Japanese get ship-based radar 1940

It's implausible to think that an alternate IJN that had decent radar by 1940 had not also worked out decent radios and fighter control.
Regarding priorities, everybody felt that Torpedoes were a bigger threat then dive bombers, against battleships. At the time most dive bombers carried 250kg bombs (apart from the Ju87) and battleships had that covered.
The IJN had ample information about how their own dive bombers had been effective against ships without armored decks (in fact inflated since they tended to over claim) and would have to be total morons not to regard dive bombers as a threat agains their carriers.
And the dive bombers would be coming at a higher altitude, and would probably be detected first.
Even if they only managed to divert four A6M-2, attacking without opposition and with are very different things.
So let's not fall into the: Let's change one thing and everything else stays the same trap...
 
It's implausible to think that an alternate IJN that had decent radar by 1940 had not also worked out decent radios and fighter control.
So let's not fall into the: Let's change one thing and everything else stays the same trap...
And lets not fall into the trap of change one thing and other stuff automatically changes for the better. Its not implausible that they don't use it any better than OTL. Getting good doctrine on radar involves a lot more than just having a better radar. German radar was arguably better than the British in 1940, the British however used theirs a lot better. Same with fighter tactics, Japanese pilots lets not forget removed radios from their planes to improve performance. Japanese Admirals ignored the radar reports they got OTL more often than not. Late war even after seeing what the US were doing and having the tech available they still failed to use it anything like the best.

Attitudes can be stubborn and it tends to take real combat you are actually in to change them. Japan did not, for instance, change from light planes without armor or self sealing tanks by 1942 even through the battle reports from the ETO would have showed the need for both by 1940. So better radar does not mean the status of radar technicians changes, if it does not, then the quality of reporting and the tendency to listen to them does not improve either.
 
It's implausible to think that an alternate IJN that had decent radar by 1940 had not also worked out decent radios and fighter control.
Regarding priorities, everybody felt that Torpedoes were a bigger threat then dive bombers, against battleships. At the time most dive bombers carried 250kg bombs (apart from the Ju87) and battleships had that covered.
The IJN had ample information about how their own dive bombers had been effective against ships without armored decks (in fact inflated since they tended to over claim) and would have to be total morons not to regard dive bombers as a threat agains their carriers.
And the dive bombers would be coming at a higher altitude, and would probably be detected first.
Even if they only managed to divert four A6M-2, attacking without opposition and with are very different things.
So let's not fall into the: Let's change one thing and everything else stays the same trap...

It's absolutely not implausible. This is the IJN we're talking about. They could decide to cram the radar operators into a broom closet below decks because keeping the carriers in circulation is more important then making them efficient. They could look at the Radar and go "It's nice, but we can't take the carriers and put them in refit because the Yamatos, which are ABSOLUTELY VITAL FOR THE DECISIVE BATTLE BTW, are sucking up all the shipbuilding resources." Just because you've got a good radar doesn't mean you also have a good radio. And it doesn't mean your admirals will actually listen to the radar reports. So no, I will not assume that just because they have a viable shipborne radar, that all the other pieces will fall into place.
 
And lets not fall into the trap of change one thing and other stuff automatically changes for the better. Its not implausible that they don't use it any better than OTL. Getting good doctrine on radar involves a lot more than just having a better radar. German radar was arguably better than the British in 1940, the British however used theirs a lot better. Same with fighter tactics, Japanese pilots lets not forget removed radios from their planes to improve performance. Japanese Admirals ignored the radar reports they got OTL more often than not. Late war even after seeing what the US were doing and having the tech available they still failed to use it anything like the best.

