Japan shares it's cavity magnetron with German in 1940?

[kfbr392]

What if Commander Ito, rather than keeping mum about the development of a cavity magnetron, instead shared it with the Germans in an Axis Tizard mission?

Best case for Germany:
a 24 month improvements over the OTL dates for development and introduction of the "Berlin-Geräte".
Meaning Germany would "only" lag the British by ~12 months instead of the OTL ~36 months.


But the mindset in Germany in 1940-42 was against the urgent development centimeter wave devices that happened in OTL in 1943-45 for the following reasons:
- a belief that such devices would have inferior range to the existing 50cm/80cm/240cm devices (when a 9cm Berlin emitter was placed in a 3m Würzburg dish in December 1943 a detection range of 8km was expected; 30km range was achieved, same as regular Würzburg - to the shock of German engineers).
- there was a decree in 1940 that no research should be undertaken that could not conclude within 6 months (in order to concentrate resources on Barbarossa I presume; churning out large numbers of radios for Barbarossa was more important then burdening Telefunken and GEMA with magnetron research)
- lack of personal for reserarch, development, and production
- lack of enthusiasm for PPI development
- general complacency and technical ignorance at high levels
- a belief that the war was won anyhow, or would be won in the East where no new radar would be necessary

[kfbr392]

What would the impact have been if Germany had had the "9cm Berlin" devices 24 months earlier than OTL:

U-Boat war:
Assuming the FuMB passive detectors would also have been introduced 24m ahead of OTL, Germany would have had the FuMB Tunis in June 1942 (OTL: June 1944) and the water proof FuMB Athos from early 1943 (OTL: early 1945). This would have saved hundreds of boats from surprise air attack. But these FuMB or even 9cm radars like FuMO 84 would not have enabled the legacy type VII and IX boats to operate on the surface as they did in 1940, reliably penetrate convoy defenses, or prevent their detection and destruction.
U-Boats still lose.

Air war:
If German night fighters had received the FuG 240 radar sets from March 1943 (OTL: March 1945), then Windows could not have blinded German defenses as it did in OTL from July 1943, and losses of Lancasters and Halifaxes from mid-1943 onwards could well have been so high that some targets deep inside Germany would have escaped destruction - at least at night.
The Mosquito could still have operated with relative impunity.
The USAAF could still have attacked during that day as it did in OTL.
Flak directed by 9cm devices like FuMG Egerland would have been more effective both day and night, but I am doubtful if this would have been enough to be a game changer against high flying Mosquitoes or B-17s.
Germany still gets smashed from the air, but with less urban destruction.

[stg 44]

What if Commander Ito, rather than keeping mum about the development of a cavity magnetron, instead shared it with the Germans in an Axis Tizard mission?

Best case for Germany:
a 24 month improvements over the OTL dates for development and introduction of the "Berlin-Geräte".
Meaning Germany would "only" lag the British by ~12 months instead of the OTL ~36 months.

That's pretty huge.

But the mindset in Germany in 1940-42 was against the urgent development centimeter wave devices that happened in OTL in 1943-45 for the following reasons:
- a belief that such devices would have inferior range to the existing 50cm/80cm/240cm devices (when a 9cm Berlin emitter was placed in a 3m Würzburg dish in December 1943 a detection range of 8km was expected; 30km range was achieved, same as regular Würzburg - to the shock of German engineers).

That would be a good reason why it wasn't pursued until too late, but relatively easily moved up with this POD.

- there was a decree in 1940 that no research should be undertaken that could not conclude within 6 months (in order to concentrate resources on Barbarossa I presume; churning out large numbers of radios for Barbarossa was more important then burdening Telefunken and GEMA with magnetron research)

That was repealed in about 6 months so that by early 1941 things were 'back to normal'.
Radar research wasn't really impacted AFAIK though. Air defense was never skimped on and in fact ate up a ton of resources that were then denied to the Eastern Front. Not only that, but a bunch of captured Soviet AAA was then used in Germany throughout 1941 and beyond as far as they could given the ammo situation.

- lack of personal for reserarch, development, and production

Given the huge resources put into radar IOTL and since Germany actually developed it before anyone else that wasn't really a problem, it was more an issue of mismanagement of resources and allowing personnel to be drafted.

