it was extremely, extremely marginal for orbital flight even if it was beefed up and attached to a bigger booster. No one would put an X-15 into orbit unless it was a crash program, but in that case a small amount of study would show that you could build a simple capsule even more quickly and cheaply, and it would be safer and more useful as well, so it's hard to see why you would ever do it. The X-20 is more interesting, but mainly as a testbed for related technologies, without a lot of capability on its own. Maybe it could serve as a substitute for Mercury, but as Polish Eagle says there were real questions about whether a pilot would be able to operate a complicated spaceplane after being in space, so Mercury's simpler and more automated design was more attractive as a first step, and then X-20 really doesn't get you anything besides testing out operational aspects of a hypothetical future spaceplane. Frankly, a lot of the time it's not really clear what a spaceplane gets you that a conventional capsule doesn't--it's no accident that one of the proposals in the Orbital Space Plane program (which was effectively killed by Columbia and the Vision for Space Exploration) was, in fact, a capsule, because all of the actual missions that the OSP was supposed to carry out could be done just as well or better by a capsule as by a spaceplane.

So what would the space program look like if it had been Vanguard and Shepard instead of Sputnik and Gagarin? Well...probably a lot like OTL's, in terms of vehicles (other aspects would likely be very different). Mercury was the obvious place to start a human spaceflight program--a small, simple capsule that could be launched a few times to check whether humans can function in the space environment and test short-duration flights before moving on. Apollo was the obvious next step--a bigger, more capable capsule that could carry more people, accomplish a wider range of missions, and test what people could do in space, assuming that they could survive. Gemini was an unexpected bonus--a development of Mercury that could do a lot of the things Apollo was meant to do but more quickly and cheaply and (arguably) more safely as well. Shuttle was an idea that had been percolating for a long time, and made sense if you thought that you were going to be in space to stay--something that could (theoretically) carry people and cargo into space more cheaply and routinely than previous vehicles, taking Apollo's tests of what people could do in space into large-scale operation. There are logical reasons to expect analogues of all of these to exist. Maybe not always as actual vehicles--you could very well see Gemini buried if there's no rush to try to prepare for the Moon landings, for instance--but the ideas were so obvious that once you get to the late 1950s it's hard to see them not appearing.

About the only way I can see this happening is if the Air Force gets control of the human spaceflight program somehow, and they balk at launching anything without wings on it into space. But even they carried out the Man In Space Soonest studies beginning in 1956 that concluded a ballistic capsule very similar to Mercury was the way to go. You really need to do some deep surgery on the space program to get anything like the posited scenario to happen.

 

[Dr. Hochmeister]

Not precisely. The idea of a "spaceplane" covers a wide range of concepts, some of which did rely on the idea that some form of high-hypersonic propulsion would reduce propellant requirements, others of which did not. Primarily, this can be seen as a divide between HTHL (horizontal takeoff, horizontal landing) proposals, which absolutely require scramjets or another form of high-hypersonic propulsion and VTHL (vertical takeoff, horizontal landing) proposals, which instead use conventional rockets for takeoff and utilize their aerodynamic capabilities only for recovery the way other rockets and vehicles use parachutes or retropropulsion. In fact every actually flown spaceplane has been of the latter type, and there are certain grounds for arguing that this type of spaceplane is good or at least sensible in at least some applications. For example, a winged booster (of the type proposed for use with the Space Shuttle at several points) could be recovered with a lower degree of technical complexity than required for pure retropropulsion and a comparable degree of weight penalty (that is, the weight of wings works out to be similar to the weight of propellant you need for a SpaceX-style approach).

In any case, though, a spaceplane-centric approach to spaceflight, while extremely interesting to contemplate, does not seem likely to occur. The sticky wicket here is that Mercury and Apollo were not crash responses to Kennedy's speech (obviously for Mercury, since the first crewed flights were before the lunar goal was announced!). Instead, they were started earlier, in the late 1950s, as programs to, respectively, do an initial flight into space and check whether humans could actually function and survive in space, and experiment with various "practical" uses of space, including supporting a space station and perhaps venturing around the Moon (that is, with a fly-by) late in the 1960s or in the early 1970s. Apollo was turned into a crash program, but it had actually broadly taken the shape we know today before Kennedy's speech--a capsule, three astronauts, duration long enough to go around the Moon or carry out a Moon landing. In both cases a number of different lifting options were studied and considered, but in both cases it became apparent that they would add cost and complexity without offering a lot of benefit, so these lifting options were dropped (this was particularly serious for Apollo, since wings are just not suitable for lunar return, so at best you can get away with some kind of lifting body). Something similar happened to Gemini, where a number of different approaches to adding some degree of lift capability, particularly the Rogallo wing, were studied, but in the end the benefits didn't seem to be worth the cost and complexity. And even, or maybe especially, if NASA has a more "step-by-step" corporate culture instead of a "giant leap" culture, being cheaper, safer, simpler, and faster to implement is pretty attractive.

