Germans had not abandoned Cavity Magnetron

  • Thread starter Deleted member 1487
  • Start date

Deleted member 1487

https://en.wikipedia.org/wiki/Cavity_magnetron#History
Despite patenting the device in 1935, the German authorities opted against developing Hans Hollman's version of the Cavity Magnetron; though it lacked the sophistication of the later British 1940 version, with further funding it could have reached it within a couple/few years. This prevented the Germans from developing the much more powerful Gigahertz band radar later in the war, despite their honing of the tube based radars to a fine art. This meant their ground based gun laying was more vulnerable to jamming and were less effective at targeting; it also meant that the aircraft mounted radar was much heavier and shorter ranged, which reduced performance due the large weight and drag of the antennae of the sets; when the Germans IOTL captured British airborne radar sets they produced the superb Berlin radar set, though far too late to matter.
https://en.wikipedia.org/wiki/Berlin_(Radar)

So what if the Germans had ran with Hollman's invention and had a working multi-cavity magnetron operational in 1938? I figure three years is enough time to improve the device and get it operation with some radar set. By 1940 the radar sets would be very powerful and exact, much more accurate and longer ranged than even the Wurzburg sets that were the world gold standard of accuracy at the time. That means German FLAK would be more effective than even IOTL, as magnetron gun laying radar enabled the British to pretty much shutdown German night attacks on Britain beyond mid-1943 and were instrumental at neutralizing the V-1 missile threat. By 1941-42 there would be a FuG 240 airborne radar set that would keep the Bf110 a serious threat to bombers into 1944. It would also enable the Germans to potentially tackle the Mosquito bomber, as they wouldn't have the draggy antennae holding them back. Also German radar would be pretty immune to 'Window' the Allied radar jamming chaff (British magnetron based sets were immune to it), which would prevent the shutting down of German night defenses in mid-1943 than enabled Operation Gemorrah and the Hamburg Firestorm. We could also potentially see a German version of H2S for night bombing, which would impact British jamming attempts at shutting down German night bombing raids in 1941. It would also enable an early airborne early warning system to get even earlier warning of incoming raids (the Germans were working on it IOTL, but they developed magnetronic radar too late to get it into service in time).

How would this impact the air war over Europe? It seems to me that had the early version of the magnetron been developed the Germans could have had some very powerful radar even earlier than the Allies IOTL, which would have conceivably made the British night bombing attempts very difficult in 1942-44 and made German air defenses much more dangerous and accurate, seriously reducing the number of shells be shoot down of bombers, even during the day. This may well have altered the Allied ability to hit German industrial targets throughout the war.
 
German air defenses are more effective for a while. The Allies have to work harder at counter measures as their aircraft losses increase by 5% - 10%.
 

Deleted member 1487

German air defenses are more effective for a while. The Allies have to work harder at counter measures as their aircraft losses increase by 5% - 10%.

What sort of countermeasures for centimetric radar were there?
 
German radar was more advanced than the British in 1940, declining to equality in about 1942 and the being well and truly outclassed. The Germans didn't win the war when they had the radar edge.

I suppose with the cavity magnetron they have a bit more of an edge than IOTL in the early years and equality is reached a bit later. This puts the CM into the class of the Me262, sweet but not enough to seriously effect the outcome.

A more effective change would be a better plotting system for the radars they did have, and better organised air defence system, but organisational changes like that don't make for interesting reading.
 

Deleted member 1487

German radar was more advanced than the British in 1940, declining to equality in about 1942 and the being well and truly outclassed. The Germans didn't win the war when they had the radar edge.

I suppose with the cavity magnetron they have a bit more of an edge than IOTL in the early years and equality is reached a bit later. This puts the CM into the class of the Me262, sweet but not enough to seriously effect the outcome.

A more effective change would be a better plotting system for the radars they did have, and better organised air defence system, but organisational changes like that don't make for interesting reading.

