1944: Flak Alone Blasts the Allies out of the Sky

[Von Schadewald]

This video clip
http://search.eb.com/normandy/video/onormay151v1.mov
shows German 2, 3.7 and 8.8 cm flak desperately trying to hack Anglo Typhoon jabos out of the Normandy sky.

Eventually they get one, but it shows their difficulty. One shot shows an aircraft bracketed by two accurate fuzed explosions, but it sails straight on through.

Aiming directly without fuzes or having proximity-fuzed rounds would have worked wonders for the flaktruppen's score.

[Lars]

Take a look at this. In one combat trial during April 1945, the contact and times fuse was more than ten(!) times as good as the average:

"In the final weeks of the war, the ammunition shortage within the flak arm became acute. The critical situation led the Luftwaffe to test a projectile with a contact and a timed fuse (Doppelzünder), the same round that a member of Speer´s ministry refused to support in 1944, based on safety considerations involved with the tansportation of these munitions.

During combat trials in Munich on April 9, heavy flak batteries using these rounds brought down thirteen aircraft at the cost of a mere 370 rounds per shootdown, an extraordinary favorable ratio compared with the existing average of approximately 4,500 rounds."

From Edward B. Westerman: "Flak. German anti-aircraft Defenses, 1914-1945":

[Huck]

Using proximity fuses in ETO, where electronic warfare reached its peak during ww2, was a poor idea. Cheap contrameasures could be developed so that proximity fuses would trigger prematurely or even on the ground. This is the reason why the Allies and Germany did not not use proximity fuses - for fear of countermeasures (Allies used proximity fuses only at the end of war, when they were sure that Germany was on the brink of collapse, and even then, only sporadically).

[Tony Williams]

Using proximity fuses in ETO, where electronic warfare reached its peak during ww2, was a poor idea. Cheap contrameasures could be developed so that proximity fuses would trigger prematurely or even on the ground. This is the reason why the Allies and Germany did not not use proximity fuses - for fear of countermeasures (Allies used proximity fuses only at the end of war, when they were sure that Germany was on the brink of collapse, and even then, only sporadically).

Eh? The British used prox fuses as soon as they could get hold of them, particularly in the 'Diver Belt' of guns along the Channel coast to guard against the V-1 assault launched from mid-1944 onwards. There was no risk of the Germans finding out about the technology because the shells didn't leave the UK. However, I have seen a long-lens photo taken by the Germans from the French coast which shows a pattern of prox-fuzed AA shell-bursts grouped around a V-1, and the Germans were puzzled as to how such accuracy of fuzing was achieved. They were puzzled because they never had any prox fuzes of their own. They were developing big ones for use in AA rockets, but they were never even close to developing ones small and rugged enough to be used in artillery shells.

The British were certainly concerned at one point that counters might be found to prox fuzes, but since they are still in use to this day for 40+mm AA guns it evidently didn't turn out to be a practical problem.

Tony Williams: Military gun and ammunition website and discussion forum

[Karri]

Very interesting topic. I am a total newbie to this matter, so very informative. I was wondering, what were the differences in production methods for different shells(time fuse, proximity fuse etc.)? And what were the differences in costs?

[Von Schadewald]

There is an interesting Bofors Company video on the Janes site
http://www.janes.com/defence/videogalle ... lery.shtml
showing how sophisticated even 40mm round proximity fuses are today.

With such rounds, POW's single Bofors would have downed every Japanese plane, saving Force Z!

[Huck]

Using proximity fuses in ETO, where electronic warfare reached its peak during ww2, was a poor idea. Cheap contrameasures could be developed so that proximity fuses would trigger prematurely or even on the ground. This is the reason why the Allies and Germany did not not use proximity fuses - for fear of countermeasures (Allies used proximity fuses only at the end of war, when they were sure that Germany was on the brink of collapse, and even then, only sporadically).

Eh? The British used prox fuses as soon as they could get hold of them, particularly in the 'Diver Belt' of guns along the Channel coast to guard against the V-1 assault launched from mid-1944 onwards.

Can you provide a source giving the procentage of AA shells that used proximity fuses for defense of Britain in mid '44? That would be a good start of an interesting discussion. I have seen no source proving with statistics that proximity fuses were used extensively, beside quotes about employment against V-1.

In overall results there is very little to indicate the use of a "wonder shell" in ETO, no German crew that flew missions over Britain in 1944 noticed any increase in efficiency of AA batteries, despite that really good technologies like centimetric gun laying radar were introduced. The results against V-1 are not conclusive: only one third of V-1s launched towards Britain were shot down by AA. This is a rather poor result by the standard of the day, considering that V-1 flew low, straight and level, so AA should have been very accurate (with of without proximity fuse) and V-1 was very fragile and had no means to keep the level flight once hit (unlike a manned aircraft). In plus V-1 came one at a time, so AA batteries were never overwhelmed by numbers.

