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The 0.5 inch Browning is likely to have been unattractive for many air forces.
The MG131 was designed around the concept of creating a compact 13.2mm gun that could directly replace rifle calibre guns.
A M2/0.5 inch browning in many cases would not have fitted, probably not in the Me 109 cowling stations or the more streamlined or smaller German turrets.
The MG131 seems to have achieved its objective of replacing those guns while providing the destructive capability that had been lost to rifle calibre machine guns as armour increased.
Perhaps the Browning might have fitted easily in the wing stations of the Me 109 without fitting gondolas but if that was the case the MG131 could have been fitted anyway.
I'd argue that the Spitfire might have done well with its 8 x 303 Browning's replaced by 8 x MG131 type guns.
Where the Germans might have benefitted from a 0.5 inch high velocity guns is in the commanders station of their tanks. The gun might have fitted there and given the problem the Germans had with air attack would surely have been a far more serious threat to VVS and allied aircraft than the traditional MG34 they used.
One advantage of an explosive round is self destruct ability. The 20mm C38 round used by German FLAK had a self destruct. It's likely the MG151/20 and MG131 also had a self destruct ability. This is useful when you are firing above your own troops and population. Falling rounds was a big killer of civilians.
Using short/light projectiles would probably be more practical than resorting to more extreme case modifications, and using short, wide projectiles tends to still allow proportionally more HE/I capacity than smaller, longer rounds. (though ballistic performance is worse due to shape and sectional density -I do wonder if using a shorter, lighter 30 mm round on the Mk 108 would have been a good compromise for improving muzzle velocity while retaining relatively high HE capacity, or perhaps the same to address the low velocity of the american 37 mm M4 -particularly as it was mixed with the high velocity .50 and .30-06 browning guns)Please note that if you keep the same receiver length (a quick conversion) you are pretty much limited to the same cartridge overall length. If you significantly increase the projectile diameter, you have to shorten the cartridge case length and powder/propellant space. Please note that the Russian 20 X 99 and Japanese 20 X 94 use light (short) projectiles of 'standard' type. ONLY the Germans used the thin wall mine shell. The process of manufacturing the mine shell, while the concept is not difficult the actual execution is, was notable enough that the company's trademark symbol is a reference to the process. It is a similar process to making brass cartridge cases. Doing it in steel is a lot more difficult. Also please note that most cases taper, this aids extraction. Totally straight cases can cause problems and the higher the pressure the more problems. The Blow back guns usually operated at lower pressures than the locked breech guns.
The WWII Fighter Gun Debate: Gun TablesGranted, the Ho-5 wasn't that a powerful (79g shell at 750 m/s), but I don't think it was under-loaded. Please check out the quote in post #5 here.
For the 18mm, I agree that it should be around 700 m/s for the 100g shell, though I'd rather have an 80 g at 750+ m/s.
Modifying the case base or overall length to a significant degree would mean more comprehensive changes to the gun itself, not impractical but not as simple and a barrel change, so more like the scaled-up Ho-5 itself. (or scaled-down Ho-103)My idea was to either push the base .50 cartridge up to the biggest size of the shell that is practically possible, or to come out with a belt fed 20 mm cannon that is lighter than MG 151/20, let alone Hispano. The 17-18mm exploding ammo was well within the scope of any major armament/ammo producer in the world, even in late 1930s.
Yep, the only other belt-fed aircraft cannon available in the 1930s was the 23 mm madsen, and that was in the Hispano's weight/recoil class (or a bit lower), but had a fairly low rate of fire. Nice destructive power though, and possibly the best pre-war anti-bomber weapon. (and if further development for speeding up RoF was possible, it could have stayed competitive throughout the war as well -or, of course, engineering a browning derivative rechambered for the 23 mm madsen cartridge)Bolded part is one of main benefits of the BMG - it was belt fed from the get go. The significantly lighter weight is another (both for gun and for ammo), and should remain so even when modified for a bit more heavier projectile.
Indeed, the 23 mm HE/T round (the one sectioned in Tony William's collection linked above) functioned that way, as did the 37x145mmR M54 HE/T shell used in the M4 autocannon.This could very well be why most HE ammunition for aircraft cannon was HE-tracer. Many designs used a passage way from the tracer compartment to the HE compartment with some sort of delay component to act as a self destruct mechanism. As the tracer burnt out it ignited the delay element which then burned into the HE compartment to detonate the shell.
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The wing gun question gets rather interesting. The 20mm MG FF cannon weighed 28kg (bare gun) vs 17kg for
Using a .50 cal Browning means the machine gun actually weighs more than the cannon (by one kg for a bare gun) but the ammo weight really skyrockets.
This is an argument that went on long after the war, The German Army NEVER went to the .50 cal gun for AA work from tanks even as a member of NATO ( and a lot of NATO countries agreed with them). .50 ammo tales up a lot of room inside the tank, a pintle mounted .50 cal isn't really all that effective (it bounces around a lot) and the Americans fired hundreds of thousands of rounds of .50cal ammo for each plane brought down.