I get the point you're making and agree about the organizational changes, but I think you're really underselling the benefits of the CM radar, especially to airborne sets. Yes, the Germans sets were superior, though shorter ranged than the British ones in 1940, but by 1942 they were well outclassed. I don't think parity would be reached by the Allies by the end of the war, due to the Germans being more advanced here in CM research, getting it earlier thanks to Hollman. Not only that, but they pioneered PPI, which when paired with CM would give them a major advantage. It would also allow for longer ranged and smaller sets, so they don't have to wait for the Mammut set to get a long range quality system (it was only introduced in 1944):
https://en.wikipedia.org/wiki/Mammut_radar

While there were certainly other issues with German air defenses, CM would fix a whole host of issues and open up major new areas where the Germans could excel given their OTL developments. Organizational changes may well follow due to having better gear; as it was IOTL part of the problem with things like Himmelbett was the lack of long ranged accurate equipment, which required a short ranged set of boxes with a complicated CiC system with gaps; having better gear with longer range and more accuracy means fewer sets are required and a better layout with better integration can be worked out.

https://en.wikipedia.org/wiki/Kammhuber_Line

Especially when coupled with a much more effective AI radar system that didn't require nearly as much ground control, a major advantage of the Berlin set, reduces a, if not THE, major issues with Kammhuber's defensive system. It also reduces the ability of the British bomber force to jam GCI, thanks to the aircraft being able to find its next target on its own. Also the lightweight, less drag AI radar would mean each night fighter can stay in the air longer due to less fuel used, plus be fasted and able to catch up and stay in the bomber stream, rather than having to get back into position for GCI to pick them up again and redirect them to the bomber stream. That was the major flaw with the German night defense system from its inception, which was related to the low powered, high weight/drag radar sets the Germans had. Its partly why the British GCI system was so good: its equipment did not require the same GCI, so they could better handle interceptions.
 
IIUC the Germans didn't take up the PPI until about 1943, using the Seeburg table in the Kammhuber line. This is despite having rotating Freya and Seetakt radars operating on much lower wavelengths than the British CH system, which should have spurred them into developing PPI at least as early as the British.

I just don't see centimetric radar making that much of a difference to the Germans in the early years when the window for great things was open. The British jump from 1.5 metres to 10 centimetres is a huge improvement, worthy of great efforts to develop. But the German jump from 53 cm to 10 doesn't strike me as nearly as significant and not worthy of great efforts when there are possibly other electronic goals to achieve.
 

Deleted member 1487

IIUC the Germans didn't take up the PPI until about 1943, using the Seeburg table in the Kammhuber line. This is despite having rotating Freya and Seetakt radars operating on much lower wavelengths than the British CH system, which should have spurred them into developing PPI at least as early as the British.
https://en.wikipedia.org/wiki/Plan_position_indicator
https://en.wikipedia.org/wiki/Jagdschloss_radar
The Germans had it in 1939 pre-war in a test set outside of Berlin. The Germans didn't really have a reason to invest heavily in it until 1942, as they were on the offensive/the British night bombing was a joke up then, but with the right technology impetus it could have an earlier use offensively and defensively. Holleman patented the concept in 1936 and being the inventor of the magnetron its not like he couldn't have used the two together in a production unit.

I just don't see centimetric radar making that much of a difference to the Germans in the early years when the window for great things was open. The British jump from 1.5 metres to 10 centimetres is a huge improvement, worthy of great efforts to develop. But the German jump from 53 cm to 10 doesn't strike me as nearly as significant and not worthy of great efforts when there are possibly other electronic goals to achieve.
The question is whether Hollman ends up grasping the offensive potentials for ground mapping and ASV. As far as gunlaying 53cm to 10cm (and later they had 1.5cm with the Berlin device, which would be available much earlier here, as once the Germans got their hands on the British magnetron they developed it within a couple of years) is huge. There was huge investments in radar gun laying both for artillery and AAA, so there is very much a use for it if they can get the high powered version of the magnetron working; IOTL they abandoned it, because they didn't see the path forward once the power issue was worked out, perhaps ITTL Hollman can convince them to give it time. 3cm and less, which the Germans IOTL did end up doing, would give them ridiculous accuracy, as at 3cm the US radar gun laying system was shooting down V-1s at 400 mph with a couple hundred AAA shells.
 
A more effective change would be a better plotting system for the radars they did have, and better organised air defence system, but organisational changes like that don't make for interesting reading.
And what would be the simplest and most internally-consistent way of getting the cavity magnetron adopted? IMO, having some bright spark set up a single reich air defence organisation to coordinate all the various technical research, production and organisation in a similar way to what the Brits did. The CM, plotting, organisation etc. would then flow from this as it did for the brits.

