30mm tater.

[GScholz]

There were many different shells available to the MK 108, even armor piercing. Despite its low(ish) muzzle velocity it is still a 30mm cannon with 66,000 joules of muzzle energy. For comparison a Hispano II has 45,000 joules at the muzzle.

[bustr]

MK108 couldn't penetrate far enough to be an issue to fuel tanks with longer range impacts than 100m being surface or very shallow penetration explosions. The MK103 shot the same round's as the MK108 between 800-900m\sec due to a larger shell capacity. While it shot the same rebated cartridges as the MK101 with a slight reduced powder load and electronic primer.

Firing tests during ww2 in England were performed at or inside of 100yds under ideal static mounted conditions. Or the round was hung inside of a fuselage and remotely detonated. Not the combat ranges over Germany in the air where most contacts were surface or very shallow penetration explosions.

By 400m the MK108 round slowed down to 400m\sec while the MK103 firing the same round from a larger capacity shell, it only slowed down to 711m\sec. Very quickly with the MK108 you need a perfect 90 degree impact to get even minor penetration before detonation. Other wise it's almost all surface detonation. But, the same explosive power as a single stick grenade going off sitting next to the skin. And there are many photos of bombers and fighters landing after direct and near direct ack hits.

The AAF identified the greatest damage done to aircraft by mine shells 20mm\30mm, was the killing and wounding of bomber crews from the casing shrapnel. But, then our game is not about dismembering humans to achieve war objectives. POST war testing of explosions to blow up planes visa exploding inside of the fuel tank, found 20\30mm rounds could not carry enough content to do the job. Aviation fuel would not stay lit in the slip stream above 110mph. So most fires took place in internal cavities while mostly black smoke was seen until the aircraft slowed down enough not to snuff out the fire in the slipstream.

Much of this is available from declassified testing reports POST WW2 1945-1948 from the Aberdeen Proving Grounds and 8th AAF. Do a search for ADA800109.pdf for fuel tank fires.

[GScholz]

By 400m the MK108 round slowed down to 400m\sec while the MK103 firing the same round from a larger capacity shell, it only slowed down to 711m\sec. Very quickly with the MK108 you need a perfect 90 degree impact to get even minor penetration before detonation. Other wise it's almost all surface detonation.

You're saying a 30mm shell weighing a third of a kilo (three quarters of a pound) going 400 meters per second... that's supersonic btw... won't penetrate the aluminum skin of a plane?

You know... on some WWII planes you could penetrate the skin with a knife.

[bustr]

If you do not hit at enough angle to the fuze so it engages the skin, the ogive will slide along the skin, and with the sudden impact throwing the striker back on the two fuze types used. Aircraft are made up of curved surfaces. I guess the AAF and Aberdeen need to confer with you in this case. Still, they no longer exist but you do. So you win by existing....cheers.....

[GScholz]

That's ridiculous. Even from a dead six shot it would rip through half the wing before detonation.

https://www.youtube.com/watch?v=sZZGaEEi8Ek

[TheCrazyOrange]

Would depend on where it strikes probably. Fabric covered control surfaces probably wouldn't offer much resistance regardless of impact angle, also placing the round 'in' the wing.

A Hurricane would be screwed.



But regardless, a 30mm round detonating on or near the airframe will still do considerable damage, so it's a somewhat moot point as to whether the round would actually penetrate the skin.

That spitfire would probably lose its wing were that damage sustained mid flight.

[GScholz]

At 400 meters per second the shell still carries 35,000 joules of kinetic energy. 10,000 joules less than a Hispano II at the muzzle or about twice that of a .50 cal M2 at the muzzle. With that energy a dud shell will pass clean through any aircraft structure and only stop if it hits a major component like an engine or a fuel/oil tank. According to the Luftwaffe the thermite-filled incendiary minengeschoss rounds were very effective in fireballing bombers.

[TheCrazyOrange]

Striking in an ideal position and angle, I'm sure it could. But striking at an off angle, the skin wouldn't have to stop 35,000j, but only maybe 5000j dispersed over the area of the shell impacting the skin. The rest of the energy is redirected onto a slightly different trajectory.

