German Luftwaffe Schrage Musik 20 mm API Round

[jay hammond]

I have a German 20 mm API round recovered from the wreckage of my uncle's Halifax which was excavated in 1997. The round is steel with what appears to be an aluminum cap at its base. Can someone explain to me the basics of how this round worked? Would it typically break apart when it hit a hard surface thereby releasing the phosphorus to burn in the vicinity of the disintegration site? My knowledge of Luftwaffe ammunition is next to nil so I would really appreciate any help you can offer. Also, any ideas as to why the round didn't break up?

 

[Greyman]

Always nervous about live rounds in the hands of regular folks.

I'm no chemist ... but if it is indeed an API round (fingers crossed for an inert AP, but could even be AP/HE), that phosphorous could still be waiting for the chance to burn your house down. A sickening cosmic joke if that night fighter managed to harm more of your uncle's family.

You have the functioning essentially correct -- as the round breaks up after impact it distributes the phosphorous filling. As to why it didn't; when you're firing projectiles at random angles into webs of randomly angled metals and bags of fluid ... anything can and will happen.

 

[jay hammond]

Always nervous about live rounds in the hands of regular folks.

I'm no chemist ... but if it is indeed an API round (fingers crossed for an inert AP, but could even be AP/HE), that phosphorous could still be waiting for the chance to burn your house down. A sickening cosmic joke if that night fighter managed to harm more of your uncle's family.

You have the functioning essentially correct -- as the round breaks up after impact it distributes the phosphorous filling. As to why it didn't; when you're firing projectiles at random angles into webs of randomly angled metals and bags of fluid ... anything can and will happen.

You're quite right about the potential danger of having a live API round lying around the house. When we found it at the dig an army guy took it home and working under water removed the phosphorus to make it safe. I still don't understand how this solid feeling shell, admittedly one with an open core that was originally armed with phosphorus, could disintegrate. Ideas?

 

[Greyman]

I would assume the main idea behind the round was to set fire to petrol tanks protected by armour plate. So in the event of a clean hit the round would puncture the armour and the phosphorous would blast through the hole along with what remained of the steel projectile.

More often though I'm sure the round hit the aircraft skin, light structure, or some piece of equipment in the aircraft, began to tumble, and smashed into something more solid. At about 2000 feet per second it would be tough to stay intact at that point.

And really 'disintegration' in this case is simply the state of no longer being in one piece. Even just the light-alloy base cap has to pop off and Newton will do the rest.

 

[jay hammond]

I would assume the main idea behind the round was to set fire to petrol tanks protected by armour plate. So in the event of a clean hit the round would puncture the armour and the phosphorous would blast through the hole along with what remained of the steel projectile.

More often though I'm sure the round hit the aircraft skin, light structure, or some piece of equipment in the aircraft, began to tumble, and smashed into something more solid. At about 2000 feet per second it would be tough to stay intact at that point.

And really 'disintegration' in this case is simply the state of no longer being in one piece. Even just the light-alloy base cap has to pop off and Newton will do the rest.

Were the fuel tanks of a Halifax protected by armour plating? I think I've read that most armour plating was removed to reduce the all up weight. Others out there know if this is true?

 

[Greyman]

Generally armour was just provided to protect the crew. Self-sealing material protected the tanks.

Specific pieces of armour were removed as the war went on as Operational Research deemed them unnecessary for the type of work they were doing. The idea wasn't to reduce the all up weight so much as it was to trade that weight for more fuel/bombs.

It was my understanding that Schrage Musik weren't loaded with AP rounds, as they certainly wouldn't have been necessary. But what the manual says and what happens in the field can be two different things.

Somewhat to that point and your observation on how substantial the round is -- on examination the British too figured it was probably too sturdy for aircraft targets and figured the design was simply copied straight from the Heer version (as used in the Panzer II's KwK, for example).