- lack of enthusiasm for PPI development

Any evidence on that? Germany fielded the first PPI system of the war:
https://en.wikipedia.org/wiki/Jagdschloss_radar

- general complacency and technical ignorance at high levels

There was quite a bit of that.

- a belief that the war was won anyhow, or would be won in the East where no new radar would be necessary

That was only sort of true in mid-1941, but definitely not once the US entered the war. Radar though was developed without pause throughout this period.

[T. A. Gardner]

Do you have a source to support that? AFAIK the British developed microwave radar first, other countries only built microwave radar after being gifted, or capturing, British magnetrons.

The History of Japanese Radar Development to 1945 by Dr. S. Nakajima, in Radar Development to 1945 Russell Burns, ed.

Lots of people produced magnetrons before Randall and Boot. They struggled for years to increase the power by tens of watts. Randall and Boot turned their prototype over to GEC who engineered production models with outputs of 10kw or more within weeks.

The Japanese M3 magnetron tube produced a 10 cm signal at 500W in 1939 and was water cooled. They had working lower power variants all the way back to 1937.

No, GEC turned it into a service model in 1940. It entered large scale production in the UK in 1941.

The Japanese problem was their entire radar program was miniscule. They had about 400 - 500 people employed in this industry split about equally between the Navy and Army with next to zero cooperation between the two programs. The IJA had far less interest in a radar set than the IJN did, only compounding this.
The IJN's first 10 cm radar set was a prototype completed using an M312 magnetron (a derivative of the M3) completed in October 1941. The set worked but because of the way it was designed using a super-regeneration receiver, it required a skilled operator and constant supervision to keep it tuned. Because of the small size of the IJN program a suitable design for mass production and use by less skilled personnel took until September 1944 when the set finally entered production.

So, the Japanese were ahead of the British inventing microwave radar and working cavity magnetrons, but couldn't turn that invention into an operational radar nearly as quickly due to the limitations brought on by the small size of their radar program.

[kfbr392]

That's pretty huge.

Given POD stipulated in the OP, 24 months ahead of OTL IMHO is, again, a best case (for Germany) scenario.
(ATL calculation is -30 months for the head-start, -3 months for lack of OTL 1943-45 bombing of German facilities, +9 months for lack of urgency and lower general HF understanding and research level earlier in war -> -24 months compared to OTL)
It would not have changed the outcome of the war. Too little, too late.

Any evidence on that? Germany fielded the first PPI system of the war:
https://en.wikipedia.org/wiki/Jagdschloss_radar

Sure, but these PPIs were few and far between. It was not until the final months of the war that PPIs became something like a standard feature in German sets (9cm devices, Fumo 65 Hohentwiel for U-Boats, etc), no doubt spurred on by finding them all over Germany in wrecks of shot down Allied bombers since 1943.

[stg 44]

That's pretty huge.

Given POD stipulated in the OP, 24 months ahead of OTL IMHO is, again, a best case (for Germany) scenario.
(ATL calculation is -30 months for the head-start, -3 months for lack of OTL 1943-45 bombing of German facilities, +9 months for lack of urgency and lower general HF understanding and research level earlier in war -> -24 months compared to OTL)
It would not have changed the outcome of the war. Too little, too late.

Ugh. First of all no one is claiming that it would change the outcome of the war, so please stop with that tired trope.
And why are you assuming this would at 9 months to research because looking over the Allied program lack of HF understanding didn't really delay research.

In terms of changing the course of the war having cavity magnetron based radar in 1942-43 would dramatically increase the effectiveness of air defense, especially when Window shows up in 1943. As it was the Egerland system was a massive step up over Wurzburg in terms of accuracy and performance and immune to the most common Allied ECM, which by 1944 had increased the number of FLAK shells per shoot down of a bomber from a yearly best average of 2,000 in 1942 to 16,000.

Any evidence on that? Germany fielded the first PPI system of the war:
https://en.wikipedia.org/wiki/Jagdschloss_radar

Sure, but these PPIs were few and far between. It was not until the final months of the war that PPIs became something like a standard feature in German sets (9cm devices, Fumo 65 Hohentwiel for U-Boats, etc), no doubt spurred on by finding them all over Germany in wrecks of shot down Allied bombers since 1943.

