tail end charlie
Senior Airman
- 615
- Aug 24, 2010
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I agree that 20mm rounds is better over all, and history proves it. I wonder how A Spit Mk I or II would have performed with 4x .50cals vs 8x.303.cals vs bombers and fighters. The .50cal weighs almost 4x the .30 cal, so gun weight would double. but the volume of the .50 cal is not much more. The cartridge itself is 67% larger than the .30-06 that the US used(exactly, as it was just blown up in scale from the rifle round)
How many rounds did the Spit I carry per gun?
How much lead weight could be put by the 8x.303s in a typical burst(0,5 to 1 sec?)
What is the same number for 4x.50cals?
Late war spits carried 250 rds of .50cals. How do the weight of 4x.50cals w/250 rds compare to weight of 8x.303 with their ammo?
Would the extra weight(if any) hamper the Spit in a dogfight with the Bf-109E?
Would the heavier leadweight of the .50cal battery(if any) be more effective in bringing down the light/medium bombers of the day(BoB), the He-111, Do-17 and Ju-88?
I know the Armour Piercing qualities of the .50cal way surpasses the .303, but I'm curious on a more holistic level, on how the Spit would fare with another existing and working gun of the time, before the HS 20mm were up to snuff.
Part of the problem when changing from 8 .303s with 300-350 rpg to American .50 cal guns is the weight.
The weight of the American .50 cal is on the order over twice as heavy per gun. Perhaps as much as 2.9 times as heavy. The Belgian 13.2mm version which went into a few Hurricanes weighed 24 kg compared to the Browning .303s 10 KG.
The next problem is ammo weight. American .50 cal ammo is on the order of 5 times as heavy as .303 ammo. Changing from 8 . 303 guns with 300rpg (early Spitifire and worst case) to 4 American .50s is going to leave you with under 100 rounds of ammo per gun on a strict weight for weight basis. And that is using the 24 kg for the Belgian guns. How much performance are you willing to trade the extra ammo? an extra 400 rounds (100 per gun for 4 guns ) weighs 120lbs.
Next question is when is the decision to be made. for most of the 30s the American .50 fired at 600rpm unsynchronized. It was only right before the war the the rate of fire was boosted to 800-900rpm. So you might be comparing 160 .303 bullets a second to 40 .50cal bullets a second. For the faster firing guns it gets up to a about 56 .50 cal bullets per second but you need 210 rounds per gun to get the combat duration of the Spitfire with it's 300rpg.
You can't do ANY damage if you don't hit.
20mm make up for lack of hits with lots of damage per hit.
U.S. .50cal is stuck between. Limited damage per hit unless something hard is hit. Limited amount of hits in a small battery with limited ammo.
Remember that MK I spitfires and MK I Hurricanes only had 880hp for take off and under 1000hp for climb without running at full throttle. later models with much more power could carry heavier armament.
No worries ZThanks a lot, Colin1!!
The .50 cal needs to hit something solid in order for the KE to work. Poking holes in fuselage or wing skinning doesn't cause much more damage than the .303. A 20mm exploding on the skin surface can make a hole around a foot across and several in small area (rear fuselage of Spitfire?) can compromise the strength of a monocoque or semi-monocoque structure. The .50 needs to hit longerons, frames, spars or ribs in order to cause real structural damage. Against fuel tanks the results are much more variable. Self sealing fuel tanks varied widely in construction and effectiveness. The .50 stands a much better chance of bursting a seam on full or nearly full tank than a .303 but if the tank is only part full the shock wave through the fuel has room to dissipate without bursting the tank. A 109 only had one tank so it was never going to be in combat in the BoB with a full tank. Bombers will vary. A hit in the radiator from a .50 means the coolant will leak out a bit faster. Ditto the oil tank/oil cooler. The .50 will punch holes in and stop engines much better than a .303 but even .303s can put holes in the water jackets, crankcases.For shell weight on target, I think 40+ rounds of .50cal would be preferable to 160 rds of .303, as each hit would have 5 times the weight of each .303 bullet. I didn't pursue physics enough in school to calculate the KE here, but I think the effect would be a dramatic improvement in disabling bombers, if one could get enough hits on vital parts like engines...
The RAAF Mk Vlll Spitfires later in the war had there outer 4x .303's replaced with 2x.50
The .50 cal needs to hit something solid in order for the KE to work. Poking holes in fuselage or wing skinning doesn't cause much more damage than the .303. A 20mm exploding on the skin surface can make a hole around a foot across and several in small area (rear fuselage of Spitfire?) can compromise the strength of a monocoque or semi-monocoque structure. The .50 needs to hit longerons, frames, spars or ribs in order to cause real structural damage. Against fuel tanks the results are much more variable. Self sealing fuel tanks varied widely in construction and effectiveness. The .50 stands a much better chance of bursting a seam on full or nearly full tank than a .303 but if the tank is only part full the shock wave through the fuel has room to dissipate without bursting the tank. A 109 only had one tank so it was never going to be in combat in the BoB with a full tank. Bombers will vary. A hit in the radiator from a .50 means the coolant will leak out a bit faster. Ditto the oil tank/oil cooler. The .50 will punch holes in and stop engines much better than a .303 but even .303s can put holes in the water jackets, crankcases.
The .50 browning was a reliable (for the most part), effective weapon, especially if used in sufficient numbers, but it actually wasn't that efficient of a weapon on a effectiveness to weight ratio.
So IMO arming with .50cal would have greatly increased the RAF's ability to quickly bring down more bombers and less getting away with only damage.