Doppelzünder FLAK shell introduced in 1942, effects on air war?

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Deleted member 1487

USN vs Japan

Type Rounds fired Kills Rounds per bird

5" VT 117,915 346.5 340
5" Com 223,770 342.0 654

VT almost doubled effectiveness, by being close enough for the radar fuze to work, and also these were director aimed at single targets, and that Mk 37 radar assisted director was the best in the world.


I just am not seeing contact fuzing increasing things that dramatically, unless you have the Nazis begin director firing at individual aircraft, than trying to throw as many shells into the bomber box area as was possible.

That's comparing apples to oranges though. The VT fuses were used against low flying Japanese individual aircraft by low caliber AAA. The Germans were firing massed large caliber AAA against high flying bomber boxes, so the situations were different and you could potentially get a different effect from using different types of shells in those situations. Its hard to say what the post-war effect of AAA against high flying strategic bombers would have been with improved radar and VT shells given the quick shift to SAMs.
https://en.wikipedia.org/wiki/Surface-to-air_missile#Post-war_deployments
 
This is just my take on it. Flak Batteries become more effective the they themselves become the target. Either of massed carpet bombing raids or the personnel become targets of raids. The gunners had to be billeted near the guns.
 
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marathag isn't comparing apples to oranges but rather is casting pearls before swine.

The data he is citing is for 5 inch USN gun. That's 127mm gun--not a small caliber gun but rather a large caliber anti-aircraft gun, particularly when compared to most of the German flak kanones.

Further, faster, low flying, smaller, more manueverable airplaines not flying in formation going to be harder to hit than squadrons larger, slower, high flying airplanes flying in rigid formation.

I realize that you have a problem with accepting facts that disprove ideas you champion, but I am glad you do. You provide me with hours of entertainment that's almost as good as YouTube cat videos, though not as intellectually stimulating.

USN vs Japan

Type Rounds fired Kills Rounds per bird

5" VT 117,915 346.5 340
5" Com 223,770 342.0 654

VT almost doubled effectiveness, by being close enough for the radar fuze to work, and also these were director aimed at single targets, and that Mk 37 radar assisted director was the best in the world.


I just am not seeing contact fuzing increasing things that dramatically, unless you have the Nazis begin director firing at individual aircraft, than trying to throw as many shells into the bomber box area as was possible.
That's comparing apples to oranges though. The VT fuses were used against low flying Japanese individual aircraft by low caliber AAA. The Germans were firing massed large caliber AAA against high flying bomber boxes, so the situations were different and you could potentially get a different effect from using different types of shells in those situations. Its hard to say what the post-war effect of AAA against high flying strategic bombers would have been with improved radar and VT shells given the quick shift to SAMs.
https://en.wikipedia.org/wiki/Surface-to-air_missile#Post-war_deployments
 

Deleted member 1487

http://www.navweaps.com/index_tech/tech-075.htm
The following tables adapted from information given in "Naval Weapons of World War Two" by John Campbell show the USN's anti-aircraft successes between October 1944 and January 1945:
[SIZE=+1]Kamikaze Actions[/SIZE]
.
Weapon Planes Shot Down Number of rounds per plane
5"/38 using AA Common 19 1,162
5"/38 using VT 24.5 310
3"/50 using AA Common 6.5 710
40 mm Bofors 114 2,272
1.1" MG 1 2,231
20 mm Oerlikon 62.5 8,972
0.5" MG 2.5 28,069

Generally speaking, Kamikaze actions were at very close range with the aircraft closing fast upon their intended target. These sort of engagements were very difficult for weapons firing time-fuzed ammunition, as the rate of change in the ballistic range to the aircraft also meant that the fuze settings needed to have large changes from one round to the next. Any lag or delay in getting a particular round into the air after its fuze had been set meant that its detonation would be too far away to reach the target aircraft. The VT fuze eliminated that problem, as noted by its far smaller rounds per aircraft rate.


