D4Y4

[Gratch1111]

Couldnt find anything but AAR about this aircraft so ask here. IRL the D4Y4 had armour protection but it doesnt in the game, anyone know why this hasnt been corrected?

[BBfanboy]

Do you have a source for the IRL claim of armour?
Is the durability of the aircraft unchanged from earlier versions?

[Chris21wen]

All references I've seen alway say it had limited armour?

[Gratch1111]

D4Y4 Suisei Model 43 (彗星四三型, Suisei 43-Gata)
Final production variant. Bomb load increased to 800 kg (1,760 lb) with the main bomb semi-recessed in the bomb bay. It had 75 mm bullet-proof glass in front of the canopy, plus 5mm and 9mm thick armour plates fore and aft of the cockpit. The fuel tanks were also given added protection, and the movable rear machine gun was removed

Ishiguro, Ryusuke; Januszewski, Tadeusz (2009). Japanese Special Attack Aircraft & Flying Bombs

D4Y4 Model 43
Final production variant with increased bombload to 800 kg. Added bullet proof glass to the canopy and armor plate to the cockpit plus protected fuel tanks.

https://pacificwrecks.com/aircraft/d4y/tech.html

Like many other Japanese aircraft of the time, the D4Y lacked armour and self-sealing fuel tanks and it was not until the final variant, the D4Y4, that the aircraft was given bulletproof glass and armor protection for the crew and fuel tanks.

https://www.silverhawkauthor.com/post/w ... -d4y-susei

The D4Y4 or dive bomber type 2 model 43 was design fopr this, without bomb bay doors and a fuselage chassis reinforced. It kept its powder rockets for take off as well, but now used also for the final approach. Survivability was improved for the first time with a 7-mm armor plate at the back of the pilot’s head and 75-mm armored glass windshield. Capacity of the fuel tanks was increased to 1,345 liters, and tanks at last were better protected.

https://naval-encyclopedia.com/naval-av ... ka-d4y.php

D4Y4 was mostly used as Kamikaze bomber but was initially intended and used as DB from what I can see

[Chris21wen]

D4Y4 model 43 was a special attack aircraft, it needed of two crew so no rear gun and it was never used as a DB. In one source I've read it also had rocket assisted take off or boost speed during final attack. It is conceivable that it did have improved armour but I lack your book ref but the web ref do support it.

[RangerJoe]

I think that the possible use as a regular dive bomber was a gift to the Japanese since they need so much help otherwise.

[PaxMondo]

RJ: I would agree with you on that, there are a number of Easter Eggs for the IJ in the game to try and keep some hope for the IJ players.

D4Y4
This is my take on this plane. You can extrapolate many of these observations to a number of other late war aircraft models in the IJ air fleet.

The D4Y program suffered greatly from a lack of working engines. The D4Y1 and D4Y2 tried to use a water cooled engine, but the engine program ended in dismal failure. Key issue was the induction ... they could NOT build a stable 2 stage induction system. Without that, the water cooled engine simply lacked the power to be effective. They could barely take off. This forced them to go to an old, but well known engine family: the 7-star Ha-33. This was a 14 cylinder engine with 2 rows of 7 cylinders each. Initially used in the Val D3A series, it had a single stage / single speed super charger and could put out about 1000 hp. In spite of all of their efforts, they NEVER succeeded in a stable 2-stage induction system of any type (super, turbo, or twin charger). By using 2 speed super chargers and adding mechanical fuel injection and Methane injection, they could get the Ha-33 up to about 1500 hp at war end. This was about half of what the P-47 was getting using a 2 stage - multi-speed charger with +140 Octane AVGas.

The mechanical fuel injection was finicky and hard to maintain. The Methanol injection was a problem as it required ultra-pure water which the airfields struggled to supply, resulting in additional engine failures due water impurities.

In game the P47 has an SR of 1 and the D4Y4 and SR of 1 as a total gift to the IJ players. The SR of the D4Y4 should be at least 3 and likely higher. Like many other mid/late war aircraft designs of the IJ it was a good design. It failed as the engines needed never got into production. If the IJ had successfully developed a 2 stage induction system and attained the 2000 hp target, the D4Y4 likely could have supported DT's, had a combat range of +350nm and been a real threat.

