Jack vs. Tojo - Which was better? Why?

[tomo pauk]

The fuel-injected derivative of the Kinsei became available in late 1941. It reached aircraft in late 1942, such as the Ki-46 III. Jiro Horikoshi mentioned in his book that a 1,500 HP Zero could have made its way into combat by the Summer of 1943, enough to slow the progression of the war.

There was a lot more than fuel injection that made the Kinsei 60 series capable for 1500 HP (and a bit more). Like the water-alcohol injection (curiously enough, not fitted on the Ki-100 in 1945?), and the bigger supercharger - 12.6 in impeller vs. the 11.4 in on the 50 series.
Granted, the fully-rated Kinsei 62 on a Zero from early 1943 on would've made the life ... interesting to the Allied pilots & crewmen.

 

[AerialTorpedoDude69]

There was a lot more than fuel injection that made the Kinsei 60 series capable for 1500 HP (and a bit more). Like the water-alcohol injection (curiously enough, not fitted on the Ki-100 in 1945?), and the bigger supercharger - 12.6 in impeller vs. the 11.4 in on the 50 series.
Granted, the fully-rated Kinsei 62 on a Zero from early 1943 on would've made the life ... interesting to the Allied pilots & crewmen.

I think according to Goodwin (?), the 50-series Kinsei (which had bowl-prime indirect injection) had MW injection. The 60 series did not AFAIK. There may have been an issue integrating direct injection with MW injection. (EDIT: The 62-Ru supposedly added MW injection and fuel injection at the same time, the 61 may have had them as well.) I remember reading about how the Kasei produced too much white smoke in the Raiden with a Kasei 23. Since the direct injection system is mixing fuel-air inside of the cylinder along with the MW mixture being sprayed into the throttle body, it would partially explain the presence of white smoke (an incorrect MW installation). It must have been easier to integrate in a carburated system. But my knowledge of this subject is old and potentially incorrect.

IMO, the issue with the Zero was its big wing. The low-speed turn rate would be great for pilots in disadvantageous position (I.E. being attacked from on high) but a liability when diving to attack or when diving to escape. This characteristic was a flaw on most Japanese aircraft, including the Raiden, Hayate, Shiden, and others. Only a few, like the Ki-44, seemed to have good controllability at high speed relative to their opponents.

 

[GrauGeist]

The J2M (Raiden) was noted for it's ability to dive and it's wing was slightly smaller than the F6F's while both types had a comparable fuselage length.

 

[AerialTorpedoDude69]

The J2M (Raiden) was noted for it's ability to dive and it's wing was slightly smaller than the F6F's while both types had a comparable fuselage length.

As far as I know, that's totally true. The Raiden was also exceptionally lightweight, which meant its dive performance wasn't as good as most American aircraft, since weight is a key characteristic of planes that can dive well. IIRC, according to the TAIC report, its airlerons got heavy at high speed in the 325 MPH range. So it could dive but it wasn't going to turn when diving at high speed.

 

[Kilkenny]

I see problems with the timing of some of these engines.

The Kinsei 61/2 engine was a very good engine, trouble is when does it show up? If the Kinsei 61 doesn't show up until 1944 it doesn't do the Japanese much good.

The Kinsei 54 was good for 1300hp for take-off, 1200hp at 3,000 meters and 1100hp at 6,200 meters. This showed up in 1942 (?)

The engine in the Ki-43 II was good for 1150hp for take-off, 1150hp at 2450 meters, and 980hp at 5600 meters.

The engine in the Ki-61 was good for about 1175-1180hp for take off and 1080-1100 hp at 3500-3900 meters. This is actually with a few percent of the Allison engines used in the P-40s/P-39s except the Japanese can't use WER.

At the time they working on the Ki-61 (1940-1941) the Kinsei engine may have been the 40 series engines, these had single speed superchargers and around 1080hp at 2000 meters for many versions.

The Ki-44 II with the Ha-109 engine shows up in the very late fall of 1942. This engine has the power to get the job done in late 1942 and into 1943. (Showed up in the Ki-49 bomber before the Ki 44 fighter).

The Japanese put two speed superchargers on many of their engines (along with other improvements) in 1940-41-42, later on there seems to have been a number jump in power so be very careful when trying to figure out what the Japanese could have done in 1941-43 as, just like the allies, many of the 1944 engines did not exist in 1941-1943.

