How Accurate Was Dive Bombing

[GrauGeist]

IJN AA was rubbish. No radar, small guns (25mm), no proximity fuses, crap ROF due to only 15 round drums, etc. Here's their main weapon Japan 25 mm/60 (1") Type 96 - NavWeaps

Read the B-26 (Suzie-Q) pilot's account of the battle of Midway - the IJN was putting up a serious curtain of AA and it was a flak hit that killed or incapacitated the pilot of one B-26, causing it to "kamikaze" towards the Akagi's bridge (narrowly missing it).

 

[Admiral Beez]

Read the B-26 (Suzie-Q) pilot's account of the battle of Midway - the IJN was putting up a serious curtain of AA and it was a flak hit that killed or incapacitated the pilot of one B-26, causing it to "kamikaze" towards the Akagi's bridge (narrowly missing it).

At that range they'd better have hit it. But we don't want to look at one offs as an example of a greater premise. Instead we should see how many Allied aircraft were lost to IJN AA rather than IJN fighters.

According to Wikipedia, the US (all services) lost 150 aircraft in the Battle of Midway. Of the 41 Devastators the USN launched, 35 were destroyed, and IIRC all by IJN fighters. In such a target rich environment we should assume the IJN AA gunners were shooting at everything - so what did they kill? Did they get any of the Dauntless that killed their carriers?

 

[MIflyer]

I recall a book by a SB2C pilot who was directed to attack a IJN destroyer that was running around Manila Bay making a nuisance of itself during the US invasion of the PI.

That flight of four Helldivers peeled off after the IJN DD, which was in a turn at the time. The first bomb hit on the forward deck and the next three hit at about 50 feet intervals behind that point. And quite suddenly the DD was no longer there.

As the Helldivers peeled off, their Hellcat escort leader got a request for the current position of the DD. He replied, "In a minute I'll tell you where it used to be."

 

[GrauGeist]

At that range they'd better have hit it. But we don't want to look at one offs as an example of a greater premise. Instead we should see how many Allied aircraft were lost to IJN AA rather than IJN fighters.

According to Wikipedia, the US (all services) lost 150 aircraft in the Battle of Midway. Of the 41 Devastators the USN launched, 35 were destroyed, and IIRC all by IJN fighters. In such a target rich environment we should assume the IJN AA gunners were shooting at everything - so what did they kill? Did they get any of the Dauntless that killed their carriers?

Quite a few SBDs were lost out of the 47 total involved, for various reasons.

But to get a solid idea of the Japanese AA action, read the translated IJN action report itself - in it, is the chronological order of the battle, complete with AA reports from all ships involved that day.
Japanese Story of the Battle of Midway

 

[MIflyer]

Did they get any of the Dauntless that killed their carriers?

When the SBD's from the Enterprise and Yorktown arrived overhead neither had any fighter escort. The Yorktown sent six F4F's and all were down covering their TBD's - unsuccessfully. The Enterprise F4F's had followed the Hornet TBD's, had already turned for home and thus never engaged. There were about 50 Zeros up, but all were going after the TBD's far down below. So the Zeros got no SBD's before they entered their dives. The Zeros chased the TBD's but the surviving crews reported the enemy fighters lost much of their interest about the time their carriers blew up.

 

[RCAFson]

Yoji Ito had invented at multicavity magnetron with circular cavities and narrow slits about a year earlier than Randall & Boot and the Japanese had a working microwave search radar by 1942 type 22 radar they used for surface search on their cruisers.

Oddly the Japanese Navy Never shared with the Germans, this may have been due to communication difficulties and it seems never with the Japanese Army who struggled to copy German Wurzburg radars for AAA defense.

Derivatives of Type 22 radar had lobe switching for blind fire.

