Ed Kyle wrote:
Still, I have to wonder if it might be easier to
develop a rocket powered by four 200,000 lb
thrust RS-27A engines than to create a nine-
engine cluster of smaller engines. Since Boeing
is disposing of Rocketdyne, RS-27A (which is
already a proven cluster machine) should be
available for commercialization beyond the Delta
family.

So why not use smaller numbers of a proven engine?

How much does the RS-27A cost? How much does the Merlin cost?

-jake