You are Josef Kammuber in 1941, how do you structure German night defenses?

[stona]

And the economics are even better for light flak, a mere $15,000 of our 'corrected' dollars per aircraft shot down (not damaged).
A typical US medium bomber, arguably a more likely victim of light flak than 8th AF heavies flying at 27,000 feet, cost $153,000 (B-25) and $240,000 (B-26). That is a fantastic return on investment.
It doesn't matter which type of flak damaged the aircraft, and for the 8th AF bombers most was heavy anyway, damaging more than 20% of total aircraft sorties is a significant achievement. We haven't even touched on the physical damage done to killed and wounded airmen in damaged aircraft, let alone the psychological toll flak took on aircrew, particularly Americans operating in daylight.

There are many reasons that allied losses fell towards the end of the war that have nothing to do with less efficient flak, not least the redeployment of flak, particularly heavy batteries, in other roles.

Cheers

Steve

 

[tomo pauk]

And the economics are even better for light flak, a mere $15,000 of our 'corrected' dollars per aircraft shot down (not damaged).
A typical US medium bomber, arguably a more likely victim of light flak than 8th AF heavies flying at 27,000 feet, cost $153,000 (B-25) and $240,000 (B-26). That is a fantastic return on investment.

Nobody said anything against the light Flak
We can just think of what kind of damage the Allied AFs would've sustained had Germans introduced the 30 mm MK 101/103 in the Flak arm, and/or introduced the 40 mm Bofors.

It doesn't matter which type of flak damaged the aircraft, and for the 8th AF bombers most was heavy anyway, damaging more than 20% of total aircraft sorties is a significant achievement. We haven't even touched on the physical damage done to killed and wounded airmen in damaged aircraft, let alone the psychological toll flak took on aircrew, particularly Americans operating in daylight.

For every aircrew member the Flak killed or wounded (both physically and psichologically) there was 10 Germans (both civilian and military) that suffered the same fate? RAF was even harsher against Germans, 1:100? Just the attack on Hamburg (Op. Gommora) killed 42000, mostly civilians. Of course, the NF force was also bounced from the game here.
I'd really like to see the arythmetics of heavy Flak vs. heavy bomber, that would also include the thousands of fire shells.

There are many reasons that allied losses fell towards the end of the war that have nothing to do with less efficient flak, not least the redeployment of flak, particularly heavy batteries, in other roles.

Cheers

Steve

The LW fighter arm was virtually wiped out by the end of the war, this is why Allied aircraft losses were low in single digits per sortie.

 

[mhuxt]

meh

 

[tomo pauk]

Seems like your files are not present, Mark?

 

[mhuxt]

View attachment D-0031.pdfView attachment D-0011.pdf

I thought these were working - couple of debriefs from Axthelm, one has some info on the double-fuse.

When I click on the pdf links, my system asks me if I want to download, when I choose download they both open correctly on my machine...

 

[wiking85]

These seem to be working - couple of debriefs from Axthelm, one has some info on the double-fuse.

I downloaded these, but they were both broken.

 

[mhuxt]

Give them a try now please, have re-uploaded, they work for me.

 

[wiking85]

Hmmm still says damaged file for me once I try to open it.

 

[mhuxt]

Hmmm still says damaged file for me once I try to open it.

Damnit - will try to upload both as a single zip. Works once for me, then Access Denied.

 

[mhuxt]

Hmmm, zipped it.

 

[wiking85]

Hmmm, zipped it.

Thanks for the effort, but the file is corrupted or something, it downloads just fine, but the pdfs just aren't working.

 

[tomo pauk]

Hmm - the PDFs are working fine here.

Re. A gun more powerful than 3,7 cm Flak: Kriegsmarine was using the 3,7 cm/83 SK C/30, the semi-auto (!) Flak that fired a powerful round - the propellant charge was twice as powerful as with usual German 3,7 cm, while the shell was also some 20% heavier. All of this, coupled with a really long barrel, warranted superb ballistics. So one of suggestions might be to adopt the full-auto version of the KM's gun, semi-auto light Flak was soon discovered as a bad thing by the KM itself.

 

[tomo pauk]

Some interesting e-books, more ot less pertaining to the subject, can be downloaded from here:

Air Force Historical Research Agency - Numbered USAF Historical Studies 151-200

Other 3 pages of the site also offer interesting stuff for download.