And? It existed in some form pre-war and you claimed it did not ever exist during the war on the German side.
Do you have a sources that the Allied developments spurred German PPI use?

[kfbr392]

Woa, dear stg 44, I responded to your OP, which I recommend others to do as well, why the hostility?
It is a good thread.
And I did not deny PPI development in Germany, I merely stated German PPIs were rare.

[T. A. Gardner]

All advanced electronics were in short supply or just a handful of prototypes in Germany by about the end of 1942. This was because the German electronics industry simply didn't have the capacity to produce more. The conflicting demands of the different services and overall demand meant that their electronics manufacturers couldn't come close to meeting demand. Current production took precedence over R & D. Companies like Dutch Philips were critical to German production, and these foreign companies couldn't be trusted with R & D most of the time having neither the engineers (many of whom fled ahead of the German invasion of their country) or drive to design something better.

[TheMarcksPlan]

- there was a decree in 1940 that no research should be undertaken that could not conclude within 6 months (in order to concentrate resources on Barbarossa I presume; churning out large numbers of radios for Barbarossa was more important then burdening Telefunken and GEMA with magnetron research)

Do you have more info on this decree or, better yet, the actual document?

[TheMarcksPlan]

Air war:
If German night fighters had received the FuG 240 radar sets from March 1943 (OTL: March 1945), then Windows could not have blinded German defenses as it did in OTL from July 1943, and losses of Lancasters and Halifaxes from mid-1943 onwards could well have been so high that some targets deep inside Germany would have escaped destruction - at least at night.
The Mosquito could still have operated with relative impunity.
The USAAF could still have attacked during that day as it did in OTL.
Flak directed by 9cm devices like FuMG Egerland would have been more effective both day and night, but I am doubtful if this would have been enough to be a game changer against high flying Mosquitoes or B-17s.
Germany still gets smashed from the air, but with less urban destruction.

IMO it's really important to quantify the likely effect on shoot-downs/shell to judge outcomes. As you say upthread, German Flak efficiency varied by a factor up to 8 during different periods of the war. If the Flak is suddenly 4-8x more effective that's a potential game-changer. Westermann's Flak notes that a late-war radar set decreased shells/kill to 300 IIRC. That system included a more advanced gun-laying computer but if the Germans have better radar resolution on aerial targets perhaps they develop better gun-laying directors earlier and build more of them.

We also have to consider adaptation in response to more-effective Flak. In economic speak, when an input (Flak) becomes more efficient at creating output (downed bombers), the rational response is to invest more in it. Radically more effective Flak would have drawn more investment (steel allocations at the expense of, say, concrete bunkers for factories) and therefore would have meant greater quantity of Flak barrels in addition to greater effective quality. At a certain point, the LW/Speer could make strategic decisions to make certain targets effective "dead zones" for bomber streams - points over which 20% losses would be expected. Production could then be concentrated under those Flak umbrellas rather than dispersed with attendant efficiency cost. If Germany "dead zoned" the Ruhr and Hamburg, for instance, that would have big knock-on effects in terms of transport capacity saved, damage avoided, agglomeration economies, etc.

Even if it doesn't stop the CBO, it would reduce the amount of bombs dropped - and therefore damage - massively: a plane that has been destroyed in March obviously can't bomb in April.

I agree there's no way this wins the war for Germany, but something like, say, a 30% increase in German output in 1943 due to less bomb damage could impact the course of the war.

[stg 44]

Woa, dear stg 44, I responded to your OP, which I recommend others to do as well, why the hostility?
It is a good thread.
And I did not deny PPI development in Germany, I merely stated German PPIs were rare.

People use that argument all the time to dismiss an entire discussion. So you'll have to understand if I don't put up with it anymore.
The rest was just responding to your points. As to PPI you did say there wasn't enthusiasm for the development of PPI, which isn't really accurate. It was just a relatively complex system for a ground unit and there was other demands for resources until 1942 that blocked wider introduction of the Jagdschloss system, especially the massive expansion of Wurzburg gunnery radars. Plus there were some issues with the unit, so they further delayed wider introduction of the system until they could fix the antenna.

