"Fortress" 2012 B-17 movie

This is a movie about B-17 called “Fortress”. We had lively discussions here about how cartridges were ejected from machine guns in WWII planes. Here is an opportunity for “it” to come alive. Also, I know for a fact that some of you are very impartial to planes (right, Pete?)

Solutions to the “Case disposal” Problem ( in B-17s) were mulltiple; Turret (Ball) Guns fed the cases thru a chute out of the aircraft; whilst the Waist Guns dropped the cases on the floor of the aircraft, where they were collected later, and tipped out the “Waist” opening, usually on the return run home ( From USAAF Photos of missions).

NO wonder Air-raid personnel and AA crews below all wore helmets, a falling .50 cal case could be just as deadly to an unprotected person as an exploding bomb or shell. Not only was MG fire “hard rain” on the ground, but Aircraft MG shell cases were the equivalent of a “Hailstorm”, when added to AA shell fragments, etc.
I suppose the casualty breakdown due to “shell case impact” was not a priority in records during WW II…

Doc AV

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.30-06 and .303 Britt as well as 8x57 mm fired casing falling from a height greater than 300 feet from a passing aircraft strafing or on a much higher bombing altitude will strike the ground at about 55 MPH. This was calculated by the AAF to see what precautions were needed for combat soldiers and ground crew. The heavier ( 3 ounce ) .50 BMG casing and some 20 MM hit at a little faster velocity of about 60- 80 MPH. How they measured this for real,I have no idea. It had to be all calculations and measuring impact damage done by the casings or to the casing themselves.
(Either casing would not fun to be hit with.)
Test were conducted to see if the casing were to stay at terminal velocity (120 mph or so) but the results showed as the air density was “thicker” ( the data I read years ago was a major snooze ) closer to sea level the casings slowed down due to resistance of the base of the cartridge casing and the way the cartridge traveled through the air. This had to be a real challenge to calculate as the casing may or may not fall the same way every time.
In later years Col. Chin in his outstanding set of books " The Machine Gun" talks about the problems of fired casings.
This is by no means having anything to do with the fired projectiles. Many photo’s can be seen about what happened at Pearl Harbor with returning “friendly” fire. The are books in England about damage done during the Blitz. Many died of shrapnel and returning projectiles.
I have never been able to find any info on the falling links.
The info on falling casings is almost nonexistent also. You’ll find more data in old military medical records for combat wounds and training injuries.
Some Navy damage reports of FOD damage to jet engines and airframes touch on the topic a little. I have yet to see an in depth study of falling fired casings.
My only hands on info on this subject was in the late 70’s I was allowed to be a safety observer working along with the Marines as my ship and others did Shore Bombardment training on the island of Culebra off of the coast of PR.
I got to see A-6’s with a 20mm pod do a long burst of fire into one of the targets. Later that afternoon we were allowed after EOD did a sweep, to visit the targets. There were hundreds of 20mm Vulcan cases all over the place. I still have a few and they have almost no marks on them what so ever from the fall and strafing run. None were buried in the dirt. Ones that hit mouth down were only a couple of inches in the soft soil and stuck up base first. My findings are not scientific what so ever. It is just what I observed in soft soil.
There is a Viet Nam slow motion film of a POD firing a very long burst and you can clearly see the casing free falling for about 20 feet.You can see that the casings slow down very quickly. If I can find the link I’ll post it.
It’s an interesting subject. I’d very much like to find a test by HP White or some Defense contractor as to what really happens to a falling casing when it hits the ground or living thing.


Calculations and tests have been conducted to determine the velocity of falling bullets that were fired straight into the air. A .30 caliber 150 grain bullet will reach a velocity of about 300 fps, a .50 caliber 700 grain bullet nearly 500 fps. Those approximate velocities are reached when the air resistance balances the weight of the bullet and the velocity can no longer increase.

A 30 caliber bullet at 300 fps (200 mph) is considered non-lethal but certainly dangerous.

Objects such as empty cases, being irregular in shape, can be expected to fall at slower speeds although calculating the terminal speed would be nearly impossible. Add in the effect of anything other than a straight down 90 degree angle and the velocities would increase.


Very true Ray. Col Hatcher in his book, “Hatcher’s Notebook” conducted many test on bullets fired straight up into the air as well as angles perpendicular to the ground. What the bullets could and could not do are well documented. His book is a great read.

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Near where I live there is a cemetry full of air raid wardens and the like who were killed during the bombing. They have a whole section of the cemetry to themselves. Causes of death would be many. I think the bigger danger would be shell fragments from the AA guns, but people certainly were killed by falling debris.

The mathematical treatment of determining terminal velocities of falling bodies taking into consideration the object’s mass, shape, and frontal area as well as air density (think ballistic coefficient) have been thoroughly worked out. I always get a kick reading about someone’s pronouncement that a bullet falls out of the sky just as fast as it went up, etc. We had a very recent local incident in which a golfer on a golf course was struck in the chest by a bullet supposedly coming from a rifle range a couple of miles away (the source of the bullet is still unknown), but he suffered little injury. However, there was an immediate court injunction which shut down part of the range. I never read just what kind of a bullet it was or any evidence that it even came from the range. Anyway, the golfer is now suing everyone. I guess the personal injury attorneys got to him faster than the bullet did.

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While searching for another topic (witch I could not find anyway), I found this interesting topic. About falling AA fragments, my father lived in The Netherlands, in De Lier near Hoek van Holland and Maassluis, near the Atlantic Wall. There where a lot of FLAK-guns in the area. He told me about two different people killed by falling AA fragments when the FLAK was firing on daylight bombers. He told me when the FLAK was very heavy, it was dangerous outside, and there was, during the war, a lot of damage on rooftiles and even more on the glasshouses in our aera. Later, when I was working with my father, who was a gardener, we often found AA shell fragments in the ground. That was around 1975!! They can easily be recognised from nails or other metalpieces in the ground, by hitting such a piece against a hard object, stone or bij a hammer. They will not break, only some rust will go of, and then you had a curved, twisted piece of metal, with amazing some razor sharp edges, even after 30 years in the ground. I have collect them and have them still in a box with my ammocollection.


Wonder why the B-17 aircrews didn’t just dump all the cartridge casings in the English Channel like they did the bombs that couldn’t be expended on German targets?

First, I want to thank all of you for not including any mathematic formulas for ths subject…

I remember seeing a photo of the area between the two clearly identified waist gunners machine gun ports, showing someone using what liiked like either a coal shovel, or show shovel, tossing the empty .50 BMG brass out the MG port. I do not remember what aircraft it was, or if the image was on the ground after the mission ended.
I am certain I have a copy of the image, somewhere…

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Cartridge casings are made off brass, a rather necessary material, so I can imagine they want to bring them, as much as possible, back to the base?