On Fri, 27 Apr 2012 17:10:13 -0400, Jeff Findley
wrote:


I know, the insulation is there to protect the rocket. But is it
REALLY supposed to be on fire like that? The incident was downplayed
by ULA, but I still think they were damned lucky not to lose the
vehicle that day.

From what I understand, the insulation is primarily there to prevent
boil-off of the cryogenics while sitting on the pad.

Not entirely. Like on the Shuttle's ET, the insulation also serves to
protect against aerodynamic heating during ascent. Delta IV is famous
for fireballs at ignition and liftoff, and ULA has always said
essentially, "that's why we have the insulation on it." But the
Vandenberg Delta IV-Heavy event (the first Heavy from VAFB) was far
beyond what we've seen at the Cape, and the first time the damned
thing was still burning away well past tower clear.

Brian