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Space/Science » in reply to EELV v HLLV

re: EELV v HLLV

While I've often proposed reviving the Energiya for heavy lift (notice I didn't say developing a Energiya-type Shuttle derived HLLV), the question remains, who needs it?

How often would we need to launch 100 tons into orbit, and would that be enough to justify the cost of developing and building an HLLV? Suppose we did develop a HLLV from Shuttle technology at a cost of $2 billion (most estimates are much higher). If we ended up flying 20 of them over a 10 year period, then simply amortizing the R&D costs over the number of flights adds $200 million (not counting interest costs) to the equipment costs, personnel costs, etc. for each mission.

I do have to question some of the author's assertions.

With only three RS-68s under a Shuttle External Tank, I place 100 tons in orbit with one shot- and have engine out capability.

Funny how he forgot to include the SRBs. Without them, the ET and RS-68s wouldn't be able to get off the launch pad, much less put 100 tons into orbit. Putting the RS-68s under the ET would require reworking the launch pads to account for the new engine geometry. This is a non-trivial expense.

He twice repeated the claim that the EELVs may inflict 25-27g loads upon any CEV.

However, he didn't provide any info to back up his claim. Was he talking about an abort scenario? Was he talking about vibration loads? Without some substanciation, I don't see any basis for this claim. Max G loads normally happen just before a booster runs out of fuel for a stage, when thrust is still high and the mass is low. None of the numbers I've seen anywhere suggest that a Delta IV Heavy loaded with a CEV (whatever that will end up weighing) would experience anywhere near that kind of G load.

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