space cadet

http://www.spaceref.com/news/viewnews.html?id=1087

"According to industry sources, NASA has encountered some problems with
its planned CLV (Crew Launch Vehicle) design as spelled out in the yet
to be (formally) released Exploration Systems Architecture Study (ESAS)
Final Report.
Sources report problems have been encountered in designing an
expendable version (RS 25) of the current SSME (Space Shuttle Main
Engine) for the CLV's second stage that can be air-started. Concerns
have also been raised that a possible alternate second stage engine, a
derivative of the Apollo era J-2S engine, may be underpowered for the
task.
These sources also talk about interest on NASA's part of moving to
using a 5 segment SRB (Solid Rocket Booster) as the first stage of the
CLV instead of the initial plan to use the current 4 segment booster
used by the Space Shuttle. In so doing, NASA would now be creating what
would, in essence, be a wholly new launch vehicle."

I don't know if I like the sound of this...proponents of the CLV have
always claimed it was safe by the fact it was suppose to use existing
designs with known/proven safety records. That last sentence makes the
argument weaker.


Just my $0.02

Space Cadet

derwetzelsDASHspacecadetATyahooDOTcom


Moon Society - St. Louis Chapter

http://www.moonsociety.org/chapters/stlouis/

The Moon Society is a non-profit educational and
scientific foundation formed to further scientific
study and development of the moon.

brian thorn

Why not replace SSME with RS-68? Cheaper, more powerful engine,
already coming off the production line...

Brian

rüdiger_klaehn

The RS-68 is a first stage engine which is optimized for high thrust
and simplicity. It has a very bad specific impulse for an upper stage
engine.

All this confirms what most s.s.p. readers have thought all the time:
the stick will neither be simple nor will it be flying soon. It remains
to be seen wether it will be safe.

Hopefully the whole project will die before too much money has been
wasted.

will mclean

The sensible way to use it is at the bottom of a Delta-IVH. Using an
EELV as the CLV should be seriously reexamined if these reports are
true and the rapid development of the stick, one of its primary selling
points, turns out to have been oversold.

Congress should also have some sort of discussion about just how
risk-averse it wants NASA to be. Currently, NASA is implicitly acting
as though each astronaut's life is worth several billion dollars while
on a space mission. If Congress wants them to do that it's still
absurd, but at least it isn't NASA's fault. If Congress doesn't, NASA
is spending a lot of extra money without good cause.

Will McLean

rüdiger_klaehn

The whole thing has been a lie from day one. The SSME is a very complex
piece of machinery with low margins. Even minor changes will be
expensive. And redesigning it as an expendable, air startable engine is
not a minor change.

But on the other hand, the program does exactly what it was designed to
do. It gives money to the usual suspects (ATK, lockheed, boeing) so
that they can spend it in certain congressional districts. And it is a
good excuse for the long overdue shutdown of the shuttle program.


Strangely enough, the life of the ground support personnel is not worth
as much.

The most devastating lethal accident with a SRB would be a SRB or SRB
segment going off during ground handling. Such an accident would kill
much more people than your typical launch accident, and it is certainly
not impossible. But nobody seems to care.

The same goes for using hypergolic propellants. It might not be a big
deal for the astronauts, but it is a big health risk for the ground
support people.

jeff findley

Not a big surprise. The SSME was never designed to be air started, so and
air startable SSME is really an engine development program in and of itself,
partly due to the complex startup procedure which partly stems from its
staged combustion design. This was one of my concerns with the "off the
shelf" components of the CLV.


In other words, a brand new upper stage, powered by an engine NASA hasn't
used for decades, sitting on top of a new 5 segment SRB, which NASA has
never flown. The "off the shelf" components are getting less and less "off
the shelf". EELV's are sounding better every day, except for people who
would be laid off if the shuttle isn't replaced by a shuttle derived vehicle.

You think? ;-)

Jeff
--
Remove icky phrase from email address to get a valid address.

john doe

The part that I don't like is that initially, it was to be a brand new
design on a blank piece of paper , open to any/all ideas.

But quickly, NASA decided it had to be a capsule. Quickly, NASA decided
that the RFP would include requirements to use shuttle SRBs and SSMEs.
(and god only knowns what other requirements NASA made).

This is like going for an RFP for computers with specification that it
must run Windows and must be built by Dell.

Making things worse is the artificial deadline of 2010, giving NASA very
little time to concuct some contraption that can fly, and of course, as
time runs out quickly, you'll see NASA quickly removing requirements and
downscaling that vehicle's mission. For something that flies in 2010, it
will probably be less functional than Soyuz.

And as NASA scales down the scope of that CEV, chances are that Congress
will grow tired of NASA's "inability to deliver what was originally
promised".


NASA may have had great ideas and concepts, but when push comes to
shove, the time constraints will force it to focus only on the fastest
solution, not necessarily the best solution.

george

<snip>


Really? No one cares, eh? Do you know of even one such incident occurring
regarding SRBs in the U.S. space program? No? I didn't think so. The
fact is that SRBs are orders of magnitude safer than a liquid-propelled
craft.

George

pat flannery

There's always the RL10 cluster option.

Pat

thomas lee elifritz

Only complete idiots like you think
that VSE, ESAS and the SCHTICK are cool.
<plonk>

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