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View Full Version : How the flak shells explode at certain altitude?



CyberWings
05-26-2005, 01:10 PM
I´ve been playing to this game for a while and I really don´t know exactly how this work. My guess is that when an arplane approaches to an artillery site the gunner guess at which altitude that plane is flying and they can set automatically with the canon the altitude the shells is going to explode. If they had to set manually every single shell it would take forever to fire a single round.
But as I say I´m just guessing and I could be completelly wrong http://forums.ubi.com/images/smilies/35.gif. Am I?

CyberWings
05-26-2005, 01:10 PM
I´ve been playing to this game for a while and I really don´t know exactly how this work. My guess is that when an arplane approaches to an artillery site the gunner guess at which altitude that plane is flying and they can set automatically with the canon the altitude the shells is going to explode. If they had to set manually every single shell it would take forever to fire a single round.
But as I say I´m just guessing and I could be completelly wrong http://forums.ubi.com/images/smilies/35.gif. Am I?

Malik_VII
05-26-2005, 01:52 PM
I'm not really sure but there is some kind of fuse. I don't know if the technology was there to have the canon programed to do this. I think they would have to set the fuse in the shell.
Anybody else know.

NietzscheMadMan
05-26-2005, 02:27 PM
An artillery peice is like just a big rifle. When the shell comes out it is spinning. This rotational force causes the fuse to spin, almost like winding a clock. When the fuse is spun a set number of times (based on the velocity of the shell or how long it will take it to get to the desired detonation altitude) it detonates the round.

Each individual shell would have to be set, however, I don't think this is a very time consuming process as the gunners would definately have some sort of reference by which to determine how to set the fuse for detonation at a given altitude.

The hardest part would be determining how high the target aircraft is. Today we've got radar, back then they had radar too, however, I don't think it was advanced enough to determine how high the target was, just that it was there. I may be wrong on this, I'm no radar expert.

It was probably just a trial and error type thing.

BTW...
In the Army, I was an Infantryman. Modern artillery works the same way so the gunner can set the fuse to detonate the shell at a given alitude above a target on the ground. That was really cool to watch! Nothing like calling in the iron curtain and watching them airburst destroying everything that wasn't under deep cover.

Zyzbot
05-26-2005, 03:17 PM
The bomber pilots were aware that the FLAK gunners had a difficult time determining their exact altitude. They made adjustments accordingly:


"We left the IP at 13,000 feet; bomb-release altitude was briefed for 11,800 feet. We would lose altitude randomly€"100 feet, 300 feet, 200 feet€"to make it harder for the flak batteries to fuse their 88mm shells precisely. Our only lateral evasive action came from the slight corrections the lead bombardier fed into his Norden bombsight. The tops of the cumulus clouds were almost at our altitude, and coverage was about five-tenths. I thought getting the crosshairs on the target might be a problem for the bombardiers, but seconds later, the "frags" dropped from the bellies of the lead group of 18 B-26s, and they turned to the right in a steep diving turn. Soot-black clusters of flak mushroomed over the group, but the young Luftwaffenhelfer below had waited too long, and our planes were out of harm's way. "

http://www.flightjournal.com/articles/loose_cannon/lynn1.asp

Capt.LoneRanger
05-26-2005, 03:22 PM
The setting and timing is done by an internal clock. It had to be set before the shell was placed in the barrel and was set off by firing the projectile.
The main difficulty is to set the right altitude for an object travelling at those speeds. The difference of being an effective hit and a miss is around 0,015sec. Most timers were of course not that precise. The mass of FlaK guns made it dangerous, well feared, because it was very ineffective. There are numbers stating that more people got hit on the ground by falling fragments than aircraft were downed.

In IL2 the Flak is way to precise, but it makes up well for the lack of flak-stations.

http://www.missing-lynx.com/library/german/flak_dmourtizsen.html

Soldier setting fuse on an 88Flak:
http://www.missing-lynx.com/library/german/flakarticle_dmouritzsen12.jpg

jarink
05-26-2005, 06:18 PM
There were 3 main types of AA fuse used in WWII.

1. Powder train fuse - Basically a length of fuse cord that was cut at the gun right before the shell was placed into the breech. It was maily used only early in the war, as it was not reliable, slowed rate of fire and also gave different burn times depending on atmospheric conditions.

2. Mechanical fuse - Used a mechanical timer to explode the shell after it had travelled a certain distance. Similar in useage to the powder tain fuse, but much more reliable and faster to set.

Both of these fuses suffered from the same limitation in that the fuse setting was basically guesswork and could not be changed once the shell was fired.

3. Proximity fuse - This was a weapon that, if the Germans had perfected it, could have spelled the end of the Allied strategic bombing campaigns. It used a small radar transmitter/receiver (which was an amazing accomplishment in miniaturization for the period) that would explode the shell when it detected an object that was within it's lethal range. This fuse had two overwhelming advantages:
A. It did not have to be set prior to firing, which greatly increased rate of fire
B. It eliminated much of the guesswork involved in rangefinding and fuse setting.

Blutarski2004
05-26-2005, 08:18 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by jarink:
There were 3 main types of AA fuse used in WWII.

1. Powder train fuse - Basically a length of fuse cord that was cut at the gun right before the shell was placed into the breech. It was maily used only early in the war, as it was not reliable, slowed rate of fire and also gave different burn times depending on atmospheric conditions.

2. Mechanical fuse - Used a mechanical timer to explode the shell after it had travelled a certain distance. Similar in useage to the powder tain fuse, but much more reliable and faster to set.

Both of these fuses suffered from the same limitation in that the fuse setting was basically guesswork and could not be changed once the shell was fired.

3. Proximity fuse - This was a weapon that, if the Germans had perfected it, could have spelled the end of the Allied strategic bombing campaigns. It used a small radar transmitter/receiver (which was an amazing accomplishment in miniaturization for the period) that would explode the shell when it detected an object that was within it's lethal range. This fuse had two overwhelming advantages:
A. It did not have to be set prior to firing, which greatly increased rate of fire
B. It eliminated much of the guesswork involved in rangefinding and fuse setting. </div></BLOCKQUOTE>


..... Powder train fuzes were the standard time fuze through WW1, prmarily used for shrapnel fire. Mechanical or clockwork fuzes were developed post-WW1 and were commonly used in WW2. Heavy Flak guns each had automatic mechanical fuze setters integrated with the battery fire control equipment. Once a desired detonation height had been determined, the FC system took into account gun elevation and automatically computed the time of flight to reach the specified altitude. This data was fed to the fuze setter. The nose of the projectile was placed in the gun's fuze setter, which set the fuze timing. The projectle was then removed from the fuze setter and rammed into the breech of the gun for firing. I believe that all heavy German and Allied AAA were so fitted. The US Navy 5-inch 38 caliber dual-purpose gun also had an automatic fuze setter. This feature is what made those 15-20 rpm rates of fire possible.


BTW Masked Man - great photo of an auto fuze setter in action.

Zeus-cat
05-26-2005, 08:46 PM
The German 88 had a large crew. I build 1/35th scale models and the old kit by Tamiya had 9 men as the crew.

Doing this from memory and a photo of the model:
1 man using a range finder
1 man spotting targets with binoculars
2 gunners (1 aiming and 1 laying the gun)
4 loaders
1 motorcycle operator/messenger

One of the loaders would set the fuses.

Zeus-cat

ClnlSandersLite
05-26-2005, 10:01 PM
All the settings on a shell where done with rings on the ordinance. You use a specialized wrench to adjust the settings by twisting the rings. I'll try and find a pic of an old shell for you.

gprr
05-27-2005, 02:34 AM
Hi all

Not so sure about the time periot but do know that the Bofors 40mm flak had this operation:

Shell basic internal parts:

1-bottom-Explosives with firing triger cap.
2-Middle-Rotating centrifuga(similar to old clocks) with simetric wieghs
3-Cap-Spring pushd firing pin(downwards)

Operation:

1.First part of shell flight shows centrifugal and backward forces effecting the internal parts,at that time the backward force is bigger and the centrifuga weights are held hard in down possision blocking the way for the firin pin to the explosives.
2.After while (predesigned time and distance for safty and functinality)the centrifugal force overcomes the weakend backwad force and the weights rotate and move up and sideways clearing the path for the firing pin to hit the explosives in the bottom.
3.There are two possibilities after 2nd stage of the shell flight,either the shell hits target and the firing pin smashes into the explosives and blows it or no hit for certain time periot which enables to the firing spring to push it through the widly open centrifuga and hit explosives,hopfully causing some damage in the sky and keeping safty of the gunners on the ground.

Cheers
gprr