John:
A fair point. The Ariane 5 data show two liquid rocket failures that left
payloads in the wrong orbit.
Still, the fact of two different liquid stage failures and no solid
failures—particularly given two solids per launch—should get our attention
in my view.
Bill
On Wed, Feb 7, 2018 at 8:55 PM John Schilling <john.schilling@xxxxxxxxxxxxxx>
wrote:
I think that not all failures require the use of an LES, at least in the
narrow sense of "LES" that you are implicitly using here.
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955
On 2/7/2018 7:09 PM, William Claybaugh wrote:
John:
I find this interesting coming out of Circle A: you think that an LES of
fixed probability of successful operation is better used on vehicles that
fail much more often than on vehicles that rarely fail?
Did I get this right?
Bill
On Wed, Feb 7, 2018 at 7:42 PM John Schilling <
john.schilling@xxxxxxxxxxxxxx> wrote:
On 2/7/2018 9:47 AM, William Claybaugh wrote:
Henry:
You do seem very fond of this “...but failures can be catastrophic”
line. However, what happens to the rockets after the escape system
activates is *irrelevant* to crew safety.
Except for the cases where the escape system itself is what endangers
the crew. And then there's the cases where the escape system doesn't
activate and you've got no other option.
Escape systems that can escape all or all-minus-epsilon of the failure
modes of large solid rocket motors, are not going to be low-risk items
from a reliability or safety standpoint. And the ability to quietly
turn off the propulsion system of a launch vehicle, rather than having
range safety blow it up, may facilitate abort modes other than sudden
bursts of 15-g rocket thrust (from rockets that might themselves fail
catastrophically). Save the LES, or at least the hard-mode LES, for
the times when you absolutely can't live without it.
John Schilling
john.schilling@xxxxxxxxxxxxxx
(661) 718-0955