Launch vehicle, Atlas V |
Launch vehicle, Atlas V |
Jun 3 2006, 01:19 PM
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#1
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Member Group: Members Posts: 134 Joined: 13-March 05 Member No.: 191 |
NASA has decided to use the Atlas V, with 4 strap-on solid rocket boosters to launch MSL. This is the same rocket that launched MRO (no solids) and New Horizons (5 solids).
Cost: $194.7 million, less than half the price of the Titan IV which would have been needed a few years ago. Rocky Mountain News article NASA press release |
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Guest_DonPMitchell_* |
Jun 4 2006, 06:20 PM
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#2
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Guests |
Let's look at some numbers. Here are some figures for vacuum and sea-level specific impulse, which measures engine efficiency (and thrust in metric tonnes). The F-1 was the biggest engine ever built, but it was based on an old-fashion gas-generator cycle:
F-1 (Saturn V) - 304 265 (790 tons) YF-20B (Long March) - 289 259 (83 tons) Staged compustion is the current state of the art, and this gives you significantly more thrust per kilogram of fuel. The Proton managed 316 sec. even using less efficient fuels (N2O4 + Dimethylhydrozine). At the time of the F-1, only the Russians had mastered staged combustion design: RD-253 (Proton) - 316 285 (178 tons) NK-15 (N-1) - 318 297 (157 tons) RD-180 (Atlas V) - 338 311 (423 tons) RD-701 (MAKS) - 415 330 (408 tons) Today we see the benefits of both staged combustion and liquid hydrogen. The SSME was the groundbreaking technology here, the starting point for all the other cryogenic staged-combustion engines. In the RD-0120, the Russians made some improvements to the SSME which NASA has been studying. It is a simpler design, and is able to achieve combustion stability without complex anti-oscillation dampening chambers. The RS 68 is also a fine engine, designed to be cheap simple and disposable. RS 68 (Delta IV) - 420 365 (338 tons) Vulcain (Ariane) - 434 318 (110 tons) SSME (Shuttle) - 453 363 (232 tons) RD-0120 (Buran) - 455 359 (200 tons) For orbital vehicles, it is better to look at the LEO payload, because that depends on the thrust of all the stages and how their sizes have been balanced against one another. Super-heavy: Saturn V: 118 tons N-1: 95 tons (if it had worked) Energiya: 88 tons Heavy: Shuttle: 27.5 tons Delta 4-H: 25.8 tons Proton: 21.0 tons Atlas V: 20 tons (551 config.) Titan 4: 17.8 tons Ariane V: 16.0 tons Atlas V: 12.5 (401 config.) Long March 2E: 9.2 tons Soyuz: 7.4 tons |
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Jun 4 2006, 06:46 PM
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#3
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
You're forgetting the engine RD-180 was derived from -- the RD-170 from the Energia strap-on boosters. With twice the thrust of an RD-180, it beats even the mighty F-1 at 800 tons of thrust. Its variant (RD-171) is being used on the Zenit rocket.
IIRC, the F-1 were actually closer to 700 tons of thrust than 800. -------------------- |
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