Very soon after design of the Ki-43 Hayabusa had been started by Nakajima, the company received instruction from the Imperial Japanese Army to initiate the design of a new interceptor fighter. In this case, however, maneuverability was required to give precedence to overall speed and rate of climb, and the company’s design team selected the 1,250-hp (932-kW) Nakajima Ha-41 as the powerplant for this new project. Of similar general configuration to the Ki-43, the new Nakajima Ki-44 prototypes also incorporated the maneuvering flaps that had been introduced on that aircraft, and carried an armament of two 7.7-mm (0.303-in) and two 12.7-mm (0.5-in) machine-guns. Fir l flown on August 1940, the Ki-44 was involved in a series of comparative trials against Kawasaki’s Ki-60 prototype, based on use of the Daimler-Benz DB 601 engine, and an imported Messerschmitt Bf 109E. The result of this evaluation, and extensive service trials, showed the Ki-44 to be good enough to enter production, and it was ordered under the designation Army Type 2 Single-seat Fighter Model 1A Shoki (demon), company designation Ki-44-Ia, which carried the same armament as the prototypes. A total of only 40 Ki-44-I aircraft was produced, including small numbers of the Ki-44Ib armed with four 12.7-mm (0.5-in) machine-guns, and the Similar Ki-44-Ic with some minor refinements.
When introduced into service’ the high landing speeds and limited maneuverability of the Shoki made it unpopular with pilots, and very soon the Ki-44-II with a more powerful Nakajima Ha-109 engine was put into production. Only small numbers of the Ki-44-IIa Similarly armed to the Ki-44-Ia, were built, the variant being followed by the major production Ki-44-IIb which, apart from the different engine, was identical to the Ki-44-Ic. The Ki-44-IIc introduced much heavier armament, comprising four 20-mm cannon or, alternatively two 12.7-mm (0.5-in) machine-guns and two 40-mm cannon, and these proved to be very effective when deployed against Allied heavy bombers attacking Japan. However, the increased power had done nothing to eliminate the reasons for its unpopularity with the pilots and, in fact, the higher wing-loading of this version meant that it had some violent reactions to high-speed maneuvers; however, it later gained their respect because of its capability as an interceptor. Final production version was the Ki-44-III with a 2,000hp (1491-kW) Nakajima Ha-145 radial engine, an increase in wing area and enlarged vertical tail surfaces, but comparatively few were built before production ended in late 1944. They included the Ki-44-IIIa and similar Ki-44-IIIb, armed with four 20-mm cannon, and two 20-mm and two 37-mm cannon respectively.
Ki-44-III: powered by a 2,000hp. Nakajima Ha-145, 18-cyl., air-cooled radial with thrust augmentation exhaust stacks; increased wing area to 204.514sq. ft.; enlarged tail surfaces; flew for the first time in July 1943; very few built as the aircraft was surpassed in performance by the Ki-84-I; two versions built, one ( Model 3A ) armed with four Ho-5 20mm cannon and the other ( Model 3B ) with two Ho-5 cannon and two Ho-203 37mm cannon
Nakajima had built a total of 1,225 Ki-44s of all versions, including prototypes, and these were allocated the Allied codename “Tojo’. They were deployed primarily in Japan, but were used also to provide an effective force of interceptors to protect vital targets, as in Sumatra where they defended the oil fields at Palembang.
Model pre-series for evaluation.
Ki-44 Type I
was powered by a 930 kW (1,250 hp) Nakajima Ha-41 engine, and had a maximum speed of 580 km/h (363 mph). Armament consisted of two 7.7 mm (.303 in) Type 89 machine guns and two 12.7 mm (.50 in) Ho-103 machine guns placed in the wing.
Fighter Type 2 of Army. (Mark Ia).
Ki-44 Type II
had a 1,074 kW (1,440 hp) Nakajima Ha-109 engine with a top speed of 604 km/h (378 mph), and four 12.7 mm (.50 in) Ho-103.
prototype-engine Nakajima Ha-109 of 1,130 kW (1,520 hp).
(Mark 2c) Four 12.7 mm (.50 in) Ho-103 or two 12.7 mm (.50 in) Ho-103 and two 40 mm (1.57 in) Ho-301 cannons. A four 20 mm Ho-3 cannon version was proposed but never produced. Four Ho-3 cannons would have been most effective against B-29s. The 20×125 mm Ho-3 round gave the 144 g ave. (127/140/164) shell (7% HE ave.) a range of 900 m (2,950 ft) and a muzzle velocity of 820 m/s. The rate of fire for the wing-guns was 400 rpm, while the synchronized cowl-mounted pair were much slower (perhaps under 272 rpm each). This equals 23 rounds per second (rps) for the four cannon against approximately 52 rps for the standard four machine gun version), but the firepower advantage (a ~2½ times stronger punch per second – including blast, for the same number of guns and only about ½ the rate of fire) would have more than compensated against bombers.
Against small fighters at speed, the sparse firing pattern density would be less than ideal. Double magazines could hold 100 rpg of 20 mm (20×125) ammunition – not to be confused with the rapid fire Ho-5 20 mm (20×94) ammunition – which was better for dogfights.