[kanadanoyamaneko]

From René J Francillon, Japanese Aircraft of the Pacific War (1970), p.460...

« A final bomber version providing crew and fuel tank protection was under development when Japan capitulated. Intended to be powered by a 1,825 hp Nakajima NK9C Homare 12 eighteen-cylinder air-cooled radial, the D4Y5 was to have entered production in late 1945 as the Suisei Carrier Bomber Model 54. »

Hello all, my first post on a Matrix Games Forum... I've purchased the game in september 2022, played the Coral Sea scenario two times as Japan, watched tutorials by Jochen Heiden and Xargun... I'm also following Jochen Heiden's various campaigns on YouTube... Some previous experience in the late 90's with Gary Grigsby's Pacific War with its one-week turns... Presently dabbling in the Grand Campaign (scenario 1) as a Japanese player (Boy what a time sink!).

[anarchyintheuk]

Welcome to the board.

[PaxMondo]

From René J Francillon, Japanese Aircraft of the Pacific War (1970), p.460...

« A final bomber version providing crew and fuel tank protection was under development when Japan capitulated. Intended to be powered by a 1,825 hp Nakajima NK9C Homare 12 eighteen-cylinder air-cooled radial, the D4Y5 was to have entered production in late 1945 as the Suisei Carrier Bomber Model 54. »

What Francillon omits, or did not know, was that the Ha45 (Homare) had the same issues. The 1825hp was a wish that was never attained ROUTINELY. They could build one-offs, but they simply could not setup a production line and get 1000/month with 1825 hp rating.

The 1825hp would have been easily attainable with a 2 speed 2 stage induction system (probably super charger for fighters) even at the 80 - 90 RON the IJ had for AvGas. But they couldn't. That meant Methanol injection and fuel injection again to hit something near there with the same problems as noted above.

I wish I could say that my studies have led me to a conclusive reason as to why. Unfortunately, they have not. Both of the other 2 Axis partners had 2 stage induction in their 1939 aircraft engines. We know that multiple samples of the engines, both completed and in kits were furnished to the IJ. We also know that the IJ was aware of the metallurgies required and were not only capable of producing them, but we know that many/most of them were being produced at some level.

What I have not been able to find as yet are:
- production limitations on these specific stainless steels needed for these 2 stage systems. I'm sure there were, but what those limits were I have not been able to find
- test results on these 2 stage systems. I can find reports of failures, but not the actual test data to see where/how they were failing. It is baffling to me that both the Nakajima AND Mitsubishi teams both apparently failed to implement this. Yes, it is a bit tricky and yes in this era there was a great deal of trial and error to get the empirical data to create your design envelope. But they were given working systems to test and copy. They should have been able to do it. Let me put it this way; Big Daddy Don Garlits figured it out in the 60's and he didn't have 25 engineers like Nakajima did. So, sure you blow a few up, but you do figure it out.

[Gratch1111]

From what I could tell the D4Y4 was designed to be a DB but it was turned into a Kamikaze aircraft, so at least in my book its a DB if Japan has the carriers/bases to use it as such. I guess no one cares very much since how many games ever get that far

[RangerJoe]

From what I could tell the D4Y4 was designed to be a DB but it was turned into a Kamikaze aircraft, so at least in my book its a DB if Japan has the carriers/bases to use it as such. I guess no one cares very much since how many games ever get that far

Another gift to the Japanese player is aircraft research. Not only can the Japanese player get aircraft in sooner, they can even skip research models completely so once the first model in an upgrade path has a research factory completed, then can just move up the line directly until they stop at the desired model that they want to use without having previous models fully researched and ready for production. Especially with PDU ON.

Then the other Japanese gift comes into play where the Japanese player can vastly increase the production of models that they want to use without producing any intermediate models if they are playing with PDU ON.