Meanwhile, the X-15 was simply not an orbital vehicle. It could get into space as a suborbital vehicle just fine, but it was extremely, extremely marginal for orbital flight even if it was beefed up and attached to a bigger booster. No one would put an X-15 into orbit unless it was a crash program, but in that case a small amount of study would show that you could build a simple capsule even more quickly and cheaply, and it would be safer and more useful as well, so it's hard to see why you would ever do it. The X-20 is more interesting, but mainly as a testbed for related technologies, without a lot of capability on its own. Maybe it could serve as a substitute for Mercury, but as Polish Eagle says there were real questions about whether a pilot would be able to operate a complicated spaceplane after being in space, so Mercury's simpler and more automated design was more attractive as a first step, and then X-20 really doesn't get you anything besides testing out operational aspects of a hypothetical future spaceplane. Frankly, a lot of the time it's not really clear what a spaceplane gets you that a conventional capsule doesn't--it's no accident that one of the proposals in the Orbital Space Plane program (which was effectively killed by Columbia and the Vision for Space Exploration) was, in fact, a capsule, because all of the actual missions that the OSP was supposed to carry out could be done just as well or better by a capsule as by a spaceplane.

So what would the space program look like if it had been Vanguard and Shepard instead of Sputnik and Gagarin? Well...probably a lot like OTL's, in terms of vehicles (other aspects would likely be very different). Mercury was the obvious place to start a human spaceflight program--a small, simple capsule that could be launched a few times to check whether humans can function in the space environment and test short-duration flights before moving on. Apollo was the obvious next step--a bigger, more capable capsule that could carry more people, accomplish a wider range of missions, and test what people could do in space, assuming that they could survive. Gemini was an unexpected bonus--a development of Mercury that could do a lot of the things Apollo was meant to do but more quickly and cheaply and (arguably) more safely as well. Shuttle was an idea that had been percolating for a long time, and made sense if you thought that you were going to be in space to stay--something that could (theoretically) carry people and cargo into space more cheaply and routinely than previous vehicles, taking Apollo's tests of what people could do in space into large-scale operation. There are logical reasons to expect analogues of all of these to exist. Maybe not always as actual vehicles--you could very well see Gemini buried if there's no rush to try to prepare for the Moon landings, for instance--but the ideas were so obvious that once you get to the late 1950s it's hard to see them not appearing.

About the only way I can see this happening is if the Air Force gets control of the human spaceflight program somehow, and they balk at launching anything without wings on it into space. But even they carried out the Man In Space Soonest studies beginning in 1956 that concluded a ballistic capsule very similar to Mercury was the way to go. You really need to do some deep surgery on the space program to get anything like the posited scenario to happen.

Some very good points here, it was probably a bit to harsh to call the X-15 a dead end, but as you point out capsules were the slower, more methodical approach while winged vehicles were more of a technological leap. Unless you're using air-breathing propulsion a winged vehicle doesn't really buy you anything in terms of getting to space; you're just going to stick it on a rocket anyway like the shuttle was. On the way down it does potentially allow you to bring back more stuff as well as expensive components like the engines, as well as have more control over where you land. But that all comes at the cost of the challenges in upkeep on the heat shielding and the mass you could be sending up into space if you didn't have to schlup a bit wing up the gravity well too.

 

[Polish Eagle]

I wonder if you couldn't leverage the X-15 technology into a reusable booster for the "original" Apollo plan. Flyback Saturn I-type vehicles with Apollo CSMs on top. If NASA does commit to Apollo-Skylab-type operations in the late 1960s, could a reusable Saturn I first stage have been in the cards?

 

[Workable Goblin]

But that all comes at the cost of the challenges in upkeep on the heat shielding and the mass you could be sending up into space if you didn't have to schlup a bit wing up the gravity well too.

For LEO flights, that all ends up being a bit "six of one, half a dozen of the other"; parachutes aren't massless, after all (and for flights that don't go to orbit at all, wings can be very competitive, a jet-powered flyback booster would be more or less competitive on weight with Falcon 9, once you take into account boostback and landing propellant). The problem is more that lifting vehicles (winged or not) don't quite scale down as much as capsules do if you only want to launch three or four people, and they can't handle BLEO flights very well (especially if winged). But if you want a slightly larger vehicle or have certain special requirements then lifting vehicles of some kind are quite reasonable, see Dream Chaser for a modern example (albeit an unflown one).