Ki-51 sonia japanese Sturmovik

So it is Ki-61 with Ki-64’s water cooled system?
I really need it, it should be best Ki-61)

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I need it, as well as the Ki-61 III

Unfortunately that is also a made-up designation. Kawasaki tried making more powerful inline engines, but none of those apparently got further than bench testing.

I think it would be best to stick with planes which have solid information about them, instead of doing as many suggestions as possible. It’s also very limited how many WWII planes they are going to implement for Japan in a year, so we should think about which ones we really want out of those.

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That’s very true. Ki-64 and N1K4 are high on my priority list.

As for the Ki-61 III, I thought it was a retronym, but my reading of Japanese Wiki confused me. Perhaps a translation error?


Ammunition count for the Ki-51’s 12.7 mm Ho-103 machine gun.

In October 1944, the Ki-51s of the 27th Flying Regiment, which participated in the support of the Battle of Leyte Gulf, carried 1200 rounds of ammunition. If we subtract 1020 rounds (15 x 68 round capacity magazine) for the flexible machine guns from this, we get 180 rounds for the fixed machine guns and 90 rounds for each gun. I think this number of rounds is a little low, but looking at the combat records of the 27th Sentai, they only consumed about 60 rounds at most on bombing and patrol missions, so this number of rounds may have been acceptable.

Of course, my calculations could be wrong. One could also consider that they reduced the number of rounds for the flexible machine gun and increased the number of rounds for the fixed machine gun. This source is not conclusive evidence.

Aircraft type Type 99 Assault
Aircraft registration 1475
Bomb type 250 kg
Fuze type Short delay
Number of bombs 1
MG ammo type AP and Incendiary
Number of rounds 1200

27th Flying Regiment 2nd Company Combat Diary September 1, 1944 - October 31, 1944


One must remember the difficulties of Japanese factories at this point in the war. The Germans also reduced their shell consumption in 1944/45 because they had to save it. Thank you very much for your contribution and help :D


That’d be nice. It looks much better with the cut-down canopy, too:


Nice and slender.

Ki-61-I Tei Kai would be even more overtiered than the regular Hei and Tei. Would be interesting but ultimately not a great addition, the Ki-61s don’t struggle with firepower.

Ki-61-II Otsu - same as above. Its issue isn’t firepower, its climb rate and weight. Speed too, to a lesser extent. Not saying no, but its not something I particularly want.

Evaporative cooling - just no, way too fragile. One hit from any caliber and you’re immediately cooking your engine.

Now, a Ki-64? That I would very much like to see, among others.


The fixed machine guns were upgraded from 7.7 mm to 12.7 mm in November 1943, but there are sources that say the flexible machine guns were also upgraded from 7.7 mm to 7.92 or 12.7 mm.

The Ki-45-Kai Hei, which was deployed to the assault squadron as the successor to the Ki-51, was equipped with a 7.92 mm Type 98 machine gun as a flexible machine gun, so it is highly possible that the Ki-51 was also equipped with the same 7.92 mm machine gun.

The 7.92 mm Type 98 machine gun has a magazine capacity of 75 rounds. If the Ki-51 had 12 x flexible machine gun magazines, the number of rounds would be 900 rounds, while the 12.7 mm fixed machine guns could use 300 rounds, or 150 rounds for each gun. This underscores the hypothesis that upgrading from 7.7 mm to 12.7 mm would cut the number of rounds in half.



“From November 1943, the 7.7 mm fixed machine guns on both wings were upgraded to 12.7 mm Type 1, and the rear machine gun was upgraded to a Type 98 flexible gun.”

Magazine Maru, ed. 2011. Type 99 Assault Plane, Rabaul Air Battle Record (九九式襲撃機ラバウル空戦録). p.29


“Flexible guns were also replaced with 7.92 mm Type 98 flexible machine guns from November 1943 due to the demand for more armament. It is said that some squadrons also used a set of 12.7 mm Type 1 flexible machine guns.”

Magazine Maru, ed. 1999. “Type 99 Assault” Mechanism of Military Aircraft. p.77


You did a great job, but there are a few question marks. First of all, the Type 98 KM has completely different magazines than the Type 89 KM, so their number on board could have been different. The Type 89 machine gun uses disc magazines, and the Type 98 machine gun uses drum magazines, which changes the way they are mounted in the machine (type 89 magazines were mounted flat on the sides of the hull).One more question, what is the 12.7 type 1 heavy machine gun? The Japanese used the Ho-103 heavy machine gun, which had no “type” assigned to it, and the only mention of the Type 1 was the 7.92 caliber Te3 machine gun.
Thank you very much for your contribution and dedication to the ki-51

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“Exploding Fuel Tanks: Saga of Technology That Changed the Course of the Pacific Air War”

This book has a drawing from US intelligence about the armor protection. It says pilot head, body and seat bottom armor were all 7mm. Their shapes and sizes are included. Unfortunately there isn’t as accurate data about the engine plates. They are said to have been 6.5mm.


