What if the Germans had radar proximity fused AA shells?

[Admiral Beez]

Let's have the Germans deploy functional proximity fuses for their flak guns in time for the RAF and USAAF strategic bombing offensives.

Proximity fuze - Wikipedia

en.wikipedia.org

The proximity fuze was one of the most important technological innovations of World War II. It was so important that it was a secret guarded to a similar level as the atom bomb project or D-Day invasion.[14][15][16] Admiral Lewis Strauss wrote that,

One of the most original and effective military developments in World War II was the proximity, or 'VT', fuze. It found use in both the Army and the Navy, and was employed in the defense of London. While no one invention won the war, the proximity fuze must be listed among the very small group of developments, such as radar, upon which victory very largely depended.[17]

The fuze was later found to be able to detonate artillery shells in air bursts, greatly increasing their anti-personnel effects.[18]

In Germany, more than 30 (perhaps as many as 50)[19] different proximity fuze designs were developed, or researched, for anti-aircraft use, but none saw service.[10] These included acoustic fuzes triggered by engine sound, one developed by Rheinmetall-Borsig based on electrostatic fields, and radio fuzes. In mid-November 1939, a German neon lamp tube and a design of a prototype proximity fuze based on capacitive effects was received by British Intelligence as part of the Oslo Report.

 

[wiking85]

Let's have the Germans deploy functional proximity fuses for their flak guns in time for the RAF and USAAF strategic bombing offensives.

Proximity fuze - Wikipedia

en.wikipedia.org

The proximity fuze was one of the most important technological innovations of World War II. It was so important that it was a secret guarded to a similar level as the atom bomb project or D-Day invasion.[14][15][16] Admiral Lewis Strauss wrote that,


The fuze was later found to be able to detonate artillery shells in air bursts, greatly increasing their anti-personnel effects.[18]

In Germany, more than 30 (perhaps as many as 50)[19] different proximity fuze designs were developed, or researched, for anti-aircraft use, but none saw service.[10] These included acoustic fuzes triggered by engine sound, one developed by Rheinmetall-Borsig based on electrostatic fields, and radio fuzes. In mid-November 1939, a German neon lamp tube and a design of a prototype proximity fuze based on capacitive effects was received by British Intelligence as part of the Oslo Report.

Estimates from the US were that it would increase Allied losses by 300%....if there was no jamming of the fuses and radar. For this to work they'd need to figure out a way to avoid jamming, which the Allies figured out before they deployed their own in case any of there was captured and reverse-engineered, and have a functional cavity magnetron to avoid radar jamming. If they had that...well look at how well Allied FLAK dealt with the V-1s once all their systems came online in 1944. I'd imagine the combo would make 400% higher Allied air losses. Unsustainable territory very quickly. The best the Germans managed was a shoot down for every 2000 shells in 1942, 400% better means 500 shells per kill in 1943.

Increase write-offs by a factor of 4 every month.

 

[ThomasP]

American daylight strategic bombing stops for sure and UK night bombing probably stops. Both types of operations would be unsustainable due to the loss rates incurred.

 

[Admiral Beez]

American daylight strategic bombing stops for sure and UK night bombing probably stops. Both types of operations would be unsustainable due to the loss rates incurred.

That's my thinking too. Putting efforts toward advanced AA tech rather than ballistic missiles and Goering's Napkinwaffe seems the better approach.

 

[Geoffrey Sinclair]

There are tables of estimated USN AA performance, one widely published table is 1 October 1944 to 31 January 1945, and sees in Kamikaze actions the 5 inch VT (proximity) required 310 rounds per shoot down, the 3 inch 710 and the 5 inch common 1,162, go to non Kamikaze actions and it became 5 inch VT 624, 3 inch 752, 5 inch common 960, In the fights with Kamikazes the USN ships reported they needed to fire 100% VT fuses, since there was normally no time to set and use time fuses. Fleet Command pointed out firing some time fused ammunition was a good way to check they were actually shooting at what they thought they were.

