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History Forum / General / British History / January 2005Logic in fighter guns?
The string of a couple days ago touched on arms carried by Mustangs and Spitfires. It brought a few questions to mind. The American 50 mm machine gun carried on Mustangs and many other American fighters was (and is) a potent weapon. The 50 has tremendous range and It'll crack an engine block with no trouble or demolish just about any amour short of a tank's. What was the need for the even heavier 20mm sometimes used on Spits and some later Hurricanes? It's ammo being bulkier and heavier put limits on how much could be carried. Was it chosen because of it's availability in Britain at the time? Spits and Hurricanes also carried 303's. Again, this seems like going too far the other way. The 303 was a suitable infantry round (Although that is a lively debate in itself. The American 30-06' charge was a bit heavier and the roound would reliably drop a man right then and there. The 303 was a touch lighter and was also just a touch less effective.) Yes, the planes could pump out a regular hail of bullets but the 303 seems rather light weight for actually shooting down an aircraft. Most Spits carried some of each which again seems like pre-Dreadnaught navel thinking. Wouldn't a single caliber be more effective ala uniform gun size on the Dreadnaught? What was the logic? Or was it a case of what was available? ??????? Rod > The string of a couple days ago touched on arms carried by Mustangs and > Spitfires. [quoted text clipped - 8 lines] > put limits on how much could be carried. Was it chosen because of it's > availability in Britain at the time? Nope. They didn't actually hit the target very often with air-to-air guns. Any hits that did happen needed to count. Explosive ammunition counts more than solid stuff, so 20mm cannon works better than any machine gun. However the more bullets you pump out the more hits you get, so loads of .303 works better than not that many .50 as most stuff just flies straight through. When trying to shoot down bombers you actually need to destroy structures rather than kill people or knock out engines as there are loads of people and engines. Explosive ammunition does that better than machine guns. The British went from 8x .303 to 4x .303 + 2x 20mmm to various combinations including .50 mixed with 20mm. The 'C' or 'universal' wing Spitfires could actually mix and match weapons depending on mission. The P.51 was stuck with its .50 because of wing thickness issues. However it wasn't trying to shoot down multi engines aircraft with large crews... -- William Black ------------------ Strange women lying in ponds distributing swords is no basis for a system of government > > The string of a couple days ago touched on arms carried by Mustangs and > > Spitfires. [quoted text clipped - 44 lines] > Strange women lying in ponds distributing swords > is no basis for a system of government there was a variant ofthe mustang that had 4 20's . the us felt the 50 was better as it could carry more ammo and was lighter . and as the usaaf didn't have to fight bombers it was the right choice . shooting out the engines and killing the pilot will take down a plane quite nicely and is easier than trying to shoot the wing off . > The string of a couple days ago touched on arms carried by Mustangs and > Spitfires. [quoted text clipped - 26 lines] > > Rod the brits didn't use a 50 cal weapon , when the 303 was deemed to be too light they went with what they did have a 20 mm cannon . i'd take 4 20's over 8 303's anytime . >> The string of a couple days ago touched on arms carried by Mustangs and >> Spitfires. [quoted text clipped - 36 lines] >light they went with what they did have a 20 mm cannon . i'd take 4 20's >over 8 303's anytime . Except if you lose one the asymmetric recoil is worse in the cannon fighter than the other. Mike  SignatureM.J.Powell > Except if you lose one the asymmetric recoil is worse in the cannon > fighter than the other. The standard armament up to the end of the biplane age was two or three Vickers MG. with the introduction of monoplane fighters and bombers and reduced engagement times an increase in firepower was considered useful. The RAF held trials first to decide on the MG that would replace the Vickers and as far as I can remember only rifle calibre weapons were submitted. As for heavier MG neither the Browning or the Vickers 0.5 was available in quantity to Britain for most of the war and when some Brownings did become available they went to bomber units. Of course by that time the need to be able to knock down an aircraft with one or two hits was pushing for the