Nakajima Ki-44-IIIa

[Grzegames]

[Would you like to see this in-game?]

• Yes
• No

Nakajima Ki-44-IIIa
This aircraft was created to be able to compete with American aircraft. Probably about 6 copies were made, but the aircraft did not enter mass production due to the creation of a better Ki-84.
History and description of the structure
From the moment the fighting with the Americans began, it became obvious that the current Japanese aircraft were too weak and had too weak armament, so work began on improving the Ki-44 interceptors. Thus, in June 1943, the prototype of the heaviest armed Ki-44 was put into service.The changes in this aircraft compared to its predecessor are:

• Replaced the Ha109 engine with the more powerful Ha145 (Ha45-43) engine
• Replacing half of the Ho-103 rifles with more powerful Ho-5 cannons
• Replacement of a three-blade propeller with a four-blade propeller
• The wing area has been increased to 19 m2
• The shape of the wings was changed and the wingspan was increased by 70 cm.
• The surface area of the vertical and horizontal tail stabilizer has been increased.

The tests lasted until December and during the tests all Ho-103 rifles were replaced with Ho-5 cannons. About 5 Ki-44-IIIa aircraft were produced, which were armed with four 20mm cannons. In 1943, comparative tests of the Ki-44-IIIa and the Ki-84 prototype were carried out, which showed that although the Ki-44-IIIa was better than its predecessors (Ki-44-II), the Ki-84 fighters were better than it, which caused the discontinuation of production of further Ki-44-IIIa aircraft.
Improvement Proposal
There was also a version of the Ki-44-IIIb, which was to have two Ho-5 cannons in the nose and two Ho-203 guns. Some sources say that it could have been created, others deny it. This does not change the fact that this modification would require either a radical modification of the wings or a deep modification of the Ho-203 cannons.
General characteristics

• Crew: 1
• Length: 8,75 m
• Wingspan: 9,44 m
• Height: 3,24 m
• Wing area: 19 m2
• Empty weight: 2,886 kg
• Powerplant: 1x Ha145 2000hp
• Propellers: 4-bladed constant-speed metal propellers

Performance

• Maximum speed: 660 - 680 km/h
• Cruise speed: 605 km/h
• Range: ?
• Service ceiling: 11 000 m
• Maximum Rate of Climb: 20,1 m/s

Armament

• 4 x 20mm Ho5 cannons (two in the wings, two in the nose)(150 rounds per cannon)
• 200 kg bombs (2 x 50 kg or 2 x 100 kg)

Special thanks to the user

• @TM_06

Summary
This aircraft is the last evolution of the Ki-44 and is very similar to the Ki-43-III, both were built in a similar period and have similar armament to help fight the Americans.Adding it would be good for the fighter aces of the Ki-44 aircraft, which would then be a preparation for the use of the Ki-84. I encourage you to discuss in the comments and share additional information if you have any.
Finally, I apologize for the linguistic and logical errors because unfortunately English is not my main language and I had to use google translator.

Internet Sources

Ki-44-IIIa Kou - Demon Slayer - Passed for Consideration - War Thunder - Official Forum
鐘馗 (warbirds.jp)
二式単座戦闘機 - Wikipedia
Nakajima Ki-44 – Wikipedia, wolna encyklopedia
Nakajima Ki-44 Shoki / TOJO - interceptor (aviastar.org)
Nakajma Ki-44-III? | Forum Tajnych Projektów (secretprojects.co.uk)
Ki-44 Shoki Nakajima (airpages.ru)
Nakajima Ki-44 Shoki (Tojo) Single-Seat, Single-Engine Fighter / Interceptor Aircraft Specifications and Pictures (militaryfactory.com)
Уголок неба ¦ Nakajima Ki-44 Shoki (airwar.ru)
Nakajima Ki 44-IIIa Shoki [Tojo] : Nakajima (valka.cz)
Nakajima Ki-44 Shoki (Tojo): Photos, History, Specification (tvd.im)
Ki-44 (j-aircraft.com)

