GIGANTIC Aviation Week story, Pentagon has been flying 2-stage orbital spaceplane throughout 1990s |
GIGANTIC Aviation Week story, Pentagon has been flying 2-stage orbital spaceplane throughout 1990s |
Guest_BruceMoomaw_* |
Mar 6 2006, 02:24 AM
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#1
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Guests |
It may even have been manned:
http://www.aviationnow.com/avnow/news/chan...ws/030606p1.xml My God, what a story -- if it's even partially true. And, judging from this article, they are absolutely certain they have proof (along with proof that the thing, although it works, has recently been mothballed as not cost-effective). It's important to keep in mind, though, that this thing is NOT a workable prototype of the originally planned 2-stage winged Space Shuttle. The second stage -- the spaceplane that actually achieved orbit -- was relatively small and probably very inefficient as a cargo carrier; its advantage lay in allowing the US to get a military reconaissance (or weapons) satellite into orbit surreptitiously, with no advance warning of the launch going to other countries. Even at that, as I say, AW reports that the thing has been recently canned as not worth its (doubtless huge) black-budget expense. |
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Guest_BruceMoomaw_* |
Mar 6 2006, 07:54 AM
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#2
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Guests |
Jeffrey Bell, that eternal party-pooper, caught not only that one but a large set of what look like additional downright fatal errors in the whole story, to wit:
______________________________________ This story is riddled with absurdities: "A large 'mothership,' closely resembling the U.S. Air Force's historic XB-70 supersonic bomber, carries the orbital component conformally under its fuselage, accelerating to supersonic speeds at high altitude before dropping the spaceplane. The orbiter's engines fire and boost the vehicle into space." Starting out from Mach 3 and ~100,000' will not give enough of a boost that a small single-stage vehicle can reach orbit, or even a once-around trajectory. Whoever wrote this article has been reading too much t/space propaganda. "The manned orbiter's primary military advantage would be surprise overflight. There would be no forewarning of its presence, prior to the first orbit, allowing ground targets to be imaged before they could be hidden." Soviet missile-warning satellites would pick up the IR plume from the second stage, and since it would not be at a known space launch site they would interpret it as a covert nuclear missile launch. At a minimum you would get a major diplomatic crisis, at worst an accidental nuclear war! "The spaceplane is capable of carrying an advanced imaging suite that features 1-meter-aperture adaptive optics with an integral sodium-ion-sensing laser." This technology only works looking up, not down. The turbulent layer in the atmosphere is close to the ground and far away from orbit. You don't need it in space (besides the provocation of firing a laser at a Soviet installation from orbit). "The orbiter's belly appears to be contoured with channels, riblets or 'strakelets' that direct airflow to engine inlets and help dissipate aerodynamic heating. These shallow channels may direct air to a complex system of internal, advanced composite-material ducts, according to an engineer who says he helped build one version of the orbiter in the early 1990s." Composite materials are held together with epoxy glue and are highly flammable (see DC-X fires). You need Ti or steel for hypersonic intake ducts because the air is red-hot. "One version of the B-70 could have been used as a recoverable booster system to launch things into low-Earth orbit. . . . The DynaSoar program, the first effort by the [U.S.] to use a manned boost-glider to fly in near-orbital space and return, was considered in this context in November 1959. The B-70 was to carry the 10,000-lb. DynaSoar glider and a 40,000-lb. liquid rocket booster to 70,000 ft. and release them while traveling at Mach 3. With this lofty start, the booster could then push the glider into its final 300-mi. orbit." Again, the rocket equation tells you this won't work. You would need something bigger than Titan II for the booster and that is far too heavy for the B-70 to lift. North American was notorious in those days for proposing unworkable ideas, e.g. the orbital X-15. So to me, this article has as much credibility as last year's article on spaceships powered by zero-point energy. It seems that AvWeek's staff now lacks even basic technical knowledge. __________________________________________ Which presumably means that I do too, since I didn't catch any of this at the time. Put not your trust in Aviation Week, apparently (although I still wonder if this may have been a distorted version of a real story). |
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Mar 6 2006, 07:56 PM
