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Why not use the Dark Sky Station to launch conventional chemical rockets? That high up Air resistence is minimal, meaning less fuel is neede to attain orbit, right?
Another design I've thought of would be similar to JPAs current design, although intsead of Helium it would use Hydrogen, the envelope would be made of steel, and it would carry onboard O2 (or H2O2 or some other Oxidiser). It would burn the Hydrogen for thrust (maybe after using an Ion drive/Vasimr to attain max. speed possible with that sort of propulsion). On orbit the crew would be able to gain access to the envelope, which would be converted into living space. On re-entry the high-drag design would help, meaning it could use steel heat shielding (like the X-33). Once in the atmosphere it would generate lift initially, and then craft would meet it (if that's feasible) and refill it with Hydrogen (unless it was possible to do that before re-entry). After docking with the DSS it would be checked over and readied for another flight.
So, any comments? I know the last parts probably aren't feasible, but the others?
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Even at that high of an altitude there is still some drag to contend with, so a low-thrust electric engine (ion, vasimr) probably can't approach orbital velocity with such a bulky space ship.
So, a DSS station is only good for giving you altitude, which as previously established is only good for suborbital flights, not orbital.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Altitude is good for reducing drag though, which does help.
I wasn't talking about using Ion/Vasimr to accelerate to orbital velocity. I was talking about burning the Hydrogen in the envelope to generate thrust.
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The amount of thrust you could generate with the very low pressure Hydrogen aboard the balloon would be very small. Remember that the pressure in the balloon decreases with altitude, and so by the time you reached near-space height its pressure would be nil. Pumping the gas would itself require energy, and given the low pressure the amount of energy needed to compress the hydrogen would be prohibitive.
Drag really isn't much of a problem, and neither is altitude, speed is everything... stop trying to fight tooth and nail for a little altitude, speed is what you need.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Why not use the Dark Sky Station to launch conventional chemical rockets? That high up Air resistence is minimal, meaning less fuel is neede to attain orbit, right?
Another design I've thought of would be similar to JPAs current design, although intsead of Helium it would use Hydrogen, the envelope would be made of steel, and it would carry onboard O2 (or H2O2 or some other Oxidiser). It would burn the Hydrogen for thrust (maybe after using an Ion drive/Vasimr to attain max. speed possible with that sort of propulsion). On orbit the crew would be able to gain access to the envelope, which would be converted into living space. On re-entry the high-drag design would help, meaning it could use steel heat shielding (like the X-33). Once in the atmosphere it would generate lift initially, and then craft would meet it (if that's feasible) and refill it with Hydrogen (unless it was possible to do that before re-entry). After docking with the DSS it would be checked over and readied for another flight.
So, any comments? I know the last parts probably aren't feasible, but the others?
Didn't we discuss this before? The logistical difficulty of launching from a balloon, greatly outweighs any advantage you get from launching 10-20km off the ground. It would be cheaper just to build a slightly bigger booster.
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Ah yes, airships part way to orbit. I remember this thread...
Drag is proportional to air density, and proportional to the square of the velocity, right? So, something going at 4km/s where the air density is say 0.001kg/m^3 will have the same drag, assuming it has the same frontal area, as something that's going at 1km/s through an air density of 0.016kg/m^3 (yes, I know this doesn't always hold true when you're going hypersonically). Anyway, we've built reusable aircraft capable of going at 1km/s, so what I want to know is whether we could build a reusable airship capable of going at 4km/s high in the atmosphere. What would be the best shape to minimise drag?
Once we're at that velocity, we'll drop off a disposable solid upper stage and put a few hundred kilogrammes in LEO. As soon as it falls away from the craft, we should rise and start to decelerate (since we'll have switched the engines off), so it should clear the craft quite quickly. I'm thinking the airship would launch from a nearspace station somewhere near America, and switch off halfway across the Atlantic so that it can decelerate to arrive at a station near Britain, where it will be checked over and fly back across for it's next launch.
Once that's ready, and we've proved the bigger version which puts 1 tonne in orbit (maybe a 10 tonne stage?), we move on to a reusable methlox spaceplane...
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