[Chris21wen]

From what I could tell the D4Y4 was designed to be a DB but it was turned into a Kamikaze aircraft, so at least in my book its a DB if Japan has the carriers/bases to use it as such. I guess no one cares very much since how many games ever get that far

Another gift to the Japanese player is aircraft research. Not only can the Japanese player get aircraft in sooner, they can even skip research models completely so once the first model in an upgrade path has a research factory completed, then can just move up the line directly until they stop at the desired model that they want to use without having previous models fully researched and ready for production. Especially with PDU ON.

Then the other Japanese gift comes into play where the Japanese player can vastly increase the production of models that they want to use without producing any intermediate models if they are playing with PDU ON.

This is only partially correct. Yes you can can skip research models but not without penalty. If you skip a model completely or even a partially repaired one then the factory reverts to completely damaged with an approx 1/3 reduction in it's size. Obviously they then have to be repaired again and that is the biggest overriding factor in research is time. The further away any ac due date is the longer it takes to repair, and by far the quickest way to get any aircraft model is to fully research earlier model before researching a later model. That way factories are not damaged.

Look at this game time 13 Feb 43 v26b. The two A6M8 factories were fully repaired A6M5. One was upgraded through the family, the second skip all and went straight to the A6M8. Guess which one?

Second if you look at the A7M2 factory, due just a month after the A6M8, you can see in it's 1(29). The A7M2 has been researched from day one and ONLY one factory has been repaired in all that time. Similay will happen to the 0(21) A6M8 factory.

For me the ability to upgrade through the family before an aircraft is fully research sould not happen without penalty. E.g. as in skipping. As it is you can but a house rule preventing it should be in place and I'm generally against most house rules, but not this.

Oh! and before I'm accused of being an Allied fan, I'm not, I prefer to lose

Screenshot 2025-02-22 075451.jpg (17.14 KiB) Viewed 222 times

[RangerJoe]

From what I could tell the D4Y4 was designed to be a DB but it was turned into a Kamikaze aircraft, so at least in my book its a DB if Japan has the carriers/bases to use it as such. I guess no one cares very much since how many games ever get that far

Another gift to the Japanese player is aircraft research. Not only can the Japanese player get aircraft in sooner, they can even skip research models completely so once the first model in an upgrade path has a research factory completed, then can just move up the line directly until they stop at the desired model that they want to use without having previous models fully researched and ready for production. Especially with PDU ON.

Then the other Japanese gift comes into play where the Japanese player can vastly increase the production of models that they want to use without producing any intermediate models if they are playing with PDU ON.

This is only partially correct. Yes you can can skip research models but not without penalty. If you skip a model completely or even a partially repaired one then the factory reverts to completely damaged with an approx 1/3 reduction in it's size. Obviously they then have to be repaired again and that is the biggest overriding factor in research is time. The further away any ac due date is the longer it takes to repair, and by far the quickest way to get any aircraft model is to fully research earlier model before researching a later model. That way factories are not damaged.

Look at this game time 13 Feb 43 v26b. The two A6M8 factories were fully repaired A6M5. One was upgraded through the family, the second skip all and went straight to the A6M8. Guess which one?

Second if you look at the A7M2 factory, due just a month after the A6M8, you can see in it's 1(29). The A7M2 has been researched from day one and ONLY one factory has been repaired in all that time. Similay will happen to the 0(21) A6M8 factory.

For me the ability to upgrade through the family before an aircraft is fully research sould not happen without penalty. E.g. as in skipping. As it is you can but a house rule preventing it should be in place and I'm generally against most house rules, but not this.

Oh! and before I'm accused of being an Allied fan, I'm not, I prefer to lose
Screenshot 2025-02-22 075451.jpg

The fully repaired A6M8 is what I am referring to as far as skipping models. I will not do this against the AI and players would have to agree to this. But then again, I have no problem with newer models coming in relatively fast either so I will research all of them so the first effective model that I want comes in immediately after the first models. An example is researching the Judy DBs so that the third Judy comes in right after the first two Judys.

[PaxMondo]

Second if you look at the A7M2 factory, due just a month after the A6M8, you can see in it's 1(29). The A7M2 has been researched from day one and ONLY one factory has been repaired in all that time.
Screenshot 2025-02-22 075451.jpg

Chris, serious bad luck on that A7M2 factory. Even the A7M3 has done better!!!