 

[Koopernic]

The thing to note about supposed FLAK ineffectiveness between January and April 1941 is the following:

1 The Luftwaffe did not have an effective blind fire radar till June 1941 when Wurzburg-D and Wurzburg-Riesse started being delivered. These featured conical scan and the ability to transfer data to the FLAK predictor. Prior to that there was only searchlights with radar cuing the lights. Best accuracy was 0.3 degrees and 25m for Wurzburg-D
2 The 8.8cm (3.5 inch) FLAK 37 has a shell only 34% the size of a 5 inch round. If the US navy reckoned it required 2000-2500 round of 5 inch DP (without proximity fuse) in daylight one would expect that al least 6000-7500 of the smaller shells, more if the fact that the space taken up by the fuse displaces a fair amount of the bursting charge.
Also note there was still much of the older FLAK 36 and even FLAK 18 around with inferior predictors that used spherical rather than Cartesian coordinates.

The bulk of German FLAK was the 8.8cm FLAK 37, about 80%. It lacked the power to deal with aircraft above 20,000ft. Its beauty lay in its economy, transportability, ease of use and manufacture.

Other guns include
10.5cm FLAK 38 and
12.7cm FLAK 39/40
Both these guns had auto loaders and fuse setting machines set into the auto loader. They tended to be too large to transport with advancing troops so most stayed within Germany. Some even had power drive so in theory could have been aimed direct from the predictors.

Of further interest is the 8.8cm FLAK 41 which was vastly more powerful than the 8.8cm FLAK 37 and could deal with any high altitude US bomber or Mosquito. It feature the auto loader, fuse setting machine and a lower profile to assist in duel purpose use. This gun ran into trouble when a change from brass to steel cartridges caused jamming as the barrel sleave was near the cartridge and so the sleave had to be re designed. It had a prodigious firing rate of nearly 30 RPM but had barrel vibration problems at those high rates of fire, these were solved by firing on the recoil so although the gun was in use by 1943 it had to be withdrawn to Germany and used with brass cases till the problems were solved.

Wruzburg rasdar were jammed by windows from Mid 1943 onwards. A recovery was made by using a Doppler device called Wurzlaus so that during the battle of Berlin the anti windows effort helped produce the following result.

"It is generally accepted that the Battle of Berlin was a failure for the Royal Air Force (RAF) as it was not the knockout blow that Harris had predicted. The RAF lost 1,047 bombers, with a further 1,682 damaged, and well over 7,000 aircrew, culminating in the raid on Nuremberg on 30 March 1944, when 94 bombers were shot down and 71 were damaged, out of 795 aircraft."

Carpet board band noise jamming wiped out Wurzburg for much of the end of the war although anti jamming circuits esp on the Wurzburg Riesse was sometimes successful. The solution was the new microwave radars such as Egerland Kulmbach but there was also a program to vastly increase the output power of the basic Wurzburg radars 20 fold to 160kW. Again testing had been complete but production proved impossible.

Hence timing couldn't have been worse as the period of the technical inferiority was also the period in which bombing caused the most damage and prevented recovery.

Mention should be made of German efforts at proximity fuses for FLAK shells.

There were two effforts, one using eloectrostic efforts was ready for production in 1944 (1943 if the reports are read) and another using radar which required shock hardened thermionic vacuum tubes was supposedly to enter production in 1945 (According to Goering's interrogation by Spaatz there would have been production in 5 months).

Any body making its way through the air produces a large electrostatic field especially if at high speed. Should another object come nearby the gradient of this field changes and this can be used to detect proximity of an aircraft. The Germans had used electrical fuzes in their bombs as both long terms and short arms delays as arming as arming. The secret was a device called a cold cathode tube. This didn't require a heated element and function as a sensitive switch. The discovery of these devices in German bombs caused the British to reactivate their own proximity fuze program which was handed over to the Americans because the man in charge, Cockcroft, had to develop the atomic bomb.

These electrostatic fuzes when fired in a test range gradually grew from 1, 2, 5 meter sensitivity to a target (in practice on firing range) and finally 10m and 15m was thought possible.

