"Dholmes" wrote in
:



Where would reusable liquid boosters come from?

The Russians are/were working on just such a design for future
use with the Angara, the replacement launch vehicle family for Proton
and Soyuz. Uses a single-chamber variant of the RD-180 engine.

Any sort of boosters with more thrust, even solids, would be a big
boost to Delta.

That's called Delta IV Heavy, using three CBCs fired in parallel.
But I was thinking of the CBC as a serious second stage, with
a couple of kerosene/LOX boosters or Titan IV-class solids. Modify
the RS-68 for altitude operation with an enlarged expansion nozzle;
a SSME with higher Isp could work here too but its expensive to
throw away.

A second stage with nore thrust would help for LEO as well.

The MB-60 or RL60 with up to 65,000 lbs/thrust are in development
to replace the current 22,000 lbs/thrust RL10; this should be
the first major upgrade to Delta IV. This will help with gravity
losses while avoiding having to use two or more RL-10s and would
make possible an enlarged upper stage, if needed.

This still wouldn't be Saturn V class, but would be reasonably
off-the-shelf.

Massively clustered Delta IV CBDs with propellant cross-feed
would be technically possible, and get into heavy-lift range with
a relatively affordable mass-produced modular design.

--Damon