[stg 44]

IMO it's really important to quantify the likely effect on shoot-downs/shell to judge outcomes. As you say upthread, German Flak efficiency varied by a factor up to 8 during different periods of the war. If the Flak is suddenly 4-8x more effective that's a potential game-changer. Westermann's Flak notes that a late-war radar set decreased shells/kill to 300 IIRC. That system included a more advanced gun-laying computer but if the Germans have better radar resolution on aerial targets perhaps they develop better gun-laying directors earlier and build more of them.

I'm not sure it was quite that good, but it was a major improvement. The 300 number was IIRC for the US centimetric gunnery radar, integrated gunnery computer, and the use of VT fuses. Still German centimetric gunnery radar got it down below the 1942 best IIRC, which is a huge improvement over OTL rates.

We also have to consider adaptation in response to more-effective Flak. In economic speak, when an input (Flak) becomes more efficient at creating output (downed bombers), the rational response is to invest more in it. Radically more effective Flak would have drawn more investment (steel allocations at the expense of, say, concrete bunkers for factories) and therefore would have meant greater quantity of Flak barrels in addition to greater effective quality. At a certain point, the LW/Speer could make strategic decisions to make certain targets effective "dead zones" for bomber streams - points over which 20% losses would be expected. Production could then be concentrated under those Flak umbrellas rather than dispersed with attendant efficiency cost. If Germany "dead zoned" the Ruhr and Hamburg, for instance, that would have big knock-on effects in terms of transport capacity saved, damage avoided, agglomeration economies, etc.

Germany did that by 1944 anyway considering the fighter arm had died in early 1944. Likely though the Allies would just fly higher over the 88's effective range and drop bombs more inaccurately over the concentrated industrial zones. Or they'd focus on using fighter bombers and go after trains and waterways, which was the bombing strategy from late 1944 on which did collapse Germany's economy and there was no good answer for.

Even if it doesn't stop the CBO, it would reduce the amount of bombs dropped - and therefore damage - massively: a plane that has been destroyed in March obviously can't bomb in April.

I agree there's no way this wins the war for Germany, but something like, say, a 30% increase in German output in 1943 due to less bomb damage could impact the course of the war.

I'd think the impact would mostly happen from 1943 on depending on when mass introduction of the system happens. It might save the German synthetic oil industry until the Wallies figure out they needed to just go after the trains between the defended zones.

[TheMarcksPlan]

Germany did that by 1944 anyway considering the fighter arm had died in early 1944. Likely though the Allies would just fly higher over the 88's effective range and drop bombs more inaccurately over the concentrated industrial zones. Or they'd focus on using fighter bombers and go after trains and waterways, which was the bombing strategy from late 1944 on which did collapse Germany's economy and there was no good answer for.

True re railways but OTOH B-17's killed most of the German fighters IIRC and if the Flak is killing the B-17's then there's more German fighters to protect interstitial spaces. Again it's only a matter of time before Wallies establish air superiority but its onset could be significantly delayed.

[TheMarcksPlan]

Still German centimetric gunnery radar got it down below the 1942 best IIRC, which is a huge improvement over OTL rates.

What are the best sources on the development of German gunnery directors?

[stg 44]

Still German centimetric gunnery radar got it down below the 1942 best IIRC, which is a huge improvement over OTL rates.

What are the best sources on the development of German gunnery directors?

I don't think there is any good ones in English and I'm not all that familiar with German sources on the subject.

Germany did that by 1944 anyway considering the fighter arm had died in early 1944. Likely though the Allies would just fly higher over the 88's effective range and drop bombs more inaccurately over the concentrated industrial zones. Or they'd focus on using fighter bombers and go after trains and waterways, which was the bombing strategy from late 1944 on which did collapse Germany's economy and there was no good answer for.

True re railways but OTOH B-17's killed most of the German fighters IIRC and if the Flak is killing the B-17's then there's more German fighters to protect interstitial spaces. Again it's only a matter of time before Wallies establish air superiority but its onset could be significantly delayed.

I've never heard that the B17 killed more fighters. They certainly way overclaimed fighters, but none of that was substantiated post-war cross checking Luftwaffe surviving records.