1944: Flak Alone Blasts the Allies out of the Sky

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Lars
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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by Lars » 18 Aug 2019 15:14

It is now more than 14 years since I started this discussion. What a treasure trove of information and good ideas it has become! Thanks to all.

I have just finished re-reading Westermann's excellent "Flak, German Anti-Aircraft Defences 1914 -1945". At page 282 another nugget turned up which has been alluded to in the above, the German Kulmbach 9 centimeter radar. Quote:

"..the experimental Kulmbach radar in the gun laying role drastically reduced the number of rounds expended per aircraft shot down to less than 300."

That is more than a factor 15 compared with the usual average of 4,500 rounds per arcraft shot down.

Only two Kulmbach radar set were operational at the end of the war. Even if we try to correct the numbers with the fact that the Allied airforce was more reckless at the end of the war due to the implosion of the flak arm and say, that it would have required 900 rounds per aircraft shot down when the Kulmcach radars were rolled out across Germany it is still an improvement of a factor 5.

Until the allied started to jam the Kulmbach radar (9 cm windows f.ex.) it would also have been huge improvement. And the Germans would counter the 9 cm windows after some time by "de-lousing " the Kulmbahcs.

Conclusion:
With the Dobbelzünder grenade and a 9 cm. gun laying radar the ratio of rounds to downed aircrafts should drop from 4,500 to under 1,000, perhaps even significantly so.

I think it fair to say that with the huge improvement from the Dobbelzünder grenade on top of a huge improvement by an earlier 9 cm. gun laying radar the Luftwaffe would have the means to what looked like flak blasting the Allies out of the sky.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by T. A. Gardner » 18 Aug 2019 19:41

Here's what the USAAF was training crews to for flak.




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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by T. A. Gardner » 18 Aug 2019 19:49

On AAM's here's what the US was developing in 1945. Compare these to the X-4 and you can see what an utter joke the German missile was:

MX-799 Ryan Firebird

Image

JB-3 Tiamat (Hughes)

Image

USN KA3N-1 Gorgon missile

Image

All of these were tried with semi-active radar homing, beam riding radar homing, and television CLOS guidance. All had a proximity fuze and used fairly large warheads (usually a hundred lbs. +) to ensure a shootdown.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by Lars » 19 Aug 2019 04:27

Well it doesn't negate in any way what I wrote about what the double fuze (timed and impact) and a 9 cm gun laying radar would do for the German flak defence.

But perhaps that was not the intention.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by T. A. Gardner » 19 Aug 2019 05:10

As I previously wrote, the move to millimeter radar would have had little real impact on the accuracy of German flak. Both the US and Britain could, and would, have quickly moved to actively and passively jam the systems and they'd be just as vulnerable as the older 54cm Würtzburg sets were. Wavelength alone changes nothing.
The Germans weren't introducing better predictors to go with that radar so they'd still be operating the same sets with the same built in errors and prediction speeds.
Fuzing, short of the Germans getting a VT type fuze in service wasn't going to change anything.

For example, since cloud cover is a pretty regular thing over Germany, German batteries were often forced to fire off radar predictions. When the radar was heavily jammed, their only real choice was to resort to a box barrage of predicted fire. That is, they'd fire shells into a square in the sky as rapidly as possible in a location they expected the enemy bombers to fly into. These barrages were incredibly both expensive in shell use-- 10,000+ wasn't uncommon-- and ineffective compared to predicted and aimed fire. Often, they failed to shoot down any bombers.

Now, that said, if the 9 cm radar system was unjammed, it would allow the fire control operators on the ground to pick out individual aircraft and accurately aim on them. That doesn't change any other factor in the system. Changing the fuzing to impact and timed would result in a marginal increase in effectiveness here as a direct hit would take the plane down. But, the odds of that are still very low.

I'd say that a few percent increase in effectiveness of flak overall would result. That effectiveness was heavily dependent on the radar being unjammed.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by TheMarcksPlan » 19 Aug 2019 09:53

T. A. Gardner wrote:
06 Nov 2016 01:31


Image
I was always suspicious of the claimed effect of the doppelzunder contact fuse on AA effectiveness.
But this diagram has me reconsidering.
Notice that the surface area of a B-24, viewed from above, is ~2,000ft2.

Image

(The wing is 1,048ft2 - engines, tail plane, fuselage are around the same area)

From Mr. Gardner's diagram, it appears that a box put ~50 planes into an area (x-z axis, ignoring vertical y-axis) measuring something like 1,000ft by 2,000ft. That's 2,000,000ft2. 50 planes would cover ~100,000ft2 of that area or ~1/20.

Shells aimed at correctly at the box, and passing through it vertically, would have a ~1/20 chance of hitting a bomber.

Assuming one hit per kill, which is probably likely with 88's, we have a 800x improvement over OTL's 16,000 shells/kill.