In my view production should have started at 2m. This is because the Germans had proven by the end of the war that fuze setting wasn't worth it. By firing a contact fuzed shell the time wasted in setting fuzes could be ignored, expensive clock work mechanism avoided and cheaper explosives used.

The thing to note about these electrostatic fuzes is that they were extremely cheap, little more expensive than a nose contact fuze, so with a 2-5m range they would have worked cost effectively since it was found that to bring down a bomber required detonation within 4 meters anyway.

Interestingly there are claims of so called double fuzes achieving extremely high efficiencies in bringing down bombers. What is odd is that fuzes already consisted of timer, nose contact and self destruct so what could a 'double fuze' really be? Perhaps it was code for the electrostatic fuze?

I will add links and pictures tomorrow.

 

[wiking85]

The thing to note about supposed FLAK ineffectiveness between January and April 1941 is the following:

1 The Luftwaffe did not have an effective blind fire radar till June 1941 when Wurzburg-D and Wurzburg-Riesse started being delivered. These featured conical scan and the ability to transfer data to the FLAK predictor. Prior to that there was only searchlights. Best accuracy was 0.3 degrees and 25m for Wurzburg-D
2 The 8.8cm (3.5 inch) FLAK 37 has a shell only 34% the size of a 5 inch round. If the US navy reckoned it required 2000-2500 round of 5 inch DP (without proximity fuse) in daylight one would expect that al least 6000-7500 of the smaller shells, more if the fact that the space taken up by the fuse displaces a fair amount of the bursting charge.
Also note there was still much of the older FLAK 36 and even FLAK 18 around with inferior predictors that used spherical rather than Cartesian coordinates.

The bulk of German FLAK was the 8.8cm FLAK 37, about 80%. It lacked the power to deal with aircraft above 20,000ft. Its beauty lay in its economy, transportability, ease of use and manufacture.

Other guns include
10.5cm FLAK 41 and
12.7cm FLAK 39/40
Both these guns had auto loaders and fuse setting machines set into the auto loader. They tended to be too large to transport with advancing troops so most stayed within Germany. Some even had power drive so in theory could have been aimed direct from the predictors.

Of further interest is the 8.8cm FLAK 43 which was vastly more powerful than the 8.8cm FLAK 37 and could deal with any high altitude US bomber or Mosquito. It feature the auto loader, fuse setting machine and a lower profile to assist in duel purpose use. This gun ran into trouble when a change from brass to steel cartridges caused jamming as the barrel sleave was near the cartridge and so the sleave had to be re designed. It had a prodigious firing rate of nearly 30 RPM but had barrel vibration problems at those high rates of fire, these were solved by firing on the recoil so although the gun was in use by 1943 it had to be withdrawn to Germany and used with brass cases till the problems were solved.

Wruzburg rasdar were jammed by windows from Mid 1943 onwards. A recovery was made by suing a Doppler device called Wurzlaus so that during the battle of Berlin the anti windows effort helped produce the following result.

"It is generally accepted that the Battle of Berlin was a failure for the Royal Air Force (RAF) as it was not the knockout blow that Harris had predicted. The RAF lost 1,047 bombers, with a further 1,682 damaged, and well over 7,000 aircrew, culminating in the raid on Nuremberg on 30 March 1944, when 94 bombers were shot down and 71 were damaged, out of 795 aircraft."

Carpet board band noise jamming wiped out Wurzburg for much of the end of the war though anti jamming circuits esp on the Wurzburg Riesse was sometimes successful. The solution was the new microwave radars such as Egerland Kulmbach but there was also a program to vastly increase the output power of the basic Wurzburg radars 20 fold to 160kW. Again testing had been complete but production proved impossible.

Hence timing couldn't have been worse as the period of the technical inferiority was also thje period in which bombing caused the most damage and prevented recovery.

Mention should be made of German efforts at proximity fuses for FLAK shells.

There were two effforts, one using eloectrostic efforts was ready for production in 1944 (1943 if the reports are read) and another using radar which required shock hardened thermionic vacuum tubes was supposedly to enter production in 1945 (According to Goering's interrogation by Spaatz there would have been production in 5 months).