That's why I have soft spot for the Ki-44... It was a good when first deployed just before WW2, and great by 1942. But the IJA just didn't promote it much or spend much effort improving it (as opposed to the slow and flimsy Ki-43)... So ATD69, I agree with you!

 

[Admiral Beez]

Making a land based fighter carrier capable (especially a small elevator carrier) is a difficult proposition and rarely 100% successful.

I understand. My thinking was for the IJN not to make the J2M and instead using the IJN's limited resources to make something entirely different for its carriers. The IJN needs to match the Hellcat and Corsair, not the B-29.... unless ten of them are flying fast and low towards your CBG!

 

[XBe02Drvr]

That big draggy wing that the Japanese used on their fighter aircraft, which improved slow-speed lift at the expense of top maximum speed and sustained turn rate, would never be able to perform at high speed. It didn't matter what kind of engine was used. The faster a Zero went, the poorer its turn performance would become.

Obsessions die hard. IJN and IJA were rather slow to move on from agility and maneuverability to speed and firepower, and naturally, as the customers, they called the shots. Reynolds and Mach LLC* just wouldn't let them have their cake and eat it too.
*Specializing in the Law of Physics

 

[tomo pauk]

I think according to Goodwin (?), the 50-series Kinsei (which had bowl-prime indirect injection) had MW injection. The 60 series did not AFAIK. There may have been an issue integrating direct injection with MW injection. I remember reading about how the Kasei produced too much white smoke in the Raiden with a Kasei 23. Since the direct injection system is mixing fuel-air inside of the cylinder along with the MW mixture being sprayed into the throttle body, it would partially explain the presence of white smoke (an incorrect MW installation). It must have been easier to integrate in a carburated system. But my knowledge of this subject is old and potentially incorrect.

Ki-46-III is, at least by my knowledge, the only aircraft powered by a Kinsei that featured a water-alcohol injection system. Engine in question was the Model 61. TAIC manual notes the same.

IMO, the issue with the Zero was its big wing. The low-speed turn rate would be great for pilots in disadvantageous position (I.E. being attacked from on high) but a liability when diving to attack or when diving to escape. This characteristic was a flaw on most Japanese aircraft, including the Raiden, Hayate, Shiden, and others. Only a few, like the Ki-44, seemed to have good controllability at high speed relative to their opponents.

Wing on the Zero was of about same area, thickness and profile as on the P-36 or P-40. Late P-40 prototype (in 1944) with a proper engine was making 420+ mph in level flight, and P-40s family was reasonably fast in dive.
Even the F4F was with a bigger wing than what Japanese fighters had.

 

[GrauGeist]

It's not the size of the wing, but the size of the aerlerons and how the leverage of the control are configured.

 

[GregP]

Ki-46-III is, at least by my knowledge, the only aircraft powered by a Kinsei that featured a water-alcohol injection system. Engine in question was the Model 61. TAIC manual notes the same.



Wing on the Zero was of about same area, thickness and profile as on the P-36 or P-40. Late P-40 prototype (in 1944) with a proper engine was making 420+ mph in level flight, and P-40s family was reasonably fast in dive.
Even the F4F was with a bigger wing than what Japanese fighters had.

The F4F-4 needed a bigger wing since it came in at 7,950 lbs in the F4F-4 model and 8,271 lbs in the FM-2 model. The F4F-4 came in at 30.6 lbs/ sq ft and the FM-2 came in at 31.8 lbs/ sq ft, both at normal gross weight.

The A6M-5 came in at 6,025 lbs and had a wing loading of 26.3 lbs/ sq ft at that weight.

So, the A6M-5 had 14 - 15% lighter wing loading than the F4F-4 and about 17% lighter wing loading than the FM-2. It also had a bout 20% better power loading than the F4F and about 15% better power loading than the FM-2, all of which should account for the superiority of the A6M-5 over the primary naval early adversary.

There weren't any P-40s that went 420 mph except for the three P-40Qs that were not selected for production and never saw combat. The A6M-5 handily outperformed the P-36, P-40, F4F-3/4, and FM-2. The A6M didn't really meet its match until the F6F came into service, at which point it really needed an engine and slight aerodynamic update or a replacement fighter, neither of which ever saw wartime service except in prototype, non-combat form.

