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[weremensch]

Just because this isn't how it's being spun by officialdom: that flight with the underwear bomber was in no real dangerHere's the drill. Two ounces of the explosive in question (PETN) would blow a hole in the multi-layered aluminum fuselage; but only if fired in contact with the aluminum. If detonated any distance away, the shock would simply be

Comments

[dr_holiday_3000]

Maybe he was set up somehow? Hard to think that al Quaeda wouldn't know their explosives. Unless they're falsely taking credit for terrorism points.

Anyway, where are you getting the explosion physics from?

[weremensch]

Nowhere I can link to anymore, alas. But the short answer is that I studied demolitions back in the 80s, and kept up with the reading (when I could) since then.

[dr_holiday_3000]

You studied demolitions? Dare I ask?

I wonder how much difference relative air pressure would make in blowing out a fuselage at altitude.

And something that I've always assumed about explosions (maybe falsely) is that, up until a certain point in the blast radius, the explosive force is actually gaining... I guess velocity, before it starts to dissipate. So if a charge isn't particularly confined, there's a point somewhere in the radius, away from the center, where the shock against a solid object would still be considerable, just from all of that gained inertia. And I'm sure that these properties would vary between substances and quantities, and we probably can't actually come to any conclusions about this particular situation on our own... but is that incorrect? Does it really just start to dissipate immediately after ignition?

[weremensch]

Don't dare. It's neater that way.

As for the shockwave; once it separates from the surface of the actual explosive, it's subject to inverse square just like everything else. The only way it could be gaining strength is if the explosive gasses were somehow keeping up, and they don't.

As for blowing out a significant chunk of the side of the plane; my first guess is that an explosive charge this small couldn't do it despite the pressure difference. If it could, poorly secured cargo (and occasionally passengers) would come blowing through the side of airliners on a regular basis when they hit turbulence. No, this could probably blow a small contact hole (which air pressure would then widen); but that's about it.