In article ,
says...

Jeff Findley wrote:

In article ,
says...

I'm confused. The program to replace the RD-180 is focused on engines
with around 400,000 lb thrust at sea level. This focuses them on the
AR-1 (kerosene/LOC) and BE-4 (methane/LOX). Why are they not looking
at the RS-25 (LH2/LOX with similar thrust) or the Raptor engine
(methane/LOX)?


RS-25 is hella expensive and ULA already knows that LH2/LOX produces a
large, expensive, vehicle (e.g. Delta IV). So that's right out since
Delta IV is already flying (no development costs there). But do note
that ULA really wants to ax Delta IV in favor of Atlas V due to its high
cost.


So why aren't they using something other than RS-25 on SLS?

Because the cheaper RS-68, used on Delta IV, isn't regeneratively cooled
and can't handle the heating environment at the base of the core stage
caused by both the main engines and the SRBs. This was discovered early
on in Ares V development, which planned on using the much cheaper RS-68.

In general, Ares V/SLS is a giant cluster *&^# of a program. If it ever
does fly it will be the biggest, most expensive, lowest flight rate
launch vehicle in history.


Raptor (methane/LOX) isn't "fully baked" yet (BE-4 is ahead of it).


That sounds wrong to me. SpaceX test fired a full up Raptor engine
(albeit a lower thrust developmental engine) at their Texas facility
last year. The BE-4 has never been test fired and they didn't even
have a full engine put together until this year.

I should say it's my opinion that Raptor is behind BE-4. Since both
companies are private and somewhat secretive, good information is hard
to come by. But from what's been reported in the press, Blue Origin has
a full size complete BE-4 development engine built and is getting ready
to test fire it. SpaceX could be at that point too but all I've heard
so far is that they've fired a lower thrust development engine, which
indicates they're not quite ready for full scale testing. Blue Origin,
on the other hand, thinks BE-4 is ready for "full scale" testing.

But the proof will be on the test stand, will it not?


Seems like we're getting a lot of different engines when it might be
more efficient to settle on just a couple.


AR-1 is a "backup" engine at this point since it's so far behind BE-4 in
both schedule and (estimated) per unit price. But, AR-1 is about the
right size for two of them to be a "drop-in" replacement for RD-180 on
Atlas V. So, if ULA stumbles on Vulcan, an AR-1 engined Atlas V might
be a good stop-gap measure.


Aerojet Rocketdyne says they can start delivering AR1 engines in 2019,
so the finish line isn't all that far behind BE-4. Blue Origin says
the BE-4 will cost 60% of what an AR1 costs (at $12.5 million each);
so BE-4 engines are only around $7.5 million each? The government is
paying a lot of money to develop AR1, so I'd bet on it being pushed
for use somewhere. And AR1 does have the advantage of not needing a
bunch of new infrastructure to handle fueling and such.

ULA is more worried about the per flight cost down the road. If they
have to install liquid methane tanks and plumbing, they'll do it to
lower costs. SpaceX is already undercutting *everyone* on launch costs
and that's without taking reuse into account. ULA is desperate to stay
alive at this point with SpaceX eating into its DOD launches that it
used to have a monopoly on.


At any rate, Aerojet Rocketdyne is being paid good money to develop AR-
1. Even if it meets the same fate as J-2X, they're getting money now
which helps keep the company alive.


How many billion dollars of taxpayer money are we going to spend
developing engines that never get used? Around $1.5 billion for AR1.
Around $1.2 billion for RS-25 (which only gets used if SLS keeps
flying). Another $1.2 billion for J-2X. Meanwhile Merlin engines
used on Falcon 9 cost around $1.2 million each with engines in the
Raptor/BE-4 class going for $7.5 million each? Meanwhile the entire
development budget for New Glenn is around $2.5 billion and what
little public data there is puts development costs for Raptor engines
in the hundreds of millions of dollars (vice billions) and I expect
BE-4 development is similar. What that says is that private companies
developing engines mostly on their own nickel is looking to be an
order of magnitude cheaper than traditional contracted engine
development programs...



Maybe the US Government should get out of the game of funding
development of engines and launch vehicles. SpaceX and Blue Origin have
both proven that private industry can do this themselves, with
sufficient funding.

AJR sat on its ass for how long after RD-180 was picked for Atlas?
They've known for *decades* that the US needed a high thrust
LOX/kerosene engine to remain competitive in the global launch market
and they literally sat on their hands waiting for a government handout
to start development. AJR deserves to go under at this point. It's
management is wholly dependent on old style cost-plus contracts. They
don't know how to innovate. They don't know how to compete on cost.

NASA and DOD need to switch their space support back to the same style
of support that NACA used to give to aircraft and (jet) engine
manufacturers in the US. NACA didn't design and build commercial
engines or aircraft. And NACA certainly didn't operate its own
airlines. It's well past time for the US Government to get the hell out
of the launch business and let good old fashioned capitalism and market
based competition sort out the cheapest way to orbit.

This is the kind of **** that the "crazy" people on the old sci.space
argued for back in the early 1990s when they were pushing CATS (cheap
access to space). It's now been over 30 years since then, and SpaceX
has proven them right. The government needs to get the *&%# out of the
way and support the commercial providers rather than building yet
another Government Luanch System which will be a drain on NASA's budget
for decades to come.

Jeff
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