Love how you cut out the word singular
a 2cm bullet would absolutely punch a hole through the spar, its explosive incendiary filler wont do much to a spar but the kinetic energy would still completely shred it in one shot. 20mm canon shot is really big and powerful, I think you’re underestimating it from never seeing or holding 20mm munitions up close
Wing spar’s are pretty fragile made from aluminum sheet metal. I don’t know exactly what kind of alloy the B29 uses or how thick the aluminum sheets are but 0.040-0.080inch thick aluminum is my best guess. And obviously a 20mm HE round would destroy that pretty easily.
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The problem is that the 20mm HEI is going to fuse on the skin of the aircraft, and is going to lose nearly all its penetrating power.
Because you don’t understand the engineering. A spar does not have to be physically cut to fail under normal loading. All it has to do is be damaged enough to create stress concentrations at any point. A few bits of metal putting holes or even just bends in it will be enough to cause it to fail. When it does, the entire structure fails like a piece of mylar is strong until a notch is made in it, then it is easy to tear.
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I understand this. What I am arguing, based on data from the optimum caliber report, is that a singular 20mm HEI shell is not going to be able to do this
It has a fuze sensitivity of 0.1mm and fuze delay of 0.1m, plenty of time to penetrate and detonate inside the wing.
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the most common aluminium alloy used around the time was called Duraluminum, It was mostly aluminium and copper but some compositions had magnesium in the mixture too. I should note this is the german commercial name for the alloy however aviation manufacturers from across the globe would have used similar if not identical alloys
the skins over airframes were not very thick at all so not much kinetic energy would be traded during penetration and a fuse no matter the sensitivity isn’t instantaneous, there would be a natural and unavoidable lag time before detonation which would be sufficient to still hit the spar
Give up bro Gaijin is never going to fix bomber models, they don’t make enough money
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I don’t know if alluminum copper would’ve been used on primary structures. They might’ve used stronger alloys like 7075.
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The B 29s wing spar is a little over a foot inside of the wing’s leading edge, so this is simply untrue
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Wing spars are directly attached to the ribs and skin, otherwise they aren’t able to transfer loads. From the leading edge sure but I don’t know if OP was hit on the leading edge.
Duraluminum was used for the frame on zeppelins before the war so its likely it was used for loadbearing parts in ww2 planes
bullets dont tend to hit flat on, when fighters attack bombers its from above
I am aware of this fact. Unless you are suggesting that a singular 20mm can destroy enough skin as to collapse the wing spar, I do not understand what point you are making
Hitting flat is the ideal scenario for the 20mm. So I’m arguing in good faith that it does hit flat on
If the 20mm HE came from below and hit the skin directly and not the leading edge then yeah. Wing skin is very very thin aluminum alloy.
While Aluminum copper alloys have good strength to weight ratio they don’t cut it for load bearing structures for bombers, at least from what I’ve worked with. They’re used mostly for general purpose.
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20mm HE can completley slaughter a win in a single hit from an ideal attack angle
