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Air Force Wants Reusable Fly-Back Rockets
FleaPlus writes "The Air Force is initiating a pathfinder program to develop a first-stage rocket booster capable of gliding back to a runway so it can be easily reused. Lockheed Martin has already launched a secretive prototype, and a Cal Poly team has a prototype based on Buzz Aldrin's Starcraft/StarBooster design (video). The Air Force estimates such a booster could cut launch costs by 50% over the current Atlas 5 and Delta 4 rockets, and could also offer a rapid surge/replacement capability if combined with reusable spacecraft like the recently launched X-37B. Initial test flights are planned for 2013."
I hope they can come up with something that works out. This should have been done decades ago when it became clear the shuttle would always be an albatross.
There are plenty of rockets which don't blow up... or at least shouldn't.
The current problem is that these rockets tend to shred themselves to pieces except for their fragile payload, and drop anything that is left into the ocean. This is considered by many to be a waste of an otherwise good rocket. Now, the feasibility and economics of repairing and reusing what is essentially a long tube filled with exploding fuel is a completely different story...
Good luck, engineers.
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Boeing did a study of making a winged Saturn V first stage back in 1962.
http://www.astronautix.com/lvs/winturnv.htm
The payload penalty might be problematic. Also, you can't really cluster more than 2 flyback stages due to the size of the wings. If you could use a parafoil and land with skids, that might solve that problem and to be fair western rockets don't really use clustering (Delta IV Heavy being a notable exception).
Graham
Fifteen years of development by committee, and they'll start construction on something that looks exactly like the Shuttle.
Because this is pretty much exactly where the Shuttle started.
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Isn't the shuttle such an albatross precisely because reusability is so impractical?
Nope. It's because somebody goofed and they made the wings too big. As I heard it back then (caveat: didn't check it myself):
The shuttle was supposed to be a combined civilian and military vehicle, so the design budgets could be combined and the cost per unit could be brought down by building a bunch of 'em.
Civilian stuff mostly orbits equatorial and near-equatorial, launching eastward to get a boost from the Earth's rotation. This would be launched east from Canaveral, so crashes would be into the Atlantic. A lot of military stuff orbits polar or near polar, and doesn't get the boost. This would be launched south from Vandenberg, so crashes would be into the Pacific.
Without the boost from the Earth's rotation you get a significant reduction in payload capacity. There's a rule of thumb for computing this.
The shuttle lands as a glider. The wings are partly for steering it for cross-track on the way down. The farther the worst-case sideways distance from your orbital track to the landing site is, the bigger the wings you need.
For typical missions the Shuttle doesn't need much cross-range capability: You just wait for the orbit closest to going right over the landing site and go down then. This happens twice per day. You could get away with little stubby wings like the X-15.
But the military wanted to be able to run another mission profile: A polar, pop-up, once-around shot, landing back at the launch site. This would be for things like spying in a war or near-war situation, when you'd want to get the shuttle down with the info right away and also before the enemy could shoot it down. Problem with this is that the earth moves the landing zone out from under the orbit and you need a lot of cross-range capability to do it. So you need big wings.
So they ran a sanity check on whether the polar orbit was still doable with the big, heavy wings needed for this mission. They're heavy, and that weight comes right out of payload, so the payload capacity would be reduced and the cost-per-pound to low orbit raised a bunch. But it looked like the polar orbit could still launch a decent-sized cargo. So they went with the big wings.
But when they'd run the sanity check they'd applied the rule-of-thumb to the CARGO weight. Somebody had forgotten that, since it also ended up in orbit, the orbiter itself, along with the crew and their consumables, WAS ALSO PART OF THE PAYLOAD. So you have to apply the rule of thumb to the TOTAL weight: Payload, orbiter, consumables, reentry fuel, yadda-yadda-yadda.
Once they did the computation right it turns out that the shuttle would only have a couple hundred pounds of payload to polar orbit. No launching spy satellites for you! Oops!
So the military didn't end up using the shuttle (except for a couple equatorial shots testing some gear). They built their own big boosters and went their separate way. The Vandenberg shuttle launch site was demoted to an emergency landing site (so the shuttle could be landed if Canaveral had bad weather and then piggybacked to Canaveral rather than relaunched from Vandenberg). The military didn't buy any craft and the whole cost of construction and operation fell on the civilian projects, raising the cost-per-pound still further.
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I think you gravely misunderstand and underestimate the rigors of rocketry. The stresses encountered are nothing at all like in your car or even a jet turbine. You're basically continually exploding gallons of fuel per second at very high temperatures and pressures. Right on the other side of the bell, you have turbopumps spinning at very high speeds and at cryogenic temperatures. Toss in the monstrous vibrations and stresses, sorry, you DON'T reuse the parts.
If a rocket flies succesfully, you know the design works, kind of. The engineering is at or beyond the bleeding edge. In the Apollo days there was a lot of fudging and kluging to get the F-1 to work, and the Space Shuttle is no better.
This is because this stuff is HARD. Materials don't get stronger or behave differently because they're in rockets. They're manufactured, designed and built by humans and are subject to the same limits as any other product,
Basically, you know the design works, you keep the design. And you build many many many rocket parts. You use those.
Sort of like Formula One motors. No one reuses them. Why not? No one cares. You build them. You use them, they wear out after 20 hours, and you build another one. Simpler, cheaper, better.
Well gee, since you insist. Over the next few years we use what we have, making minor improvements while we're still using it. But a horse can only go so fast and so far. And this tech could never hold up to thousands of daily flights needed for true commercial development. It's way too complex and fragile.
The more distant future will require an entire rethink of our understanding of nature. If lightspeed is a true brick wall, then we can forget about it. Space travel will remain forever impractical. It would be like being stuck with nothing faster than the old sailing ships and their not exactly great survival rates. I think we're still missing many key ingredients to make these (to me unfathomable) assumptions. So I still have hope.
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How often it happens is a product of orbital inclination and orbital altitude, for a typical Shuttle mission it happens on average twice a day.
That's what the designers of the Shuttle thought too, way back at the start of the design process. Then they actually started doing mission analysis - and discovered how very wrong they were. It turned out that average of only twice a day could leave the crew stranded, unable to reach a safe landing site, for periods of up to eighteen hours. Not good in the event of a problem on orbit, and the only way to fix it was to add cross range capability (read: bigger wings). They also discovered that lack of cross range capability limited the choice of abort scenarios and limited the orbital inclinations the Shuttle could reach. All of this meant the wings started growing - big and fast.
Wrong. Shuttle capacity to polar orbit is notionally 28000 pounds. (Probably greater now with the reduced weight External Tank developed for ISS missions.)
Wrong again. At least one military Shuttle mission went into a 61 degree orbit. Several launched classified satellites.
Sort of like Formula One motors. No one reuses them. Why not? No one cares. You build them. You use them, they wear out after 20 hours, and you build another one. Simpler, cheaper, better.
SpaceX regularly test-fire their engines with full mission-duration burns, then use the same engines on their launchers. Their engines are designed for re-use, to the extent of avoiding ablative coatings and materials wherever possible. They've even been careful to design for immersion in salt water so that in theory they can recover first stages, give them a quick going over, and whack them back on the launch pad.
As someone who works in the space industry, I think that saying, "You shouldn't reuse rockets," is a rather blinkered and negative attitude. With that sort of stance, how could we ever improve the state of the art?
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