The allies first fitted proximity fuses to the 5 (127mm) and 4.5 (114mm) shells at a cost of explosive content, the smaller the shell the bigger the effect on explosive content, the lethal burst radius for a standard 88mm shell was around 30 feet, or 9 metres. Given the standard fire control radar some 59,000 88 mm shells were needed to cover the volume the aircraft could be in when flying at 24,000 feet. The number of flak batteries out ran the German ability to provide them with proper fire control systems. Hence there were still sound locators in use in 1944 to use an extreme example. The idea of massed batteries was also driven by the amount of fire control systems needed. At 3 to 7 times the efficiency the 1944 level of 16,000 88mm shells per shoot down fired would be reduced to 2,300 to 5,300. The Germans did better early in the war in terms of shells per aircraft but this was the sort of price paid for using effectively reserve manpower in the flak units alongside less accurate fire control systems and higher flying targets. According to the USAAF Statistical Digest 146,011 8th AF effective heavy bomber sorties September 1944 to April 1945 saw 1,159 lost to flak, or 0.8%, monthly figures ranging from 0.4% to 1.5%. The 15th AF reports for the war known flak losses were 0.6% of effective sorties for B-17 and 0.9% for B-24, assume all the unknown cause losses were to flak and the figures become 0.8% and 1.2%. The oil campaign cut German explosive production which helped cut allied loss rates in 1945.

The USAAF estimate was losses to flak would triple (not total losses), bombing heights would have to increase and the B-24 not used against well defended targets. The B-24 made up around 1/3 of the 8th Air Force and 2/3 of the 15th Air force, all up under half the USAAF bombers. When the German flak concentration around the main synthetic oil plants became so great the USAAF started to use cloudy days, relying on radar aids, assuming the loss of accuracy for the gunners was greater than that of the bombers, it also helped the Germans used smoke screens. Bomber Command did a similar thing for daylight raids on Ruhr targets. Flak losses were never above the critical loss rates, but would have approached it if they were tripled. It took fighters to really cut up a bomber formation.

The USAAF would have flown more night missions and deployed B-29s to Europe. The allies would have devoted more to flak suppression. The allies would have flown more missions on cloudy days using the better radio aids in 1944.

Before the RAF introduced window Bomber Command was recording that around 6 to 9% of returning aircraft on night missions had flak damage, March to July 1943. This dropped to 2.85% in August and averaged 2.3% for all of 1944 and 1.4% for 1945. Window remained effective against the fire control radars for the remainder of the war. The average for aircraft returning damaged by flak on night raids February to December 1942 was 6.5%, for all of 1943 5.8%. In effect a proximity fuse at around 3 to 7 times the lethality would restore to exceed the pre window hit rates.

The USAAF carried window and active jammers but, of course, by day the gunners could correct their aim by eye. Some batteries even had the ability to track the H2X radars of USAAF pathfinders and use this for ranging, electronic warfare is a 2 way street.

WWII was very much a radio war and only the US electronics industry had the sort of capacity to match the demands made, millions of proximity fuses were needed.

 

[Shortround6]

From your post #1

In Germany, more than 30 (perhaps as many as 50)[19] different proximity fuze designs were developed, or researched, for anti-aircraft use, but none saw service.[10] These included acoustic fuzes triggered by engine sound, one developed by Rheinmetall-Borsig based on electrostatic fields, and radio fuzes. In mid-November 1939, a German neon lamp tube and a design of a prototype proximity fuze based on capacitive effects was received by British Intelligence as part of the Oslo Report.

Ideas were not the problem. Turning the ideas into stuff that actually worked was the problem. Worked in a real live fire test, not experiments to see if the idea itself worked.

