On Dec 31, 2:57*pm, Pat Flannery wrote:

Half of *the four chambered RD-171 forms the two chambered RD-180 engine
for Atlas V.


And 1/4 of it forms the single-chambered RD-191 for at least one
Angara version and the air-launched Baykal.

I'm beginning to wonder if we shouldn't take A and maybe B slightly
seriously. With Russia it's hard to tell, but those rockets do look
doable. At least technically -- what would then be done with them
that's worth doing is another question.