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This Defense Intelligence Reference Document, prepared by the Defense Intelligence Agency and dated 8 March 2010, was produced under the Advanced Aerospace Weapon System Applications (AAWSA) Program. It gives a historical and technical review of how to reach space and return. It covers hypersonic gliders, air-breathing and rocket propulsion, thermodynamics and materials, and launch options. It argues that reliable, schedulable access to low Earth orbit is mainly a hardware and propulsion problem rather than a technology one.
“The Advance”12 pages
UNCLASSIFIED//FIHl 8FFHil.t.k Wfili IH.k\f cases, the low-pressure hydrogen exiting the expansion turbines is entered into the rocket motor at a matching pressure. LACE Deeply Cooled -H,----, Figure 29. Two Rocket Air-Breathing Rocket Cycles to Mach 5.5. To the left is one employing liquefied air (LACE cycle). To the right is one employing high-pressure air cooled to near saturation. There is always the option of direct ascent by rocket into a trajectory. Whether by turbojet or rocket, a million pounds of thrust is always noisy and smoke filled. We can thank the Russian design bureaus for arriving at a concept that eliminated the noisy, smoky, and hazardous launches by increasing the operational flexibility of the British HOTOL concept. Figure 30 shows the development of the all-rocket HOTOL system from the original HOTOL. 23 The original air-breathing rocket HOTOL, powered by the Rolls Royce 545 engine as developed by Alan Bond, essentially used all hydrogen fuel (except for space operations). The hydrogen required a volume about 5 times greater than a 6: 1 LOX/hydrogen propellant for a rocket engine. The classical aerodynamicist's approach was to minimize drag and maximize the L/D ratio. But accelerating to orbital speed requires a low angle of attack and minimum drag coefficient at l<>c.,"HB.,I II<>!<>] =-_,_----,- -- ______ D_I__ Figure 30. HOTOL Evolution: From Aerodynamic Optimum Configuration to Practical Launcher Configuration. The latter was developed through British Aerospace-Russian cooperation. zero lift (Coo), not maximum L/D ratio. The simple problem, recognized by KOchemann, was that the vehicle was too slender and therefore had a large wetted area compared with its reference planform area; hence, zero lift drag and structural weight were too high. Even when the BAE Systems team switched to an all-rocket and compromised the slenderness, this did not significantly reduce the wetted area. The Russian approach was to design a stout vehicle with a much lower ratio of wetter area to reference planform area. 24 The trapezoidal cross section of the FDL-7/Model 176 yields a ratio of wetted area to planform area less than the circular cross section of the 27 UNCLASSIFIED/;CEiOAt OFFIGIPk IP&'i Ollk¥
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 56 pages are in the text index: search them above, or from the library's search.