Type 22 General Purpose Radar:
Wavelength10 cm
Pulse Width10 microsecond, Pulse Repetition Frequency 2500 Hz
Scan rate 5 rotations per minute
Power 2 kW
Range:
20 nautical miles (35 km) aircraft group
10 nautical miles (17 km) single aircraft
13 nautical miles (24 km) battleship
Antenna Horn
Display A scope
Accuracy 220 yards/3 degrees
200 meters/3 degrees
Resolution 1600 yards/40 degrees
1500 meters/40 degrees
Weight
2910 lb (1320 kg) as installed on surface ship
4717 lb (2140 kg) as installed on submarine
Production: 300 sets. Fitted to modern destroyers in summer 1942, to Kongo-class battleships 1942-10, to light cruisers 1943-6, to the Yamatos 1943-10, and to other destroyers 1944-9.


The Japanese Type 22 radar, also known as Mark 2 Model 2, saw wide operational use in the war, being installed on surface ships and submarines. Though nominally a surface search radar, it was also used for air search and for fire control. It was based on an early Japanese version of the cavity magnetron, the M-312, used 40 vacuum tubes, and had limited power. Quality control during production was a serious problem: Of the first sixy sets built, only about six actually worked. The chief difficulty was achieving adequate precision in machining the oddly-shaped cavities in the M-312 magnetron to achieve the precise frequency required to match the magnetron with the M-60 vacuum tube used in the receiver.

The first set was tested in October 1941 and a pre-production version called the Model 103 was experimentally shipped on Hyuga just before the battle of Midway. With its dual steerable horn, it was nicknamed "Bluefin Tuna" or "Horse Mackerel." Mass production was authorized by the end of 1942 but no materials were allocated. One of the Army technicians on the project proceeded to acquire materials through the black market, which led to some of the accountants on the project being arrested and held by the police for a month. Its first operational triumph was allowing the evacuation flotilla for Kiska to navigate under cover of heavy fog. Because of continuing difficulty matching components, production never came close to the target of 150 sets a month.

An improved version, the Mod 1, with a more stable heterodyne receiver, was rushed to the fleet in time for the Battle of the Philippine Sea. Another version, the 22-Kai-3, was designed for submarines and differed in having a pulse repetition rate of 600 Hz.

The first UK microwave radars were tested in the summer of 1940. The very first operational UK naval microwave radar, Type 271, was tested at sea in March 1941 and deployed operationally in May 1941, with over 30 in service use by Oct 1941. It had 5 Kw power output, and this was raised to 25kw in 1942.

 

[Admiral Beez]

When the SBD's from the Enterprise and Yorktown arrived overhead neither had any fighter escort. The Yorktown sent six F4F's and all were down covering their TBD's - unsuccessfully. The Enterprise F4F's had followed the Hornet TBD's, had already turned for home and thus never engaged. There were about 50 Zeros up, but all were going after the TBD's far down below. So the Zeros got no SBD's before they entered their dives. The Zeros chased the TBD's but the surviving crews reported the enemy fighters lost much of their interest about the time their carriers blew up.

No, I mean did the IJN AA gunners get any. I am replying to the post above on the efficacy of AA.

 

[Admiral Beez]

Oddly the Japanese Navy Never shared with the Germans, this may have been due to communication difficulties and it seems never with the Japanese Army who struggled to copy German Wurzburg radars for AAA defense.

I don't believe the Germans ever fitted air intercept radar to their warships. Bismarck and Tirpitz had surface radar for their guns. For all their apparently backwardness, of the three Axis powers only Japan had air intercept radar on their warships..... just too late, and without radios in the Zero in order to vector them onto detected threats.

Imagine Midway with working radar, CIC and radios in the Zeros. Nagumo's dilemma is no more. All Zeros can be recalled, refueled and rearmed and pilots rested between attacks. Kate and Val strikes can be orderly launched and formed up without hurry. Fuel lines can be flushed and secured when incoming strikes detected. McClusky's SBD attack is detected well out and destroyed. The IJN focused on the wrong things..... get radar, get radios, focus on CIC.... the Japanese embassy in London must have reported to Tokyo the efficacy of radar directed fighters.

 

[MIflyer]

Imagine Midway with a working air to surface radar in the B-17's and B-26's......


