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Skylon Spaceplane Design Passes Key Review
gbjbaanb writes "A revolutionary UK spaceplane concept has been boosted by the conclusions of an important technical review. Skylon is a design for a spaceplane that uses engines that work as normal jets near the ground and switch to rocket propulsion in the upper atmosphere. The concept means the plane will not have to carry as much fuel and so will not need disposable stages. It is estimated (by its developers) that the Skylon will drop the cost of delivering payloads to orbit from $15,000 per kilo to $1000."
This spaceplane is still in the concept phase. They're not even planning to build it until the 2020's. Right now it's all just fund-raising and hype. All this review says is "Well, it COULD work."
In fact, this thing has apparently just the latest version of a spaceplane that has been in the development stage since 1982 (no, that's not a mistake--1982), and has already went through quite a bit of government and private money, with little more to show for it than some concept art and promises. Add to this the fact that they're emphasizing cause-du-jour selling points like "the environmentally-friendly green rocket" in their promotional literature, and I'm a little skeptical.
More power to them if they can build it though. The real first test will come when they're supposed to actually build a test engine this summer. Deliver something to me in the real world that actually works, and you'll get my attention.
SJW: Someone who has run out of real oppression, and has to fake it.
A few points:
1) Everyone else is still using capsules. Don't see how going back to using one ourselves means we're now "behind" the others.
2) The shuttle itself is little more than a glorified, odd-shaped capsule. It still depends on rockets to push it into space; and it has to basically be re-built between flights.
3) You're neglecting the work done by companies in the US. NASA isn't all we've got. Sure, virgin galactic and the others aren't there yet, but they're a hell of a lot closer than this piece of marketing -- and that's ALL this piece is; they haven't made anything yet, much less a working anything.
"The 10 or 20 kilometers that you can save by using this kind of design is really a small fraction of the distance to cross"
Distance isn't the problem for getting to orbit, velocity is.
By running as a plane you don't have to burn thrust to support the weight of the craft and fuel, you can accelerate up to Mach 5 (as they plan to) using the atmosphere to support you. That's a truly massive gain, for reference the first stage of the Saturn V got you up to just over mach 6. Now I don't know what percentage of their fuel they burn to get to that speed but to not have to support that weight with thrust for such a long period is a huge gain. Remembering as well that during this phase they are air breathing too which is another massive gain.
Fine you say mach 5 is 1/5th of the way to mach 25. so at best they've saved 20%, better but still not amazing.
Not quite because you get a weird multiplier effect, because (when you are at say mach 5) you have accelerated the fuel you carry to mach 5 so it effectively has more energy that when it was at rest on the ground. If you run the numbers for a multistage rocker you'll find that they can't reach orbit unless you take this effect into account. Trying to find a good source for this, will hopefully reply to this later with said source...
"The weirdest thing about a mind, is that every answer that you find, is the basis of a brand new cliche" -
From what I learned in physics class, the cheapest way to get through the thick atmosphere is to go straight up.
That's only true for conventional rockets. The longer you remain in the lower atmosphere, you more rocket fuel you must carry. The more fuel you must carry, the larger the rocket you require. The larger the rocket you require, the larger the engine. The larger the engine, the more fuel you must carry. This is a nasty spiral simply because you obtain 100% of your lift from thrust.
With the skylon design, you are obtain a lot of your lift - from lift. Its only after you're passed through the lower atmosphere, where you don't get much lift and where you now need an oxydizer for your fuel, that you need to start a rocket engine. Thusly, they've side step a massive problem with traditional rockets.
Furthermore, its the first stage on traditional rockets which requires the most fuel to obtain orbital velocities. By using a plane's features, a massive weight burden (and associated size) is removed from the design.
>> "And now, while the ESA is moving forward, America is jumping backwards even more, going back to 60's Apollo-era capsules. And that's after a long development schedule while we're piggybacking on the Russians."
The Space Shuttle concept was designed in the late 1960. Aside from upgraded cockpit avionics much of the system is 60's era tech.
Take a position. Are we behind or not? Everyone is ahead of us (you say) yet the only other countries to launch men into space (Russia and China) have done so with capsules. China's capsile was a disposable single use system. The CEV is a re-usable system which finds close parity with the Soyuz.
The US using capsules again is an acknowledgment that strapping your vehicle and crew to the side of a rocket is more dangerous than placing them at the top. A capsule can be mission specific. A capsule can be redesigned much easier than modifying a space shuttle or place where a system wide impact study must be done. The Space Shuttle was a difficult system to upgrade for this reason. A capsule can have the latest system upgrades since it is self-contained. The Soyuz has gone through dozens revisions for this reason.
Aside from landing on a runway what was gained from the shuttle in a practical sense? Longer turnaround between missions? A small fleet a complex vehicles instead of a large inventory of simpler capsules? When safety is concerned, simple wins. The Russians launch men into space more often because they use a simpler system.
America really should never have been a superpower; it was an accident of history. The only reason America became a superpower is because of WWI and WWII; Europe was devastated in those two wars, and America got rich rebuilding them, as we were the only industrialized nation left standing (except maybe for Australia, but they didn't have much industrial capacity like America did).
Yes, it was also an accident of Geography that America was full of natural resources, farm-able land, and room to expand. And an accident of politics and colonialism that led to America's freedom of speech and religion which was a big early draw for immigration. But yea, if you discount the massive natural resources, the great natural protective barriers of the Oceans, the political climate that cause immigration, the policies that kept her out of European wars as long as possible, and the huge industrial base is used to help win those wars, I don't see why America ever should have become a super power. I mean, it's not even the Country with the most letters in it's name.