[SIZE=+1]Non-Kamikaze Actions[/SIZE]
.
Weapon Planes Shot Down Number of rounds per plane

5"/38 using AA Common 33.5 960
5"/38 using VT 20 624
3"/50 using AA Common 4 752
40 mm Bofors 46 3,361
1.1" MG 0 (4,764 total)
20 mm Oerlikon 50.5 7,152
0.5" MG 3 15,139

In this table the advantage of the VT fuze, while still significant, is not nearly so pronounced as in the previous table. This may be due to the fact that the rate of change of the attacking aircraft's ballistic range did not change as rapidly as did a Kamikaze aircraft, thus allowing the fire control computers more time to process the incoming data and produce better time fuze settings. It is interesting to study the success rate of the 3"/50 gun, as this weapon was adapted post-war with automatic loading and VT fuzes to replace the 40 mm Bofors on most US warships. Even without VT fuzes, the shoot-down rate of the smaller weapon compares favorably to that of the 5"/38 firing VT-fuzed ordnance. Although, the high numbers for the 5"/38 may be a result of the fast firing rates of these weapons and the fact that nearly every warship destroyer-size and larger carried several of these weapons. So, even a pair of destroyers could fire over 200 rounds per minute.

For more information on the VT fuze, see the Ralph Baldwin book, "The Deadly Fuze - Secret Weapon of World War II." An analysis in this book of the 278 aircraft shot down by VT fuzed projectiles between October 1944 and August 1945 indicates that only 46 of these would have been destroyed if time fuzed projectiles had been employed. However, Will Jurens, noted ordnance authority, estimates that Baldwin's 6:1 ratio apparently assumes that 70% of the VT fuzes worked. A 50% failure rate - the Navy's lower limit of acceptability - meant the effectiveness ratio was closer to 4:1. In comparison, mechanical time fuzes such as the Mk 18 typically worked about 90%-95% of the time.

There are a lot of pitfalls in this sort of analysis, and it is extremely difficult to arrive at meaningful numbers. With this caveat firmly in mind, I will quote some of the better figures for World War II:


Type of Attack Planes Shot Down Rounds per Plane 20 mm 40 mm 5"/38 MT* 5"/38 VT
Kamikaze 24 27,200 6,000 1,000 200
Non-Kamikaze 41 30,100 4,500 1,000 550

* MT = Mechanical Timer (i.e., Time Fuzed AA Common)
These figures are from the Special Defense Operations Research Group (SpecORG) study, "AA Defense of the Fast Carrier Task Force - 24 October 1944 To 21 March 1945", Anti-Aircraft Study No. 8, revised 11 September 1945. They address only carrier task groups, for which the best data were available.
As we can see shooting down Kamikazee attacks was a lot easier with VT fuse shells, but it didn't matter nearly as much against normal engagements.
 

CalBear

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http://www.navweaps.com/index_tech/tech-075.htm
As we can see shooting down Kamikazee attacks was a lot easier with VT fuse shells, but it didn't matter nearly as much against normal engagements.

As was noted, one significant difference is that the Luftwaffe was shooting at large bomber boxes that were part of a bomber stream that extended back for miles flying toward a target in formation, while the situation, by that time in the Pacific was almost always singletons or pairs entering the area at 10K or below.

Those are two very different target sets, one very large, flying along a known course and speed (and, normally, altitude) from which the aircraft could not deviate and the other a small target set, flying at a variable altitude toward a set of moving targets.

To the OP:

How are these shells different from any other shell? The explanation has to be more than just having dual fuse modes, every AAA shell used by all sides from 40mm up had dual fusing. Otherwise it is rather like trying to shoot a goose 500 feet over you house with a .22 pistol. If you hit it, well, dinner is served, otherwise the bullet misses and lands a mile away killing Mrs. Jones' Jack Russel Terrier on the way down. (This, BTW happened at Pearl Harbor, things were very disorganized, with a number of the 5"/25 shells being fired without having the timer set. These shells rained down on Honolulu causing considerable damage)
 
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Deleted member 1487

As was noted, one significant difference is that the Luftwaffe was shooting at large bomber boxes that were part of a bomber stream that extended back for miles flying toward a target in formation, while the situation, by that time in the Pacific was almost always singletons or pairs entering the area at 10K or below.

Those are two very different target sets, one very large, flying along a known course and speed (and, normally, altitude) from which the aircraft could not deviate and the other a small target set, flying at a variable altitude toward a set of moving targets.

