My opinion is that the 20mm guns were in the pipeline for the Navy. They just didn't rewrite existing contracts and change existing delivery schedules to get them.
While I do not think the 20s were in the pipeline at the time the report was written, October, 1944, (They were still waiting for inputs from the fleet), they were certainly preparing for its possibility by building and buying aircraft with the capability of both the 20s and 50s. It is, however, apparent that the Navy had no urgent need to replace the 50s as the 20s remained on the backburner until the end of the war, and not finding it necessary to retrofit. It is also interesting to note in the report that not one single Naval representatives (over sixty, of which I am sure many had some combat experience and all had inputs from the fleet) demanded or even commented that their fighters needed more firepower, clear evidence that they felt comfortable with the 50s and considered them effective air-to-air weapons.
It is interesting to note that, while Commander Monroe was a proponent of the 20s, he was most excited about the high velocity 60 caliber.
Claidemore said:
For me a better hunting analogy would be comparing a .25-35 Winchester to a .375 H&H.
Both have similar velocities (approx 900 m/sec), and .375 bullets are about 3 times as heavy as .25-35s... just as 20mm are about 3 times as heavy as .50s.
You can take coyotes or antelope with a .25-35 reliably, but anything bigger than that and you are undergunned. The .375 will also take coyotes and antelope (bit messy), but it will also do the job on any other animal you might choose to shoot, up to and including large pachyderms.
I think this is a completely inadequate analogy to use. How many times do hunters take down running game with a rifle? A more accurate analogy is trying to shoot birds on the fly.
Shortround6 said:
This quite true, but both the US Navy and the US navy favored 20mm guns for night fighters so as to inflict the most damage in the shorter firing times expected during night engagements. In other words they expected a plane with four 20mm cannon to be able to inflict fatal damage to an enemy plane with less firing time during the engagement than a plane with six .50s.
Or, perhaps they realized that the night targets are likely to be larger bombers and were non-maneuvering.
A flawed analogy. The "hunter" is allowed more "bursts" of the same duration using the smaller gauge gun. Against the aircraft the 20mm guns may require a shorter burst at times. The target plane is is seen to be smoking, on fire, or large pieces falling off in 2 seconds vs the (perhaps) 3 seconds needed by a .50 cal armed plane. The hunter with his shotgun cannot adjust his "bursts", he cannot fire only 2/3s of a shell.
The "idea" that the .50 was good enough almost got the USAF in trouble in Korea. Despite using guns that fired 50% faster than the WW II guns and having radar range finders tied into the gunsights it may have been the better training of the pilots that allowed the USAF pilots to prevail.
While I don't disagree with your comment about multiple targets, I do believe shooting birds with a shotgun is appropriate. Hunters use birdshot for birds and not buckshot. While the probability of kill for buckshot is close to one, the probability of a hit is quite low (of course cost may be a factor, but I am sure you understand the point.) I certainly do not agree with you that the 50 cal "almost got the USAF in trouble in Korea". Take for instance comparing a one second burst from the F-86 with six M3 50 cal, an F9F with four 20mm M2, and the Mig-15 with two NS-23, 23mm, and one N-37 37mm.
F-86, six M3s, rof 1250 r/min, total r/m 7500, total r/sec 125,
throw weight/sec. 187.5 oz. (1.5 oz/bullet)
F9F, four, Hispano M-2s, rof 700 r/m, total r/m 2800, total r/s 47,
throw weight/sec 141 oz (3.0 oz./bullet)
Mig-15 two NS-23s, rof 550 r/m, total r/m 1100, total r/s 18, one N-37, rof 450 r/m, total r/m 450, r/s 7.5, overall r/s 26
throw weight/sec 138.8 oz. (6.2 oz/23mm bullet, 27 oz/37mm bullet)
So, from a raw hitting power, not including the explosive power, standpoint, the six M3s of the Sabre does not give up anything to the F9F or Mig-15. While installation weight of the guns is roughly the same, 50s vs. 20s, the real advantage of the 20 is carried ammunition weight. For the probability of striking the target, the F-86 weapon package is much higher. All of this becomes moot after the fast firing M39 cannon comes along.
I think the comments about the F-86 making hits and the Mig flying away so there was a need for a bigger gun is not a logically supportable argument. It is analogous to a hunter, on seeing feathers come off a bird and it continues to fly, wanting to switch to buckshot to increase probability of kill once hit. Had the F-86 had 20s, with less than half the projectiles fired, it might have had a significantly lower probability of even hitting the Mig. In addition, that one, higher probability, injuring 50 cal, may have forced the Mig out of the fight, which is also significant. Also, I think that the highly penetrating 50 cal bullet is effective against the jet aircraft in that one bullet hitting the fuselage section from the turbine through to the pilot, has a high probability, close to one, of disabling or destroying a jet. That is a very large target.
Six 50 cal M3 is a powerful weapons package and, firing for one second, provides a massive wall of high energy projectiles, and, if striking, easily taking down any fighter, and most likely bomber. I don't think the AF was anywhere in danger from using it in the Korean War.
