raymond%europa@uunet.UU.NET (Raymond Man) (08/28/90)
From: raymond%europa@uunet.UU.NET (Raymond Man) I believe it was Adolf Galland who talked about the pros and cons of carrying Cannons vs MGs. In addition to increase drag and weight and lowering performance, Cannons jam quit often and the vibration was bad for the engine and airframe. But Cannons out-range the MGs on the Fortress and were very effective. So it was a matter of wether the pilot was more likely to attack bomber formations or dog-fight with the escorts. In terms of mass deliver rate, which is important for improving the chance of hitting a figther with short bursts in a dog-fight, MGs are actually better. At the Battle of Britain, the Spits and Hurricanes had something like 10 lb/s from their MGs. Later in the War, the rate was doubled to 20 lb/s with 8 MGs. While a single cannon shell can blast a fighter out of the sky, it takes a pretty good shot to do it with only a few rounds. Just call me `Man'. "And why take ye thought for " -- Matt. 6:28 raymond@jupiter.ame.arizona.edu
ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib) (08/30/90)
From: ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib) >In terms of mass deliver rate, which is important for improving the chance >of hitting a figther with short bursts in a dog-fight, MGs are actually better. >At the Battle of Britain, the Spits and Hurricanes had something >like 10 lb/s from their MGs. Later in the War, the rate was doubled to 20 lb/s >with 8 MGs. Hmm.. the early spitfires and hurricanes all had eight wing mounted .303 machine guns. The Mark V and IX spitfires had four .303 machine guns and two 20mm cannon. The pilot had the option of using all guns, machine guns only, or cannon only. Later variants had either four 20mm cannon, or two 20mm cannon and two .50 caliber machine guns. I wonder if the early spitfires and hurricanes gave the pilot the option of using four or eight machine guns at a time. The cannon definitely had the edge over the machine guns as far as range was concerned. The low ballistic coefficient of the .303 bullets (200 grain spitzers, I believe) caused tremendous bullet drop over the 250-400 yards that most engagements took place at. The .50 caliber machine guns were a definite improvement over the .303. (700 grain projectiles, close to 3000 fps velocity as opposed to about 2400 for the .303). The cannon had their own disadvantages: low rate of fire and a limited number of shells. The 30mm cannon on the P-39, for instance, had something like 12 shells - enough for one burst at most. [mod.note: The P-39 carried either a 37mm or 20mm cannon; in this case, I think you're referring to the 37. - Bill ] What really amazes me is that they could get a rimmed shell (the .303) to work in a machine gun. The British did use the german 8mm Mauser cartridge in some of their terrestrial guns and they ought to have used it for their aerial guns too.