To the OP:

How are these shells different from any other shell? The explanation has to be more than just having dual fuse modes, every AAA shell used by all sides from 40mm up had dual fusing. Otherwise it is rather like trying to shoot a goose 500 feet over you house with a .22 pistol. If you hit it, well, dinner is served, otherwise the bullet misses and lands a mile away killing Mrs. Jones' Jack Russel Terrier on the way down. (This, BTW happened at Pearl Harbor, things were very disorganized, with a number of the 5"/25 shells being fired without having the timer set. These shells rained down on Honolulu causing considerable damage)

I don't think the Germans used dual fuses because they were using box barrages, so were only using timed fuses. The dual fuse as far as I understand it was relying on masses of shells trying to score a direct hit and the timer of these being in place to detonate it after it started to fall back to earth. By going primarily going for direct hits with huge masses of shells fired into bomber boxes as fast as possible (i.e. without needing to pause to set timers for the box barrage) they could fire more in a shorter period, which on conjunction with the rest of the batteries firing (by later war they were using mega-batteries of 32 batteries commanded by one fire direction computer/radar) at the same target would saturate the airspace and be more likely to hit than firing box barrages or in the case of the USN at fast moving single targets at low altitude.
I imagine trying to hit bomber streams would be a lot harder at night given how they staggered the altitudes, even though they were mostly bombing between 16-18k feet. Being more spread out they'd be a lot harder to hit than a tight knit bomber box.
https://en.wikipedia.org/wiki/Bomber_stream
A typical bomber stream of 600 to 700 aircraft was on average 8 or 10 miles broad, and 4,000 to 6,000 feet deep.[2]
 
Were any studies done to assess the damage done by the shells that missed and fell back to the ground? Whatever fuse was used these were the vast majority.
 

Deleted member 1487

Were any studies done to assess the damage done by the shells that missed and fell back to the ground? Whatever fuse was used these were the vast majority.
In terms of German shells? They were mechanically times and blew up, so the vast majority was just metal shards falling back to earth; people in shelters wouldn't be effected and most homes would just have some minor roof damage. I'm sure an occasional shell fell back to earth due to a defect in the timer fuse, but if it lacked an impact fuse it wouldn't go off. AFAIK there aren't any studies about that I've seen from the Germans, for that you'd probably have to go archiving.
 

Deleted member 1487

To the OP:

How are these shells different from any other shell? The explanation has to be more than just having dual fuse modes, every AAA shell used by all sides from 40mm up had dual fusing. Otherwise it is rather like trying to shoot a goose 500 feet over you house with a .22 pistol. If you hit it, well, dinner is served, otherwise the bullet misses and lands a mile away killing Mrs. Jones' Jack Russel Terrier on the way down. (This, BTW happened at Pearl Harbor, things were very disorganized, with a number of the 5"/25 shells being fired without having the timer set. These shells rained down on Honolulu causing considerable damage)

I just came across a report from the German general of FLAK artillery about the double fuse shell that explains exactly how it worked and why the method worked and describes the method's used in combat and the result:
http://downloads.sturmpanzer.com/FMS/NARA_FMS_D031.pdf

It apparently was 3x as effective as the normal box barrage against daylight bombing and 2x as effective against night bombers. The only difference was that instead of solely using timed fuses they added a contact fuse and set the timer for 200 meters above the height of the highest bomber in the group and rapid fired with the goal of getting a direct hit. They hit on this in late 1944 and were getting it implemented historically in early 1945 and were planning on getting every battery to use these shells. The one downside according to the general was that it largely gave up the benefit of 'indirect' fire, that is the shrapnel damage to bombers in box barrages, which then made them more vulnerable to being picked off as they fell out of formation. He felt the direct shoot down benefits outweighed this though.

As to Calbear's point about all sides using dual fusing, apparently the Germans did not for use against strategic bombers because doctrine was to fire a box barrage, so contact fuses were effectively a pointless and unnecessary cost. But it was found that the box barrage was less effective than trying to score direct hits against bombers in formation. The idea of trying to use a .22 to hit a target a mile away is apt, but only if you assume its got a lot of propellant behind it, several hundred guns firing with radar and gun laying computer guidance, and a bunch of large targets in formation. Against a single target trying to get direct hits would be pointless to be sure, but large bombers flying in formation in a straight line creates a target rich environment and filling the specific airspace they are flying through with a lot of shells will score a lot of hits.

