Cannon rounds

[sigintwarrior]

I have noticed my cannon rounds from my 109 exploding in the distance after I fire them off. Almost like they are hitting a wall. I did'nt know that cannon shells did that unless they were fitted with a proximity fuse. Is this working as intended or a bug?

[winny]

It's correct, the cannon rounds had self distruct mechanisms built in.

[Strike]

Yes it's true :)

I read somewhere that it's to avoid the cannon rounds potentially hitting something else and exploding. If you're in a tense dogfight over berlin you wouldn't really want the 20mm rounds to explode when impacting german houses would you?

On another note later ammunition types are proximity fuzed being able to detect targets by miniature radars.

Americans started using radar detonated artillery rounds during the later parts of the war I believe against the germans. Instead of digging into the ground before exploding, the proximity radar in the nose of each shell would go off at a given height above ground (say 1-2 meters) effectively barraging the area with shrapnel, where the older rounds would leave probably 50% of the shrapnel under ground.

[JG14_Jagr]

On another note later ammunition types are proximity fuzed being able to detect targets by miniature radars.

Americans started using radar detonated artillery rounds during the later parts of the war I believe against the germans. Instead of digging into the ground before exploding, the proximity radar in the nose of each shell would go off at a given height above ground (say 1-2 meters) effectively barraging the area with shrapnel, where the older rounds would leave probably 50% of the shrapnel under ground.

American Prox. fuses were only for large artillery and naval guns, and came in the late stages of the war, especially in the ETO.

[sigintwarrior]

Well, I guess you learn something new everyday. Thanks for the info guys, it sure clears up that little mystery.

[Freycinet]

The German shells were set to go off when they stopped rotating, either by hitting the target or just by flying out far enough...

[JG14_Jagr]

Frey is partially correct.. The shells had a simple device that when the shell was spinning fast the centripetal force kept the contacts apart..once the spinning slows the lower force would allow the contacts to meet and boom.. self destruct..

[ARM505]

Did it really occur so close to the firing aircraft?

[winny]

Did it really occur so close to the firing aircraft?

2-4 seconds after firing. Depending on a few variables.

[Sternjaeger II]

Yes it's true :)

I read somewhere that it's to avoid the cannon rounds potentially hitting something else and exploding. If you're in a tense dogfight over berlin you wouldn't really want the 20mm rounds to explode when impacting german houses would you?

On another note later ammunition types are proximity fuzed being able to detect targets by miniature radars.

Americans started using radar detonated artillery rounds during the later parts of the war I believe against the germans. Instead of digging into the ground before exploding, the proximity radar in the nose of each shell would go off at a given height above ground (say 1-2 meters) effectively barraging the area with shrapnel, where the older rounds would leave probably 50% of the shrapnel under ground.

...seriously? Radars in shells? Uhmmmm, I have a fair knowledge of ammunition and ww2, but I swear I never heard of it, it is also true you learn something you everyday.. Do you have any reference on this?

AFAIK Proximity fuzes were normally magnetic. As for the rest fuzes could be time set and/or altitude set.

[akronnick]

http://en.wikipedia.org/wiki/Proximity_fuze#Deployment

They were only allowed to be used over water until the Battle of the Bulge to prevent the Germans from reverse engineering unexploded shells.

[JG14_Jagr]

Do a google on 5" Proximity Fuses. Introduced in the Pacific and not allowed to be fired over land until the Battle of the Bulge for fear duds would be found and reverse engineered. Made radar guided arty batteries extremely deadly...

[Sternjaeger II]

aaah ok we're talking about big shells here, not aircraft cannon rounds :)

[skouras]

so is any kind variand of cannon shells in the sim that don't explode:confused:

[speculum jockey]

so is any kind variand of cannon shells in the sim that don't explode:confused:

Duds! :)

[skouras]

Duds! :)

:eek:
i lost you:-)

[Sternjaeger II]

lol it was a joke ;0) the Luftwaffe used a varied set of cannon rounds, AP, API, APT, HE, HET (I have a small collection of these, crazy stuff!), but in the end it was down to the pilot's choice/availability.

[Art-J]

Nah, the VT fuses were not "late war" invention, and not for "big naval guns" only, although one might discuss when the gun is considered big enough to be called "big" :D. The first american operational Mk 32 fuse for standard naval 5 inch AAA gun was introduced on the Pacific in november '42, with the first plane shot down by it in january '43. Later marks were small enough to fit into 90mm army AAA gun.

From technical point of view, the fuse was based on a kind of a small radar, very simplified of course. Here are some details:

By June 1941, circuit work had been carried to the point where a circuit of sufficient sensitivity and small enough size to be contained in a fuze could be made. The circuit consisted of an oscillator, a two-stage audio frequency amplifier, a thyratron, and an electric detonator developed by Hercules Powder Company connected in the thyratron output in such a fashion that it would initiate the explosive detonation. A dry battery built by the National Carbon Company and similar to the unit used in the 37mm test projectile was used as a source of power. Switches, known as set-back switches and developed by Section T, were used in the fuze to close the battery circuits upon firing of the projectile. An electrical arming delay was incorporated in the circuit to prevent arming of the fuze until after the tube filaments had heated and the unit had quieted down after the initial impact of firing. The oscillator radiated a radio frequency signal. Some of the energy from this radiated field would be reflected back from any target in the vicinity of the projectile in such a fashion as to react upon the oscillator, causing an audio frequency signal which was then amplified by the amplifier and used to trigger the thyratron. The electric detonator in the thyratron output circuit initiated detonation of the auxiliary detonator and hence the explosive charge. At this time development had progressed to the point where a complete mechanical design of a proximity fuze was laid out.