And at Coral Sea the air surveillance radar enabled the USN to find out where the IJN carriers were, by tracking the airplanes and noting where they dropped off the scope as they started to descend.

 

[tomo pauk]

<snip>

Copy and paste the text from here.

 

[Thumpalumpacus]

It was based on an early Japanese version of the cavity magnetron, the M-312, used 40 vacuum tubes, and had limited power.

My god, could you imagine the tube-rolling required to find a defective tube in that mess?

 

[Koopernic]

I don't believe the Germans ever fitted air intercept radar to their warships. Bismarck and Tirpitz had surface radar for their guns. For all their apparently backwardness, of the three Axis powers only Japan had air intercept radar on their warships..... just too late, and without radios in the Zero in order to vector them onto detected threats.

Imagine Midway with working radar, CIC and radios in the Zeros. Nagumo's dilemma is no more. All Zeros can be recalled, refueled and rearmed and pilots rested between attacks. Kate and Val strikes can be orderly launched and formed up without hurry. Fuel lines can be flushed and secured when incoming strikes detected. McClusky's SBD attack is detected well out and destroyed. The IJN focused on the wrong things..... get radar, get radios, focus on CIC.... the Japanese embassy in London must have reported to Tokyo the efficacy of radar directed fighters.

The anti aircraft radar suite was never quite as strong as a British capital ship or cruiser but they were not helpless.

Below is an AAA variant of Seetakt Flakleit-G on a land installation and on Prinz Eugen. This is probably the most accurate height finding radar of the war (less than 0.1 degrees accuracy) using the nonminimum phase method. It had lobe switching so could provide blind fire against both ships and aircraft. It looks a fairly bulky radar.

Standard Seetakt could detect aircraft, it could measure their range. The standard versions could not asses height. The latter versions from about 1941/42 (FuMO24/25 on destroyers and torpedo boots) and FuMO 26 and FuMO 27 on capital ships like Tirpitz had lobe switching on the receive side and were capable of accurate blind fire control.

Early pre war versions such as FuMO 20/22 (destroyers and torpedo boats) and FuMO 23 (Cruisers, Battleships) did not have lobe switching (neither did US or UK at this time) .

So from 1938 onwards any aircraft approaching a German ship above a torpedo boat would be detected and its range localised to 70m and its bearing (within the 6 degree beam width localised to about 1-2 degrees. From later 1941 to early 1942 they would be able to localise to 0.25 degrees.

No height finding except in those with Flakleit-G. However it could certainly direct a search light or set the range of its guns.

Here is where it gets interesting. In Harry von Krogge's book "GEMA Birthplace of German Radar" he mentions delivery of 58 height finding radars for use on ships.
At least one expert on kbismark.com when I asked him said that FuMO 26 had height finding built in by phase shift like the GEMA Wassermann radars.

There was a German naval gunlaying radar called FuMO 231 Euklid. It used a 1.5m dish and a wavelenght of 27cm but was being converted to 3cm and known as Euklid Z.

A few may have been installed in destroyers in dry dock, they were delivered.

Germans did have a PPI set called Hohtenweil (1943) and a microwave PPI set called FuMO 81 Berlin. (Mid 1944)

 

[SaparotRob]

Quite a few SBDs were lost out of the 47 total involved, for various reasons.

But to get a solid idea of the Japanese AA action, read the translated IJN action report itself - in it, is the chronological order of the battle, complete with AA reports from all ships involved that day.
Japanese Story of the Battle of Midway

Thanks for that post. I'm going to have to set aside a nice comfortable block of time for reading that link.

 

[Koopernic]

I remember some propaganda or television history special showing a Stuka hitting a moving tank, and at the time I thought that's unlikely. Then again, they claimed thousands of kills in Russia.

Actually, the 35mm contender which was beaten by the Sgt York was also firing prox-fuzed ammo - its the smallest round that has used that, I think, and it was evidently considered too small as it never entered service. In part, this was because Oerlikon had a better idea and introduced the AHEAD ammo in 35mm; basically like a shrapnel round which was timed to burst open just in front of the target aircraft or missile, showering it with a shotgun blast of tungsten pellets. This works well and is still in service today.