The US spent more money and effort on the Proximity fuse than they did the Atomic bomb.
I would note that it took quite a while to shrink the proximity fuse down from the size used in the 5in/38.
First operational use of the proximity fuse by the US Navy was the Mk 32 fuse in the 5in/38 in either late 1942 or Jan 1943 (USS Helena).
British got the MK 33 fuse for the 4.5in AA guns in Sept 1943.
British got the MK 41 fuse for the 4in AA guns in Nov 1943.
The British 4in shell would hold the MK 33 fuse, it just didn't have room for much explosive left.
The US came up with fuses for the US 90mm AA gun in late 43 or early 1944.
The US had to redo the Mk 32 Fuse as the dry cell battery did not have the shelf life wanted. The batteries were going dead in just a few months in tropical conditions. Fortunately the solution was already at hand. The smaller, newer fuses used a sort of sealed wet battery because the small fuse could not hold a big enough dry cell and the wet battery was adapted.
They also fixed the low altitude problem, 5in/38 Proximity fuses were detonating on wave reflection at low altitude over water.
The fixed fuses were being issued in May of 1944.

The US issued the MK 45 fuse for the 3in/50 gun in May of 1944 but it was not satisfactory and was replaced in Nov 1944 by the MK 58 fuse.

The Crosley company had over 10,000 employees and built about 25% (roughly) of the Proximity fuses built in the US. That is the scale of production, Crosley hit peaks of over 16,000 fused per day.

More information here.

Radio Proximty (VT) Fuzes

Radio Proximity (VT) Fuzes and How They Operate Significance and Background of the Radio Proximity Fuze (VT) in World War II Development of Proximity Fuzes (VT) for Projectiles - VT Fuzes MKS 32 to 60

www.history.navy.mil

 

[Shortround6]

Putting efforts toward advanced AA tech rather than ballistic missiles

It was actually much easier to design and build a proximity fuse for a rocket or missile than a proximity fuse for an AA gun.
You have more space to work with.
You don't have the shock/g forces from firing the gun. Like zero to Mach 2.4 in 16 ft? let alone the blow to the back of the shell.
You don't have the rotational forces (spin) acting on the fuse parts.

 

[Admiral Beez]

It was actually much easier to design and build a proximity fuse for a rocket or missile than a proximity fuse for an AA gun.
You have more space to work with.

Was there any reasonable feasible route for the Germans to mass produce and deploy wireless guided SAMs with proximity fuses?

The Wasserfall Surface-to-Air Missile seems too big for mass production and application against a thousand bomber raid.

 

[Shortround6]

A successful Proximity fuse would have gone a long way into making a successful SAM.
You still need successful propulsion and successful guidance.
Tracking the missile with a 2nd radar and using that to either detonate the warhead or to command the operator to do it (very fast reflexes ?) is also a little wasteful?
How many radar beams using close to identical frequencies in the air at one time?

Size of the rocket was somewhat dependent on the size of the warhead. Using a 306 kg warhead (an area weapon) rather than a 100kg warhead obviously means a much larger missile.

 

[Admiral Beez]

A successful Proximity fuse would have gone a long way into making a successful SAM.
You still need successful propulsion and successful guidance.
Tracking the missile with a 2nd radar and using that to either detonate the warhead or to command the operator to do it (very fast reflexes ?) is also a little wasteful?
How many radar beams using close to identical frequencies in the air at one time?

Size of the rocket was somewhat dependent on the size of the warhead. Using a 306 kg warhead (an area weapon) rather than a 100kg warhead obviously means a much larger missile.

And how do you direct radar and guide a missile onto a single aircraft when there's a wall of hundreds coming at you? I guess that was thinking behind the AIR-2A Genie, each missile takes out many bombers.

 

[ThomasP]

There was at least one Luftwaffe(?) concept where the AA rockets were fired to a pre-set altitude - determined by the equivalent of radar altimeters mounted on the ground and aimed upward. The incoming formations would fly over the ring of inverted radar altimeters, the target height of the formation would be measured and transmitted to the rockets batteries, the detonation height set, and the rockets launched. There were various ideas for warheads - including seriously large unitary warheads, and cluster warheads with the submunitions thrown outward by the motion of the spin stabilized action of the rocket. In one case, each submunition was similar in concept to the UK aerial mine.

Aerial Mine

The idea was to fire a number of rockets just in front of the formation, or in the midst of multiple formations, to the appropriate height - with the submunitions being ejected over a vertical interval sure (hopefully) to distribute the aerial mines in front of the bombers.

There was also the idea of the large grenade type submunitions being ejected in a similar manner to the aerial mines, but timed to detonate after a short preset time interval.