Book source

• Japanese Aircraft of Wolrld War II : 1937-1945 ,Thomas Newdick, Edition 2 2017, page 40
• (PDF) FlugRevue - Nakajima Ki-44 Shoki - DOKUMEN.TIPS
• (PDF) Bunrindo - Famous Airplanes of the World 16 - Nakajima Ki-44 ‘Shoki’ Army Type 2 Fighter - DOKUMEN.TIPS
• 『航空情報』1956年3月号
• 『航空ファン』1961年7月号
• 『ミリタリー選書14 日本陸軍の試作・計画機 1943~1945 』
• 『航空ファン1981年7月号』
• Mr. 秋本実『日本の戦闘機』
• 『日本航空機大図鑑 : 1910年-1945年 中巻 』

Additional sources

[PercussionCap]

+1, though it’s a shame there’s so little data on this plane. Seems like all the documents were either burned when they surrendered or never existed in the first place. Not even a photo survives…

[TM_06]

Unfortunately I’m not able to find any information about the speed, you can find it on the old forum, but they are also estimated.

Howdy, creator of that old suggestion here! There are a lot of errors in this suggestion.

• The aircraft was built and did fly. It was completed in June 1943 and completed its first flight in December 1943. Either 2 or 3 aircraft were built.
• The top speed is known, there are a few sources that confirm it to be ~413 mph / 665 kph.
• The rate of climb is also known, 20.1 m/s was given in a few sources.

If you look back at the old suggestion in the comments, there’s a lot of source material there provided by Cherry_Blossom and Lineins. It’d be a good idea to update that with the information there, because all of the information in my old suggestion is accurate.

[PercussionCap]

Do you know what the final wing shape was? Wingspan stayed the same, but area went from 15m2 to 19m2. Engine cowling must have changed too, but that’s easier to guess.

[TM_06]

I believe the overall wing shape was similar to that of the Ki-84’s while retaining the rounded tips of the previous Ki-44’s. At least, that’s what I can glean from what might be the only image of the aircraft:

[Grzegames]

I won’t be able to improve the suggestions in the near future. But I will do it as soon as possible.

[PercussionCap]

I dunno, the wings on those two look identical. Without any further information I would hypothesize that they moved the whole leading edge to where the root extensions for the landing gear are:

so it would be more like the Ki-84, which was in development at around this time. This might give it the 19m2 wing area that is often mentioned.

EDIT: this guess was wrong, each wingtip was extended by 700mm. Scroll down for more.

[Noveos_Republic]

Wow, the Ki-44 really was an incredible aircraft, even without the more powerful engine upgrade.

[PercussionCap]

Alright, I checked the fantastic source material in the replies for the original old forum suggestion.

This is of particular interest:

It is a translation of a series of documents (all in japanese) posted above it, and clarified a couple things - for one, the data in this image

Spoiler

about the Ki-44-III’s wingspan is wrong. The wingtips were extended by 700mm each, thus leading to the higher 19m2 wing area. Elevator and rudder were enlarged. Takeoff and landing performance stayed the same (and therefore so did low speed maneuverability).

Engine is a Ha-45-21 as we have now in the Ki-84. Ha-145 was likely a provisional name for this engine, while the Ha-45-11 was just named Ha-45.
At this point the engine that would later be named Ha-145 (a Ha-45-43) didn’t exist yet. Also, extremely confusing naming with the army and navy having their own, plus the unified naming scheme on top of that.

And about the new engine cowling with individual thrust ejector exhausts - since the Ki-84 had the same engine and was in development at this time, they would be very similar.

[Grzegames]

Thank you for this information. As soon as I return from vacation, I will immediately correct the suggestion about the Ki-44-IIIa. I would do it right away, but it’s almost impossible on the phone

[PercussionCap]

Understandable, mobile makes it quite annoying to make these large edits. Have a good vacation!

[TM_06]

It is a translation of a series of documents (all in japanese) posted above it, and clarified a couple things - for one, the data in this image about the Ki-44-III’s wingspan is wrong. The wingtips were extended by 700mm each, thus leading to the higher 19m2 wing area. Elevator and rudder were enlarged. Takeoff and landing performance stayed the same (and therefore so did low speed maneuverability).

The information isn’t “wrong” per say. The Data for the aircraft is extremely hard to find, the table was most likely made without the knowledge provided from the interviews. Almost every other source says 19 m², so it’s still something to take into consideration. Lineins also told me that it wasn’t a perfect translation, so that’s important to remember as well.