There was no risk of the Germans finding out about the technology because the shells didn't leave the UK.

Bombers returning with unexploded shells incidents occured rarely but did occur. One such incident and the whole technology was not only useless, but potentially dangerous for its users.

However, I have seen a long-lens photo taken by the Germans from the French coast which shows a pattern of prox-fuzed AA shell-bursts grouped around a V-1, and the Germans were puzzled as to how such accuracy of fuzing was achieved. They were puzzled because they never had any prox fuzes of their own. They were developing big ones for use in AA rockets, but they were never even close to developing ones small and rugged enough to be used in artillery shells.

Sure they were puzzled since they did not know about such a technology. That does not mean that Germany did not develop and used proximity fuses. A secret technology is used only where it can make most of impact. Germans were using radio proximity fuses by mid '44 - each V-2 fired was fitted with radio proximity fuse, otherwise instead of blasting large areas it would have only dug deep wholes into the ground.

The British were certainly concerned at one point that counters might be found to prox fuzes, but since they are still in use to this day for 40+mm AA guns it evidently didn't turn out to be a practical problem.

Early radio proximity fuses could be easily countered. There were instances when proximity fuses were triggered by long wave radars that happened to run on frequencies close to those emited by the fuses. Despite being potentially useful, both parts feared to use them in ETO for fears of countermeasures. "Window" was another potentially useful technology, however quickly rendered useless in ETO. Despite this, neither chaff or proximity fuses disapeared. Both had potential to be discovered and used later (just to be countered again - and the cycle repeats to this day).

Proximity fuses went a long way since ww2. Probably first level of sophistication was to use the Doppler effect. This made them much less sensitive to countermeasures of their time. But they were defeated, one current system that does it is SEPS (Shortstop Electronic Protection System). Today it is not a problem to defeat any proximity fuse technology, but to defeat all technologies used by proximity fuses of shells employed in a certain conflict area. This is very hard to do with a single device. SEPS, for instance, is able to defeat various types of proximity fuses.

The arrival of such powerful countermeasures like SEPS, brought the AA technology to pre ww2 years, when the operator had to feed the time to impact into the fuse. Today, when powerful countermeasures are expected, the fuses use range data for triggering (measured by a rangefinder mounted on the gun), instead of relying of proximity measurements. That proximity fuses were successful in postwar years tells more about the nature of the postwar years conflicts than the qualities of this technology. Of course proximity fuses fared well against technologically underdeveloped countries, but nowadays when military engineering knowledge is so cheap and ubiquitous, such technologies are less and less useful (there is a similar debate regarding the future of missles vs guns, guided vs unguided).

[Tony Williams]

Eh? The British used prox fuses as soon as they could get hold of them, particularly in the 'Diver Belt' of guns along the Channel coast to guard against the V-1 assault launched from mid-1944 onwards.

Can you provide a source giving the procentage of AA shells that used proximity fuses for defense of Britain in mid '44? That would be a good start of an interesting discussion. I have seen no source proving with statistics that proximity fuses were used extensively, beside quotes about employment against V-1.

I don't have percentages, but Hogg states that the prox fuse was used 'extensively' in the Diver Belt, and the following quote comes from: http://www.vectorsite.net/twcruz2.html

"Even more significantly, the Americans introduced two new wonders of technology to the battle that proved to be particularly effective. The first was was the "SCR-548" gun-laying radar, which was used in conjunction with an analog computer to automatically track and fire on aerial intruders. The second was the radio proximity fuze, which allowed a shell to explode when it came to within a certain radius of a target, instead of being detonated by a time fuze set before firing. The fuze had been designed for larger machines than the V-1, but it was "calibrated" against full-sized models of the V-1 hung from towers. The V-1's straight and level path made it a relatively easy target for the new automated anti-aircraft gun system, and as gun crews became more experienced with their new tools, the number of kills rose dramatically. "

Incidentally, starting in December 1944 the British used prox-fuzed artillery shells in N Europe to provide accurate airburst fire over enemy troop concentrations.

However, I have seen a long-lens photo taken by the Germans from the French coast which shows a pattern of prox-fuzed AA shell-bursts grouped around a V-1, and the Germans were puzzled as to how such accuracy of fuzing was achieved. They were puzzled because they never had any prox fuzes of their own. They were developing big ones for use in AA rockets, but they were never even close to developing ones small and rugged enough to be used in artillery shells.