Any body mocking through the air produces a large electrostatic field especially if at high speed. Should another object come nearby the gradient of this field changes and this can be used to detect proximity of an aircraft. The Germans had used electrical fuzes in their bombs as both long terms and short arms delays as arming as arming. The secret was a device called a cold cathode tube. This didn't require a heated element and function as a sensitive switch. The discovery of these devices in German bombs caused the British to reactivate their own proximity fuze program which was handed over to the Americans because the man in charge, Cockcroft, had to develop the atomic bomb.

These electrostatic fuzes when fired in a test range gradually grew from 1, 2, 5 meter sensitivity to a target (in practice on firing range) and finally 10m and 15m was thought possible.

In my view production should have started at 2m. This is because the Germans had proven by the end of the war that fuze setting wasn't worth it. By firing a contact fuzed shell the time wasted in setting fuzes could be ignored, expensive clock work mechanism avoided and cheaper explosives used.

The thing to note about these electrostatic fuzes is that they were extremely cheap, little more expensive than a nose contact fuze, so with a 2-5m range they would have worked cost effectively since it was found that to bring down a bomber required detonation within 4 meters anyway.

Interestingly there are claims of so called double fuzes achieving extremely high efficiencies in bringing down bombers. What is odd is that fuzes lready consisted of timer, nose contact and self destruct so what could a 'double fuze' really be. Perhaps it was code for the electrostatic fuze?

I will add links and pictures tomorrow.

Can't wait to see more, do you have any more info about the German proximity fuses?

 

[parsifal]

Production of heavy flak guns by the Germans was roughly:

12.8cm Z 34
12.8cm 569
10.5cm 2010
10.5 cm 38 approx. 4200
8.8cm Flak 41 about 300.
8.8cm Flak 18 /36 over well 10,000

The 8.8cm Flak 41 was supposed to replace the earlier models but proved very unreliable in service and the problems with it were never fully worked out. This is the gun that eventually becomes the 8.8cm L71 in Pak form. The 10.5 and 12.8 cm simply could not be produced in quantity. So, the 8.8cm of prewar design soldiered on as the standard heavy flak gun until the end of the war.

Its unrealistic to suppose that the germans would have anything other than the old flak 36 to work with. Moreover, most of these guns were well past it by 1944, as witnessed by the large number of barrel failures. Further, the crews manning these were mostly ersatz home guard Dads Army types who could not be expected to cope with anything more sophisticated to a sustained barrage fire. Basically pointing the gun in the general direction of an aircraft and hope it frightens them away.

This was no different to the charade mounted by the British flak crews in 1940. For the british, despite enormous ammunition expenditure, for the entire year, less than 400 enemy aircraft could possibly have been shot down by British flak. German flak in 1944, faced with similar problems cannot be expected to do any better.

 

[Koopernic]

You missed the FLAK 37. Wikipedia lists total FLAK 18/36/37 production at over 20,000. The latter FLAK 37 had improved instruments and gauges for anti aircraft use and so was obviously more favoured for FLAK use rather than duel purpose use. About half the guns ended up at home and the other half on the front.

The 10.5cm C38 was a naval weapon not an anti aircraft weapon so shouldn't be counted as part of German air defence.

I'm saying about 8000 modern 8.8cm guns and 2000-2500 guns in the 10.5cm to 12.7cm range for German air defence.

The 8.8cm must have been ineffective against US heavies despite 88 terror. I can't see it working above 20,000ft. B-26 could operate at 12,000ft with it around for short periods.

The 12.7cm was often used in a twin mount recessed into the massive bomb proof FLAK towers. These towers also had the large 7 meter diameter version of Wurzburg known as Wurzburg-Riesse. Due to the large diameter it had a sharper beam that increased angular accuracy considerably and was more resistant to interference by jamming.

The Wurzburg-Riesse radar installed on FLAK tower also had often had another unusual feature: they often integrated a GEMA Freya radar operating at 2.4m as well as the Wurzburgs 54cm into the dish. The Freya component was meant to be used as a search radar but turns out to have been an reasonably effective aiming radar device particularly in range. By using the two components together the FLAK towers could retain effectiveness in jamming where other systems had declined. The firm foundations and alignment possible also must have helped accuracy. Possibly helps explain the RAF's losses over Berlin. These radars also seemed to receive the latest anti jamming circuits such as k-laus.