[PercussionCap]

Yes, every source says 19m2 but didn’t say exactly how that was achieved. You can make the wings longer, or you can make the distance between the leading and trailing edges bigger (like in my little paint sketch).
This was more complicated by that small table saying the wingspan stayed the same, which has to be wrong - at least that number specifically. Wingspan went up and so did wing area, and I haven’t seen anything to make me doubt that statement. Making wings longer is a tried and true method for making an aircraft takeoff and land more easily.

Sure, the translation isn’t perfect but it doesn’t have to be, and we can gather pretty concise information from there.

[TM_06]

Well done on the remade suggestion, and thank you for incorporating my corrections!

[PercussionCap]

It is better, but the engine model is still wrongly listed - I don’t think the Ha-45-43 existed at that point in time and was likely just a -21, like in the in-game Ki-84s.

[Grzegames]

I know Wikipedia is a poor source, but here’s what it says on the Japanese Wikipedia

[PercussionCap]

I know this, but when the Ki-44-III was made and tested, the Ha-45-43 simply didn’t exist exist yet. It was a very late war engine and the Ki-44-III’s testing and design stage happened at the same time as the Ki-84 prototypes started flying. Ha-145 was likely a provisional designation for the Ha-45-21, while the “Ha-45” was the -11, in the army designation system.

A 2 stage, 3 speed supercharger is quite big, it wouldn’t fit in the Ki-44’s airframe without making it quite a bit longer or doing some big internal changes, more on that below. Coincidentally that’s pretty much the same engine as on the J6K1 in-game and in x-ray view you can see that there’s a LOT more (empty) space behind the engine.

Ki-44-II

J6K1

The Corsairs also have a 2 stage 3 speed supercharger.

The one drawing of the Ki-44 that we have doesn’t show it being any longer:

And repositioning the oil and fuel tank to make space wasn’t mentioned anywhere in the translated documents, which is a massive change to the Ki-44’s design and would be pretty weird to omit.

There’s another issue, which is power output. A 2 stage, 3 speed supercharger-equipped engine isn’t gonna lose much power with altitude, but this is exactly what is claimed about the “Ha-145” - scroll up a little to the big user-translated comment that I posted.
An excerpt from a book claims the Ha-145 made just 1450hp at 6400m, while at this same altitude the in-game Ki-84s will do ~1600-1650hp with their Ha-45-21 (single stage, two speed supercharger) depending on speed. Funnily enough, the Ha-45-42 in the J6K1 at the same 6400m is making ~1660hp.
One of the documents I have on the N1K2-J, with the same Ha-45-21 as the Ki-84s, claims 1625hp at 6100m.

With all this in mind, I simply don’t believe that it was a Ha-45-43 with a 2 stage 3 speed supercharger, and Ha-145 was instead a provisional designation for the Ha-45-21, which was later changed. It making 1450hp instead of 1600+ up high was likely due to it being an earlier version of the Ha-45-21 that didn’t make as much power up high, maybe because it had to use reduced RPM/throttle settings; the J6K1’s engine might be underperforming in-game at that altitude and the Ki-84 might be slightly overperforming, but hey I’m not telling that last part to gaijin. Or maybe Nakajima just had a better intake system than Kawanishi did.

And on top of that, IF it was a Ha-45-43 with a 2 stage 3 speed supercharger, its top speed would be at a much higher altitude than just 6400m - J6K1 has a very similar engine and its top speed is at 10000m. Meanwhile, all the Ha-45-21-equipped planes have their top speeds at altitudes very close to 6400m, with all the Ki-84s having theirs at 6000m; the document on the N1K2-J I referenced above puts its top speed at 5600m (maybe Nakajima really has a better intake design than Kawanishi for these two aircraft!).

[Teh0]

Apparently just “Ha-45” meant Ha-45-21 in IJA, but it could well mean a derated engine.

I’m not certain what kind of supercharging system Ha-145 had, but indeed it had 3 critical altitudes. The bottom says that - - - line indicates expected performance.

Spoiler

[PercussionCap]

Every time the Ha-45-43 is mentioned, it’s as a 2 stage 3 speed model so I have no reason to doubt it, and your chart confirms this. In either case, I really don’t believe it could be the 2 stage supercharger model engine due to all the reasons I outlined above.

[PercussionCap]

@Teh0

Apparently just “Ha-45” meant Ha-45-21 in IJA, but it could well mean a derated engine.

Also to clarify this: there were derated Ha-45-21s, and it’s very clearly said that it was rated for 2000hp (at low altitude) so it can’t be the earlier Ha-45-11 either.