Hi Pinsog,
>5 rounds of 303 may have the same energy as 1 50 round, BUT you could shoot all 5 of those 303's into the seat armor or maybe engine block of a 109 and they won't penetrate, neither would 10, 20 or more.
It's true that different rounds will have different effect on the various parts of the aircraft they might hit, but an aircraft consists of enough different part to make energy a good yardstick nonetheless.
A different method of assessing damage potential (based on momentum, with a modifier for chemical energy) can be found here:
WORLD WAR 2 FIGHTER GUN EFFECTIVENESS
The difference to the total energy approach is not that big, and in fact we recently noticed that the table on Tony's site that compares the two methods has a slight inaccuracy that makes the deviations appear somewhat greater than they actually are.
>In the BoB I don't think the 20mm was the right weapon due to the inexperience of many of the British pilots(I'm not running them down, please don't start an argument about that) 60 rounds isnt enough for an inexperienced pilot.
Hm, look at the total energy of one round:
Browning ,303 7,7x56R: 4,38 kJ per round (average)
,50 Browning M2 12,7x99: 21,8 kJ per round (average)
Hispano II 20x110: 106,2 kJ per round (average)
The total energy of the batteries:
8 x 333 rounds Browning ,303: 11,7 MJ
6 x 93 rounds ,50 Browning M2: 12.2 MJ
4 x 140 rounds ,50 Browning M2: 12.2 MJ
2 x 60 rounds Hispano II 20x110: 12,7 MJ
Accordingly, the inexperienced RAF pilot with the same level of shooting skill resulting in the same hit probability will bring (approximately) the same amount of energy on target with each of these batteries. The number of rounds necessary for this varies, the effect on the target not so much.
Regards,
Henning (HoHun)