A couple of difficulties with this though. Such a coordinated effort would not be well aligned with the Nazi rats-in-a-sack way of doing business. Even if it was set up, they might end up with some well-connected numpty in charge who decides that putting nose radomes on night fighters would make them look too Jewish, or something equally stupid.
 

Deleted member 1487

Such a coordinated effort would not be well aligned with the Nazi rats-in-a-sack way of doing business.

This may be the single best description I've heard about the Nazi organizational scheme.
 
Is it possible that if the Germans had invested in Cavity Magnetrons that Britain would have managed to get hold of it earlier too?
 

Deleted member 1487

Is it possible that if the Germans had invested in Cavity Magnetrons that Britain would have managed to get hold of it earlier too?

Definitely possible, but they wouldn't have it prior to 1940 when the Germans might have used it over Britain; by then the British would have invented it themselves. I think really the first chance that it would have been captured from the Germans on the defensive if they hadn't made it an offensive weapon by 1940 is in 1942 with Operation Biting. Of course by then the British would have had it themselves and in service. If it were superior in design, then the Allies could have reverse engineered it into something better than what they had IOTL. I think though it wouldn't have offered much if anything better than what the Allies had IOTL; really its the Germans who IOTL were behind the 8-ball and who stood to benefit over OTL from having it.
 

Deleted member 1487

Based on some recent information I've come across about cavity magnetron technologies that were belatedly developed by Germany as a result of capturing British and US devices, I wanted to necro this thread because I know much more about the subject now and can actually include answers to my OP. Below I attached a page form a volume about German ground radar based on captured Allied Cavity Magnetron technology and was basically immune to the major effects of Window, which had often reduced the FLAK arm and night fighters to irrelevance from 1943 on. The Allies using such technology even without proximity fuses were able to reduce shell usage per aircraft shot down in bombing missions in Europe to about 300 shells, which is 1/10th the average German shells per bomber shoot down in their best year in 1942. Window and other countermeasures had increased German FLAK shell use per bomb to over 16,000 by 1944. The Egerland system reduced it to the Allied average of 300 shells per bomber. Without abandoning cavity magnetrons and centimetric radar by 1940 the Germans would have things like this given that their first patented cavity magnetron was in 1935. Investing in that technology more and doing a V-weapon style program (or US MIT Radiation Lab one) would have yielded radar immune to window and other ECM. They'd also have their own version of H2X and small airborne intercept radar, but earlier than the Allies even (again if they actually pursued their 1935 innovation; the Brits didn't invent one like it until 1940 and then had to ship it to the US in the Tizard mission to have Bell Labs and MIT develop it into useful technology):
https://en.wikipedia.org/wiki/FuG_240_Berlin
https://en.wikipedia.org/wiki/FuG_224_Berlin_A

These technologies would have been war changing due to the impact on the ability of the Allies to strategically bomb by day or night given the accuracy of the radar for FLAK guidance and for night fighter interception, as well as immunity to WW2 ECM.

ground-radar-systems-of-the-luftwaffe1939-1945-34-638.jpg
 
Is 1935 enough time to have 10cm surface gunnery sets fitted to German warships by 1939? If it was robust enough and not knocked out early on by British return fire at the River Plate would Graff Spee have put enough 11" shells into Exeter to sink her and hit Ajax more often? Might the Twins have sunk Renown off Norway in 1940 if they had been fitted with gunnery radar of that quality and/or sunk the Glorious, Acasta and Ardent fast enough to prevent Scharnhorst being torpedoed?
 

Deleted member 1487

Is 1935 enough time to have 10cm surface gunnery sets fitted to German warships by 1939? If it was robust enough and not knocked out early on by British return fire at the River Plate would Graff Spee have put enough 11" shells into Exeter to sink her and hit Ajax more often? Might the Twins have sunk Renown off Norway in 1940 if they had been fitted with gunnery radar of that quality and/or sunk the Glorious, Acasta and Ardent fast enough to prevent Scharnhorst being torpedoed?
Its difficult to say for sure given that the 1935 version of the cavity magnetron was not fully strapped, which allowed for the resonance necessary to make it really useful. Had enough resources been devoted then yes, as the 1940 British version took about 2 years to turn into all sorts of field service advanced 10cm radars.
Much about the naval fire-fight had to do with more than just the gunnery radar, though perhaps a longer range, higher resolution radar would have given them the necessary edge, I don't know enough about the radar influence on those battles and if that could have been improved on. As it was the large targets were such that even lower resolution Seetakt radar was enough to spot them accurately.
 