Attitudes can be stubborn and it tends to take real combat you are actually in to change them. Japan did not, for instance, change from light planes without armor or self sealing tanks by 1942 even through the battle reports from the ETO would have showed the need for both by 1940. So better radar does not mean the status of radar technicians changes, if it does not, then the quality of reporting and the tendency to listen to them does not improve either.
It's not a trap, it's a TL. You want to change one thing, in the case give the IJN radar in 1940, and have to figure out a way to getthere.
Japanese pilots removed their radios because their radios were bad quality unreliable heavy machines that were not worth the weight.They got fed up with saying "What? Repeat! again and again and gave up. Few countries made good eletronics in 1940. Germany was one of them, and the reason that the germans took to radio enthusiatically was not just sound tactics, it was that their radios actually worked.
Why do you think that Czechoslovakian 38 tanks had morse radios and german ones had voice radios? Because with Czechoslovakian voice radios you couldn't understand a thing that was being said on a moving tank most of the time.
Would the OTL IJN have radar in their ships in 1940 with minor changes?
Hell no.
Any route that takes them there also gives them a lot of other stuff.
Regarding other points:
The Ki-44 and ki61 were ordered in 1939/40. The IJN OTL commanders ignnored radar because their early radar was unreliable. HAd some USN commanders done the same in the early Solomons battles and they would have done better. Japan, like Italy, lacked the industraial base to move from concept to in-service material rapidly. You cannot date their awareness of what was needed from when they used things, but have to date it from when they asked for them. The first models of P39 P40 and P43 had the same lacks of their Japanese contemporaries. US industry just solved them faster than the Japanese one.
 
It's absolutely not implausible. This is the IJN we're talking about. They could decide to cram the radar operators into a broom closet below decks because keeping the carriers in circulation is more important then making them efficient. They could look at the Radar and go "It's nice, but we can't take the carriers and put them in refit because the Yamatos, which are ABSOLUTELY VITAL FOR THE DECISIVE BATTLE BTW, are sucking up all the shipbuilding resources." Just because you've got a good radar doesn't mean you also have a good radio. And it doesn't mean your admirals will actually listen to the radar reports. So no, I will not assume that just because they have a viable shipborne radar, that all the other pieces will fall into place.
If they were the conservative morons you make them out to be, the allies would not have had such a hard time against the IJN in 1942/43.
And the main priority for the IJN was the carrier force. They had parity with the USN in carrier aviation while the 2+2 Yamatos have to be compared with 2 North Carolinas + 4 South Dakotas + 6 Iowas + 5 Montanas + 2 Alaskas in the same time frame. Who was really fixated on battleships?
 
Last edited:
Air warning radar will have the most impact.
The most obvious example would be allowing to divert some of the fighters to intercept the dive bombers before they start their attack in Midway, potentially saving the carriers.
Not sure that would have helped. By the time the last wave of American torpedo bombers attacked, the low level Zeroes had used up all of the 20mm ammunition. Their 7.7mm machine guns were almost useless against the sturdy American planes and the much maligned Devastator TBMs blew right through the Zeroes (shooting down two of them!). If the high level Zeroes hadn't come down to help, the Japanese carriers might have still ended up sunk, except this time by torpedoes instead of bombs :)
 
Not sure that would have helped. By the time the last wave of American torpedo bombers attacked, the low level Zeroes had used up all of the 20mm ammunition. Their 7.7mm machine guns were almost useless against the sturdy American planes and the much maligned Devastator TBMs blew right through the Zeroes (shooting down two of them!). If the high level Zeroes hadn't come down to help, the Japanese carriers might have still ended up sunk, except this time by torpedoes instead of bombs :)
Could have happened. Like I said before, the higher flying Dauntless could have been detected first while the sea hugging Devastators could have been detected later reversing the OTL scenario, with the dive bombers being slaughtered and the torpedo bombers having theis day.
The number one rule in AH is "be careful with what you wish for..."
 
If they were the conservative morons you make them out to be, the allies would not have had such a hard time against the IJN in 1942/43.
And the main priority for the IJN was the carrier force. They had parity with the USN in carrier aviation while the 2+2 Yamatos have to be compared with 2 North Carolinas + 4 South Dakotas + 6 Iowas + 5 Montanas + 2 Alaskas in the same time frame. Who was really fixated on battleships?

The carriers were ALWAYS a strike/recon force. Kantai Kessen. The Carriers would whittle down the Americans so that the battleships could defeat them in the decisive battle. The Japanese WERE OBSESSED with the idea of a Decisive battle. They were trying to stage it as late as 1944 for gods sake.
 

