November 30, 2013
Our current rocket technology is, needless to say, quite primitive. Because of inherent problems with using a reaction drive, space launch is very expensive.
But it doesn't need to be. A reaction drive (that's any drive that is based on momentum change caused by high speed ejection of propellant) can be extremely efficient if the exhaust velocity is high enough. Our current problem is that the exhaust velocity of our rockets isn't all that high, so propellant efficiency is terrible.
In Mouretsu Pirates they have direct conversion of matter to energy, which is able to provide the kind of power that current rocket engineers could only dream of. And they also have inertia control and gravity control.
I was trying to think about how their thrusters work, and it suddenly occurred to me that it might be a form of gravity control. If the propellant is subjected to several hundred G's, and achieves an exhaust velocity of one or two percent of C, the propellant efficiency would be very high, and you've solved the major problem.
They have single-stage-to-orbit shuttles, and if they were powered the way I think they are, then it becomes very practical to build large structures in orbit, like the docking station orbiting Uminoakehoshi. Combined with efficient FTL drives (which they also have) then bulk interstellar trade becomes practical.
We can only dream of such technology, but it doesn't cost anything to dream.
UPDATE: Of course, they couldn't operate that way all the time. If they were firing 0.02*C while exiting from a space dock, they'd punch a hole in the side of the station with their exhaust.
Have you seen the recent stories on the theoretical warp drive? The Puppyblender just posted one today--the mathematical estimate for the required mass just dropped from Jupiter to a subcompact car. I particularly liked the scientist's approach--the math says it's theoretically possible, but he makes no promises that it will actually work in the real world, and is building small-scale tests to find out.
Posted by: BigD at November 30, 2013 02:41 PM (VKO9N)
Have you seen the recent stories on the theoretical warp drive?
Yes, but I don't want to talk about it here. Please avoid topic drift.
Posted by: Steven Den Beste at November 30, 2013 04:29 PM (+rSRq)
(I have some personal theories about the relationship between time and gravity that are irrelevant to the discussion of thrusters, but might come into play with Warp technology).
Posted by: Mauser at November 30, 2013 06:08 PM (TJ7ih)
I figure they're using water. There's no reason to use anything else. The density is reasonable, and it's easy to pump around, and it isn't very corrosive, and it isn't poisonous. And, of course, it's plentiful down on the planet.
Certainly they could be using something like lead, but why bother? Anything they could get by using something truly dense, they can also get by increasing the exhaust velocity. Assuming easy energy and gravity control, they don't have a problem doing that.
Posted by: Steven Den Beste at November 30, 2013 09:08 PM (+rSRq)
Posted by: Pete Zaitcev at November 30, 2013 09:09 PM (5aqkA)
As for not throwing away rockets, one should take a good long look at what SpaceX is doing with their booster, once they're ready to re-ignite and stabilize on re-entry, they might be touching down on its tail at the launchpad the way God and Robert Heinlein intended. Kerosene is cheap, they say.
Posted by: Mauser at December 01, 2013 04:44 AM (TJ7ih)
You're still thinking in terms of expensive lift. When you have the technology to lift material in thousand-ton lots, water isn't particularly any more valuable than anything else.
But water can be held in tanks, and run through pipes, which is a bit difficult for nickle-iron.
Posted by: Steven Den Beste at December 01, 2013 06:40 AM (+rSRq)
Granted, this depends on being able to do the m/e conversion in a rocket chamber.
Posted by: metaphysician at December 01, 2013 08:32 AM (3GCAl)
Well, probably not. The system seems to be set up like a diesel-electric engine is set up, with power being produced by the matter converters Ago and Ungo, and power then being fed to the thrusters.
Posted by: Steven Den Beste at December 01, 2013 09:30 AM (+rSRq)
Posted by: Siergen at December 01, 2013 04:27 PM (c2+vA)
Posted by: Steven Den Beste at December 01, 2013 07:07 PM (+rSRq)
Posted by: Mauser at December 01, 2013 08:21 PM (TJ7ih)
Enclose all spoilers in spoiler tags:
[spoiler]your spoiler here[/spoiler]
Spoilers which are not properly tagged will be ruthlessly deleted on sight.
Also, I hate unsolicited suggestions and advice. (Even when you think you're being funny.)
At Chizumatic, we take pride in being incomplete, incorrect, inconsistent, and unfair. We do all of them deliberately.
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