wonder the effect on aircraft and naval development?

for instance radar-equipped auxiliary cruisers (and tankers) could eclipse (more) Panzerschiffe. in home waters they might rely on citadel fleet of smaller ships and shore based guns? (and minefields)

once Germany developed own radar systems would imagine radar seeking glide bombs would be priority? to degrade enemy radar? https://en.wikipedia.org/wiki/Blohm_&_Voss_BV_246
 

Deleted member 1487

wonder the effect on aircraft and naval development?

for instance radar-equipped auxiliary cruisers (and tankers) could eclipse (more) Panzerschiffe. in home waters they might rely on citadel fleet of smaller ships and shore based guns? (and minefields)

once Germany developed own radar systems would imagine radar seeking glide bombs would be priority? to degrade enemy radar? https://en.wikipedia.org/wiki/Blohm_&_Voss_BV_246
A surface fleet for Germany is a dead end. They'd have better gunnery and smaller antennae, but investing the required raw materials is a waste to them. As to the BV246 it wasn't a radar bomb, it used a passive homer that homed in on ground radar signals. With better radar it would have the biggest impact on night fighters (as they wouldn't need that huge antennae plus with the higher power and better resolution they'd be able to see through 'Window' and have better gunnery radar, plus a FAR more flexible air defense system than Himmelbett, which the Brits were able to overwhelm with the Bomber Stream. In fact with better gunnery radar and night fighters the Bomber Stream may well present them with the ideal target.
 
for instance radar-equipped auxiliary cruisers (and tankers) could eclipse (more) Panzerschiffe. in home waters they might rely on citadel fleet of smaller ships and shore based guns? (and minefields)

A surface fleet for Germany is a dead end. They'd have better gunnery and smaller antennae, but investing the required raw materials is a waste to them... With better radar it would have the biggest impact on night fighters...

maybe my post was not clear, meant (nearly) all the KM buildup scrapped in favor of radar equipped raiders (which were after all converted merchant ships) and small coastal ships (many coal-powered, many converted fishing vessels.)

only building program would be mooted (IOTL) class of minelayers and some updating of existing RM fleet. saving all the BBs and oversized destroyers.

this is to facilitate u-boat centered navy, biggest beneficiary of more advanced radar in terms of effectiveness? (in the navy)

some of that might be seen in 1930's? they would have hindsight of WWI AND there are immediate savings from adopting such a program.

as opposed to "we want to develop radar to protect us from Allies bombing our cities" (which WOULD be a major resulting benefit but maybe a difficult concept to advance pre-war?)
 

Deleted member 1487

As I said, surface ships were a dead end in WW2 due to Allied ASV radar and naval superiority (plus of course air superiority as a function of raw numbers). They'd be better off with more Elektroboote and electronic warning systems for aircraft ASV. Sonar and the like would probably be more helpful for Uboats in terms of searching out targets once being on the surface of water become too dangerous. Radar was developed by the Germans pre-war precisely to protect surface ships from aerial bombing and spotting enemy ships AND protecting cities:
https://en.wikipedia.org/wiki/Radar_in_World_War_II#Germany
 
Is 1935 early enough to have radar proximity fuses in service for 1940? AFAIK the Luftwaffe's flak arm was so large even then that it might be possible to get the cost reductions that the Americans achieved later in the war.
 
I wasn't thinking in terms of the Germans having more surface warships, but it might give the ones they had an advantage over the Royal Navy before they caught up. For example in night actions such as the destroyer attack on the Bismarck, Hipper's encounter with a British troop convoy and some of the Russian Convoy battles.

Would better AA gunnery radar either with or without proximity fuses have helped the Bismarck when she was attacked by torpedo bombers from Victorious and Ark Royal? IIRC a combination of the Mk 37 director and VT fuses helped the South Dakota shoot down 20 Japanese aircraft at the Battle of Santa Cruz.
 
Top