I had a series of business trips to Cape Canaveral Air Force Station (to work with some folks on an upcoming Titan-IV launch) starting about 5 months after this failure. The craters and burned-out cars were still there -- the people I worked with said that many of those whose cars were damaged/destroyed were still fighting with their insurance companies. The argument was: is "falling rocket debris" considered an act of God and therefore not reimbursable? Eventually, everyone got their insurance money.

There a good two-page writeup about the failure at:

http://www.afspacemuseum.org/archive/histories/Delta.pdf

starting on page 24.

As this article states, they estimated that there were 2000-2500 "firebrands" of solid propellant released by the explosion, four of which caused secondary explosions estimated at 1250-2000 pounds of TNT.

Each of the 9 GEM-40 solid motors had 25,940 lb of propellant at launch. Here's a good picture of the GEM-40:

It's hard to imagine the horror experienced by those nearby and in the blockhouse as they watched ~200,000 pounds of flaming solid rocket fuel rain down.........

Interesting how the casing split grew from 71" to 254" BEFORE the motor failed. Sound pretty robust to me.

Odd that the propellant fragments released caused explosions. Seems that once they were out of the casing (no longer any chamber pressure), they would just burn.

-Ken

Good point about the explosions. They're probably referring to the explosion-like bursts you can see when a large chunk hits the ground, but I'm not sure of what exactly is going on.

Perhaps when a large chunk, engulfed in flames, hit the ground, the fuel on the bottom (and in any cracks, holes, etc) now had a "chamber" caused by the weight of the fuel on top of it, which caused an explosion.....

My guess is that when a large chunk of fuel hits the ground, it cracks or fragments, substantially increasing the burn surface area and dispersing burning chunks.

So, were they flying under NAR guidelines and is THIS a case where you call in the for the insurance coverage... j/k :))