use of cannon anyway. Ken Young kenney@cix.co.uk Maternity is a matter of fact Paternity is a matter of opinion >> Except if you lose one the asymmetric recoil is worse in the cannon >> fighter than the other. [quoted text clipped - 10 lines] >an aircraft with one or two hits was pushing for the use of cannon >anyway. I read recently, can't remember where, about an RAF Sqn Ldr who conducted test in about 1936/7 to how many guns were necessary to do significant damage to an aircraft considering that the firing pass would be about 2-4 seconds. He came to the conclusion that 8 were necessary Mike SignatureM.J.Powell >>> Except if you lose one the asymmetric recoil is worse in the cannon >>> fighter than the other. [quoted text clipped - 17 lines] > >Mike It was mentioned in the first episode of the 'Spitfire Ace' series which is showing on Channel 4 on Monday nights. > The string of a couple days ago touched on arms carried by Mustangs and > Spitfires. > > <snip> > > What was the logic? Or was it a case of what was available? You should put the question on news:sci.military.moderated. One of the regular contributors there is Tony Williams, who has published on the subject. He also has a site: http://www.quarry.nildram.co.uk/. Quite well done, IMLTEO. -- Andrew Chaplin SIT MIHI GLADIUS SICUT SANCTO MARTINO (If you're going to e-mail me, you'll have to get "yourfinger." out.) > You should put the question on news:sci.military.moderated. One of the > regular contributors there is Tony Williams, who has published on the > subject. He also has a site: http://www.quarry.nildram.co.uk/. Quite > well done, IMLTEO. Thank you, Andrew! If you go to my website and scroll down the front page to the 'Aircraft' heading you will find several articles which are relevant to this subject. Most important of all is 'WW2 Fighter Armament Effectiveness' which provides a large quantity of data, analysis and explanation comparing the guns, the ammunition and the weapon fits of a range of WW2 fighters. To find out one reason why the US didn't make more use of the 20mm which they had in production, take a look at 'The Hispano-Suiza HS.404 20 mm Aircraft Gun in US Service' but brace yourself, it doesn't make pretty reading! Tony Williams Military gun and ammunition website: http://www.quarry.nildram.co.uk Discussion forum at: http://forums.delphiforums.com/autogun/messages/ "Rod Keys" wrote in message > The string of a couple days ago touched on arms carried by Mustangs and > Spitfires. [quoted text clipped - 22 lines] > > What was the logic? Or was it a case of what was available? Rifle caliber guns were what pre-war planes were built to carry and sufficient for the purpose at the time. Their higher cyclic rate of fire made hits easier and the guns were light enough to be carried by low powered aircraft engines. Remember in '38 650 hp was real power. During the war fighters doubled that horsepower which made heavily armored seats and plates possible which in turn made them more difficult to shoot down. Bombers added more power, multiple engines, and greater defensive weapons which made greater stand-off and hitting power of the 20mm weapons necessary. The US never had to worry about shooting down bombers larger than the JU88 or Betty. The .50 cal was a good gun, simple and reliable. It fit into our manufacturing scheme of volume over high-tech jiggery pokery and the gun was used successfully throughout the war by all services in just about every imaginable role possible for a gun. By '45 the gun was becoming obsolete in the air role mostly because of its shorter range and lack of an explosive projectile. -the Troll > The string of a couple days ago touched on arms carried by Mustangs and > Spitfires. [quoted text clipped - 3 lines] > The American 50 mm machine gun carried on Mustangs and many other American > fighters was (and is) a potent weapon. Although built in America, the Mustang was designed for and first ordered by the RAF. >... What was the need for the even heavier 20mm sometimes > used on Spits and some later Hurricanes? A combination of factors. First, a single hit from an explosive shell would do more structural damage than several hits from ball ammunition. Second, German aircraft started to carry heavier armour, against which the larger calibre was more effective. Third, cannon were good against many types of ground target. Some Hurricanes even carried 40mm cannon for tank-busting duties. ... > Spits and Hurricanes also carried 303's. Again, this seems like going too > far the other way. It was proven technology in their predecessors. It was also what British suppliers were geared up to produce. When it was first proposed to increase the firepower from two to four guns, that was considerd to be technically impossible. However, trials on old bomber fuselages showed that fighters would need to carry at least eight guns to be effective when attacking bombers. In the event, the Hurricane proved to be capable of carrying up to 12 .303 machine guns and the Spitfire up to eight. ...