Brian Thorn wrote:
To reach the LES, the piece would have to travel through the upper
stage...then through the Orion spacecraft itself.


Way too many variables to say that with any authority, I think.

If chamber pressure falls and triggers an abort, and then the SRB lets
go, you have a very exposed Orion/LES, pitching over to get out of the
way from an expected on-rushing Ares I, which instead of on-rushing in
one piece, is on-rushing in a few hundred thousand flaming pieces each
on slightly different trajectories. The upper stage won't take them
all.


That would require a catastrophic _rise_ in chamber pressure, not a drop.
If the chamber pressure drops on the SRB, it's not going to cause it to
explode.
(in fact, if it's severe enough it could cause combustion to cease in
the SRB - that was the concept used on the SRBs developed for the Titan
III C variant that was going to be used on Dyna-Soar and MOL, which had
blowout vents mounted at the top of the casing.)
Other than the whole nozzle dropping out of the SRB, I don't know what
could cause it to lose internal pressure; pressure excursions in the
other direction are a lot more likely than a loss of thrust, and a far
more dangerous situation also.
The top dome on the SRB blowing off of it and up into the second stage
is a very severe situation that NASA looked at as being probably fatal
as it could occur so fast that the LES wouldn't have time to activate.

But its the "time to react" problem that really has me worried.


If it was all-liquid, you might be able to get away with the Apollo
manual/automatic system, but for a solid there almost has to be a
automatic option if the crew's likelihood of survival is to be upped
significantly.
We've had explosions of SRBs on both Delta and Titan IV that occurred
with virtually no warning and were instantly catastrophic

Pat