20mm HE fuses?

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scott585

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the recent necrothread on artillery projos got me thinking.
how do they keep 20mm cannon rounds from exploding if dropped? on big arty fuses an inertial system seems easy, but on a tiny thing like a 20mm fuse, how were they safe to handle while loading? some even rattle around in a mag like the orlikon, and they wouldnt pull hundreds of pins out on an aircraft belt before take off would they?

anyone got any good info?
thanks
 
My dad had a story. ;) Was on a 20mm AA gun in Holland during the last days of WWll. Most of the crew was down below in the bunker with one guy left on watch at the gun. Loud bang and they ran up to see what had happened. Turned out the guy was bored, played with a round and it went off, lost all his fingers.
Supposed to be an inertia device that ensures the bullet travels a set distance before arming and another self destruct device that detonates it if it doesn't hit anything.

Grizz
 
I'm not an ammo tech, but I have heard some are "spin armed" by the rifling rotation, while others are armed by the sudden acceleration.
 
Most are both now. An inertial set back and then a spin sensor. Sometimes a clockwork timer coupled to the fuse and or a self destruct.
 
WW2 German 20mm fuzes tended to be fairly complex, often with ball bearing detentes that were activated into the "fire" position by rotation. British/Commonwealth fuzes were simpler with less parts, but by the end of the war both sides were using very simple air column fuzes. These relied on the sudden compression of a small column of air on impact to heat the air sufficiently to initiate the gaine. No safety was needed with these.

There were also hydrostatic fuzes for fuel tanks whereby the pressure of the liquid forced the striker on to the detonator.

Regards
TonyE
 
C77 said:
Most are both now. An inertial set back and then a spin sensor. Sometimes a clockwork timer coupled to the fuse and or a self destruct.
Click to expand...

I have a "cut-away" if a WWII artillery fuse.

Basically three things occurred before the fused was "armed" for detonation.

1) First was the "inertia sat back". This event occurred when the shell was fired and ACCELERATION occurred.

2) The second event was SPIN. This occurred as the shell traveled the barrel and was caused to SPIN due to the rifling in the barrel.

3) The third was DECELLERATION. This occurred after the shell had left the barrel and was no longer being accelerated by the propellants. This event usually happened by the time the shell was about 100 yards out the barrel.


At this point the three events had occurred ACCELERATION, SPIN and DECELLERATION and now the fuse was "armed". All mechanical devices preventing the fuse from operating were no longer in place.

At this point the fuse WOULD operate on IMPACT, TIME or whatever the fuse was designed for.

20mm were much smaller and of course less room for safety devices, however as noted by others , there would be some method employed to prevent premature operation of the explosive projectile.

I will try to add photos later.........


Best regards,

B
 
All accurate and excellent info. I should also like to add the following.

In order to detonate the warhead it required a fairly significant impact against something hard like the skin of an aircraft or vehicle. There are probably many unexploded shells littering Europe that hit soft earth or skipped off the water and didn't have a self destruct mechanism.

Also, as an explosives tech this point bugs me. The matter under discussion is properly called a FUZE, not a fuse. A FUZE is a mechanical exploder used in bombs, shells, grenades, etc. A FUSE is a device for communicating fire.

(Not just to-may-to/to-mah-to, but professional lingo)
 
I did a shoot at Shiloh with defective/old ammunition with the 105mm howitzer in the late 50's, early 60's.
The ammunition's safety mechanism was based on a fixed number of revolutions of the projectile.
A troop, 4 guns, firing at once would at times produce 2 air bursts side by side, just far enough away so shrapnel was not a problem.
It looked very similar at anti-aircraft fire.
 
AK said:
Also, as an explosives tech this point bugs me. The matter under discussion is properly called a FUZE, not a fuse. A FUZE is a mechanical exploder used in bombs, shells, grenades, etc. A FUSE is a device for communicating fire.

(Not just to-may-to/to-mah-to, but professional lingo)
Click to expand...

I didnt know that. I would have guessed it was a Brit/US spelling issue...
 
scott585 said:
so how do these air column fuzes work? just compression of air like a diesel?
Click to expand...
Pretty much, the compressed air is forced through a disc which heats it and causes the primary high explosive to detonate which in turn ignites the main charge.

Fascinating how much intricacy goes into such a (comparatively) small projectile to accomplish such a straightforward task. One could theoretically duplicate such results using a Federal 209 and a BB glued on top. Probably not drop safe though. ;)
 
Compare the simplicity of an air column fuze with no moving parts to the German 20mm fuzes below, the AZ1505 nose fuze and the BdZ 1513 base fuze.

Regards
TonyE


 
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