Sure they were puzzled since they did not know about such a technology. That does not mean that Germany did not develop and used proximity fuses. A secret technology is used only where it can make most of impact. Germans were using radio proximity fuses by mid '44 - each V-2 fired was fitted with radio proximity fuse, otherwise instead of blasting large areas it would have only dug deep wholes into the ground.

But that's exactly what the V-2 did - it was known for creating deep but narrow craters because it detonated after penetration and it was therefore less destructive than the V-1. Do have a source for claiming that the V-2 had a proximity fuze? I have never come across any suggestion that they might have done. The Germans tried many ideas with prox fuzes including acoustic and optical, but never had an equivalent to the compact Allied radio prox fuze.

The British were certainly concerned at one point that counters might be found to prox fuzes, but since they are still in use to this day for 40+mm AA guns it evidently didn't turn out to be a practical problem.

Early radio proximity fuses could be easily countered. There were instances when proximity fuses were triggered by long wave radars that happened to run on frequencies close to those emited by the fuses. Despite being potentially useful, both parts feared to use them in ETO for fears of countermeasures. "Window" was another potentially useful technology, however quickly rendered useless in ETO. Despite this, neither chaff or proximity fuses disapeared. Both had potential to be discovered and used later (just to be countered again - and the cycle repeats to this day).

Proximity fuzes have been used continuously in AA and artillery shells, and later in SAMs and AAMs, from WW2 up to the present day. SAMs and AAMs simply wouldn't work without them. Of course the technology has improved along with other areas, but the prox fuse has never been successfully countered.

Tony Williams: Military gun and ammunition website and discussion forum

[Lars]

Stolen from a forum outside AHF, here a post that says that "direct fire" technically was made by setting the time fuse on maximum hight. The technique saved manpower and increased the rate of fire:

"All Flak shells (for all nations) are dual-fused, with a contact fuse and a time fuse. Ideally the shell hits a target and detonates due to the contact fuse, with devastating results. If not, the time fuse, which is set before firing to detonate the shell after sufficient time to be at the altitude of the bombers, sets off the shell, creating a puff of black smoke and a small lethal area of shrapnel, which hopefully includes an aircraft within its radius.

With small-calibre shells, that is 40mm and under, the time-fuse is not set before firing, but is pre-set on nnaufacture. This detonates the shell at its 'maximum range' to prevent it travelling on until it hits something, like a friendly vessel in the case of a shipboard weapon, or onto friendly territory for a land-based weapon. The time-fuse at maximum setting fulfils this latter function for heavy AA as well, stopping the shell falling back to earth and onto the target city being protected.

Late in the war - IIRR, Mar-Apr 45 - someone suggested leaving the time-fuze set on maximum for heavy AA, and relying solely on the contact fuse, on the grounds that direct hits were bringing down the majority of aircraft, whereas proximity detonations only damaged them in most cases. This change to doctrine would reduce the manpower requirement (the fuse-setter job becoming redundant), and increase rate of fire (no delay waiting for the fuse-setter to do his thing). While reducing the amount of damage done (and aircraft downed) due to proximity detonations, it would increase the number downed by direct hits from the increased volume of fire far more. Some tests were done (exactly how I don't know!) and the theory found to have some merit. It was used in practice over the last weeks of the war but it was too little, too late. The aircraft downed for shells fired did increase slightly, as did the total aircradft downed, but the numbers were mere pinpricks against the massive Allied air armada.

The above is from memory from 'Anti Aircraft' by Ian Hogg."

[Mark V]

It was used in practice over the last weeks of the war but it was too little, too late. The aircraft downed for shells fired did increase slightly, as did the total aircradft downed, but the numbers were mere pinpricks against the massive Allied air armada.

The above is from memory from 'Anti Aircraft' by Ian Hogg."

Also, what is not said.

If solely contact fuzes would had been used by German heavy FlaK:

- number of Allied aircrew KIA would propably stay around the same, or diminish a bit
- number of Allied aircrew WIA would diminish considerably
- number of Allied aircrew taken as POW would diminish considerably
- number of Allied aircraft damaged over the target (large part of them were damaged beyond repair, many crash landings with fatal consequences in Channel or British Isles) would diminish considerably
- number of damaged Allied aircraft shot down by (light and heavy) Flak on their way to home (low and slow flyers) would diminish considerably
- number of damaged Allied aircraft that would be left behind the bomber stream to struggle alone towards their base (as an easy prey for German fighters) would diminish considerably
- number of damaged Allied aircraft and aircrew lost as interned in neutral territory would diminish considerably
- resources needed to be devoted to the maintenance of damaged but repairable planes of 8th AF and Bomber Command, would diminish markedly, that would mean higher number of available bombers - and with saved human resources in aircrew - propably would result still heavier bomber attacks...
- the stress of Allied aircrew flying over enemy airspace would be lessened, and their bombing accuracy would propably be much better, without FlaK bursts

The other side of coin. For an (QUOTE) slight (and not adequately proven) increase of shot down bombers over target - not an good trade for defender.