[GScholz]

What would this angle have to be to allow a 0.032 inch or 0.040 inch (one millimeter ... ONE) plate of aluminum (as on the B-17) to deflect a three-quarter pound supersonic projectile?  Is there an angle where a sheet of paper will deflect a pistol round? No. Not unless were talking hypothetical and academic. In real life situations the MK 108 round easily penetrated any aircraft skin it hit, at any angle.

[TheCrazyOrange]

What would this angle have to be to allow a 0.032 inch or 0.040 inch (one millimeter ... ONE) plate of aluminum (as on the B-17) to deflect a three-quarter pound supersonic projectile?  Is there an angle where a sheet of paper will deflect a pistol round? No. Not unless were talking hypothetical and academic. In real life situations the MK 108 round easily penetrated any aircraft skin it hit, at any angle.

It's the same principle as tank armor. Take even the KwK 43 and shoot it at the side of an M4 angled 80 degrees from perpendicular, and it will bounce off, despite having enough energy to punch through the side 7 times over. Because the tip of the shell does not engage the armor, there is no penetration, only deflection.

Now at any real angel, is it going to deflect? No, 1mm of armor isn't thick enough to gain any real benefits of effective thickness. If the tip engages, the round will penetrate. But dead 6? There's a chance of deflection off the wings and fuselage sides, not because the round isn't carrying enough energy, but because 95% of the energy isn't directed against the skin.



To answer your original question, I would guess 65+° for deflection to occur, depending on which round you posted above is impacting the skin. Far right would need ~75+° just because the tip is so steeply angeled.

[GScholz]

Are you serious?! IT ISN'T ARMOR! It's ALUMINUM. It's a tin can! The shell could be tumbling sideways and it would still penetrate every time.

[TheCrazyOrange]

Are you serious?! IT ISN'T ARMOR! It's ALUMINUM. It's a tin can! The shell could be tumbling sideways and it would still penetrate every time.

Irrelevant, once again, the skin isn't taking the full force of the round. It's absorbing whatever energy is directed perpendicular to the skin, as defined by the component vectors defining the rounds instantaneous vector of travel.

But once again, whether or not the round penetrates is a bit irrelevant, given that it's 19g of HE filler detonating against or very close to the skin. It will cause considerable damage either way.

[GScholz]

19g huh? ... you're clueless. It carries 85g of explosives; 73g for the tracer version.

[GScholz]

Oh, and to continue your tank-armor analogy... slope means nothing, nothing at all, when you have a shot overmatch factor of 30:1!

Overmatching negates the effective slope of the armor, making the armor not as strong if hit by a drastically thicker shell. Overmatching can be determined by a simple formula T/d (Thickness of armor / diameter of shell). Overmatching will not occur if T/d = 1.00 or greater, but will occur if T/d is less then 1.00.

You can angle the armor any way you want, but beyond a certain point of shot overmatching plate, the obliquity will cease to be relevant. A one millimeter plate resisting a 30 millimeter shell is like the 51 mm front glasis plate of an M4 Sherman trying to resist a 1530 mm shell... It is simply ridiculous.

[TheCrazyOrange]

Oh, and to continue your tank-armor analogy... slope means nothing, nothing at all, when you have a shot overmatch factor of 30:1!

Overmatching negates the effective slope of the armor, making the armor not as strong if hit by a drastically thicker shell. Overmatching can be determined by a simple formula T/d (Thickness of armor / diameter of shell). Overmatching will not occur if T/d = 1.00 or greater, but will occur if T/d is less then 1.00.

You can angle the armor any way you want, but beyond a certain point of shot overmatching plate, the obliquity will cease to be relevant. A one millimeter plate resisting a 30 millimeter shell is like the 51 mm front glasis plate of an M4 Sherman trying to resist a 1530 mm shell... It is simply ridiculous.

Once again, the armor isn't resisting the shell in this case, nor is the plane's skin.