Thread: 4.12.2 de-bugging
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Old 09-19-2014, 08:25 PM
Pursuivant Pursuivant is offline
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Another period video showing exactly how rifle caliber MG fire works against both unsealed and sealed fuel tanks.


Both guns appear to be .30 caliber MG, firing from about 20 yards with a mixture of tracer and ball.

Notice that against the unsealed tank, the initial burst of bullets DON'T cause a fire, nor does the fuel in the tank ignite. Instead, several seconds after the bullets hit, once sufficient fuel has spilled, the incendiary or tracer bullets ignite the spilled fuel. The fuel in the tank itself only starts to ignite several seconds after that, once the heat from the spilled fuel fire has had a chance to volatilize the contents and make gasoline vapor spill out of the tank to mix with air.

In the second part of the video, you have a self-sealing tank filled 3/4 full of AvGas. Multiple 0.30 bullets which penetrate and exit the otherwise rigid tank fail to produce serious fuel spills and do not ignite the tank.

I count 8 entrance holes and 6 exit holes in the tank, with some obvious tumbling by a few of the bullets.

Notice that almost no fuel has spilled, since the tank stops leakage almost instantly.

This video is circa 1940, so represents equipment that would be installed on Western Allied planes by late 1940 to 1941.

As a side note, some planes (e.g., the LaGG series) vented exhaust gasses into the fuel tanks to prevent fuel vapor and air from mixing. This is now standard on most planes, but many WW2 planes didn't have this technology. In part, this was because the hydrocarbons in the fuel exhaust interacted badly with the rubber material that made up the fuel cell.
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