30mm tater.

[GScholz]

Then the shell isn't hitting the skin and this is all academic... As I said. As long as the shell's path of motion is intersecting with the plate, penetration will occur no matter what. The End.

[TheCrazyOrange]

It is contacting the skin, but at such an angel that it's trajectory is near parallel to the skin.

The result is that the tip does not even contact the skin, what first contacts the skin is the corner of the round (if you want to call it that) where the side of the casing begins, and the nose ends. This makes a very poor penetrater, and coupled with the severe angle and resultingly small effective force (only a few thousand joules are actually directed against the skin), the normal force applied BY the skin is sufficient that the round will slightly alter it's course to be either perfectly parallel to or directed slightly away from the skin.

This is part of what makes APDS rounds so effective. The tip can be extremely steep without being extremely long and less practical, thus requiring a correspondingly steep angle of impact before the tip does not engage, and normalization fails to occur.


Now this isn't to say the skin will be unmarked, denting, and minor tearing is likely to occur. But unless the tip gets below the skin, almost all resistive forces will be pushing the round back away from the skin.

[GScholz]

And the resistive forces are effectively nil. The shell will continue to push the tin-can skin aside until the nose contacts the skin. Deflection will effectively be nil. The friction of contact with the skin will even normalize the shell causing it to nose into the skin.

Is there an angle where a sheet of paper will deflect a pistol round? No. Obviously not. And a supersonic 30 mm shell vs a 1 mm plate of aluminum is an even more lopsided case.

[SmokinLoon]

You guys need to tuck away your e-noodle and relax a bit. 

Me thinks you both are on the same page, just different angles of how you're getting there.

[Xavier]

So we're talking about a scenario where a 30mm shell is fired at an angle almost perfectly parallel to the skin of another aircraft, where it has an incredibly small chance to skid along the aircraft's surface instead of penetrating. For this to work the shell would also have to dodge any rivets, not catch on a panel line, tumble or simply dig a channel in the aluminium that ends up catching and detonating it. For me it's such an improbable scenario that I really doubt it happened over german skies in WWII. We're at "two bullets shot from two guns collide in mid-air" level speculation.

Or maybe I'm entirely mistaken and I deserve a spanking 

[GScholz]

No, you got the gist of it...

[TheCrazyOrange]

So we're talking about a scenario where a 30mm shell is fired at an angle almost perfectly parallel to the skin of another aircraft, where it has an incredibly small chance to skid along the aircraft's surface instead of penetrating. For this to work the shell would also have to dodge any rivets, not catch on a panel line, tumble or simply dig a channel in the aluminium that ends up catching and detonating it. For me it's such an improbable scenario that I really doubt it happened over german skies in WWII. We're at "two bullets shot from two guns collide in mid-air" level speculation.

Or maybe I'm entirely mistaken and I deserve a spanking 

not really. The plane is more sheet aluminum than rivets, and a shell may or may not deflect before traveling along the skin and having the side scrape against a seam.

Besides that, depending on the sensitivity of the fuze, it might not just fly off into the distance and detonate an inch above the skin, but an inch below it. In this sense, it's purely academic.

Any dead six shot has a chance at generating this and I would bet the fate of the entire free world that it happened.

Now I'm not saying it saved any aircraft, given that it might just detonate against the skin, still doing catastrophic damage, and it's an autocannon.

[Xavier]

Any dead six shot has a chance at generating this and I would bet the fate of the entire free world that it happened.

Now I'm not saying it saved any aircraft, given that it might just detonate against the skin, still doing catastrophic damage, and it's an autocannon.

The more I think about it, the less sure I am that it couldn't happen. It would be impossible to reproduce that scenario nowadays, but I could try something very roughly similar. I got an air rifle (european noguns master race here... ), some aluminium sheets thinner than 1mm and an awful lot of free time. Give me a few days and I'll give you my veredict. Or another complaint from the neighbours  .

[morfiend]

 as an experiment,take 1 rock and a body of water,now drop the rock,does it penetrate the water?

  Ok now throw the rock at an angle to the water,what happens?

  Same principle as the round striking on an angle,what is the angle required to deflect the round,that is the only thing in dispute here.


  Or to use the pistol,take a piece of aluminum and place it at a 90 degree angle,will the bullet penetrate?

  Now take the same piece of aluminum and place it at an angle,only the degree of angle will matter.

  The LW spent alot of time and money trying to get the fusing correct to acheive the most damage,IIRC I read they had trouble with the rounds going off too soon and not penetrating into the A/C.


   

[Lusche]

  The LW spent alot of time and money trying to get the fusing correct to acheive the most damage,IIRC I read they had trouble with the rounds going off too soon and not penetrating into the A/C.

That's why they developed a fuse like the Bodenzünder 1584, which was armed by the first impact and only went off at the second impact.

[morfiend]

That's why they developed a fuse like the Bodenzünder 1584, which was armed by the first impact and only went off at the second impact.

  Yup!




   

[GScholz]

as an experiment,take 1 rock and a body of water,now drop the rock,does it penetrate the water?

  Ok now throw the rock at an angle to the water,what happens?

Except that water has a lot more resistance than a 1mm aluminum plate. Water will stop just about any high velocity round in just a few meters. You can skip artillery rounds off water and 4-ton bombs... A 1mm aluminum plate, not so much...

[morfiend]

Except that water has a lot more resistance than a 1mm aluminum plate. Water will stop just about any high velocity round in just a few meters. You can skip artillery rounds off water and 4-ton bombs... A 1mm aluminum plate, not so much...

  AS I expected you missed my point,because you are bound and determined to prove yours!


  If you dropped a rock on the aluminum will it sink through it? No because it has a much higher density.... doh!


  I'm surprize an ex military type like you has never seen a round deflect off a branch or similar substance of less resistance....


  YMMV.




   

[Stampf]

  AS I expected you missed my point,because you are bound and determined to prove yours!


  If you dropped a rock on the aluminum will it sink through it? No because it has a much higher density.... doh!


  I'm surprize an ex military type like you has never seen a round deflect off a branch or similar substance of less resistance....


  YMMV.




   

Was shooting pickerel on L.Champlain one evening.  My Dad's round skipped off the surface hit a tree, traveled up the tree, hit a branch, deflected straight back, and hit my ole man right in the chest.

True story.

[morfiend]

Was shooting pickerel on L.Champlain one evening.  My Dad's round skipped off the surface hit a tree, traveled up the tree, hit a branch, deflected straight back, and hit my ole man right in the chest.

True story.

   



   Your Honour,I rest my case!