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Before the MG-131 was available, even going back to wing-mounted MG-17s would be better than nothing (and wouldn't compromise the streamlining as the MG-FFs had -complying with the 109F's design philosophy), particularly given the early Fw 190s were still mounting 4 MG-17s along with the pair of MG-FF/Ms. That said, it seems like the MG-FF/M (particularly with 90 round drum) would have had advantages over the MG-151/15 used on early 109Fs as well. (more so if they'd compromised to retain the MG-FF wing mounts, 3x MG-FF/Ms would make a lot of sense and be a bit easier than the mixed trajectories, heavier recoil -and added weight- of MG-151/20s; deleting the cowl guns could save a little weight/drag too)I've never quite understood why the ME 109F/G gave up on wing stations, it was a mistake as attempts to restore the ability in the ME 109K6 show. Even with MG131 they would have added significant fire power.
Wouldn't such turrets at least be useful adapted to anti-aircraft tanks or were the existing cannon mounts on those types effective enough?For the Germans I'm surprised the adoption of the 20mm power driven turret used on some Fw 200, JU 290 and Ju 352 as well as several sea planes didn't make it onto their armour. If the traverse and power mechanism was suitably recessed so that the expensive drive mechanism wasn't exposed it might have significantly boosted the defensible ability of armour. Perhaps the philosophy was just to take cover given the inaccuracy of weapons big enough to hurt a tank.
In that case, wouldn't a high velocity heavy machine gun or light cannon be attractive as well? Ignoring HE/I carrying potential entirely and purely looking at AP, there's a lot you can do with smaller weapons than the hispano, especially for aircraft armor and especially looking at anti-tank rifle rounds in the 13-15 mm range, including high velocity AP rounds of the .50 BMG cartridge itself. (armor penetration is certainly a reason to ignore the Oerlikon FFF and .5 Vickers round ... somewhat less so the FFL)Once again, you're allowing yourselves to get blinded by all sorts of technical wizardry, while forgetting (or ignoring) what the Air Ministry actually wanted.
If a round, from the main armament, couldn't penetrate German bombers' armour, they weren't interested, hence the concentration (from before the war) on the Hispano. Early Hispanos had drum magazines because of difficulty finding a working belt feed, not due to any fault in the design of the cannon; the first four-cannon-armed Hurricane II had Chattelerault belt-feed, with 100 rounds per gun, in mid-1940.
Which you can't do, because the Air Ministry wanted armour-piercing and explosive in the same round.In that case, wouldn't a high velocity heavy machine gun or light cannon be attractive as well? Ignoring HE/I carrying potential entirely and purely looking at AP,.
Because they were able to get a licence agreement with the owners of the Hispano to build it here, in specially built factories, ensuring that there would be no interruption of supply.Something closer to the MG-151 would seem ideal for air to air armor penetration within the limits of small late-30s fighter aircraft, so why not concentrate on something more like that? (or even consider necking the Oerlikon FFF DOWN to something like 15 mm or even the .55" Boys projectile)
And, with "slower firing" you've immediately blown it, since the consideration had to be on getting as much hitting power in one or two seconds as possible. How many aircraft were fitted with the Madsen, incidentally? The Ministry files never mention it.Aside from that there's still the Madsen cannon. Slower firing than the Hispano, but lighter and belt-fed
Pointing many guns in different directions to compensate for poor aim is hardly compatible with fewer guns that are more effective on an individual basis.
However we also have to consider that the British barely had enough .303 Brownings to go around. Or perhaps they didn't have all that they wanted and used substitutes to some extent. In 1940 they certainly didn't have enough of the better types of .303 ammo that they wanted. Given that little fact, trying to make hundreds of thousands of little shells with fiddly little fuses seems a complication they didn't need at the time. During the BoB many eight gun fighters were flying with only one gun loaded with De Wilde ammunition. It had only gone into mass production in the spring of 1940. Scaling it up to suit various 11-18mm schemes in 1935-39 would have needed a time machine. Only two guns were loaded with MK IV incendiary/tracer which dates from WW I. Two guns were loaded with AP. Using infantry style lead filled (with soft nose filler) ammo in 3 guns certainly points to some sort of ammo shortage. By the middle of the war the four .303s left in Spitfires were firing two guns with AP and two guns with De Wilde. The De wilde was rated as twice as effective as the old incendiary/tracer at setting fuel tanks on fire.
However the change would NOT have allowed the 4 engine heavies to operate any better by day ...
Harris may have disagreed but if B-17s and B-24s couldn't operate in daylight with 10-13 .50 cal guns each and flying at over 20,000ft the actual chances of Halifaxes or Lancasters with 8-10 .50 cal guns and flying lower seem pretty slim.
This is with the benefit of hindsight. What people thought in 1943 was different. .50 cal guns in British bombers may have been better for shooting at nightfighters, I don't know.