About WW2 fighter aircraft firing power

[Rob Philips]

Thanks, Harri. In his analysis Tony Williams included factors such as the benefits of mass production of a single weapon type rather than a multitude, and most of all the fact that the US considered their .50 to be, perhaps not the most efficient gun, but a combat proven and adequate one. Benefits of a different nature than can be expressed with gun & ammo technicalities only.

Regarding the complexities of a hitting capability definition: let's go the hard way, and see where we end. If the matter was easy, and with that most likely well known, then I would not have raised it. I agree that equasions with rate of fire, muzzle velocity and energy content shall lead to conclusions that were already nicely summarized by Tony. I do not agree with his proposed calculation of explosive energies, that rather simplifies the matter, but would agree that a more elaborate calculation would probably lead to the same or similar results in a table with comparative data.

In any case, I'm not finding pattern density, or dispersion, anywhere in these considerations. It strikes me that this could be a flaw, that is not present in the world of hunting shell ballistics. Note that "dispersion" has a negative ring to it, as in "deviation from the perfect line". That would be valid at the target practice range, but it might be a desirable feature in aerial combat.

I once witnessed so-called accidental automatic fire coming out of an AR 15 rifle. Obviously the interruptor was modified to produce automatic fire from this civil version of the M16. Three rounds, and all three in a group of 3 cm diameter at a 100 meter range, and on top of that all within the inner circle of the bullseye of the 100 m target. First class accuracy, that would however be pointless in actual combat, where one of these hits would have been quite enough to incapacitate the opponent. This splendid accuracy does not increase the chances of hitting, it merely wastes ammo at the same point of a basically motionless target. The pattern is too dense to make sense under these conditions.

In aerial combat things would be different, as the target is moving fast, in four dimensions. Multiple hits at the same spot with non-explosive rounds could accumulate the damage done. If not at the same spot, which is very unlikely anyway at regular firing ranges, then multiple hits close together could lead to a greater net effect than can be calculated as the sum of the effects of all hits. A wing spar may not yield after a hole has been shot into it. It may not yield after several holes. But it may yield if several holes are shot close together. This is another way of saying that, if we forget about explosives for the moment, pattern density is a factor that needs to be considered. And surely, as stated by Tony in his post of today, this makes sense only if the individual rounds can do damage at all.

Pattern density is presented here as a factor in damage infliction. It is also a factor in my key interest: hitting capability. Perhaps it would be better to speak of "pattern spread" here. The larger the pattern, the easier it is to score hits on a target of a given size on a given distance. The pattern cannot be enlarged beyond the point where the projectile density becomes too low to score hits, and/or to be effective in inflicting damage. There must be an optimum here. My question is: how can we define that optimum? Leaving out explosive rounds, then this optimum is likely to be a trade-off between number of rounds per second, their damage inflicting properties, and their dispersion in a plane vertical to the line of fire.

Regards,

Rob