Some of the warheads were in the 2200 lb range - so upto 200 of the aerial mines (4 lb HE each), or IIRC upto 400 of the large grenade type.

 

[mack8]

Very interesting thread. A FOUR time increase in losses to heavy flak sound devastating. Are there examples of german proximity fuses that were the most feasible/got closest to production? One can theorize that even if the german fuses were not as good as the allied ones and only increase losses by say 3 times, that is still a massive improvement in efficiency.
Also, one can onsider other effects such as german proximity fuses being handed over to the japanese. Presumably the bigger the shell the easier is to fit proximity fuses, so the japanese could fit such fuses to their big gun San-shiki-dan shells on their cruisers, battleships etc. as well as land based mounts.

 

[Admiral Beez]

Are there examples of german proximity fuses that were the most feasible/got closest to production?

Some info here. Proximity fuze - Wikipedia

In Germany, more than 30 (perhaps as many as 50) different proximity fuze designs were developed, or researched, for anti-aircraft use, but none saw service. These included acoustic fuzes triggered by engine sound, one developed by Rheinmetall-Borsig based on electrostatic fields, and radio fuzes. In mid-November 1939, a German neon lamp tube and a design of a prototype proximity fuze based on capacitive effects was received by British Intelligence as part of the Oslo Report.

 

[wiking85]

Very interesting thread. A FOUR time increase in losses to heavy flak sound devastating. Are there examples of german proximity fuses that were the most feasible/got closest to production? One can theorize that even if the german fuses were not as good as the allied ones and only increase losses by say 3 times, that is still a massive improvement in efficiency.
Also, one can onsider other effects such as german proximity fuses being handed over to the japanese. Presumably the bigger the shell the easier is to fit proximity fuses, so the japanese could fit such fuses to their big gun San-shiki-dan shells on their cruisers, battleships etc. as well as land based mounts.

AFAIK the only proven ones that were functional were the ones for rockets and missiles since they were easier to make as they didn't deal with the small size of a cannon fired shell or the g-force acceleration. There have been allegations about electro-static FLAK fuses, but that they weren't operational by the end of the war.

 

[Admiral Beez]

Given their postwar lead in innovation, it's noteworthy just how behind the Germans were in some many essential military capabilities. Air warning/intercept radar and overall air defence, naval fire control radar, cryptography, logistics and supply chain, production/weapons/kit prioritization, and so much more.

A great example is when the Germans take the Russian oil fields but brought no expertise or ability to reverse the Soviet's entirely-predictable sabotage. Barbarossa was all about seizing the USSR's resources, and now you've done it, but you didn't bring the kit to use it. D'oh.

 

[z42]

Given their postwar lead in innovation, it's noteworthy just how behind the Germans were in some many essential military capabilities. Air warning/intercept radar and overall air defence, naval fire control radar, cryptography, logistics and supply chain, production/weapons/kit prioritization, and so much more.

A great example is when the Germans take the Russian oil fields but brought no expertise or ability to reverse the Soviet's entirely-predictable sabotage. Barbarossa was all about seizing the USSR's resources, and now you've done it, but you didn't being the kit to use it. D'oh.

For the land war, the image one comes up with is Tiger tanks and Stukas. However, while these existed they were a small tip of the spear kind of thing. The vast majority of the army moved like this:

Except for the few trucks in the background, this picture could almost have been taken during the Napoleonic wars.

 

[Admiral Beez]

I suppose it doesn't help Germany's advanced weapons programs, be it proximity shells, radar, atomic weapons, etc. if many of your leading mathematicians and physicists have been murdered by the state or forced into the welcoming arms of the Allies. But then, they wouldn't be Nazis.

 

[tyrodtom]

I took thousands of at least semi skilled, if not skilled workers to make these fuses.
Where's the Germans going to get these people, from their usual pool of slave labor ?
Working under the threat of death.
They really seemed to think that insured quality, but then they were Nazis.

 

[Shortround6]

I took thousands of at least semi skilled, if not skilled workers to make these fuses.
Where's the Germans going to get these people, from their usual pool of slave labor ?
Working under the threat of death.
They really seemed to think that insured quality, but then they were Nazis.

