Re: Space Access Update #112 9/19/05



John Schilling wrote:


If you want to do better than "crashes once every fifty flights", the Stick
is *not* the answer. The Stick proudly bases all of its claims to safety
on its legacy from a system that crashes once every fifty flights.



Only one of which was due to a SRB failure, so that's 1 SRB failure in 218 SRB firings, giving us a proven reliability rate in that stage of 99.54%. 218 launchings is a large enough number to be statisticly usable as a indicator of overall reliability, so we are dealing with a very reliable rocket stage here. And:
1.) The failure mode on Challenger occurred slowly enough that a LES could easily have been activated.
2.) The design flaw that led to that particular failure has been fixed.
Besides which, neither Delta IV or Atlas V has the payload capacity that NASA wants for the CEV carrier.
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.
We've had one semi-succesful flight of Delta IV Heavy, so it's awfully early to start making judgments of its reliability.
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.

Pat
.

Relevant Pages

  • Re: Space Access Update #112 9/19/05
    ... >Only one of which was due to a SRB failure, so that's 1 SRB failure in ... >as a indicator of overall reliability, so we are dealing with a very ... >If we went with Atlas V, then we'd have to use solid strap-ons to up the ... >flights under their belt they might by taken more seriously in the EELV ...
    (sci.space.policy)
  • Re: Japans Moon Ambitions - Theyre KIDDING, Right ?
    ... > That is an indictment of current standards more than anything else. ... But it is an additional failure mode that reusable vehicles ... What I am is disputing is how much of a reliability improvement you get ... fewer flights, ...
    (sci.space.policy)
  • Re: NASA Picks In-Line (Maybe)
    ... > Lockmart's estimate for the failure probability of the Atlas V Heavy is ... Lockmart estimated the safety of one version of the ... including the Atlas V Heavy. ... >>> reliability was in fact one of the program goals. ...
    (sci.space.policy)
  • 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)
Loading