The German Mannheim Radar FuSE 64 in its early 1944 issue got range accuracy down to 6m with a reliable autotrack that was free of opperator error and thus improved range accuracy. The electronics never made it to the 7m Wurzburg though this was planned.

A range accuracy of 6m is still not adequate in my view and 2m would have been minimum acceptable to eliminate range as a source of error.

Errors in calculations and fuse setting as well as timer variations were bad enough not to have a range error to deal with.

In terms of British AAA. The British never deployed an AAA radar of their own so their FLAK could never be effective.

The first British radar was the US built SCR-584 delivered by the Americans to deal with the V1 in july 1944. It came equipped with synchro transmitters for British predictors.

There is no doubt Britain could have made a FLAK radar, but they didn't have the resources. The team developing and improving H2S just about dropped dead from mental and physical exhaustion.

The unit they did make was called GLAXO was quite competitive though Canadians may want to take credit for it. It never was deployed. I like it as it used twin aerials so that only the receive instead of the transmit was conically scanned thus avoiding disclosing the scanning pattern.

 

[stona]

In terms of British AAA. The British never deployed an AAA radar of their own so their FLAK could never be effective.

I can't agree with that!
The GL/EF and GL Mk II systems had already vastly improved the accuracy of British ack-ack by 1940. The GL Mk. III version was being introduced in 1943 when it was indeed partially replaced by the superior SCR-584, though the British still operated GL Mk. III sets against the V-1s, particularly in the south-east . These were in turn replaced, post war, by a more advanced British system (the imaginatively named Radar, Anti-Aircraft No. 3 Mk. 7) a descendant of those early systems.

The GL Mk.II sets would be resurrected late in the war as part of the effort to counter the V-2 rocket threat. Some AMES Type 9 stations equipped with cathode ray height finding were installed in hollows on the east coast. They could spot the rockets on the early upward part of their trajectory, but estimation of the point of impact was poor. Some of the good old GL Mk II sets (nine of them) modified for high-looking were positioned along the coast to give information further along the trajectory. Up to January 1945 92% of V-2 launches were detected and a five and a half minute warning was being given to the filter room. It is a common misconception that these weapons without warning. The firing points were being pin-pointed within two hours to an accuracy 2kms by 5-10kms. The Germans really had to shoot and scoot to avoid retaliation. Not bad for a radar originally developed five years earlier.

It's also worth remembering that the British were not faced with large formations of enemy bombers after 1940/41 and understandably concentrated on developing GCI and airborne radar systems to work with their already developed command and control system to counter Luftwaffe 'nuisance' raids during the mid war (for us) years.

Cheers

Steve

 

[parsifal]

In terms of British AAA. The British never deployed an AAA radar of their own so their FLAK could never be effective.

The first British radar was the US built SCR-584 delivered by the Americans to deal with the V1 in july 1944. It came equipped with synchro transmitters for British predictors.

There is no doubt Britain could have made a FLAK radar, but they didn't have the resources. The team developing and improving H2S just about dropped dead from mental and physical exhaustion.

The unit they did make was called GLAXO was quite competitive though Canadians may want to take credit for it. It never was deployed. I like it as it used twin aerials so that only the receive instead of the transmit was conically scanned thus avoiding disclosing the scanning pattern.

GL Mk. I, was an early radar system developed by the British Army to provide range information to associated anti-aircraft artillery. There were two upgrades to the same basic system, GL/EF (Elevation Finder) and GL Mk. II, which added the ability to accurately determine bearing and elevation. At least 140 sets were in service by the outbreak of WWII, of which about half were sent to France and lost there.

The first GL set was a crude design developed during the 1930s. Based on Chain Home, GL used separate transmitters and receivers located in wooden cabins mounted on gun carriages, each with its own large antenna that had to be rotated to point at the target. The antenna produced a signal that was semi-directional and was only capable of providing accurate slant range information; it could not locate a target better than about 20 degrees in bearing, and did not provide elevation information at all. A number were deployed with the British Expeditionary Force and at least one was captured by German forces during the Dunkirk evacuation. Their evaluation led them to hold a low opinion of British radar systems.