Edit: as far as I can tell there is no technical reason for this to not have been a viable option even in 1939, it just needed someone to recognize it's superiority to the box barrage and gun laying systems to be available, which makes 1941 or 1942 more than doable for this method to work and get a similar level of effectiveness. It would have some issues when radar jamming made cloudy or night time shooting hard to accurately pinpoint, but by and large it should do roughly 2x as much damage to night bombers and 3x as much damage to daylight bombers in terms of kills with major savings in terms of shells, as you can shoot down bombers with fewer shells needed per bomber and get more kills within the limited time the bombers are in range. That would have interesting effects too, as with less need for AAA shells that can mean more raw materials for other needs; as it was FLAK was eating up at least 1/3rd of all munitions production.
 
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I just came across a report from the German general of FLAK artillery about the double fuse shell that explains exactly how it worked and why the method worked and describes the method's used in combat and the result:
http://downloads.sturmpanzer.com/FMS/NARA_FMS_D031.pdf

It apparently was 3x as effective as the normal box barrage against daylight bombing and 2x as effective against night bombers. The only difference was that instead of solely using timed fuses they added a contact fuse and set the timer for 200 meters above the height of the highest bomber in the group and rapid fired with the goal of getting a direct hit. They hit on this in late 1944 and were getting it implemented historically in early 1945 and were planning on getting every battery to use these shells. The one downside according to the general was that it largely gave up the benefit of 'indirect' fire, that is the shrapnel damage to bombers in box barrages, which then made them more vulnerable to being picked off as they fell out of formation. He felt the direct shoot down benefits outweighed this though.

As to Calbear's point about all sides using dual fusing, apparently the Germans did not for use against strategic bombers because doctrine was to fire a box barrage, so contact fuses were effectively a pointless and expensive luxury. But it was found that the box barrage was less effective than trying to score direct hits against bombers in formation. The idea of trying to use a .22 to hit a target a mile away is apt, but only if you assume its got a lot of propellant behind it, several hundred guns firing with radar and gun laying computer guidance, and a bunch of large targets in formation. Against a single target trying to get direct hits would be pointless to be sure, but large bombers flying in formation in a straight line creates a target rich environment and filling the specific airspace they are flying through with a lot of shells will score a lot of hits.

Edit: as far as I can tell there is no technical reason for this to not have been a viable option even in 1939, it just needed someone to recognize it's superiority to the box barrage and gun laying systems to be available, which makes 1941 or 1942 more than doable for this method to work and get a similar level of effectiveness. It would have some issues when radar jamming made cloudy or night time shooting hard to accurately pinpoint, but by and large it should do roughly 2x as much damage to night bombers and 3x as much damage to daylight bombers in terms of kills with major savings in terms of shells, as you can shoot down bombers with fewer shells needed per bomber and get more kills within the limited time the bombers are in range. That would have interesting effects too, as with less need for AAA shells that can mean more raw materials for other needs; as it was FLAK was eating up at least 1/3rd of all munitions production.

That's interesting because it answers my earlier question - why wasn't the improvement around x2 rather than x10.
x2 to x3 (given the higher rof possible) seems a lot more believable.
 

CalBear

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I just came across a report from the German general of FLAK artillery about the double fuse shell that explains exactly how it worked and why the method worked and describes the method's used in combat and the result:
http://downloads.sturmpanzer.com/FMS/NARA_FMS_D031.pdf

It apparently was 3x as effective as the normal box barrage against daylight bombing and 2x as effective against night bombers. The only difference was that instead of solely using timed fuses they added a contact fuse and set the timer for 200 meters above the height of the highest bomber in the group and rapid fired with the goal of getting a direct hit. They hit on this in late 1944 and were getting it implemented historically in early 1945 and were planning on getting every battery to use these shells. The one downside according to the general was that it largely gave up the benefit of 'indirect' fire, that is the shrapnel damage to bombers in box barrages, which then made them more vulnerable to being picked off as they fell out of formation. He felt the direct shoot down benefits outweighed this though.

As to Calbear's point about all sides using dual fusing, apparently the Germans did not for use against strategic bombers because doctrine was to fire a box barrage, so contact fuses were effectively a pointless and unnecessary cost. But it was found that the box barrage was less effective than trying to score direct hits against bombers in formation. The idea of trying to use a .22 to hit a target a mile away is apt, but only if you assume its got a lot of propellant behind it, several hundred guns firing with radar and gun laying computer guidance, and a bunch of large targets in formation. Against a single target trying to get direct hits would be pointless to be sure, but large bombers flying in formation in a straight line creates a target rich environment and filling the specific airspace they are flying through with a lot of shells will score a lot of hits.