Now of course I wouldn't suggest 800x improvement is feasible with contact fuses. There'd be aiming error, the shell trajectories aren't quite vertical, and other fudge factors. But it at least suggests that the small-scale doppelzunder trial results weren't anomalous.

Were something like the doppelzunder strategy implemented large-scale, the Allies would of course respond - probably by dispersing bomber formations to a greater extent. That would, however, make them more vulnerable to fighters and give the Flak greater engagement time with the longer bomber stream.
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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by Lars » 19 Aug 2019 12:49

Yes, shooting through the entire bomber box is the idea with the double fuze. That and a smaller time loss when a grenade is fired because the altitude (time) does not need to be set.

I don't know if the counter to the double fuze are loser and more shallow bomber boxes. As you state it makes the bombers more vulnerable to fighters. If we get to the point where the fighters are more or less absent due to lack of fuel (4 last months of 1944) then yes, the bomber stream could be shallower and loser as a counter to the double fuze.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by TheMarcksPlan » 19 Aug 2019 21:25

Lars wrote:I don't know if the counter to the double fuze are loser and more shallow bomber boxes. As you state it makes the bombers more vulnerable to fighters. If we get to the point where the fighters are more or less absent due to lack of fuel (4 last months of 1944) then yes, the bomber stream could be shallower and loser as a counter to the double fuze.
...raises the question of the timing of your ATL. If the contact strategy starts successfully in 1942 then probably the Allies don't have sufficient daytime bombing strength to hit specific targets like oil refineries.

Really if contact tactics get to 300 shells/shootdown the strategic bomber offensive is over until maybe the B-29 flies above the swarms of 88's.

It's still not a war winner, IMO. Slightly higher armaments production helps the German army but not enough to stop the Red Army. Redeploying heavy bombers to tactical missions in support of the Allied armies and/or to tertiary targets undefended by flak (e.g. rail lines themselves instead of marshalling yards) could still bite. And of course if the strategic bomber offensive is abandoned earlier, those resources can massively amplify Allied land power.
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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by T. A. Gardner » 20 Aug 2019 06:38

The problem remains, that you are changing just one minor aspect of the whole flak system. The time of flight of the shells remains the same. The error(s) in fuze setting for time fuzes remains the same. The dispersion of the shells remains the same. The accuracy and time it takes to run a fire control solution remains the same. If you get a direct hit the shell goes off. That's a really minor change.
At the same time, you have the US practicing flak avoidance techniques that make accurate fire harder. Then you add in that most of the time you have cloud cover to contend with. Toss in the same amount of jamming against radar.
I think all-in-all it would have made little difference. Flak has been used since WW 2, and much of that with vastly improved equipment. Yet, it never proved highly effective against high flying aircraft.

What the Germans needed wasn't a better fuze. They needed an entirely new and better system.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by thaddeus_c » 20 Aug 2019 17:40

T. A. Gardner wrote:
20 Aug 2019 06:38
I think all-in-all it would have made little difference. Flak has been used since WW 2, and much of that with vastly improved equipment. Yet, it never proved highly effective against high flying aircraft.

What the Germans needed wasn't a better fuze. They needed an entirely new and better system.
the suggestion over the course of this thread that made the most sense to me was "long ago" idea of sub-caliber tracer shells but even that maybe just negates having to ever increase the caliber of guns (to reach) Allied aircraft?

found an interesting article for "reverse fuel air weapon" https://www.wired.com/2007/09/reverse-fuel-1/ that concept might have been worthwhile as Allied bombers survived numerous hits?

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by T. A. Gardner » 20 Aug 2019 19:19

I think a better way than an FAE would be go big on the missile thing. For example, a V-2 rocket would reach 25 to 30 thousand feet in about 8 to 10 seconds give or take. That's quick. You set these up, modifying them so they can be shot with reasonable accuracy into a bomber box, possibly with more of a slant range and slightly longer flight time, say 15 to 20 seconds. Add a command detonation fuzing system to them and you have a 2000 lbs. + warhead (given you need far less fuel) that detonates close to or within the box. With added fragmentation that takes down the whole box pretty much, and if it doesn't it would be a hell of disruption to surviving aircraft.
The engagement time is so short you really don't need much, if any course correction to achieve sufficient accuracy for a "hit."

Essentially you are making a horribly inaccurate SAM out of a large ballistic missile. Against jamming you simply aim your fire at the strongest signal and command detonate at the estimated proper altitude and distance.

The sub-caliber rounds is trying to reduce another part of the flak sequence to increase accuracy. The British did this postwar with their Green Mace monstrosity. Higher velocity sub-caliber rounds mean less flight time, meaning greater accuracy in prediction.

The best choice, and the postwar one, was simply a guided weapon from launch to intercept. Thus, the SAM.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by Lars » 20 Aug 2019 19:26

I belive the tracer shells was a psychological weapon and not really designed to bring down planes. If we are talking about alternate weapons I believe that the most promising would be derived from the fact that you only need a 50 mm grenade to hit the plane anywhere and it goes down.