(Mark 3a) engine of 1,491 kW (2,000 hp) and four 20 mm Ho-5 cannons.
(Mark 3b) two 20 mm Ho-5 cannons and two 37 mm (1.46 in) Ho-203 cannons.
Total production: 1,225
* Crew: one, pilot
* Length: 8.84 m (29 ft)
* Wingspan: 9.45 m (31 ft 01 in)
* Height: 3.12 m (10 ft 23 in)
* Wing area: 15 m² (161 ft²)
* Empty weight: 2,105 kg (4,641 lb)
* Loaded weight: 2,764 kg (6,094 lb)
* Max takeoff weight: 2,995 kg (6,602 lb)
* Powerplant: 1× Nakajima Ha-109 radial engine, 1,133 kW (1,519 hp)
* Maximum speed: 605 km/h (376 mph)
* Cruise speed: 400 km/h (249 mph)
* Stall speed: 150 km/h (93 mph)
* Range: 1,700 km (1,060 mi)
* Service ceiling: 11,200 m (36,750 ft)
* Rate of climb: 5,000 m–4 min 17 sec (3,940 ft/min)
* Wing loading: 200 kg/m² (41 lb/ft²)
* Power/mass: 0.38 kW/kg (0.13 hp/lb)
* 4 × 12.7 mm (.50 in) Ho-103 machine guns, two synchronized cowl mounted (perhaps 657 rpm rate each), and one in each wing (900 rpm rate of fire each), 760 rounds in all. The 12.7×81 cartridge propelled the 35.4 g AP bullet 760 m/s, the 38 g HE 796 m/s, and the 33 g HE (2.2%) 770 m/s, with an effective firing range of 750 m. Not always reliable.
Ki-44 handling characteristics
I was just recently rereading Francillon’s “Japanese Aircraft of the Pacific War”. In the Ki-44 section it is mentioned that the Ki-44 was restricted against flick manouvres. Do I have to assume that usually Japanese fighters were cleared for flick manoeuvres? After all, most WW Two fighters’ (at least US and British) are restricted against snap rolls etc. At least so according to pilot manuals. I remember reading a story of a US pilot who did fly the Ki-44. He did like it very much.
The following manoeuvres were forbidden in the pilot’s handbook:
I don’t believe this type can be compared with other JAAF fighters – it was unique. The Ki44 represented a radical departure for the JAAF in its design concept and originally it was envisaged that only pilots with at least 1000 hours could fly the fighter. Wing loading was high and landing speeds consequentially fast which made for tricky handling. On the plus side the aircraft was a superb gun platform, invariably scoring the highest points in gunnery competitions against both Army and Navy fighters. Shoki also possessed excellent dive and climb characteristics permitting fast hit and run tactics, which, when they were first introduced by Ki44 units in China, also represented a radical departure from “traditional” JAAF “dogfighting” tactics.
Pilot opinion of type is often subjective and such is human nature that opinions can differ widely, even in respect of the same aircraft (witness the P-39 Airacobra for example). Most sources agree that initial concerns over the aircraft’s lack of maneuverability and high landing speed, expressed by pilots used to such nimble performers as the Ki27 and Ki43, were replaced with respect by those pilots who exploited and enjoyed the type’s best qualities – “a rapid roll rate, outstanding dive characteristics and excellence as a gun platform”. That this was so is supported by the fact that a number of pilots became “aces” with the Ki44.
It was, however, only produced in relatively small numbers; representing barely 9% of JAAF single engined fighter production (and that excluding the Ki27). Outside Japan, where it is most commonly associated with B-29 defence operations, it’s most significant deployment was in China. Here, in December 1942 Imperial General Headquarters instructed the China Expeditionary Army to prepare for air operations in the spring of 1943 “after the successful completion of the first phase of operations in the Pacific”. An interim defensive posture was obliquely referred to when the China Expeditionary Army was instructed to “arrange for the use of Type 2 single seater fighters on at least one of each of the front line airfields in north, central and south China as promptly as possible”.
Shoki was also issued in small numbers to Sentais equipped primarily with other types to provide an improved interception/air defence capability and also deployed to protect locations of particular strategic importance.
In common with other Army types the Ki44 has been underestimated by aviation writers. In a recent and definitive account of the Flying Tigers, the AVG, it was described as “cobbled together from a Hayabusa airframe and a 1,500-horsepower bomber engine”! That it certainly was not and the description does scant justice to the efforts of Hideo Itokawa and his design team in successfully meeting the 1939 specification for an interceptor fighter possessing almost revolutionary (for the JAAF) capabilities. You have raised the question of “forbidden” snap rolls on some Allied types and this is where I believe the flying characteristics of the Ki44 can be more usefully compared. Its design imperatives probably had more in common with some of its adversaries than with other more forgiving JAAF types such as the Ki43, whose aerobatic qualities were perhaps only surpassed by its predecessor the Ki27.
As a side note, the Ki-44 could climb at 4,286 ft/min at its peak altitude of 6,888 feet – which equals or exceeds most allied types (P-51 max climb rate was ~3,800ft/min).