Nakajima 'army fighters' after the Ki-27

[tomo pauk]

Nakajima was certainly a prolific company when it is about the number of aircraft designs they pu in the air; granted, some were good, some not so good. So let's give them a second chance, at least when it is about the fighters for the IJA: once the Ki-27 production starts, how should the next fighters look like? Using the aerodynamics, engines, guns etc. of the day, as available to the company.
To make their job easier, we'd have the IJA brass being less stringent on required maneuverability, perhaps after a few instances of Tupolev SB bombers getting away from their fighters due to insufficient speed and firepower of the Ki-27s, or for whatever the plausible reason.

 

[SealTheRealDeal]

Nakajima was certainly a prolific company when it is about the number of aircraft designs they pu in the air; granted, some were good, some not so good. So let's give them a second chance, at least when it is about the fighters for the IJA: once the Ki-27 production starts, how should the next fighters look like? Using the aerodynamics, engines, guns etc. of the day, as available to the company.
To make their job easier, we'd have the IJA brass being less stringent on required maneuverability, perhaps after a few instances of Tupolev SB bombers getting away from their fighters due to insufficient speed and firepower of the Ki-27s, or for whatever the plausible reason.

Didn't they get exactly that with the Ki-43, -44, and -84?

 

[Peg Leg Pom]

You use the same aircraft, add self sealing fuel tanks, armour back plates, better guns and make sure every aircraft has a radio while squeezing every possible bit of power out of the engines.

Also rotate experienced pilots back to the training establishments regularly and put some effort into recovering pilots that have been shot down.

 

[tonycat77]

Nuke the Aichi-DB deal, so no DB-601s.
Ki-61 flies as the Ki-100 by 1942.
Heavier armed Ki-43, with a more powerful engine and working radios.
Single seat Ki-45 instead of two seater, make the BF110 be trialed in China or Spain in 1938 and fail to do this.

 

[M79]

Use pratt and whitney 2140 engine clones in place of the Ha5 on the Ki-44. Otherwise add safety features as above.

 

[Belisarius II]

Actually, Nakajima did a pretty good job after the Ki-27. They did a better job in designing and producing a new generation of aircraft then Mitsubishi did for the IJN, where upgraded versions of the Zero had to soldier on till the end of the war. The problems stemming from the shortages of strategic metals were beyond their control. Quilty control should have been better, but many issues stemmed from those shortages of strategic metals. The Ki-84 Frank was one of the best Japanese fighters of the war. The IJAF's obsession with maneuverability was a mistake. The speed, firepower, and toughness of the Frank made it a tough opponent for the best American fighters of the war.

 

[173rd LRRP]

Now called Subaru

 

[Chris Triangle]

Actually, Nakajima did a pretty good job after the Ki-27. They did a better job in designing and producing a new generation of aircraft then Mitsubishi did for the IJN, where upgraded versions of the Zero had to soldier on till the end of the war. The problems stemming from the shortages of strategic metals were beyond their control. Quilty control should have been better, but many issues stemmed from those shortages of strategic metals. The Ki-84 Frank was one of the best Japanese fighters of the war. The IJAF's obsession with maneuverability was a mistake. The speed, firepower, and toughness of the Frank made it a tough opponent for the best American fighters of the war.

On the other hand, who was it who made the engine that so limited the Zero's capabilities?

 

[marathag]

On the other hand, who was it who made the engine that so limited the Zero's capabilities?

The other main manufacturer of Japanese engines, Mitsubishi,who had a larger engine, the 1970 cubic inch Kinsei radial of 48 in diameter and 1000hp well before WWII started.
They also Ha101 aka Kasei in Naval service, 14 cylinder radial of 1500HP in 1939. It was 2567 cubic inches and 1700 pounds. 53 inch diameter.
Roughly equal to the Wright R-2600, that was slightly heavier with a 55 inch diameter, and a lot lighter than the P&W R-2800 of slightly smaller diameter.
They had plenty of engines to choose from, if wanting a little more punch than provided by the Nakajima Sakae.

 

[Chris Triangle]

The other main manufacturer of Japanese engines, Mitsubishi,who had a larger engine, the 1970 cubic inch Kinsei radial of 48 in diameter and 1000hp well before WWII started.
They also Ha101 aka Kasei in Naval service, 14 cylinder radial of 1500HP in 1939. It was 2567 cubic inches and 1700 pounds. 53 inch diameter.
Roughly equal to the Wright R-2600, that was slightly heavier with a 55 inch diameter, and a lot lighter than the P&W R-2800 of slightly smaller diameter.
They had plenty of engines to choose from, if wanting a little more punch than provided by the Nakajima Sakae.

The Kinsei certainly had more potential than the Sakae, though admittedly, by the time the A6M needed a serious upgrade, it should have been in the form of a whole new aircraft.

Would a wider engine by three inches have really been that big of a challenge to accommodate and still meet the design requirements? Could it have kept such good range with the Kinsei?

 

[marathag]

Would three inches more have been that big of a challenge to accommodate?

Not enough to worry about, given that the Hellcat and Corsair used the 53" R-2800.
The Kasei was a lot lighter than the P&W, but also less powerful.
Like the USA and the troublesome effort to close cowl the larger radials for reducing drag, the Mitsubishi J2 'Jack' had slow development, and frankly, too small a wing- smaller than the F8F Bearcat or even the original A6M Zero

 

[tomo pauk]

Alternative Ki-43:
Have them make a small-ish fighter instead, like the J 22, or MC.200 (but obviously with enclosed cockpit and decent engine cowling). Or even as small as the Ki-44, but around the early Sakae engine. Small size = lower drag = usually better speed. Also the aircraft with small wings rolled better than the ones with big wings, and might dive better. Start with 4 LMGs, switch to 2 LMGs and 2 HMGs once the HMGs are available. Have other companies make it under licence, so it will be easier to focus on better fighter(s) later. Introduce better exhausts for better exhaust thrust, protection, water-alcohol injection as war progresses.