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#3
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Member Group: Members Posts: 688 Joined: 20-April 05 From: Sweden Member No.: 273 |
Actually this is a rather typical Jeff Bell effort. Partly true, partly exaggerated and partly nonsensical
QUOTE This story is riddled with absurdities: "A large 'mothership,' closely resembling the U.S. Air Force's historic XB-70 supersonic bomber, carries the orbital component conformally under its fuselage, accelerating to supersonic speeds at high altitude before dropping the spaceplane. The orbiter's engines fire and boost the vehicle into space." Starting out from Mach 3 and ~100,000' will not give enough of a boost that a small single-stage vehicle can reach orbit, or even a once-around trajectory. Whoever wrote this article has been reading too much t/space propaganda. Actually it just about would. It would cut the deltavee needed for LEO from 9.5-10 kms-1 to something like 8.5 kms-1. With an Isp of 450 s (similar to the Shuttle main engine or the X-33 aerospike engine) this would require a fuel fraction in the 80-85% range which is perfectly practical for a small single stage ELV with a recoverable Corona-style capsule. Whether it is practical for a spaceplane is perhaps more dubious. QUOTE "The manned orbiter's primary military advantage would be surprise overflight. There would be no forewarning of its presence, prior to the first orbit, allowing ground targets to be imaged before they could be hidden." Soviet missile-warning satellites would pick up the IR plume from the second stage, and since it would not be at a known space launch site they would interpret it as a covert nuclear missile launch. At a minimum you would get a major diplomatic crisis, at worst an accidental nuclear war! Fortunately the Soviet Union doesn't exist any longer, and even when it did I don't think they would have started a nuclear war every time a smallish missile or sounding rocket was launched anywhere in the World. QUOTE "The spaceplane is capable of carrying an advanced imaging suite that features 1-meter-aperture adaptive optics with an integral sodium-ion-sensing laser." This technology only works looking up, not down. The turbulent layer in the atmosphere is close to the ground and far away from orbit. You don't need it in space (besides the provocation of firing a laser at a Soviet installation from orbit). True QUOTE "The orbiter's belly appears to be contoured with channels, riblets or 'strakelets' that direct airflow to engine inlets and help dissipate aerodynamic heating. These shallow channels may direct air to a complex system of internal, advanced composite-material ducts, according to an engineer who says he helped build one version of the orbiter in the early 1990s." Composite materials are held together with epoxy glue and are highly flammable (see DC-X fires). You need Ti or steel for hypersonic intake ducts because the air is red-hot. This is the nonsense part. Titanium and steel besides being heavy are useless at hypersonic speeds. The X-15 used them, and that was about the end of the line. There was repeated problems with heat damage and when the X-15 was modified to exceed Mach 6 an ablative coating had to be added (and even so there was serious damage on that Mach 6.72 record flight). Apparently Bell is unaware that more than one type of composite material exists. Actually just about the only feasible material would be SiC-coated RCC composite. QUOTE "One version of the B-70 could have been used as a recoverable booster system to launch things into low-Earth orbit. . . . The DynaSoar program, the first effort by the [U.S.] to use a manned boost-glider to fly in near-orbital space and return, was considered in this context in November 1959. The B-70 was to carry the 10,000-lb. DynaSoar glider and a 40,000-lb. liquid rocket booster to 70,000 ft. and release them while traveling at Mach 3. With this lofty start, the booster could then push the glider into its final 300-mi. orbit." Again, the rocket equation tells you this won't work. You would need something bigger than Titan II for the booster and that is far too heavy for the B-70 to lift. North American was notorious in those days for proposing unworkable ideas, e.g. the orbital X-15. Since the Dyna Soar was meant to be launched from the ground by a Titan III it seems to me a rather smaller booster would suffice. A 40,000 lb booster does sound a bit on the small side to reach orbit, but not absurdly so. tty |
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