The quote above comes from: Dilley, N. E. "Development of Proximity Fuzes (VT) for Projectiles - VT Fuzes MKS 32 to 60, Inclusive (General Description)." chapter 1 of The World War II Proximity Fuze: A Compilation of Naval Ordnance Reports by the Johns Hopkins University Applied Physics Laboratory. (Silver Spring MD: The Laboratory, 1950): 1-12. [declassified 16 Jun. 1976]. Much longer fragment of it was posted at Ubi forums ages ago, I don't have the link, but copied some of it.

The British fellaz were cooperating in the development program and later they were working on their own fuse, but I admit I don't know much about it!

Cheers.

[zipper]

The proximity rounds were made possible by, and were the first major use of, printed circuit boards and solid state electronics. Yay, wartime development.

[Freycinet]

Frey is partially correct.. The shells had a simple device that when the shell was spinning fast the centripetal force kept the contacts apart..once the spinning slows the lower force would allow the contacts to meet and boom.. self destruct..

Jagr is partially correct. It was actually the centriFUGAL force... ;)

(Thx Jagr for the explanation, just kidding here...)

[JG14_Jagr]

Nah, the VT fuses were not "late war" invention, and not for "big naval guns" only, although one might discuss when the gun is considered big enough to be called "big" :D. The first american operational Mk 32 fuse for standard naval 5 inch AAA gun was introduced on the Pacific in november '42, with the first plane shot down by it in january '43. Later marks were small enough to fit into 90mm army AAA gun.



The original poster was talking about 20mm "Proximity Fuses" Another was talking about them being magnetic. They were in fact small radars inside the fuse, and they were only produced in the 5" range then finally in the 4" range (90mm)

Prox or VT fuses were not authorized for use in the ETO until December 1944/January 1945. That is LATE WAR :) 5" Naval guns are the biggest AAA used in the Pacific by the allies.. they are THE "big guns" for Prox Fuses. They were allowed to use them earlier at sea for AAA since the odds of capture were almost zero. In the ETO 155 VT Fuses were devastating as they could be reliably airburst over massed infantry with incredible results.

There is a very good chow in History channel on its development.. the G Forces involved made the reliability quite difficult to acheive.. amazing they were able to actually..

[choctaw111]

I have some German wartime cannon rounds and found that rounds had a very simple self destruct mechanism.
The tracer component at the base of the cannon projectile and the main explosive charge in the front of the bullet were connected by a small hole.
The tracer element would burn through the hole and explode the shell.

[Art-J]

The original poster was talking about 20mm "Proximity Fuses" Another was talking about them being magnetic. They were in fact small radars inside the fuse, and they were only produced in the 5" range then finally in the 4" range (90mm)

Prox or VT fuses were not authorized for use in the ETO until December 1944/January 1945. That is LATE WAR :) 5" Naval guns are the biggest AAA used in the Pacific by the allies.. they are THE "big guns" for Prox Fuses. They were allowed to use them earlier at sea for AAA since the odds of capture were almost zero. In the ETO 155 VT Fuses were devastating as they could be reliably airburst over massed infantry with incredible results.

There is a very good chow in History channel on its development.. the G Forces involved made the reliability quite difficult to acheive.. amazing they were able to actually..

Rgr that. Being mostly PTO fan, I'm not familiar with the history of their usage in ETO :D. Will read some more about it, thanks!

[JG14_Jagr]

Rgr that. Being mostly PTO fan, I'm not familiar with the history of their usage in ETO :D. Will read some more about it, thanks!

The reason they overruled the order not to use them was because of the Battle of the Bulge... It was considered desperate enough to make full use of them. German VG Infantry units got literally shredded by massed Time on Target 155 fire using the VT fuses.. Typically with Arty most of the casualties are caused in the first 10-12 seconds before the "target" has a chance to seek cover.. using TOT techniques all the rounds arrive over the target at the same time.. using VT fuses meant that suddendly and without warning all those rounds arrived over the target and detonated in an air burst showering all the exposed infantry from above.. it destroyed entire regiments..

The other little known but key use was in the AAA role against V-1 Rockets.. 90mm batteries on the English coast with prox fuses were deployed along the coast where the rockets had to travel..they were firing in battery.. 4 or more guns at once..and they were often getting the bombs in one volley..

[Freycinet]

radar-guided triple-A vs. V-1s, 1944:

http://www.youtube.com/watch?v=R-GhqhUKRVU

First time in warfare that robot fought robot.