As noted earlier Crosley built about 25% of the Proximity fuses built in the US using a work force of 10,000 workers.
Crosley did not build everything in house, they had a number of subcontractors.

As a further note, The US did not authorize tooling up for the production fuse for the 5in shell until it passed the 50% success rate (duds were under 50%) with the expectation that the dud rate would be improved while tooling up or in early production. They thought that the 50% rate showed they were at least on the right track.

The program relied on US battery manufacturers and vacuum tube manufacturers for both development and production.

another note, The US and British did not get 100% proximity fuse ammunition until late in the war and until late 1944 it was was only used from ships or for protecting Britain.
There periods of time were very little proximity fused ammo was being fired.

If it took even 5000 rounds of AA Shells to bring down a bomber and even if the Proximity fuses would cut that to only 25% (1250 shells) that is 25,000 fuses for 20 bombers.
You need millions of fuses. You need millions of small fuses.

The Germans only built about 1125 12.8cm Flak guns.
shells work on the cube law. volume of the shell is proportional to the cube of the caliber.
5in = 125
4in = 64
3.5in = 42.87
3in = 27

That (or less) is the relative volume you have to work with. As noted earlier, you could fit an early fuse from a 5in shell into a 4in shell body (assuming matching threads) but you didn't have much room for explosives as the fuse took up most of the volume inside the shell. The 88mm/90mm/3.5in was even worse.
They built over 20,000 88mm flak guns. Granted production could have been tweaked in 1943-44 in favor of heavier guns but the Germans needed a smaller fuse than the earlier allied one which complicates initial development a lot.

 

[wiking85]

Given their postwar lead in innovation, it's noteworthy just how behind the Germans were in some many essential military capabilities. Air warning/intercept radar and overall air defence, naval fire control radar, cryptography, logistics and supply chain, production/weapons/kit prioritization, and so much more.

A great example is when the Germans take the Russian oil fields but brought no expertise or ability to reverse the Soviet's entirely-predictable sabotage. Barbarossa was all about seizing the USSR's resources, and now you've done it, but you didn't bring the kit to use it. D'oh.

Unfortunately you have several misconceptions. At the start of the war they were ahead in radar, but lost the lead due to the US and UK merging their programs, the Germans giving up on cavity magnetron research (which they had the lead in until 1940), and the Japanese not sharing their technology (they were at the same place with cavity magnetron research as the British in 1940 and arguably kept pace until the end of the war). They also had the best air defense system in the world until US production was able to take Britain to the next level somewhere in 1943-44. Cryptography saw the German achieve immense success, something the Allies covered up until the 2000s:

Christos military and intelligence corner

<br> <br> <br> <br> <br> <br> <br> <br> <br> <br> Military and intelligence history mostly dealing with World War II.

chris-intel-corner.blogspot.com

Amazon.com

Much of the wartime issues was lack of resources, lack of manpower, lack of preparation for war (contrary to the claims there is no indication that the Germans were seriously preparing for war until 1938-39 when it was clear the Allies were preparing for war).

Also German records complicate the claims about the Russian oil fields in the Caucasus:

https://en.topwar.ru/174335-pravda-o-zahvachennoj-majkopskoj-nefti.html

Logistics was far more the reason behind decisions they made there. Also keep in mind the Germans advanced MUCH further over far worse infrastructure than the Allies did in 1944 France and had less issues with supply. Much of the claims about how bad the Germans were at logistics is post-war propaganda to bolster the image of the Allies, as they really made a ton of mistakes that the generals were very interested in covering up. After all they mostly ignored the ports and then were shocked when they ran out of supplies at the German border. Like how could the vaunted Allies miss how important Antwerp was? Then even after they captured it they didn't allocate enough labor to even fully utilize it. And they ran out of infantry replacements so were using untrained clerks as meatshields by late 1944. During the Bulge the US even had to beg the Brits for 400 Sherman tanks even as thousands of Shermans were waiting in depots in the US to go to Europe.

So yeah, lots of misconceptions about many many things surrounding the war.