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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."
"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" -
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.