On 2/24/2010 7:30 AM, Jeff Findley wrote:

It's likely to be "more robust" simply becaue it is a Russian design. The
"more complex" part, I'm not so sure about. If you have an engine like the
RD-180 which is a staged combustion engine which is regeneratively cooled,
there is no fundamental reason that it can't be classified as reusable.

So maybe you can make a expendable one that's simpler and cheaper, sort of
the kerosene/LOX equivalent of the RS-68.
Unless they intend to resurrect the F-1 in some modified form.

True you often can make an expendable version of an engine which is
simplified in some ways, but I have a feeling that what you're really doing
when making an expendable version is tweaking the design so it's easier to
manufacture. If that results in some trade-offs which would otherwise
reduce "reusability", then that trade would likely be made. But there is a
point where shaving margins off an engine makes it less reliable, even for a
single use.

I could picture them going with a simple non-staged combustion engine
and ablative nozzle that lowers isp in exchange for lower production costs.

Pat