> Yes, the planes > could pump out a regular hail of bullets but the 303 seems rather light > weight for actually shooting down an aircraft. Killing the pilot is a good way to shoot down an aircraft and, in the early days, .303 calibre was quite adequate for that. > Most Spits carried some of each which again seems like pre-Dreadnaught navel > thinking. Wouldn't a single caliber be more effective ala uniform gun size > on the Dreadnaught? On tank-busters, the machine gun was used to walk the guns onto the target, before opening up with the cannon. I presume that tracer in the machine guns on a mixed-gun aircraft would serve the same purpose in air-to air combat. As you say, the aircraft could carry a lot less cannon ammo than they could of .303 ammo. Colin Bignell "nightjar .uk.com>" <> Although built in America, the Mustang was designed for and first ordered by > the RAF. the mustang was designed by the north american aircraft company , not the british , the design was new and the brits were the first to order it . they were looking for any fighters they could get their hands on and they were in america to buy p-40's . they realized the p-40 was obsolete and saw some potential in the mustang . but the p-51 was an american design ,,edgar shumued was the chief of design . > "nightjar .uk.com>" <> Although built in America, the Mustang was > designed for and first ordered by [quoted text clipped - 7 lines] > but the p-51 was an american design ,,edgar shumued was the chief of > design . Yes, it was an American design, but it was originally designed for the RAF. When the RAF found that they couldn't get enough P40s fast enough they approached North American to see if they'd be interested in building the P40 under license, North American counter offered with a commitment to produce the Mustang prototype withing 90 days, the rest as they say is history. SignatureNik Simpson > "nightjar .uk.com>" <> Although built in America, the Mustang was designed > for and first ordered by > > the RAF. > > the mustang was designed by the north american aircraft company , not the > british , I didn't say it was designed BY the British. > the design was new and the brits were the first to order it . they > were looking for any fighters they could get their hands on and they were in > america to buy p-40's . they realized the p-40 was obsolete and saw some > potential in the mustang . The British had decided to buy the P-40 and they approached North American Aircraft (NAA) to build it at their plant, because Curtiss were at full capacity. It was only then, with no existing plans nor any proof that they could do it, that NAA suggested that they could build something better. At the request of the British, NAA bought the wind tunnel data of the XP-46 from Curtiss, as the basis for their new design. The P-51 came into existence only because of a British need and a lack of capacity at Curtiss. Colin Bignell >> "nightjar .uk.com>" <> Although built in America, the Mustang was >> designed for and first ordered by [quoted text clipped - 20 lines] > > Colin Bignell Not quite. In April 1940 'Dutch' Kindleberger (president of NAA) visited Sir Henry Self of the British Purchasing Commission to sell him B25 bombers. Self didn't want any but did want a modern fighter (something better than P40's and the like that would be on a par with a Spitfire, but in greater numbers) but Kindleberger had nothing to offer. Self told him that Curtiss were developing such an aircraft but were too busy to build it. Kindleberger went straight to Curtiss and bought the design for $56,000. Kindleberger told Self he would have some ready for Sept. 1941 - the prototype was the NA-73 and was OK but lacked high altitude ability and limited to 11,800ft becuase of the old-fashioned Allison V1710 engine which was not supercharged and very thirsty. It flew it's first mission on May 10th 1942 against Breck-sur-Mer. In 1943 when the Merlin went in it became a proper fighter. The P51 had huge fuel capacity to cope with the very thirsty Allison, so when the much more efficient Merlin was fitted it suddenly had a huge range. As pilots of the time were quoted as saying '. . . . it won't do what a Spitfire can, but it will do it over Berlin. . .' SignatureJulian --------- = Pretentious Sig required = |
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