It's a bit more complicated than that. Rheinmetall developed an automatic naval AA gun in 3,7cm, the SKC/36, which fired its own unique ammo. The gun seems to have been a copy of the Bofors. It wasn't successful but was revived (presumably with improvements) and entered service as the Flak M42. The Flak M43 was the one with the MK 103 mechanism and was adopted by all of the services, but didn't have the time to prove its worth. The earlier army/Luftwaffe 3,7cm Flak guns were also mounted on ships.

I though the issue was that 40mm round had a proximity fuse whereas the 35mm did not (though it was under development) during evaluation every 40mm round that detonated on proximity was counted as a kill whereas the 35mm did not have one. As we know Oerlikon went and developed AHEAD ammunition. This used a muzzle velocity sensor and a fuze programming device to accurately set the burst time. In addition the round was a kind of shaped charge that projects tungsten cubes forward.

 

[Koopernic]

The anti aircraft radar suite was never quite as strong as a British capital ship or cruiser but they were not helpless.

Below is an AAA variant of Seetakt Flakleit-G on a land installation and on Prinz Eugen. This is probably the most accurate height finding radar of the war (less than 0.1 degrees accuracy) using the nonminimum phase method. It had lobe switching so could provide blind fire against both ships and aircraft. It looks a fairly bulky radar.

View attachment 621065View attachment 621066

Standard Seetakt could detect aircraft, it could measure their range. The standard versions could not asses height. The latter versions from about 1941/42 (FuMO24/25 on destroyers and torpedo boots) and FuMO 26 and FuMO 27 on capital ships like Tirpitz had lobe switching on the receive side and were capable of accurate blind fire control.

Early pre war versions such as FuMO 20/22 (destroyers and torpedo boats) and FuMO 23 (Cruisers, Battleships) did not have lobe switching (neither did US or UK at this time) .

So from 1938 onwards any aircraft approaching a German ship above a torpedo boat would be detected and its range localised to 70m and its bearing (within the 6 degree beam width localised to about 1-2 degrees. From later 1941 to early 1942 they would be able to localise to 0.25 degrees.

No height finding except in those with Flakleit-G. However it could certainly direct a search light or set the range of its guns.

Here is where it gets interesting. In Harry von Krogge's book "GEMA Birthplace of German Radar" he mentions delivery of 58 height finding radars for use on ships.
At least one expert on kbismark.com when I asked him said that FuMO 26 had height finding built in by phase shift like the GEMA Wassermann radars.

There was a German naval gunlaying radar called FuMO 231 Euklid. It used a 1.5m dish and a wavelenght of 27cm but was being converted to 3cm and known as Euklid Z.

A few may have been installed in destroyers in dry dock, they were delivered.

Germans did have a PPI set called Hohtenweil (1943) and a microwave PPI set called FuMO 81 Berlin. (Mid 1944)

Further to this:


Re: Use of Seetakt on German ships for FLAK direction.

Post by Dave Saxton » Tue Nov 22, 2011 4:11 pm

The data circuits for the surface fire control could access the flak fire control circuits. Thus radar data could be transmitted via selsyns directly to the flak fire control by-passing the optical flak directors. So this statement is more or less correct:

or could the main directors accomplish FLAK direction on their own?​

However, German optical surface fire control for day light operations did not use combination rangefinder-directors like other navies. The optical range finders and the optical directors were separate instruments divorced from each other.