Plans to introduce the Mk. II with accurate bearing and elevation were underway from the start, but these would not be available until after September 1940. An expedient solution was the GL/EF attachment, providing bearing and elevation measurements accurate to about a degree. With these improvements, the number of rounds per kill fell to 4,100 , a ten-fold improvement over early-war results. About 610 of the Mk. I and slightly modified Mk. I* units had been produced by September 1940, when production was halted, shifting to the Mk. II, which had enough accuracy to directly guide the guns. Higher accuracy and simpler operation lowered the rounds-per-kill to only 2,750 with Mk. II. After the invasion of the Soviet Union in 1941, about 200 Mk. II units were supplied to the Soviets who used them under the name SON-2. 2,679 Mk. II's were ultimately produced. Hardly "no gunlaying radar by the British".....And the known results speak for themselves.

The introduction of the cavity magnetron in 1940 led to a new design effort using highly-directional parabolic antennas to allow both ranging and accurate bearing measurements while being much more compact. These GL Mk. III radar units were produced in the UK as the Mk. IIIB (for British), and a locally designed model from Canada as the Mk. IIIC. Both were generally replaced starting in 1944 by the superior SCR-584.

I suspect you are relaying on German reports of the time concerning British radar. There were enough GL-1 parts left behind at Dunkirk for Wolfgang Martini's radar team to piece together the design and determine the basic operational capabilities of the systems. What they found did not impress them. Luftwaffe radars for both early warning (Freya) and gun-laying (Würzburg) were significantly more advanced than their British counterparts at that time.

This evaluation, combined with the failure of a mission of LZ-130 to detect British radars in August 1939, appears to have led to a general underestimation of the usefulness of the British radar systems. In spite of being aware of Chain Home, German reports on the state of the Royal Air Force written just before the Battle of Britain did not even mention radar at all. Other reports mention it, but do not consider it to be very important. Other sections of the Luftwaffe appear to be dismissive of the system as a whole. This included the Gun Laying Radars mentioned above.

I should briefly mentiuon that the transition from GL-1 to II was not entirely a smooth or seamless affair. From 1939 the British were introducing an interim modification to the GL-1, the GL EF (EF = Elevation Finder). Not a lot to say, but it was an attempt to overcome the GL-1 calibration problems.

Aerial photo of a gun laying matting used in conjunction with some GL-1 installations installed on the east coast, north of Sunderland. The ramp and platform at the center are prominent.

 

[parsifal]

The story did not however end in 1940, with the generally unsatisfactory GL-1 series. Neither did the continued improvements to AA command, which began a long road to improved efficiency from September 1940 under its leader Gen Pile.

In addition to the continued technical advancement of the GL systems, Pile greatly improved the overall state of AA starting in September 1940 by appointing a scientific advisor to the highest echelon of the AA command. For this role he chose Patrick Blackett, who had WWI experience in the Royal Navy and had since demonstrated considerable mathematical ability. Blackett planned to study the AA problem from a pure mathematical standpoint, a concept that proved extremely valuable and would evolve into the general field of operational research.

Blackett formed a group known as the Anti-Aircraft Command Research Group, but referred to universally as Blackett's Circus. Blackett deliberately chose members from different backgrounds, including physiologists David Keynes Hill, Andrew Huxley and L. Bayliss, mathematical physicists A. Porter and F. Nabarro, astrophysicist H. Butler, surveyor G. Raybould, physicist I. Evans and mathematicians A.J. Skinner and M. Keast, the only woman on the team. Their goals were neatly summed up by Blackett:

"..the first task was to work out the best method of plotting the radar data and predicting the future enemy position for the use of the guns on the basis only of pencil and paper, range and fuse tables. The second task was to assist in the design of simple forms of plotting machines which would be manufactured in a few weeks. The third state was to find means of bringing the existing predictors into use in connection with the radar sets."

Meanwhile, in November 1940, John Ashworth Ratcliffe was moved from the Air Ministry side of Bawdsey to start an AA gunnery school at Petersham on the west side of London. One problem that became immediately evident was that the inputs to the predictors, the analog computers that handled ballistics calculations, were very easy to get wrong. This information was fed back through the Army hierarchy, and again it was Bedford who produced the solution. This resulted in the building of several Trainers that were used at the AA school, allowing operators to hone their skills.

