- #106
MattRob
- 211
- 29
twofish-quant said:I am mixing science and politics. There's no way that you can deal with issues like the space program without mixing science, politics, and economics.
Quoted out of context... :
MattRob said:...(or more specifically, bending science to match political goals)...
twofish-quant said:It's not. Airplanes are flying fuel tanks. They can get away with a lot because they don't have to carry oxidizers. The problem is that getting you to mach 0.9 at 6 miles is is pretty insignificant for getting you to mach 25 at 100 miles.
The idea is that it would have turbofans so it could fly back to a runway, with a fuel-efficient flight path and good choice of landing site, it wouldn't need to be a "flying fuel tank" because it wouldn't cruise across the Pacific Ocean purely using Turbofans like 747's do, it would just use them to climb. The idea is to take advantage of the fact it already has turbofans, and wouldn't it be more fuel efficient to use turbofans below ~40,000 feet than using rockets the whole way? Once it reaches ~40,000 feet, the mothership could ascend with rockets. There's no reason it can't carry rockets and jet engines. Most airliners carry engines in completely separate modules under the wings. And mixing two different types of engines worked with the B-36 Peacemaker in 1949, it's not exactly a large technical challenge. And wouldn't necessarily have to be limited to ~40,000 feet, the U-2 could cruise above 70,000 feet using turbofans, though I suspect that would require too much performance out of the jet engines for them to remain a modest weight.
twofish-quant said:If you are holding liquid oxygen, then you have to deal with cryogenic fuels. You can deal with room temperature fuels but those don't have the energy content.
Liquid oxygen and Liquid hydrogen are in entirely different temperature ranges. Liquid Oxygen can be liquid at 90K (-297 *F), but Hydrogen boils at 20K (-423 *F). That's not it, either. Absolute zero is an asymptote, which means that half the temperature is far more than twice as hard to reach. Many metals become brittle well before the boiling point of nitrogen, 77K or -320 *F, so I can only assume it must be a great engineering challenge to find a material that is not only still malleable at the range of Liquid Oxygen, but at twice as cold as that. Then you have to build many, many moving parts out of it, turbopumps, valves, etc. and build the entire rocket assembly out of it, fuel tanks, pipes, and other bits. And finally, icing becomes even more of a problem. The insulation on the ET is only needed because liquid Hydrogen is so cold. If the Space Shuttle used RP-1/LOX, Columbia would not have happened, because much stronger insulation could be used, unlike the foam-like material needed for Liquid Hydrogen.
An aside, to illustrate the difference; You could pour liquid oxygen in a coffee thermos, put the lid on (careful not to screw it on), and it'd take it a day or so to boil off. As for liquid hydrogen, I have yet to ever see or even hear of it being stored in anything other than a thick, double-walled vaccum-insulated container.
twofish-quant said:If you ask me the problem with Communism is that they assumed that people would act in different ways than they actually do. *OF COURSE* people will act for personal gain.
If you assume that people don't act for personal gain, you'll end up with a political and economic system that just doesn't work. There are no-doubt people that are self-sacrificing, but people that aren't in it for personal gain, rarely end up in positions of major political or economic power, because they are nice and get eliminated by people that are hungry.
Politicians want votes. Business people want money. Workers want bread and circuses, and scientists (being human) aren't more self-sacrificing than anyone else. Your typical scientist wants funding and glory so that they can papers written. If you get a group of senior scientists together, they'll start gossiping like old women about how they are trying to get funding for their university, and also who is "in" and who is "out".
The problem of getting people to the LEO or the moon is not a scientific problem. We've done it before. It's a business/political problem.
I couldn't agree more, but there is a difference in-between pressing an idea solely for political purposes and personal gain as opposed to doing it for the advancement of mankind, etc. The whole debate over the existence of altruism aside, there's a balancing point where most people fall, and scientific endeavors done because someone wants to make money aren't as successful as ones purely for the sake of science. If it's done to make money, then there are plenty of ways to "succeed" that would actually be failing when it comes to developing the technology. I.e, you don't need the technology to work, you just need to get money out of the whole deal (I believe this is called a scam.). It doesn't matter what technology it is, it's development can be marred in this way.
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