Regards, Mark V

[Von Schadewald]

If the Germans had had in 1944 a proximity fuse for the 88 and 128 mm equivalent to that used on the British 3.7", what sought of increase in Allied bomber losses might be expected from OTL: 10-15%. Or more?

[Mark V]

If the Germans had had in 1944 a proximity fuse for the 88 and 128 mm equivalent to that used on the British 3.7", what sought of increase in Allied bomber losses might be expected from OTL: 10-15%. Or more?

USN experience of ammunition usage per plane shot down at Pacific in non-Kamikaze action between October 1944 and January 1945:

5"/38 using AA Common
960 rounds per plane shot down

5"/38 using VT
624 rounds per plane shot down


http://www.navweaps.com/index_tech/tech-075.htm


Regards, Mark V

[Huck]

If the Germans had had in 1944 a proximity fuse for the 88 and 128 mm equivalent to that used on the British 3.7", what sought of increase in Allied bomber losses might be expected from OTL: 10-15%. Or more?

USN experience of ammunition usage per plane shot down at Pacific in non-Kamikaze action between October 1944 and January 1945:

5"/38 using AA Common
960 rounds per plane shot down

5"/38 using VT
624 rounds per plane shot down


http://www.navweaps.com/index_tech/tech-075.htm

Regards, Mark V

Unfortunatelly this ammunition expenditure decrease does not translates in equivalent increase in loss rate for the enemy.

[Mark V]

If the Germans had had in 1944 a proximity fuse for the 88 and 128 mm equivalent to that used on the British 3.7", what sought of increase in Allied bomber losses might be expected from OTL: 10-15%. Or more?

USN experience of ammunition usage per plane shot down at Pacific in non-Kamikaze action between October 1944 and January 1945:

5"/38 using AA Common
960 rounds per plane shot down

5"/38 using VT
624 rounds per plane shot down


http://www.navweaps.com/index_tech/tech-075.htm

Regards, Mark V

Unfortunatelly this ammunition expenditure decrease does not translates in equivalent increase in loss rate for the enemy.

Not directly - but for Germans which were in defence against huge bomber streams - and were limited in their time-envelope to engage enough targets - it should give rough estimate.

Also, use of VT fuze would increase the rate of fire similarily as the previously suggested use of contact-only fuzes (the difference increased still by the very slow fuze setting methods Germans used) still markedly improving effectiveness.


Regards, Mark V

[Lars]

Also, what is not said.

If solely contact fuzes would had been used by German heavy FlaK:

- number of Allied aircrew KIA would propably stay around the same, or diminish a bit
- number of Allied aircrew WIA would diminish considerably
- number of Allied aircrew taken as POW would diminish considerably
- number of Allied aircraft damaged over the target (large part of them were damaged beyond repair, many crash landings with fatal consequences in Channel or British Isles) would diminish considerably
- number of damaged Allied aircraft shot down by (light and heavy) Flak on their way to home (low and slow flyers) would diminish considerably
- number of damaged Allied aircraft that would be left behind the bomber stream to struggle alone towards their base (as an easy prey for German fighters) would diminish considerably
- number of damaged Allied aircraft and aircrew lost as interned in neutral territory would diminish considerably
- resources needed to be devoted to the maintenance of damaged but repairable planes of 8th AF and Bomber Command, would diminish markedly, that would mean higher number of available bombers - and with saved human resources in aircrew - propably would result still heavier bomber attacks...
- the stress of Allied aircrew flying over enemy airspace would be lessened, and their bombing accuracy would propably be much better, without FlaK bursts

The other side of coin. For an (QUOTE) slight (and not adequately proven) increase of shot down bombers over target - not an good trade for defender.


Regards, Mark V

Mark V,

Good points ideed. One of the problems for the Flakwaffe was that only direct shootdowns "counted" for the Nazi-leadership. All the planes damaged, all the personel killed and wounded while the plane survived didn´t count, as the Germans had no clear idea of these indirect effects of flak. Still, I believe that Flak-fire with the timer set on max. as practised in the last weeks of the war was a better solution than conventional shooting. But I really need to more studying on this. Ian Hogg´s book is on my reading list.

BTW, Erhard Milch was the most ardent supporter of the build-more-planes-instead-of-flak-school, while Hitler himself was an ardent flak-supporter, especially during the last ½ year of the war when the Jagdwaffe achieved next to nothing while the flak still managed to be an effective weapon.