MatthewB

Banned
Could have happened. Like I said before, the higher flying Dauntless could have been detected first while the sea hugging Devastators could have been detected later reversing the OTL scenario, with the dive bombers being slaughtered and the torpedo bombers having theis day.
The number one rule in AH is "be careful with what you wish for..."
The Combined Fleet did a remarkable job of combing the torpedoes at Midway, but those dive bombers couldn’t be stopped.
 
Last edited:
The carriers were ALWAYS a strike/recon force. Kantai Kessen. The Carriers would whittle down the Americans so that the battleships could defeat them in the decisive battle.
Nothing reval more what people think then we're they spend their money. The IJN spent a higher percentage of its budget on carriers than any other navy of the world. In December 1941 the RN sent a BB and a BC to defend Singapure. The IJN sent modern aircraft. Real life choices are much more realistic indicators than yearly updates of defense plans. Follow the money.
 
Nothing reval more what people think then we're they spend their money. The IJN spent a higher percentage of its budget on carriers than any other navy of the world. In December 1941 the RN sent a BB and a BC to defend Singapure. The IJN sent modern aircraft. Real life choices are much more realistic indicators than yearly updates of defense plans. Follow the money.

Follow the actions. The Japanese kept their gun line in being as long as possible, because it would be needed for the Decisive Battle. The Carriers, on the other hand, and critically, their aircrews, were expendable. It was not till AFTER Midway that the Japanese pivoted to seeing Carriers as the central part of the battle plan, with an ability to strike over the horizon.
 
Alanith is correct, the pre-war emphasis of the IJN was on the Decisive Battle with the final destruction of the opposing force by the IJN battleships, subs and aircraft carriers and their aircraft were intended to attrit the opposing force and provide the IJN battleships with a superiority in numbers. That mindset continued through at least 1943.
The IJN were not morons and no one has stated that but they were definitely fixated on the concept of offensive superiority and that affected (almost would say tainted) their decision making process immensely.
They always went for offensive capability over any type of defensive capability. The IJN would have seen radar (I'm talking about Air Search radar) as a defensive capability; they would have shoe-horned the system and its operators into their carriers and not pulled the carriers out for a major refit. Additionally, the Japanese mindset was always for a short war with the US, so the attitude of putting together a makeshift solution for the short-term is good enough; we can do a proper remodeling once the war is over.

Nothing reval more what people think then we're they spend their money. The IJN spent a higher percentage of its budget on carriers than any other navy of the world.
Was the amount the IJN spent on carriers higher than the amount spent on battleships? I don't have that info but the Yamato's were major resource hogs. At what point are you selecting your data, because the construction of the Essex class and the CVL's and CVE's should skew that percentage towards the US by 1944?
 
Alanith is correct, the pre-war emphasis of the IJN was on the Decisive Battle with the final destruction of the opposing force by the IJN battleships, subs and aircraft carriers and their aircraft were intended to attrit the opposing force and provide the IJN battleships with a superiority in numbers. That mindset continued through at least 1943.

The IJN were not morons and no one has stated that but they were definitely fixated on the concept of offensive superiority and that affected (almost would say tainted) their decision making process immensely.

They always went for offensive capability over any type of defensive capability. The IJN would have seen radar (I'm talking about Air Search radar) as a defensive capability; they would have shoe-horned the system and its operators into their carriers and not pulled the carriers out for a major refit. Additionally, the Japanese mindset was always for a short war with the US, so the attitude of putting together a makeshift solution for the short-term is good enough; we can do a proper remodeling once the war is over.
As the Japanese were also going for quality over quantity would the IJN concentrate on developing gunnery radars to help their battleships win the decisive battle?
 

SsgtC

Banned
As the Japanese were also going for quality over quantity would the IJN concentrate on developing gunnery radars to help their battleships win the decisive battle?
Probably. A gunnery radar is a logical outgrowth of a surface search radar and meshes well with the Japanese focus on night fighting
 
Follow the actions. The Japanese kept their gun line in being as long as possible, because it would be needed for the Decisive Battle. The Carriers, on the other hand, and critically, their aircrews, were expendable. It was not till AFTER Midway that the Japanese pivoted to seeing Carriers as the central part of the battle plan, with an ability to strike over the horizon.
No.
The IJN build a second to none carrier force at the expense of spending money on battleships. No one could have anticipated that naval aviation alone could stop the USN battle line with 30s tech, so they had to have a battle line of their own. But no one gave as much importance to carriers has the IJN did.
Everything in the IJN was expendable. They didn't expect their BB to all survive their clash with the USN either.
The IJN put its money and it's best people on the carrier force, and kept its battle line with what was left.
It was only when the Carriers could no longer operate with any chance of success that they reverted to battleship centered tactics.
The idea of a conservative battleship obsessed IJN is a convenient cliche.
 
