Why have armor piercing shells on planes?

[hotard]

quote from the patch notes of version 2.27

"Wirbel and Ostwind turrets can no longer take on indefinite damage after they've been destroyed without eventually destroying the vehicle."

I take this to mean that if I kept smacking a turret before I could never kill a wirbl.

no I can,  I think this has been recently addressed.  Hitting them in the hull is no easier or harder than a regular panzer as near as I can tell.

Perhaps they have finally have fixed this.. but I'll swear I've put multiple rounds into the hull of a wirb/ostie.. much more so than the tank version.. Now if they would only fix the warping drones

[Vulcan]

First it was the F3

If you were a Panzer 3F then yes it will die from strafing 20mm/50 cal aircraft. Interestingly enough this debate was done to death in WW2OL... and the outcome was yes a Panzer 3 has thin top turret armour and thin top armour over the engine. And historically aircraft did run a mix of ball/HE/AP ammo - iirc that was done to death over there as well.

One thing I think is underused in AH tanking is the top Mg's or 50's. They make for great camp-breakers especially when there's a ton of M18's at a spawn