Re: Man-Rating Atlas V


Will McLean wrote:

This argument would be more compelling if the Atlas V was a vehicle
with a well established track record. Not that it's a bad record, it
just isn't enough flights to confidently much more than its probably at
least 90% reliable.

And it really is significantly different from Atlas II, with different
tank structure and different main engines.

Agreed - the Atlas II experience proves little. This is exactly the
problem with "shuttle derived", as well.

Nor are the changes for the CEV version *that* minor. Besides the
changes you mention, NASA believes it needs a higher thrust upper
stage, probably with more RL-10 engines. And the three core
configuration, which Atlas has never built.

No, the Atlas that is proposed to be man-rated is the 401 varient, with
just one core engine, a single centaur, and no solids. See
http://www.lockheedmartin.com/data/assets/13344.pdf
where this is very explicit. This is because this is the simplest
configuration, with the least to go wrong, and has the most experience
(which it can share with un-manned launches, which should help by
creating a larger experience base). This is also the one that is
launched in a higher stress configuration when launched with solids, so
we know the structural margins are there. There is a hit (estimated at
about 10%) for using the single Centaur, since then trajectory changes
are needed to enable aborts throughout the flight. There is a two
engine centaur varient, but Atlas is not proposing to use it since it
is not proven yet - a sensible approach.

And a assembly line in the US for the main engines rather than just uncrating the imports.

Yes, it is this kind of thinking everyone suspects NASA is using, with
safety as a smokescreen....

Lou Scheffer

.

Relevant Pages

  • Re: MA-8 FLight Plan questions.
    ... > Thanks Andre, ... > Im in FLA in May so I will take a close ook at the Atlas at KSC while ... >> base, three engines. ... continues firing up to orbital insertion. ...
    (sci.space.history)
  • Re: Man-Rating Atlas V
    ... tank structure and different main engines. ... Agreed - the Atlas II experience proves little. ... configuration, ... (which it can share with un-manned launches, ...
    (sci.space.policy)
  • Re: MA-8 FLight Plan questions.
    ... Apollo missions, I didn't know the two side engines only came away and the ... Im in FLA in May so I will take a lclose ook at the Atlas at KSC while I am ... continues firing up to orbital insertion. ...
    (sci.space.history)
  • Re: Space Access Update #112 9/19/05
    ... giving us a proven reliability rate in that stage of 99.54%. ... If we went with Atlas V, then we'd have to use solid strap-ons to up the performance, and if a single solid is a bad idea on the Stick, then using multiple solids on Atlas V is also a bad idea. ... As for SpaceX and it's Falcon 9....well, once they've got some Falcon 1 flights under their belt they might by taken more seriously in the EELV market. ...
    (sci.space.policy)
  • Re: Falcon 1 is... well it is space history
    ... The first 4 R7 launches were as ICBM tests, and so were not counted in ... Of those ICBM tests, the first two both failed in the first stage. ... the Atlas B is listed as succeeding on its first try. ... try, and 3 previous flights had failed, including the first one. ...
    (sci.space.history)