Is there any informative mentions about Fuel Tank fire extinguisher systems in this book?

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Quite many short mentions all over. I haven’t read much of it yet. One interesting thing was about A6Ms with the system. In some units they stopped using the front fuselage tank, since that one wasn’t protected by CO2 system, while the wing tanks were.


The problem is that the Japanese were the only ones who massively used fire extinguishing fuel tanks, and any study of the issue of tank explosions without studying these systems is just a book without any adequate information.
I’m just afraid that this is another book in the series “Everything was better with us, everything was worse with them”
But if there are adequate descriptions and studies of these systems, then this is very good

Can you send me the page number in this book where it says this so I can add it as a source?

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Any news? (I’m a big G3M3 fan)

Moderators have been considering the suggestions for three weeks

Ki-201 sent to moderators on March 26
Ki-46 III-Kai sent 27 March
Ki-147 sent 27 March
Ki-44-III sent 29 March
Ki-12 sent 29 March
G3M3 sent 30 March
Ki-98 sent 2 April


Let’s hope it won’t take too much

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It doesn’t have page number. It’s called: Appendix IV - Japanese Armor Protection [U.S. intelligence report]

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“Everything was better with us, everything was worse with them”

Perhaps as an additional form of protection for already well protected plane if extra weight wasn’t too much of an issue. The fuel tank extinguishing system is usually best known from N1K2-J and few other late war types, however it’s important to know where the use started to understand why only Japanese used them.

The first uses in combat that I can find were with A6M5 and G4M, both of which didn’t have self-sealing fuel tanks at that point. It is well known how IJN took very long to implement self-sealing tanks into their aircraft. In this IJA wasn’t far ahead as their early “leakproof” tanks, which are said to have been only somewhat effective against .30cal. The jump from mainly rifle caliber armed Chinese fighters to US fighters of 1942 and onwards with up to 6x.50cals was too big for Japanese to keep up. In the same year they were still trying to acquire more advanced fuel tank protection technology from Germany. In fighter aircraft Japanese only fielded satisfactory self-sealing tanks from start of 1944, though improvements were still desired. Compare this to other major air powers of the war.

Early on with IJN aircraft, it appears those fuel tank extinguishers weren’t even expected to save the aircraft, but rather put out the fire so the valuable aircrew would have time to jump. The danger was even worse, because non self-sealed tanks didn’t only catch fire easily, but they could also quickly “deform” and explode from large caliber hit and the following fire.

Later on Japanese developed effective self-sealing fuel tanks, but these became thicker and heavier than comparable Allied types. This was mainly a problem for single engine fighters as it was difficult to fit these type of tanks into the wings without sacrifing fuel load. Army was satisfied with Ki-84 with fully self-sealing tanks, even when the range was slightly less than desired. Ki-61 probably couldn’t just switch to the thickest tank type as it’s said these had fuel tank extinguishers as well. Anyway IJN and Mitsubishi had very different approach to this problem: J2M and A7M were made with non self-sealing wing tanks. Only the fuselage tank was self-sealing and all tanks had extinguishers.

The fuel tank extinguishing system was overall very simple: They were just tanks with piping and thermostat as trigger. I don’t see any reason to suspect why the system itself wouldn’t be effective, but without dozens of reports it is impossible to write down any kinds of statistics how they changed results of the combat. This is further complicated by all the very different types of aircraft where the system was used. Furthermore an aircraft which would get to test the system in combat, was already damage, thus it had lower chances of getting back home to report. There are still Japanese archives where something related could be found, but how comprehensive report would one realistically expect?

At any rate the flaws of the system are very obvious:

  1. CO² or nitrogen bottles and their piping added weight.
  2. The system could be damaged by hits.
  3. There was only one shot for each fuel tank.
  4. It didn’t seal the tank like a self-sealin fuel tank.

Overall well made self-sealing fuel tanks were a better option.

There are few things I have not seen mentioned in other sources than that book:
-IJA used nitrogen extinguishers. I do not know if these changed to CO².
-Some variants of Ki-21, Ki-48 and Ki-49 had extinguishers.