[AR] Re: shuttle SRBs (was Re: Re: Phenolic regression rate)
- From: Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Wed, 7 Feb 2018 12:31:20 -0700
On 2/7/2018 11:59 AM, Norman Yarvin wrote:
On Wed, Feb 07, 2018 at 05:47:21PM +0000, William Claybaugh wrote:
We spent many thousands of hours during ESAS looking for any solid rocket
failure mode that would create a more difficult escape environment than a
liquid rocket; that team identified one only which applies only when the
solid rocket is in line with and below the crew capsule. Despite much hand
waving by an Air Force employee, there were no identified failure modes
that created a more difficult escape environment when the solids were side
mounted.
That makes it sound as if the failure mode in question is one that
shoots debris straight up, like a cannon, and in no other direction.
Or no?
I might guess it's more a matter of where a solid may go if it breaks
loose largely intact.
Given that the whole point of strapons is adding thrust to a stack, on
their own they'll tend to accelerate quite briskly. No reasonable
capsule is likely to stand up to direct ramming by a loose solid.
For that matter, a near miss by a still-burning solid wouldn't likely do
deployed parachutes much good.
Which reminds me of another solid failure mode affecting the escape
environment: The spreading cloud of burning chunks of solid fuel you get
after a solid explodes (or is exploded for range safety reasons.)
I recall mention of the need to reliably clear this cloud before
deploying chutes as a significant constraint on the Ares 1 escape
system. It seemed to me a plausible concern at the time.
Could this be what Bill refers to by "much hand waving by an Air Force
employee"? Either way, I'd be interested to hear reasons why it
wouldn't be a significant factor in the escape environment from a
booster with side-mounted solids.
Ah. I think I broke the code. Could the idea have been NOT to
range-safety detonate the solids till after they had cleared the
escaping capsule by a wide margin?
If so, the word "sporty" occurs to me. It presumes both that the
problem being escaped in the first place isn't a disintegrating solid,
and that the solids can be reliably separated from a stack with other
fatal problems without either unpredictably disturbing their flight axis
or damaging them such that they either explode or veer off-axis.
Sporty does seem to be the proper word.
Henry
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