 

[XBe02Drvr]

Leave it to Greg to point out there are multiple factors that combine to make a fighter's performance superior/successful, not just a single superior quality such as horsepower, wing area, aileron effectiveness, or weight. Every aircraft is a bundle of compromises to be considered in their totality, complicated as that may be, and not given to one-liner simple answers.
I used to fly a commuter airliner that was optimized for serving small town airports and being operated and maintained by less experienced personnel. Its powerful engines, high lift wings, high gear and flap speeds, and excellent prop beta and brakes gave it great airport performance, but those same features, plus its boxy fuselage and profusion of stabilizing fins and vortex generators gave it a Vne of 247 knots and an economical cruise of <200. We never broke one in a TO/Ldg accident or incident. Our competition flew "Lawn Darts" (Metroliners) which were go-fast machines, sacrificing everything for speed, such as handling, takeoff & landing performance, even passenger seating comfort and luggage capacity. Because of their >250 knot Vne, they always got high altitude ATC handling into the big places, while we got sequenced with the Pipers, Cessnas, and Twin Otters. They would check in 2K altitude above us and ten miles behind and beat us to the gate by 5 or 10 minutes. They also managed to leave wreckage on many of the back country airports in northern New England.

 

[GregP]

Sometimes the absolute best-performing aircraft is NOT the best choice for the task.

A Mosquito is a very high-performance aircraft for its configuration and mission, but has a Vmc of 165 mph! If anything happens before you get to 165 mph, you are going straight in or crashing. That was acceptable for a wartime bombing airplane designed to penetrate enemy defenses with speed, but would NEVER be accepted for peacetime executive air travel.

A B-25 wasn't as fast, but was quite safe in civilian hands. Lots of them still flying reliably.

If I were hauling rectangular boxes of freight ( be honest, that is MOST freight) over short/medium distance, a Short Skyvan or Cessna Caravan might be a great choices. But they can hardly be considered stylish ramp presences.

 

[Clayton Magnet]

That's why I have soft spot for the Ki-44... It was a good when first deployed just before WW2, and great by 1942.

Ki-44 wasn't fielded until well after the war started

 

[GrauGeist]

The KI-44 prototype was first flown in 1940 and two prototypes and seven pre-production models were sent to Indochina for evaluation and were operational in December of 1941.

 

[EwenS]

Ki-44 wasn't fielded until well after the war started

On 15 Sept 1941 the second and third Ki-44 prototypes and 7 pre-production with the latest modifications were assigned to an experimental squadron that became the 47th Independent Chutai. By 7 Dec 1941 this unit was based in Indochina. 3 force landed on 24 Dec 1941 while in transit to Don Muang, Thailand. By mid Jan 1942 they were operational in the skies over Singapore and had moved to Kuantan in Malaya.

Bloody Shambles Vol 1.

Production Ki-44-1a began to come off the production line in Jan 1942.

 

[AerialTorpedoDude69]

Ki-46-III is, at least by my knowledge, the only aircraft powered by a Kinsei that featured a water-alcohol injection system. Engine in question was the Model 61. TAIC manual notes the same.



Wing on the Zero was of about same area, thickness and profile as on the P-36 or P-40. Late P-40 prototype (in 1944) with a proper engine was making 420+ mph in level flight, and P-40s family was reasonably fast in dive.
Even the F4F was with a bigger wing than what Japanese fighters had.

Thanks, my memory is failing me. Shinpachi posted a document which showed that water-methanol injection didn't show up until the Kinsei 62-Ru, which also received an exhaust driven turbosupercharger. According to that document, there was no Kinsei Ha-32-62. There was only a 62-Ru (turbo). Which means every version of the Kinsei up until the 62-Ru had a carburetor and lacked WM injection. That also means it was the Ki-46 IV that had water methanol injection and that the Ki-46-III lacked it. The Ki-46-III apparently had a Kinsei 61 engine.

Shinpachi's translation suggests that the Ki-46 III had WM injection though. It may be that the table in that document misplaced the Kanji and that both the 61 and 62-Ru have MW-injection. Given (in your excellent post) the Soviet testing of the Ki-46 (assumedly a III as the IV was a prototype) revealed MW-injection in the Kinsei, I think we have to assume it did indeed have MW injection.

