Re: NASA Picks In-Line (Maybe)


Murray Anderson wrote:
> "Will McLean" <mclean1382@xxxxxxx> wrote in message
> news:1125178271.028526.215380@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > Rand Simberg wrote:
> > > On 26 Aug 2005 04:44:35 -0700, in a place far, far away, "Will McLean"
> > > <mclean1382@xxxxxxx> made the phosphor on my monitor glow in such a
> > > way as to indicate that:
> > >
> > >
> > > >The other factor is reliability. The propulsion components of the stick
> > > >have flown a lot, and were designed to carry crew, so I think it's very
> > > >plausible to argue that the stick will be more reliable than an EELV.
> > >
> > > There's no particular reason to believe that, unless you subscribe to
> > > the myth that "man-rated" vehicles are more reliable.
> >
> > The SRB has a lot more flight experience than either EELV core. All
> > things being equal, newly designed components fail a lot more often
> > than those with a track record. Delta IV-H has already had one mission
> > failure.
> >
> > SSMEs have flown to space about as often is RL-10 engines, and have had
> > far fewer propulsion-related mission failures.
> >
> > The EELV heavies have more engines and staging events to fail.
> >
> > LockMart's own study concluded that an Atlas V-H lofting a stick-sized
> > payload would be more likely to kill a crew than the stick, even giving
> > their own product the benefit of the doubt as much as possible.
> >
>
> Are you seriously suggesting that LockMart studied the safety of a
> hypothetical launcher proposed by another company? Or are you saying that
> Lockmart's estimate for the failure probability of the Atlas V Heavy is
> higher than the estimate provided by ATK for their proposed "stick"?


Both of the above. Lockmart estimated the safety of one version of the
stick, a hypothetical launcher proposed by another company. It compared
it to various LockMart proposals, including the Atlas V Heavy.

http://exploration.nasa.gov/documents/reports/cer_final/Lockheed_Martin.pdf

Delta IV? These aren't the droids you are looking for. Move along,
please.

It concluded that the (as yet unflown) Atlas V heavy would kill more
crews than the stick, assuming CEVs of similar size.

But wait! LockMart has an even better option. NASA can buy an Atlas
Phase II, with an entirely different airframe, which will be entirely
different as far as defects are concerned.

Any virtues of the previous version will carry forward 100%, of course.

Will McLean

> > > There was a lot
> > > of pressure on the EELV developers from both their customer (the Air
> > > Force) and the insurance industry to design it to be reliable, and
> > > reliability was in fact one of the program goals. It's not at all
> > > clear what they could have done to it to make it more so.
> >
> > And Ariane V and Zenit were supposed to be more reliable than the
> > earlier design. They probably will be eventually, but they aren't yet.
> > The EELV has a similar challenge.
> >
> > Will McLean
> >a

.

Relevant Pages

  • Re: Man-Rating Atlas V
    ... Estimates of its reliability are also educated ... Atlas has overestimated the reliability by a factor of 2, ... kills the crew 1 in 500 times, and does not meet the NASA spec. ... And the closer you get to a new vehicle, ...
    (sci.space.policy)
  • Re: What is the best brand of engine.
    ... have come to the conclusion that my Atlas engines seems to be the ... smoothest running, ... My Bachman is ... Durability and reliability are pretty good with every maker, and every maker is very good about repairing or replacing defective units. ...
    (rec.models.railroad)
  • Re: Atlas V Falters
    ... Some of us still think of the vehicle as "Atlas-Centaur". ... flight that Atlas and Centaur are no longer one launch vehicle is just ... A modest failure, to be sure. ... Perhaps we should say Atlas didn't fail, ...
    (sci.space.policy)
  • Re: "Heavy lift: examining the requirements"
    ... >> But if you count the Delta II and Atlas II cores, ... > how you classify the latter failure, ... > samples as first stage samples for Atlas IIAS. ...
    (sci.space.policy)
  • Re: Atlas V Falters
    ... system, it's an Atlas problem, in the second stage. ... It was a Centaur failure, ... but use a different upper stage (perhaps similar to the current ...
    (sci.space.policy)