 

[tomo pauk]

Alternative to Ki-44 and Ki-84: make one fighter type.
In-between in size (wing area of 200 sq ft is a nice, round number, vs. 160 sq ft for the -44 and 230 sq ft for the -84; about 31 ft length), 1st outfitted with Ha-41 engine, later with Ha 109, and then with Homare once it is available. Basically I'm aiming at an 'Japanese Fw 190'. We'd be slightly slower than the original Ki-44, and slightly faster than the original Ki-84.
Guns - going with 4 HMGs is a minimum, alternative being 2 HMGs and two Ho-3 cannons. Switch to all-cannon set-up once there is enough of Ho-5 cannons around (these are light and compact enough to be used as cowl guns). Protection for the pilot and fuel from day one. Water-alcohol injection for engines ASAP.
Out-source the 'not Ki-43' to other factories, so Nakajima can concentrate on the 'Ki 190'.

 

[M79]

Would studying (if not cloning) the Pratt & Whitney engines off the DC-4e prototype help?

 

[Peg Leg Pom]

Would studying (if not cloning) the Pratt & Whitney engines off the DC-4e prototype help?

After 1941 Nakajima were building a more powerful engine, though in limited numbers. What projects are you going to cancel to pursue development though, baring in mind that Japan has already been at war since 1937 and resources are limited?

Nakajima Mamoru - Wikipedia

en.wikipedia.org

 

[M79]

After 1941 Nakajima were building a more powerful engine, though in limited numbers. What projects are you going to cancel to pursue development though, baring in mind that Japan has already been at war since 1937 and resources are limited?

Nakajima Mamoru - Wikipedia

en.wikipedia.org

So the DC-4e was bought by Japan in late 1939...

Douglas DC-4E - Wikipedia

en.m.wikipedia.org

...and the Mamoru engine was *supposed* to power the G5N bomber derived from it. Early Mamoru engines were so unreliable that the project was ultimately abandoned, the design as planned would have given the Japanese a bomber with over 2000nm maximum range carrying nearly 9000 pounds of ordnance.

 

[mack8]

Regarding japanese engines and their approximation to US ones, imo they missed a golden opportunity to get their own R-2800, if Nakajima instead of the OTL 45 litre Mamoru worked on an 18 cylinder radial with Ha-5 cylinders, this is in effect an earlier 48 litre Ha-219. Based on the contemporary Ha-109 specific HP per cylinder, my ATL Mamoru should be good for 1850-1900HP, but with smaller diameter than R-2800 (1,28m vs 1,34m). A methanol boosted version would be good for say 2100HP? But running at much lower rpm compared to the highly tuned Homare, prehaps it would be more reliable.

A rough japanese equivalent of the R-2180 mentioned earlier is the Ha-5/41/109 family btw. So i really see no need for the japanese to copy the R-2180.

 

[Garrison]

You use the same aircraft, add self sealing fuel tanks, armour back plates, better guns and make sure every aircraft has a radio while squeezing every possible bit of power out of the engines.

Also rotate experienced pilots back to the training establishments regularly and put some effort into recovering pilots that have been shot down.

All common sense, but the latter in particular didn't fit the Japanese military philosophy, and when you start taking serious losses it becomes impossible.

 

[tomo pauk]

Regarding japanese engines and their approximation to US ones, imo they missed a golden opportunity to get their own R-2800, if Nakajima instead of the OTL 45 litre Mamoru worked on an 18 cylinder radial with Ha-5 cylinders, this is in effect an earlier 48 litre Ha-219. Based on the contemporary Ha-109 specific HP per cylinder, my ATL Mamoru should be good for 1850-1900HP, but with smaller diameter than R-2800 (1,28m vs 1,34m). A methanol boosted version would be good for say 2100HP? But running at much lower rpm compared to the highly tuned Homare, prehaps it would be more reliable.

A rough japanese equivalent of the R-2180 mentioned earlier is the Ha-5/41/109 family btw. So i really see no need for the japanese to copy the R-2180.

Nakajima (and Japanese military - both the IJN and IJA) really missed opportunity to go all-in with the Ha-5/41/109 family IMO. The 18cyl derivative also makes a lot of sense. Too much was wasted for extending the life of Sakae to go against the Allied best, as well as too much of hope and time wasted for the V12 engines.

On the other hand, the Homare with compression ratio slashed from 7:1 down to 6:1, and possibly with the cooling fan, would've probably have had less problems with the low-octane fuel the Japanese had for the last 12 months of the war?
Granted, Japanese were way too late to introduce the 2-stage superchargers, the only aircraft I'm aware that flew with a 2-stage S/Ced engine was the IJN's Kyushu J7W pusher fighter prototype (engine in question being a version of the Ha-43, yet another late-comer). Fighters powered by 1-stage supercharged engines will not fare well vs. P-47s, Merlin Mustangs or late marque P-38s the Americans were deploying in the last 20-24 months of the Pacific war

 

[mack8]

Fully agree about the V12 waste of time, it did not worth the effort. Just build Kinseis instead, or indeed any other radial.

As to superchargers, hindsight it may be but imo they would have been better served by just forgetting about trying to get working turbos (they had no metals for it) and try to focus on getting workable 2 stage or 3 speed versions of their radials. I think the J2M5 had a 3 speed supercharger? Would a 2 stage supercharger be more achievable than a turbo for them, what you think?