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If I'm going dove hunting with 7.5 shot, I'd rather not take a 25 pound shotgun to shoot it with.To me the following is a pretty good analogy of the cannon-50 BMG topic. A hunter who hunts doves will probably choose size seven and a half shot shell. The reason he does that is that he knows that a few solid hits with 7.5 shot will bring down a dove. A hunter who hunts geese will probably choose size two shot shell because a few solid hits with a size 2 will bring down a goose. Those size twos will bring down a dove also but the pattern is not very dense and a dove can fly though a pattern of twos at thirty yards and only lose a few feathers. Conversely size 7.5 shot will bring down a goose but the range has to either be very close, before the pattern opens up, so that a bunch of solid hits are made or else a lucky pellet hits a vital place. The pattern of a seven and a half is dense enough at thirty yards or even a little further that a dove cannot fly through the pattern without taking some hits.
Now the 20 mm cannon has a ROF of about ten rounds a second, so if a four cannon armed fighter fires a two second burst. he has sent 80 rounds down range at the target. A lucky hit with any of those rounds can bring down a fighter but more probably it will take several hits to be lethal. The 50 BMG has a ROF of about 15 rounds per second and a six gun fighter in a two second burst will then send 180 rounds down range at the target. The 50 BMG round is not as lethal as the 20 mm but still one lucky hit can bring down a fighter and he is far more likely to get hits with 180 rounds in the target vicinity than with only 80 rounds. The fighter is like the dove, which does not take a lot of lead to bring down. On the other hand a bomber is much more rugged, like a goose, and also a much bigger slower target, like a goose. It takes more killing but the pattern does not have to be as dense because the target is slow and big. Another factor is that the P51A with four 20 mm cannon carried 125 rounds per gun which gave it a firing time of 12.5 seconds or slightly more than six two second bursts. The P51D with six 50 BMGs carried 313 rounds per gun which gave it a firing time of 20.9 seconds or slightly more than ten two second bursts. The argument favoring the 50 BMG for fighter versus fighter combat seems clear to me.
I think the analogy broke down somewhere. I'd use a Berezin UB or MG-131 (or similar lighter gun) rather than an M2.So you use a full choked 10 gauge punt gun because it weighs a little less than your inproved cylinder 12 gauge?
I think the analogy broke down somewhere. I'd use a Berezin UB or MG-131 (or similar lighter gun) rather than an M2.
As for the P-40 in North Africa, I find it odd that so many people doubt it's effectiveness. I'd expect a 1:1 kill ratio against the 109. Most of the combat was at low level, where the P-40s naturally aspirated Allison was in it's element, and the P-40 had a marked advantage over the Bf-109 in turn and roll rates. The 109, for it's part, had superior climb/vertical performance and acceleration. These performance disparities generally counter each other. Firepower was a wash; the 109 was a fragile aircraft so the Warhawk's .50s were more then sufficient, and the 109s cannons were less effective against the incredibly durable P-40.
This analysis, of course, pertains to early war- the Emil versus the Kittyhawk, for example. Both aircraft received substantial upgrades as the war progressed; the Warhawk usually doesn't get enough credit for it's horsepower upgrades since those numbers are usually given for power at 10,000 feet, and as intelligent minds on this forum have told me, the power drop-off is dramatic even at that modest altitude. So later P-40s generating 1,325 HP at sea level would be right back to 1,000 HP by the time they were at 10K.
I don't know if the Gustav was ever deployed to North Africa, or if the campaign there was over by the time it was developed, but if memory served the Gustav was a dramatic improvement over earlier 109s- the turn performance was greatly effected by the improved engine power and other modifications, IIRC. If anybody knows more about that, I'd love to hear it.
So later P-40s generating 1,325 HP at sea level would be right back to 1,000 HP by the time they were at 10K.
We had 20 years to develop a purpose built aircraft gun and didn't pay any attention to it except for the M4 37mm cannon, which doesn't compare well to other contemporary heavy AC cannon.You go to war with the guns you've got. Which is, in fact, why the P-40 was used in the Second World War at all after the first months of 1941- the Curtiss-Wright factory was available NOW, and they needed fighters NOW, not in three months after the factory was re-tooled to produce Spitfires.
The reason the Americans got away with using the M2 is because they were in the habit of cramming hideously powerful engines into their airframes anyways, so the extra weight didn't hold down their more successful designs. The planes that would have benefited the most from the weight reduction- early-war underpowered birds like the Warhawk or the Wildcat- never would have gotten them, since the pressure on American forces was the most dire then, and co-operation between America and the Soviet Union was still gearing up- and given who was bearing the brunt of the enemy's attention, the aid was flowing one way.
As for the P-40 in North Africa, I find it odd that so many people doubt it's effectiveness. I'd expect a 1:1 kill ratio against the 109. Most of the combat was at low level, where the P-40s naturally aspirated Allison was in it's element, and the P-40 had a marked advantage over the Bf-109 in turn and roll rates. The 109, for it's part, had superior climb/vertical performance and acceleration. These performance disparities generally counter each other. Firepower was a wash; the 109 was a fragile aircraft so the Warhawk's .50s were more then sufficient, and the 109s cannons were less effective against the incredibly durable P-40.
This analysis, of course, pertains to early war- the Emil versus the Kittyhawk, for example. Both aircraft received substantial upgrades as the war progressed; the Warhawk usually doesn't get enough credit for it's horsepower upgrades since those numbers are usually given for power at 10,000 feet, and as intelligent minds on this forum have told me, the power drop-off is dramatic even at that modest altitude. So later P-40s generating 1,325 HP at sea level would be right back to 1,000 HP by the time they were at 10K.
I don't know if the Gustav was ever deployed to North Africa, or if the campaign there was over by the time it was developed, but if memory served the Gustav was a dramatic improvement over earlier 109s- the turn performance was greatly effected by the improved engine power and other modifications, IIRC. If anybody knows more about that, I'd love to hear it.
The M2 weighed around 70 pounds, was 54 inches long and had a ROF of 800 to 900 RPM. The 20 mm cannon weighed 129 pounds, was 78 inches long and had a ROF of 600 RPM. 70 pounds does not seem excessive for a weapon of that power and reliability. How much weight could be saved by a redesign. If 10 pounds per gun were saved times six guns that would only be 60 pounds. There could be that much difference in pilot weight. Methinks there is hair splitting going on.
You still don't get that I'm talking about the gun and not the caliber (ammunition)? (although I think the .50 should have had HE ammo like every other .50 in the war). The M2 was not an aircraft gun.Sorry, but it still comes down to arming your aircraft for the threat it is going to encounter. The .50 was enough to counter the 109 and 190 and other LW or Japenese aircraft. Had the US been up against bombers, they would have surely armed them with heavier weapons.
You still don't get that I'm talking about the gun and not the caliber (ammunition)? (although I think the .50 should have had HE ammo like every other .50 in the war). The M2 was not an aircraft gun.