Edit: as far as I can tell there is no technical reason for this to not have been a viable option even in 1939, it just needed someone to recognize it's superiority to the box barrage and gun laying systems to be available, which makes 1941 or 1942 more than doable for this method to work and get a similar level of effectiveness. It would have some issues when radar jamming made cloudy or night time shooting hard to accurately pinpoint, but by and large it should do roughly 2x as much damage to night bombers and 3x as much damage to daylight bombers in terms of kills with major savings in terms of shells, as you can shoot down bombers with fewer shells needed per bomber and get more kills within the limited time the bombers are in range. That would have interesting effects too, as with less need for AAA shells that can mean more raw materials for other needs; as it was FLAK was eating up at least 1/3rd of all munitions production.
Thanks for the update. That makes a lot more sense. Makes it a doctrine issue, not a technology one.
 

Deleted member 1487

Assuming that per this what if the Germans realize that direct hits are the better option in 1942, might we then see them going smaller with a different design of FLAK gun for later in the war? Like a 70-75mm shell that is 70 calibers like they did with the FLAK 41 for the 88mm (essentially the FLAK version of the long 88mm gun used on the Tiger II)? They wouldn't need a large shell the size of the 88mm one if they didn't need shrapnel damage, even a 50mm shell could get a 1 hit kill on a B-29. A 75mm gun would be overkill, but given that they already had worked out a L70 75mm gun with the KwK42 (Panther gun) they could pretty quickly turn out a ultra high velocity 75mm FLAK meant for rapid first and high altitudes that would be cheaper and easier to make than the overkill FLAK 41, which apparently had the performance of the 128mm FLAK 40.
In fact with something like that they wouldn't need to make anything over a 75mm FLAK gun, as the heavier calibers weren't really necessary, as you could make a ultra high velocity smaller shell and require less gun and propellant to get to high altitudes. That way that would allow standardization on one caliber for that role and result in pretty big economies of scale, plus allow more rapid fire within a narrow time frame with a lighter shell, then preventing as much exhaustion of crews that the bigger calibers caused. ITTL then by 1944 they could just use the high velocity 75mm FLAK gun instead of the bigger calibers.
 
the United States and the Soviet Union took everything that wasn't nailed down from the Third Reich (and some of what was nailed down too). If this was a viable weapon system, why didn't we see it being used by Soviet medium and heavy caliber AAA guns used in the Mideast, Vietnam, and North Korea? They used VT shells, and got a very respectable success rate with them too against high speed jets at a variety of altitudes (far better than SAM systems for that matter). The US too would have certainly used it with their 75mm, 90 mm and 120 mm gun systems deployed in the late 40s and early 50s (later replaced by SAMs) and aboard ships armed with the 3 inch and 5 inch gun

I am aware of no such deployment, but I am not a specialist. But one would expect they would be used if they are better than a proximity fuse shell
 

Deleted member 1487

the United States and the Soviet Union took everything that wasn't nailed down from the Third Reich (and some of what was nailed down too). If this was a viable weapon system, why didn't we see it being used by Soviet medium and heavy caliber AAA guns used in the Mideast, Vietnam, and North Korea? They used VT shells, and got a very respectable success rate with them too against high speed jets at a variety of altitudes (far better than SAM systems for that matter). The US too would have certainly used it with their 75mm, 90 mm and 120 mm gun systems deployed in the late 40s and early 50s (later replaced by SAMs) and aboard ships armed with the 3 inch and 5 inch gun

I am aware of no such deployment, but I am not a specialist. But one would expect they would be used if they are better than a proximity fuse shell
VT replaced contact fuses; IOTL the Germans did not mass produce one, so this method was the best option available with existing technology, better than the box barrage.
 
That's a greater improvement than you'd get from using VT fuzes - AKA "magic fuzes which explode when the enemy is nearby". I'm skeptical.
To say the least.

I seem to recall reading about contact fuses being more likely to bring down a target - while less likely to score any damage per number fired any 'hit' was far more likely to result in a total loss of the target

Also given the tolerances of VT Fuzes in the mid 40s and the relatively new tech in determining altitude etc fractions of a second can result in the shell exploding near enough to the plane to damage it or too high/low

In Antony Williams OTL (ASB) Novel the British throwback Protagonist using this same theory has the British using Smoothbore flak cannon and using sabot shells to achieve a higher MV
 
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