Later versions of the Seetakt series such as FuMO 24,25 and 26 had a type of fine direction finding similar to lobe switching often quoted as being accurate to 0.3 degrees and 0.25 for FuMO 26.​

This was a type of lobe switching introduced in 1940, but as far as is known not used on major warships until the fall of 1941, first on the Tirpitz. The type of lobe switching was known "radattel peilung". In this type of lobe switching the receiving antenna dipoles (only) were set up in a phased array scanning loop by a 1/2 wave delay line and a motor driven contact was circulated around the 1/2 wave delay line. The contact made a raddling sound when in use, hence the nick name. The pip on the bearing indicator scope took the form of a saddle shape and with the notch of the pip centered right in the middle of the null mark in the middle of the scope; the antenna was aimed directly at the target within a directional accuracy of 0.1*. 0.3-0.25* accuracy is incorrect. The bearing accuracy attainable with radattel peilung was 0.1* If the target wandered off line, the pip on the indicator moved accordingly. It was just a matter of adding another crt indicator module to the radar for the vertical lobe switching indication.

Flakleit-G (literally translated as Flak directing -GEMA -g wave length) used the "owls ears" attachments to the antenna as seen on the Prinz Eugen in 1942 and early 1943. These owls ears antenna additions were for locating the aircraft on the vertical axis. One owl ear was for transmission and the other with radattel peilung lobe switching was for receiving. Thus radattel peilung could be used on both the vertical and the horizontal axis providing full blind fire capability against aircraft as well as surface targets. In 1943 a new model radar superseded both FuMO27 and Flakleit-G on warships. This was known under the 1944 designation system as FuMO26 with a huge 6.5 meters x 3.2 meters common mode antenna. This antenna could employ vertical lobe switching without the use of owls ears attachments because it had four rows of dipoles. The common mode technology could also be retrofitted to existing radar sets/antennas bringing all available dipoles into service for both send and receive. Hence some existing Flakleit -G sets only needed one owl ear antenna attachment late war.

Without vertical lobe switching, the radars with antennas mounted to the rangefinders, could be used to track aircraft; providing accurate range and bearing, and the optical flak directors only need provide elevation data. In some film footage of Tirpitz during 1942, the foretop rangefinder mounted radar can be seen tracking a fast moving Luftwaffe aircraft from the port side across the bows to starboard in a radial arc. Even prior to the employment of horizontal lobe switching the radars could be used to provide accurate range data to the flak control comput

 

[Koopernic]

The first UK microwave radars were tested in the summer of 1940. The very first operational UK naval microwave radar, Type 271, was tested at sea in March 1941 and deployed operationally in May 1941, with over 30 in service use by Oct 1941. It had 5 Kw power output, and this was raised to 25kw in 1942.

Yes, I'm aware of the dates. Britain was quite for ahead in radar in general but the Japanese beat them to a multicavity magnetron by 1 year. The UK Army under Pollard & Buttment proposed a AAA radar in 1930. Unfortunately their proposal was rejected and it was not until 1934 when the Air Ministry demonstrated success that the program was restated. Hence Dowding and Watson Watt got the glory. The radar was called TRU (Transportable Radio Unit) or GL Mk 1 (Gun Laying Radar 1). Accuracy about 0.6 degrees and 70 yards and it increased hit rate of UK AAA from 16000 rounds to bring down a bomber at night to 4000. Used by the Russians throughout the war. Pretty good for a radar with a 4 meter wavelength. But for the UK army rejection UK could have had a radar system much earlier.

The problem for the Japanese was that they started radar development relatively late. Hence when their microwave radar came along they hadn't built a core of officers and technical people who understood conventional radar let alone microwave. So they had conventional radars but didn't appreciate them or their potential due to their limited time exposed to the technology. IOn addition their Pentax nigh vision binoculars were better than even the Zeiss units of the Germans which were well ahead of UK/USA practise.

Technically the German Navy invented radar. They detected and measured ranges to both ships and aircraft nearly 1 year before the UK. Development proceeded more slowly for various reasons but Seetakt, Freya were all ready before the war (1938) and Wurzburg in early 1940. The Germans actually showed the Japanese their radar and told them to get moving.

 

[RCAFson]

The anti aircraft radar suite was never quite as strong as a British capital ship or cruiser but they were not helpless.

