50 BMG case weight/damage from falling

Cool photos. Thank you, guys. Nobody has the math chops to try to tackle the question about the impact force of a .50 BMG case falling five miles? I'm still interested.

I think I formed this question after hearing some of the stories I heard from a guy I worked with whose father flew a P-47. I was thinking more about structures and livestock. From what has been posted so far, it sounds like my calculations are off some.

I had a Great Uncle who flew a P-38 in Europe. He was shot down in 1944 and spent the remainder of the war as a POW. I found the Missing Aircrew Report regarding him. I never heard him talk about it, but this roughly matches what my grandfather told me.





Because this may be drifting away from firearms, I do have a couple of family heirlooms from him. But I've posted those pics at least once here on some thread or another already.

 

Depending on the station, they carried between 400 and 500 rounds.

I've seen this at Fort Carson and Kaho'o'lawe as well. The links are easy to find on hardpan.

Having been in the impact areas as part of EOD and as an archaeologist, i have seen this. It is rare to find a point, but there is plenty of evidence in the form of chipped stone and hearths.

 

The GAU-8 gun system in the A-10 is what is referred to as a double-ended feed system, that means the empties are returned to the back of the feed drum. Nothing is dumped over-board.



The only 30mm cannon I know of that dumps empties over-board is the AH-64 Apache

 

A "terminal velocity" of 133 ft/s is a little over 90 mph. I still say an 850 grain piece of brass falling at that speed would have less "impact" than it would have if a B-17 ran into it at a B-17's normal cruising speed (I googled it) of 170 mph.

 

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They truly are the greatest generation!

 

I usually put a "like" on photos but I just can't bring myself to do so on those damaged planes!

 

No doubt you are correct. Especially when things get cattywhampus as shown in some of the pics posted earlier.

 

The terminal velocity will decrease as the object falls due to the air becoming more dense. Assuming your weight is close, the velocity profile will be something along the lines of:

20,000 ft - 17.5 mph
15,000 ft - 16.0 mph
10,000 ft - 14.8 mph
5,000 ft - 13.7 mph
2,000 ft - 13.1 mph
1,000 ft - 12.9 mph

Now, it will take some time for the case to slow down as it passes through the denser air, so it might hit the ground at 10 to 12 mph.

(Estimated using the drag coefficient of a cylinder falling base (heavy end) down with a length-to-diameter ratio of greater than 2, which is around 0.8)

 

I found a 50 BMG that failed to fire that fell out of a plane near Rawlins Wyoming back around 1982. Been out in that high desert for some 40 years before I found it while looking for arrowheads.

 

Then they must have came out of the apaches- remember that we were a safe(ish) distance from whatever was getting dropped- and some of our TIC's looked like a live fire airshow, depending on what was sent. So yes, there were occasions where apaches and A10's were on station, obviously not slinging ordnance at the same time. Driving out after, I just assumed they were from the A10's.

 

Cool. Your table demonstrates an almost 30% decrease in velocity due to air drag. I used a constant drag coefficient of 2.8125 in my calculations. I figured air density would slow the fall but didn't include it in my final calculation of 33 lbs.

Having climbed 14,000 ft mountains I can attest to the "sparsity" of air at that altitude. I read that the changing density of air was a major concern when taking shots with the Paris Gun in WWI (but I digress)....

 

The 30mm gun on the A-10 holds the spent cartridges.