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The whole point of a Rocket Based Combined Cycle (RBCC) engine is to smoothly transition from SCRAM jet, to air-augmented rocket (some air and some LOX), to pure LOX/LH2 rocket. In fact the usual objective for RBCC is to start as RAM jet, that's a fourth mode. RAM jet means ignition at mach 1, flying supersonic with subsonic combustion. I'm saying we can simplify the RBCC engine by eliminating this low-speed mode of operation. Remember, once you do get to the maximum speed you'll need a LOX/LH2 rocket for the final push into space. You might as well smoothly transition to maximize use of air.
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That sounds all pretty and junk, but the mass of the engine and the LOX you need to go from Mach 10-15 to 20+ where pure rocket takes over is going to be pretty big. It can't provide enough subsonic thrust for runway takeoff either I bet.
[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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It's been a while since I talked about this, I guess you forgot. I would use a turbine jet engine that's capable of supersonic combustion. The X-43A was capable of engine start at mach 5, and papers I read in the Journal of Propulsion and Power describe wind tunnel tests by military contractors who already demonstrated a jet-fuel fed turbine engine at mach 6. Using kerosene-based jet fuel to mach 6 not only reduces LH2 required, it permits air-starting the turbine engine after re-entry to provide powered landing.
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Turbine engine capable of supersonic combustion? You must mean to simply use a jet engine (with ramjet or low speed mini-scramjet bypass?) like the ones on the SR-71 Blackbird but updated, to get from the runway to the main Scramjet ignition speeds.
[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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This sounds exactly like the Starrunner concept that I presented at the last Joint Propulsion Conference. We used turbine low speed, ram/scram high speed and then rocket orbital speed. All was integrated into the same engine with the ACES. This was a large concept vehicle as it was for a large payload (something on the order of an ISS module), but the ideas are interesting. In hindsight, I think we would have done somethings different. An RBCC sounds more attractive for simplicity. If you really like to learn about RBCC spaceplanes check out the Hyperion concept by Dr. John Olds of Georgia Tech. StarRunner you can read about in AIAA 2004-3729 and the Hyperion you can read about in AIAA 99-4944.
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I meant a 2 engine system: kerosene fuelled turbine engine to get you up to SCRAM jet ignition speed, then an LH2 fuelled RBCC to thrust into space. An OMS would be needed for orbit circularization and de-orbit, and RCS for manoeuvring.
Hyperion isn't ideal. It would use an ejector SCRAM jet to mach 10, then rocket engines the rest of the way. IIRC, it didn't use an RBCC. I'll look for the papers you mentioned.
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You should be able to find them at http://atlas.ae.gatech.edu/main/publica … index.html.
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I actually thought of this awhile back, but maybe it just didn't sound practical at the time; to scrub off speed so that your entering the atmosphere at the demonstrated entry speed Rutan has shown is possible, we could use nuclear energy.
http://www.spacedaily.com/news/energy-t … 5zzzu.html
The above link is the confirming experiment for sonoluminescent fusion; the funding there will certainly go through the roof in the coming years.
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Uhhhhh. No.
Burt managed to keep his little "shuttlecock" Space Ship One from cooking at suborbital velocities (around Mach 3-5 generally) by adding alot of drag at high altitude where the air is thin... but if you tried to do that from orbital velocities (Mach 25+, over eight times faster), the wings would rip right off and the composite crew cabin would vaporize Columbia style, since you can't use high drag at such high speeds. Burt can't solve that problem with the current SSO design.
I ought to also point out that Burt's ship never made it to orbit. In fact, it never even got anywhere CLOSE to orbit. In order to go into space and stay in space, you have to not only reach an altitude of 200km or so (double what Burt's SSO did), but you must have a ground speed at Mach 25 (parallel to the Earth's surface). Burt's rocket burned every last drop of fuel and inertia to just barely get half way to orbital altitude, and up there it was basically stopped and had almost zero ground speed. In order to push SSO into orbit and carry the other nessesarry equipment that SSO lacks, it would need 200-300X (two or three hundred times) the fuel. It would be so big, it would hardly fit on a 747 jumbo jet.
And thats just for passengers, no payload at all.
If your hope was that the X-Prize was supposed to foster real development of orbital commertial infrastructure, then it failed badly.
MarsDirect, in its stock unmodified form, would NEVER work.
I would like to point out here that the boundry for space is the Karman line. The Karman line is 62 miles ( thats about 100km for you).
"...all I ask is a tall ship, and a star to steer her by."
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Technically yes, but 200km is the minimum for a stable orbit that will last for any length of time, 400km preferably, to avoid air drag even with the very low pressures.
[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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