The Mississippi crash

[IAHM-COL]

https://mobile.nytimes.com/2017/07/10/us/military-plane-crashes-mississippi-delta-deaths.html?action=click&module=Latest&pgtype=Homepage


USAF KC130 crashes in Mississippi

[HJ1an]

Mid-air disintegration.. not pretty.

RIP.

[J Maverick 16]

[KL-666]

That plane looks rather "complete" to me for a mid-air disintegration. True i can't see the nose due to the smoke. But considering that all the rest is there, i suppose the nose is too.



Kind regards, Vincent

[HJ1an]

That plane looks rather "complete" to me for a mid-air disintegration. True i can't see the nose due to the smoke. But considering that all the rest is there, i suppose the nose is too.



Kind regards, Vincent

Well it was based on the article saying that the plane broke up mid air and the cockpit some ways away from the main crash site. Of course, eyewitness accounts from news reports are never reliable - it might possibly have been a collision of some sort. I was gonna say that the wreck seemed complete though, but left it out.

[jwocky]

That looks neither like mid-air disintegration nor like collision. The plane was not that high at the time of the crash, so I would expect in case of a collision maybe two or three big parts, in case of a disintegration a higher number of parts, all kind of spread out in a cloud stretched in flight-direction.
The way this looks to me is more like something sparked the refueling system, a part exploded, but the plane actually refused to disintegrate. Like the roof was blown off over the full cabin length, but she hit the ground on her belly. It is hard to see due to the smoke where the nose is, but the damage forward makes me think, this part also broke only off when she went belly down in the field. Only I don't see any trace of sliding. As if she fell just down belly first and had no forward speed at all anymore. Maybe some weird cumulation of factors leading additional to some stall attitude while she went down?

[HJ1an]

Ir the cockpit was really separated, then it probably would be going straight down, in a flipping motion.

[jwocky]

Yeah, but then, look at is, no sliding, and the whole visible part of the fuselage is just flat on the ground. It looks still almost symmetric, so, she didn't flip either. So, this is a little bit a mystery to me. The half-official speculations, she suffered in in-flight explosion (maybe) and disintegrated at around FL200 (nope, she really didn't or her parts would be small and more spread out) or the other idea, she lost wing due to fatigue and disintegrated (nope, we see both wings and well, she hit the ground obviously in at least one big chunk) appear to be conclusions from clumsy wordings in the first reports. There was talk about a debris field of almost six miles in length. But that could be only small debris because we see in the photo still the mass of the plane.

Now, curious cat as I am, I dug a bit. The absence of sliding tracks made me thinking. The refueling system has some pipes and pumps in the area behind the cockpit and in all reports it was mentioned the cockpit was separated. Now, a quite hefty explosion there could separate the cockpit, giving it an additional acceleration forward, while it would give a deceleration (or actually a backward acceleration) to the rest of the plane. Now, depending on what kind of fuel she had in the system, for example jet fuel to refuel jets, such an explosion would produce easily about 2.2MW/m^2 at a burn rate between 1.5 and 3.5 kg/m^2 * min (roughly, there were two major burn tests, the HDR test showed it could be even higher).
So, just over the thumb, a KC-130 has a weight of 70,000 kg fully loaded of which would be 33,000 kg payload weight, in this case fuel for other aircraft. Now, generously ignoring the weight of the cockpit, which we in fact would have to distract, the part we see in the picture could actually have got enough impact backwards to eat up it's forward momentum (37,000 Kg*340-350 knots over ground) if the explosion had some time and containment to build up this amount of pressure. Time is really no factor, because at this burn rate, we talk only split seconds if the burn surface was sufficient. But such a scenario would explain some extended debris field of small parts while two major parts (cockpit and the rest) would stay each together till impact.
However, this theory still doesn't explain how the mass of the plane came down almost vertically without any spinning. 20,000 ft are a long way and she didn't roll or flip at all, she went belly down, like a paper dragon. This would be possible if the elevators would be set up to hold the plane's nose slightly up and would have stuck there after the cockpit was gone. With both wings still there, not much wind from any side, maybe ... yes, the main fuselage would not flip but go down in an almost stall attitude. It is mathematically, highly unlikely, but it appears to me, most aircrashes include some mathematically highly unlikely factors nowadays because all likely things are quite well covered. Planes go down from something that is predictable and likely to happen because that happened already sixty years ago and someone put some counter measures in it. Which makes basically unlikely factors the most likely ones in aircraft crashes. I looked once at this JAL Jumbo that went down over Japan like 20 years ago? They lost a part of the tail and rudder and stabs due to explosive decompression in the rear. The reason was a sloppy repair after a tail strike, years earlier. But it came down to some bolts that cracked over time. So in the hindsight, it was all explainable, but because it was so unlikely ... nobody thought about it before it happened. Which is in essence, the true nature of a black swan event. Not that it was not there or absolutely impossible to detect, it was just out of the perception.
Sooo, calculating that KC-130 not so much as a plane but more like a giant pipe bomb, could give maybe some answers.