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If you were a fighter pilot in WWII, would you rather have the high rate of fire of the 50 cal, or the hitting power of the 20mm? I personally feel the 50 cal was plenty hard hitting enough to take out ANY aircraft, and its high rate of fire made it even more effective...the slow rate of fire for the 20mm meant you had to be a much better marksman...
As has been said there are many threads on this. In 1939 the RAF armament was 8 x 303 MGs and that was considered devastating, enough for a 2 second burst to take down a bomber, the effectiveness was increased with incendiary rounds. However even then the preferred armament for a fighter was for 4 x 20mm cannon, that's what the Whirlwind was all about. Prior to the USA entering the war the RAF standard armament for fighters was 4 x 20mm cannon. This was fitted to the Hurricane Mk2, the Typhoon Tempest Mosquito and Beaufighter. The Spitfire was an exception, they started to fit cannon in 1940, and had problems getting them to work, but even when it did work the decision was to have 2 cannon and 4 x 0,303mgs for various reasons, weight at high altitude and heating. While RAF pilots may have preferred cannon in the BoB, it is a fact that the LW ran out of serviceable bombers and gave up. But the Spitfire wasn't limited to 2 cannon and 4mgs by any law, some carried 4 cannon and 4 x 0.303 mgs which would ruin anyone's day.
There are statistics already discussed about rate of fire, you can then discuss weight of fire and effect of fire but the LW had another statistic of how many hits you could land in a "pass" and how effective those hits would be. This is concerned with bringing down a 4 engine bomber, but the problem then becomes the ballistics of large calibre rounds even rockets that can devastate a large bomber become increasingly unlikely to hit a fighter.
It was discussed on the forum here, some Spitfire MkVc had 4 cannon and 4 mgs, used in the Med theatre, I was surprised to read it too.Some carried 2 x 20mm and 2 x 0.5 on the universal wing. They could be fitted with 4 x 20mm but this created handling issues. The 20 series Spitfires which had a new wing and cut of hispanos seemed to work fine.
It was discussed on the forum here, some Spitfire MkVc had 4 cannon and 4 mgs, used in the Med theatre, I was surprised to read it too.
As has been said there are many threads on this. In 1939 the RAF armament was 8 x 303 MGs and that was considered devastating, enough for a 2 second burst to take down a bomber, the effectiveness was increased with incendiary rounds.
There's a picture of a Spitfire with 6 cannon. Don't know if they were dummies maybe for aerodynamic testing but imagine being hit by 6 20mm HE rounds. That's one burst B29 killing power.
The standard armament of a Mosquito or Beaufighter would ruin anyones day. 4 x 20 mm firing at 600 (as a round number) RPM means a 2 second burst is 80 shells, it wouldn't only wreck an aircraft but made a mess of shipping too, it wouldn't sink a ship but damage much of the superstructure. The same could be said of a P-47s 8 x 0.5 mgs. Two seconds of those would wreck any aircraft made. One thing I noticed from reading pilots memoirs, it didn't seem to matter where a Hurricane or Spitfire was hit by a cannon shell, if it wasn't in the engine, wing tips or tail the pilot frequently got injured in some way by splinters, usually in the legs.If your engine is hit by a couple of .50 armour piercing incendiaries they might hit an oil line or a fuel line. If your engine is hit by one 20mm HE round that explodes you have lots of hot shrapnel spraying all over the engine compartment like shotgun pellets. Two.50 rounds is two hits one 20mm round is lots of hits.
4 x 20 mm firing at 600 (as a round number) RPM
As I said it is a round and not unreal number (600 is 10 per second), the advised firing time for pilots was 2 seconds, no reason at all why it couldn't be longer.I have seen various rates of fire from 600 to 700 for the Hispano MkII so I usually write 650 rpm not that it makes a great deal of difference it will just make you 10% deader. The later Hispano MkV was 750 rpm.
One thing I noticed from reading pilots memoirs, it didn't seem to matter where a Hurricane or Spitfire was hit by a cannon shell, if it wasn't in the engine, wing tips or tail the pilot frequently got injured in some way by splinters, usually in the legs.
There's a picture of a Spitfire with 6 cannon. Don't know if they were dummies maybe for aerodynamic testing but imagine being hit by 6 20mm HE rounds. That's one burst B29 killing power.