So find a way to get a 50mm grenade fast and high enough up and the problem is solved. The Pennemunde Pfeilgeschoss or a 50 mm sabot fired from say a 88, 105 or 128 mm gun or design a new 50mm Flak-gun.

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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by TheMarcksPlan » 20 Aug 2019 21:07

T.A. Gardner wrote:The time of flight of the shells remains the same. The error(s) in fuze setting for time fuzes remains the same. The dispersion of the shells remains the same. The accuracy and time it takes to run a fire control solution remains the same. If you get a direct hit the shell goes off. That's a really minor change.
Contact strategy eliminates the fuse setting issue. Re dispersion, that's arguably a strength if you're aiming several batteries at the center of box: dispersion ensures you get a somewhat random series of shells ~vertically through the bomber box. Re accuracy - you're aiming at a box so accuracy isn't all that important.

Basically the contact strategy eliminates the vertical timing component of the timed fuse. For a shell firing into 3,000ft-tall box, which has to explode within ~3m of its target to be fatal, you have a ~1/300 chance of getting just the vertical component exactly right. Add the premature-/non-detonation problem with timed fuzes and it's probably a bigger challenge. Eliminating that issue is a major change IMO.
T.A. Gardner wrote:I think a better way than an FAE would be go big on the missile thing. For example, a V-2 rocket would reach 25 to 30 thousand feet in about 8 to 10 seconds give or take. That's quick. You set these up, modifying them so they can be shot with reasonable accuracy into a bomber box, possibly with more of a slant range and slightly longer flight time, say 15 to 20 seconds. Add a command detonation fuzing system to them and you have a 2000 lbs. + warhead (given you need far less fuel) that detonates close to or within the box. With added fragmentation that takes down the whole box pretty much, and if it doesn't it would be a hell of disruption to surviving aircraft.
This is an interesting idea. So far it seems more realistic than your V1 idea because I'm not sure the V1 could operate at altitude - wing and thrust are probably too small given the thinner air.
Using something like the V2, you could use one ~$13,000 rocket (1945 V2 production price) instead of $100,000 of shells plus the cost of arty tubes etc.
One problem is the V2 can't wait around fueled-up: the fuel corrodes the rocket. Plus it's a deadly target if hit by a marauding Mossie.
Was it primarily the less-corrosive fuel issue that delayed the Wasserfalle?
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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by TheMarcksPlan » 20 Aug 2019 21:13

T.A. Gardner wrote:The best choice, and the postwar one, was simply a guided weapon from launch to intercept. Thus, the SAM.
One thing to consider about post-war SAM vs. Flak, however, is the scale of resources deployed. Flak is only going to work if deployed at something like the ridiculous levels of WW2 Germany, where there were hundreds of thousands of Flak crewpeople, and where Germany was devoting ~15% of its total military budget to Flak. It's far cheaper to use SAM's once the tech is available but it isn't totally clear to me that you couldn't devastate a relatively-slow bomber stream with thousands of Flak guns if using the right strategy. The problem for the theoretical discussion, IMO, is that we have a sample size of 1: WW2 Germany is the only case of Flak deployed on this scale. Given that small sample size, IMO it's reasonable to ask whether something just went wrong with Germany's Flak arm.
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Re: 1944: Flak Alone Blasts the Allies out of the Sky

Post by thaddeus_c » 21 Aug 2019 00:53

T. A. Gardner wrote:
20 Aug 2019 19:19
I think a better way than an FAE would be go big on the missile thing. For example, a V-2 rocket would reach 25 to 30 thousand feet in about 8 to 10 seconds give or take.

The sub-caliber rounds is trying to reduce another part of the flak sequence to increase accuracy. The British did this postwar with their Green Mace monstrosity. Higher velocity sub-caliber rounds mean less flight time, meaning greater accuracy in prediction.
Lars wrote:
20 Aug 2019 19:26
I belive the tracer shells was a psychological weapon and not really designed to bring down planes. If we are talking about alternate weapons I believe that the most promising would be derived from the fact that you only need a 50 mm grenade to hit the plane anywhere and it goes down.
my reference was to the speculative subcaliber munition mentioned in this thread, the tracer was to serve as the fuse(?) and the psychological effect was only a bonus.

the fuel air weapon was a reverse FAE "there's a German concept which turns this idea on its head: rather than having a warhead made of fuel which requires oxidiser, the warhead is the oxidiser and the target itself provides the fuel." https://www.wired.com/2007/09/reverse-fuel-1/

cannot say how viable, but a weapon that could ignite the aircraft fuels and not require ever increasing caliber?

not sure about the V-2 in the role outlined? have always thought the Enzian (resembles an ME-163 in miniature) was the sleeper project, as it could be fired from flak gun frame or air-to-air. (had a 1,000 lb. shell)

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