You have your choice of 19 grams or 85 grams of HA41 (hexogen aluminium) in a 20mm or 30 mm Minengeschoss round ammo feed group in the outer wing right where those hexogen style explosions were happening in that gun cam footage. American .50 cal API ammo cannot cause an explosion like that without something with an energenic propensity to contact first, causing a detonation.
Remember that war time test footage of a 30mm fired at a static spitfire. Amasing how the hexogen explosion to the wing looks like the hexogen ammunition explosion from inside of the FW190 wing. Wonder how many countries 20mm wing gun's ammunition were susceptible to this kind of external detonation source if the detonator was like penthrite and the HE content was not TNT? Anyone have the time to look at WW2 guncam footage against japan again to see if this signature explosion happens to wings right about where the 20mm ammo group is stored?
The german fuzes AZ1502 in the 20mm and ZZ1589 in the 30mm were both primed with penthrite. An HE rounds detonator cap and body would not withstand the impact of a .50cal API round. The fuze bodies and secondairy inline duplex detonaitors were made of three possible materials. Aluminum, Copper or Magnesium.
Hexogen (RDX) and TNT are the most common explosives used in military explosive compositions. The percentage of these two are set to achieve the desired detonation speed and detonation pressure.
Hexogen or RDX is the more powerfull one, with density around 1.8 g/cm3. TNT is less dense, around 1,65 g/cm3. So if you have two rounds and fill one with RDX and the other with TNT, the RDX round will be 35% more powerfull, but also approx. 5 times more sensitive (dificult to handle).
Aluminium dust is used to increase the detonation speed - side effect: it increases the sensativity.
Hexogen has about 50% more power than TNT (measured as calories per gram x cc per gram) and 100% more brisance or shattering effect, measured by power x velocity of detonation x density. However, it was twice as sensitive.
No cook off in those FW wings. Hexogen explosion.
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Spitfire 30mm static fireing test.
http://www.youtube.com/watch?v=ZoLLDi-M3fk