Below is an AAA variant of Seetakt Flakleit-G on a land installation and on Prinz Eugen. This is probably the most accurate height finding radar of the war (less than 0.1 degrees accuracy) using the nonminimum phase method. It had lobe switching so could provide blind fire against both ships and aircraft. It looks a fairly bulky radar.

View attachment 621065View attachment 621066

Standard Seetakt could detect aircraft, it could measure their range. The standard versions could not asses height. The latter versions from about 1941/42 (FuMO24/25 on destroyers and torpedo boots) and FuMO 26 and FuMO 27 on capital ships like Tirpitz had lobe switching on the receive side and were capable of accurate blind fire control.

Early pre war versions such as FuMO 20/22 (destroyers and torpedo boats) and FuMO 23 (Cruisers, Battleships) did not have lobe switching (neither did US or UK at this time) .

So from 1938 onwards any aircraft approaching a German ship above a torpedo boat would be detected and its range localised to 70m and its bearing (within the 6 degree beam width localised to about 1-2 degrees. From later 1941 to early 1942 they would be able to localise to 0.25 degrees.

No height finding except in those with Flakleit-G. However it could certainly direct a search light or set the range of its guns.

Here is where it gets interesting. In Harry von Krogge's book "GEMA Birthplace of German Radar" he mentions delivery of 58 height finding radars for use on ships.
At least one expert on kbismark.com when I asked him said that FuMO 26 had height finding built in by phase shift like the GEMA Wassermann radars.

There was a German naval gunlaying radar called FuMO 231 Euklid. It used a 1.5m dish and a wavelenght of 27cm but was being converted to 3cm and known as Euklid Z.

A few may have been installed in destroyers in dry dock, they were delivered.

Germans did have a PPI set called Hohtenweil (1943) and a microwave PPI set called FuMO 81 Berlin. (Mid 1944)

The German shipborne radars used a fairly narrow beam radar and would have to have the receiver/transmitter aimed at the aircraft in order to detect it. There is no evidence via Tirpitz's War Diary (March 1942) that she was able to detect aircraft at long range via radar.

 

[RCAFson]

Yes, I'm aware of the dates. Britain was quite for ahead in radar in general but the Japanese beat them to a multicavity magnetron by 1 year. The UK Army under Pollard & Buttment proposed a AAA radar in 1930. Unfortunately their proposal was rejected and it was not until 1934 when the Air Ministry demonstrated success that the program was restated. Hence Dowding and Watson Watt got the glory. The radar was called TRU (Transportable Radio Unit) or GL Mk 1 (Gun Laying Radar 1). Accuracy about 0.6 degrees and 70 yards and it increased hit rate of UK AAA from 16000 rounds to bring down a bomber at night to 4000. Used by the Russians throughout the war. Pretty good for a radar with a 4 meter wavelength. But for the UK army rejection UK could have had a radar system much earlier.

The problem for the Japanese was that they started radar development relatively late. Hence when their microwave radar came along they hadn't built a core of officers and technical people who understood conventional radar let alone microwave. So they had conventional radars but didn't appreciate them or their potential due to their limited time exposed to the technology. IOn addition their Pentax nigh vision binoculars were better than even the Zeiss units of the Germans which were well ahead of UK/USA practise.

Technically the German Navy invented radar. They detected and measured ranges to both ships and aircraft nearly 1 year before the UK. Development proceeded more slowly for various reasons but Seetakt, Freya were all ready before the war (1938) and Wurzburg in early 1940. The Germans actually showed the Japanese their radar and told them to get moving.

The Japanese magnetron was not the same design as the cavity magnetron developed by the UK (Randall and Boot) and was never capable of generating high power output.

 

[pbehn]

This has some good information on the early British efforts in radar tech. Chain Home Low - Wikipedia

 

[A.G. Williams]

I though the issue was that 40mm round had a proximity fuse whereas the 35mm did not (though it was under development) during evaluation every 40mm round that detonated on proximity was counted as a kill whereas the 35mm did not have one.

Exactly at what stage the 35mm prox fuze reached I don't know. All I know is that such a fuze was intended for the system, and was (at least) designed.