EDIT: The Zero definitely had good low-speed handling characteristics, which is a sign of a high lift wing. Larger control surfaces and big wings (relative to the aircraft) do not perform well at high speeds. It's why there are no fast planes that have great low-speed handling characteristics. Laminar wings stall out earlier than non-laminar wings.

 

[GregP]

Tomo's posts are usually excellent.

He is definitely one of the forum assets.

 

[Just Schmidt]

Just a hunch, but I suspect Clayton Magnet is referring to the second world war instead of the pacific war.

 

[Clayton Magnet]

Just a hunch, but I suspect Clayton Magnet is referring to the second world war instead of the pacific war.

That would be correct.
The post that I replied to implied that WW2, not specifically the pacific portion, started in late 1941

 

[GregP]

OK, finally. Jack versus Tojo, or J2M versus Ki-44. First, I'm using the TAIC Report # 2 dated 1945 for the comparison. Never mind when they first flew, I'm talking about the J2M3 versus the Ki-44 II. They first started flying the Ki-44 family operationally in some numbers in Jan 42 and the J2M family was first seen in some numbers in Dec 42. So, the Ki-44 had about 10 months on the J2M operationally. They built some 1,225 Ki-44s and some 621 J2Ms, so there were about twice as many Ki-44s as J2Ms.

Weights: Ki-44 was 4300 lbs empty, 6100 lbs normal load, 6610 lbs overload. The J2M was 6259 lbs empty, 7079 lbs normal load and 8130 overload. So, the J2M was slightly heavier empty than a Ki-44 at normal fighter take off.

Power Loading: Look at takeoff, best mil power, and best WER power. Ki-44 II: PL takeoff: 4.07 lbs/ hp. Best mil power: 4.69 lbs/ hp at 17,200 feet. Best WER: 3.89 lbs/hp at 5,000 feet. J2M3: takeoff: 3.91 lbs/ hp. Best mil power: 4.69 lbs/ hp at 18,100 feet. Best WER: 4.10 lbs/hp at 16,600 feet. So, there is very little to choose as far as power loading goes and, at best military power, they are even up. J2M has about 2,500 feet better service ceiling (38,800 feet versus 36,350 feet). But, after finding out they couldn't hit anything at 30+ thousand feet, the B-29s were coming in at around 20,000 feet anyway, so the advantage is not really all that useful.

Wing loading at normal weight: Ki-44 II: 36.09 lbs/ square foot. J2M3: 33.89 lbs/ square foot. Very little to choose between them, but the J2M comes in maybe 6% better. Doesn't translate into much in the real world.

Speed: J2M3 is 32 mph faster at best height and 24 mph faster at sea level. At sea level, both are around as fast as the US opposition. Around 20,000 feet, the Ki-44 is maybe about even with US opposition or slightly slower, but the J2M3 is 30+ mph faster. That 32 mph would make a BIG difference if chasing a B-29, but little difference practically if engaging with fighters because the faster fighter opposition is faster than both Japanese aircraft and the slower opposition is about even with the Ki-44 II, making it not so much of a factor unless chasing B-29s.

Climb: Both are 1,000+ feet per minute better than any US counterpart.

Armament: US opposition has 4/50-cal or 6/50-cal. Technically the Ki-44 II has 6/50-cal and 2/40mm cannons … but the cannons have only 10 shots and the shells are slow, so they are not much use. The J2M3 has 4/20 mm cannons for an obvious armament advantage, especially against bombers.

From the above, I say the Ki-44 was an EXCELLENT choice, especially for 10 months when there were no J2Ms around. There were twice as many available and the Ki-44 likely was more reliable, given reports of J2M malfunctions. Range without extra fuel tanks was about a wash, with the Ki-44 II having slightly more combat range at 1,500 feet (740 miles versus 670 miles). Admittedly there wasn't a lot of fighting at 1,500 feet, but it is the comparison we have.


I'd say twice as many Ki-44 IIs would tip the balance in favor of the Ki-44, but nobody would be unhappy with a J2M3 as long as it was running correctly. From what I hear, that was a gamble for many J2M pilots. I'd take the old reliable Ki-44 II if offered the choice, based on the numbers. But, the Ki-44 was more lightly built, and that MIGHT affect the choice. Still, a reliable airplane is likely a better choice than an unreliable airplane.