Hi Ack-Ack,
>One more question for you, why would they go in favor of the 20mm Hispano instead of the 37mm Oldsmobile cannon? Was the Hispano that much better than the larger Oldsmobile cannon?
Have a look at Tony's site:
http://www.quarry.nildram.co.uk/WW2guneffect.htmBased on Tony'd data, I calculated the Hispano II's total firepower as 1.06 MW (kinetic and chemical energy at the muzzle), while the 37 mm M4 had only 0.91 MW.
The Hispano cannon only weighed 50 kg compared to 91 kg for the M4, and while I don't know the total cartridge weight for the 37x145R rounds, I suppose an equivalent ammunition supply would have been roughly twice as heavy as the Hispano's, too ... only that the M4 didn't use ammunition belts but a mechanized feed that was yet heavier and only held a limited number of rounds so that it would be impossible to actually load an equivalent supply of 37 mm shells.
So the use of the Hispano cannon appears to be a very good decision.
On the other hand, one has to wonder why only one Hispano was used.
Historical battery:
- 4x .50 Browning M2 - 500 rpg - 336 kg - 100% firepower (38 s of fire)
- 1x Hispano II - 150 rpg - 87 kg - 94% firepower (15 s of fire)
- Total: 423 kg 194% firepower
Cannon-only battery:
- 2x Hispano II - 281 rpg - 238 kg - 187% firepower (28 s of fire)
That would have yielded about the same firepower at just 56% of the weight. In fact, you could have mounted a third Hispano for a substantial firepower increase and still have saved a few kilograms. The nose of the P-38 certainly should have offered enough space!
Regards,
Henning (HoHun)