found this interesting chart in Americas most celebrated fighter pilots handbook
'Fighter Combat tactics and maneuvering' by Robert L Shaw
note the difference in lethality between the 1933 M2 .50cal and the 1941 or 1944 20mm M2/M3.
I dont really understand the way the lethality is calculated but judging from the numbers its easily less than half the lethality of the 20mm.Also note the rates of fire
in the book it says this about working out thelethality of weapons:
'Table 1-1 is a collection of statistics on many of the guns which have been important in American combat aircraft, and is fairly representative of the armements of other nations, as well.Agood indication of the technological development of a gun is the weight of the projectiles that it can fire in one minute(assuming the barrel limitations and ammunition supply allows).In this table weight of fire is measured by the factor Wf.Tremendous progress can easily be seen here by comparing the post-world war I browning .30cal M2 with the 20mm M61 Gatling gun of the 1950's.'
'Lethality of a gun can be measured by multiplying the destructive power of its projectile and the number of hits.for non-explosive bullets, destructive qualities are generally proportional to kinetic energy: half themass of the projectile times the square of its velocity.To be more technically correct, the velocity used should be the relative impact velocity, but for comparison purposes, muzzle velocity will do.The factor FL in table 1-1, a measure of the lethality of the gun, is proportional to the kinetic energy of each projectile and the rate of fire.
FL should be roughly indicative of the lethality of a nonexlosive bullet fired at a specified rate from a gun,Cannon are a somewhat different case,since much of the lethality of these weapons is derived from their explosive shells.Therefor FL is a fairly accurate relative assessment of the destructiveness of machine guns , but underates the cannon in comparison.Likewise, it can be used to compare cannon of the sam projectile size, but it would slight larger guns in comparison with smaller ones.'
interesting stuff.maybe someone (with plenty of time on their hands
) could do a calculation for all AH guns and give a figure for them all?
anyway heres the chart:
