Historical question, flak.

[SkyTiger]

Perhaps someone can answer my question.

When we see flak in old WWII films, it's puffs of smoke that appear in the air when a shell explodes. Now this is caused by a fuse going off inside of the shell. What I'm wondering is, how exactly they adjusted the fuse of the shell before it was fired.

I sort of imagined some kind of egg timer built into the side of an 88mm AA shell, which is obviously impractical. So, how did they do it? And how accurate were the fuses? Were they set to 1 second increments? 2 second? Was there something on the nose of the shell you'd twist to set the fuse?

Just something I've thought about for a long time.

[Buzzard7]

I thought they had magnetic fuzes. Get close to a big metal object and poof.

[Wreked]

Axis triple A were set manaully before loading - timed or altimiter fuses.

Proximity fuses were invented by the Brits (radio scensing devices onboard) (not sure if some were magnetically/electronic field triggered - torpedoes were).

The Germans did do preliminary research on proximity fuses but not to the point of it seeing active employment in the field - not sure about the Japanese.

....cheers eh!

[Wagger]

You tell them Wreked.  After the British did the initial concept and testing of the Proximity fuse between May and June of 1940. The information was transferred to the United States in September 1940 under a informal agreement between the two countries where the test result by the British were duplicated.  The fuse initially used a breadboard circuit which was changed by using 2 tubes , one for transmission and one for receiving signals.

After the allies introduced it, it was instrumental in a 7 fold improvement in accuracy in anti aircraft fire when used with radar ranging systems in the Pacific, Neutralizing the V-1 threat and when released for land warfare just prior to the Battle of the Bulge was found to be devastating and extremely effective against ground targets. 

[Lusche]

German flak used timed fuzes.

What you can see on this picture

Is the automatic fuze setter on a German 128mm flak gun.


A sectional drawing of a flak fuze


The timer in detail:

[SkyTiger]

Thanks Lusche, that's exactly what I was looking for. I understand the concept of the proximity fuses and such, but I was wondering how the timed fuses were set. I'd imagined a crew of guys adjusting some kind of timer on the shell before it was fired, but it seemed impractical.

[Ratpack1]

All that is most certainly correct, but the most innovative and advanced system was designed by the AH Task Groups.

They use whats called a "Super Uber Double Secret Chase You Down No Matter How High Or Far Away You Are" Fuse. It's deadly I tell ya! 

Here is a crude schematic that was recently discovered from an "insider" at Hi Tech!

 

[A8Hunter]

and people wonder why we Rooks fly so high, excellent graphic to illustrate our concerns! BTW, how u get a photo of me flying so low, the moon is "above" me???

[Wreked]

Proximity fused AAA ordinance going up created absolutely no problem to friendlies (unless you're chasing what ever the ack is shooting at.)

BUT on the way down - as when they landed back on earth - KABOOM???

Could have been dealt with 2 ways I imagine - a fail safe that set them off at a maximum altitude (if the Prox fuse didn't set them off earlier )and some sort of device that would set them to "safe" as they fell to earth.

100's of Ack shells coming down into an industrail steel foundry area or shipping lanes and being set off by the prox fuses would certainly cause a bitta drama!!

Anyone know how they "safed" them??


...cheers eh!

[Strip]

Anyone know how they "safed" them??

They didnt...

Strip

[Beefcake]

Heh. It always amazes me at how much detail goes into building something that will be blown to bits.


Poor P-38s.

[Chalenge]

The FlaK 37 guns had two men continuous adjusting the gun to track the target aircraft by matching settings sent from the battery central fire direction post through a visual alignment system. An analog computer system updated the gun through a 'Predictor' which calculated the aimpoint by taking into account the aircraft position and gun positions relative to one another. The operator of the Predictor acquired the target through a telescope and as the altitude and airspeed were calculated the Predictor would make adjustments to the fuse through the 'fuse setter' before firing. Because the central fire direction post and the gun positions were seperated by some distance the triangulation made distance calculations very accurate.

Point blank range for the FlaK 37 was considered to be 15-21 thousand feet but the Germans learned quickly that they could hit 30000 feet aircraft by moving the guns up onto mountain tops and then their gun fire was point blank. Thats why bombers from Italy (B-17s and B-24s) really got torn up on the way in and out.