Re: SSME vs. J2 / RS-68

landings.geo@xxxxxxxxx wrote:
Any thoughts on the proposed possible engine changes to the proposed
HLV?

URL: http://tinyurl.com/omhpx
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"Some people think it will cost less to use the RS-68 because the
engines are so much cheaper," said a source knowledgeable about the
earlier analysis. But taking into account the "total integrated
picture," the source said, the life-cycle cost of the RS-68 could be
higher.

Why not settle for less payload? If the original payload was a result
of a mix and match affair, why keep on to it so hard?
How much worse would it be anyway? I see the RS-68 has a slightly
worse T/W too. But plumbing might be easier?

It makes sense not to throw away 5 SSME:s on every flight.

Is it really true that nowadays man-rating costs such huge amounts
of money when the whole industry process must be validated and tracked
somehow? Dr. Stanley (of ESAS) mentioned things like that regarding
EELV:s.
.