WWII was not just a technical war, but also a production one. Just don’t see radar overcoming the fact that the US built 24 Essex class carriers and scrapped several more being built. A crap ton of light carriers, 19,000 B-24, 12,000 F6F, 12,000 F4U and around 9,000 B-29s. 2,700 Liberty ships, around 60,000 Sherman’s, etc. The US not only had the numbers, but their equipment, training, command and doctrine was better as well. Radar might put off defeat for a little while, but the Essex’s, F6Fs, subs and everything else are still coming.
 
Alanith is correct, the pre-war emphasis of the IJN was on the Decisive Battle with the final destruction of the opposing force by the IJN battleships, subs and aircraft carriers and their aircraft were intended to attrit the opposing force and provide the IJN battleships with a superiority in numbers. That mindset continued through at least 1943.
The IJN were not morons and no one has stated that but they were definitely fixated on the concept of offensive superiority and that affected (almost would say tainted) their decision making process immensely.
They always went for offensive capability over any type of defensive capability. The IJN would have seen radar (I'm talking about Air Search radar) as a defensive capability; they would have shoe-horned the system and its operators into their carriers and not pulled the carriers out for a major refit. Additionally, the Japanese mindset was always for a short war with the US, so the attitude of putting together a makeshift solution for the short-term is good enough; we can do a proper remodeling once the war is over.


Was the amount the IJN spent on carriers higher than the amount spent on battleships? I don't have that info but the Yamato's were major resource hogs. At what point are you selecting your data, because the construction of the Essex class and the CVL's and CVE's should skew that percentage towards the US by 1944?
At any point you want. The Essex have to be viewed against a background of six Iowas and five Montanas. The IJN stopped at two Yamatos and converted the third to a carrier canceling all other battleships planned. After 1942 the USN had so much money that they could buy anythinh you want, so it's not realistic to talk about priorities. Compare ships actually laid down at any point before Pearl Harbor and you'll see a much greater emphasis on battleships on the US side.
Regarding cost, remember that the Yamatos had little R&D cost while the Carriers required three to four different aircraft types that got obsolete and had to be replaced every four years, representing a massive sustained cost.
 
WWII was not just a technical war, but also a production one. Just don’t see radar overcoming the fact that the US built 24 Essex class carriers and scrapped several more being built. A crap ton of light carriers, 19,000 B-24, 12,000 F6F, 12,000 F4U and around 9,000 B-29s. 2,700 Liberty ships, around 60,000 Sherman’s, etc. The US not only had the numbers, but their equipment, training, command and doctrine was better as well. Radar might put off defeat for a little while, but the Essex’s, F6Fs, subs and everything else are still coming.
Nothing can stop Japan being defeated. As I've often said, they went to war expecting the Germans to defeat the USSR and a general peace conference to take place in Mid 1942.
They knew their plans depend on an unlikely lack of resolve from the US to fight back after initial defeats. There is a reason why they only attacked when they did.
 
It was only when the Carriers could no longer operate with any chance of success that they reverted to battleship centered tactics.
The idea of a conservative battleship obsessed IJN is a convenient cliche.
I don't know where you are getting your information from but your assertion is totally inaccurate. IJN strategy was based on the Decisive Battle concept. The IJN envisioned their submarines, land-based aircraft and aircraft carriers as a means to locate and attrit the US battle fleet as it came across the Pacific. There were to be night engagement with cruisers and destroyers using the Long Lance torpedoes to further attrit the US battle fleet. Once, it had been reduced sufficiently, the main IJN battle squadrons (ie, battleships) were then to engage and destroy their opposing numbers. It never worked out that way but that was their strategy and their tactics were developed to support that strategy. It wasn't until Midway that the IJN that aircraft carriers could be considered the decisive combat force as opposed to the battleship.
 
Top