To better study the AA problem, the Circus soon added a fourth trailer to some AA sites in the London area, dedicated solely to recording the inputs to the predictors, the numbers of rounds fired, and the results. These numbers were fed back through the AA command structure to look for any chance of improvement. The official history, published just after the war, noted that between September and October 1940, 260,000 AA rounds had been fired with the result of 14 aircraft destroyed, a rate of 18,500 rounds-per-kill. This was already a great improvement over pre-radar statistics which were 41,000 rounds-per-kill. But with the addition of GL/EF, GL mats and better doctrine, this fell to 4,100 rounds-per-kill by early 1941.

Pile commented on the improvements by noting:

"The initial difficulties had largely been smoothed away, and on May 11–12 1941, when the raids were so widespread that we were given greater scope, we obtained 9 victims, with one probable and no fewer than 17 others damaged. [These losses for that night are verified from LW own loss records] the Blitz virtually ended that night. By the end of the Blitz, we had destroyed 170 night raiders, probably destroyed another 58, and damaged, in varying degree, 118 more. "

GL Mk. II arrives

Production of the Mk. II was by the Gramophone Company and Cossor. Prototype Mk. II sets began to appear as early as June 1940, but considerable changes were worked into the design as more information from the Mk. I sets flowed in. The final design began to arrive in production quantities in early 1941.

Displays were located in a wooden cabin below the receiver array, including separate CRTs for range, bearing and elevation, allowing continual tracking throughout the engagement. The transmitter antenna now came in two versions, one with a wide angle beam for initially picking up the target or searching for it, and another with a much narrower beam that was used while tracking a single target. Although this introduced complexity, it also greatly reduced the problem of more than one target appearing on the displays.

The Mk. II also included a new transmitter, which had increased in power three times from 50 to 150 kW. This extra power offered somewhat better range, but more importantly it allowed the pulse width to be significantly reduced while offering the same range. The sharpness of the echo is a function of the pulse width, so by reducing it the system became more accurate. The Mk. II could offer bearing measurements as accurate as ½ degree, about twice as accurate as the Mk. I, and just within the range needed to directly aim the guns. The Mk. II had largely replaced the Mk. I by mid-1942 and remained in service until mid 1944. An analysis demonstrated that the Mk. II improved the rounds-per-kill to 2,750, another significant advance. 2,679 GL Mark II sets were produced between June 1940 and August 1943.

Transmitter cabin of the Mk. II radar. The individual antennas can just be made out. This version appears to combine the wide and narrow angle antennas on a single unit.

Mk III shortwave sets

The introduction of the cavity magnetron in 1940 allowed radars to operate effectively at much shorter microwave wavelengths, which reduced the antennas to only a few centimetres long. These antennas were so short that they could be placed in front of parabolic reflectors, which focused the signal into a very tight beam. Instead of the broadcast pattern being as much as 150 degrees wide, typical microwave designs might have a beam width of perhaps 5 degrees. Using a technique known as conical scanning, this could be further reduced to well under ½ a degree, more than enough to directly lay the guns.

In late 1940 the Army was well into an effort to built an X-band GL radar system, and by 1942 had already sent the plans to companies in the UK for production. Work also began in Canada in 1940 on an entirely Canadian designed and built version with production starting in September 1942, and deliveries arriving in the UK starting in November 1942, as the GL Mk. IIIC, with British units arriving the next month as the Mk. IIIB. Final Production numbers are not known, but thge numbers were significant. These were dramatically more mobile than the earlier designs, consisting of wheeled trailers and a generator set. The need for the wire ground mat of the earlier models was eliminated, and sites could be fully operational in hours.

The new microwave sets began replacing the Mk. II during 1943, but deliveries were not particularly fast and these sets were often sent to new units as opposed to replacing Mk. II's in the field. The GL-iis were more than satisfactory and the threats posed by the LW from 1943 fairly insignificant. There was nothing wrong with either the GLIIs or the GL IIIs, but in 1944 with arrival of the US SCR-584 radar, there was a rapid switch to this superior set. SCR 584 was the catalyst for the rapid replacement of all of these sets, as it combined scanning and tracking into a single unit with and internal generator set. In the immediate post-war era, these were in turn replaced by the smaller and lighter AA No. 3 Mk. 7 radar, which remained in use until AA guns were removed from service in the late 1950s.

GL Mk. III C radar