"Ed Kyle" wrote in news:1126724563.896377.307370
@z14g2000cwz.googlegroups.com:

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?

Crap, I typed this up and lost it... here's the quick answers:

1) Rocketdyne has no incentive/reason to build cheap engines for small
companies. It would only risk tarnishing their image as the premium
rocket engine supplier for the US government.

2) Old engines aren't necessarily cheap. Parts for classic cars
initially get cheaper as the tooling is paid for, and later on more
expensive as the materials/processes become obsolete and supplier base
dries up. This is a very real supplier issue in the rocket industry, with
all the old engine designs.

3) To make money, SpaceX needs a small, focused, efficient, in-house
engineering team -- government contractors are brainwashed to prioritize
things besides making a profitable product.