The Nakajima Ki-44 Shoki (Demon) was an unusual fighter by Japanese standards, with high speed and a good rate of climb emphasised at the expense of manoeuvrability.
The first significant Nakajima fighter was the Ki-27, a much more traditional Japanese fighter, with manoeuvrability emphasised over speed, protection and firepower. This was followed by the Ki-43, the most common Japanese army fighter of the Second World War. This too was a manoeuvrable but lightly armed aircraft, and after a successful period after the Japanese entry into the war would prove to be vulnerable to more modern Allied fighters.
Work on the Ki-44 began in 1938, at almost the same time as the Ki-43. The Japanese Army Air Force decided that it needed two types of fighters - the manoeuvrable dog-fighter for normal use and a defensive interceptor for use against high flying enemy bombers. As a result Nakajima were asked to design a fighter that could reach 13,120ft in 5 minutes, with a top speed of 373mph at that altitude, and armed with two 12.7mm and two 7.7mm machine guns.
The Nakajima design team, led by Toro Koyama, were faced with an immediate problem. None of the 'fighter' engines available in Japan provided enough power to achieve this level of performance, and so they decided to use the Nakajima Ha-41, a two-row 14-cylinder radial engine capable of providing 1,250hp. This was seen as a 'bomber' engine, and was used in Nakajima's own Ki-49 heavy bomber, but twin-row radials would go on to power some of the most successful American fighters of the war.
The Ki-44 was a low-wing monoplane, with short stubby wings. The wings had a straight leading edge but a tapering trailing edge. The fuselage was circular near the engine but narrow and flat-sided near the tail, a design that helped to improve its stability in the air. The aircraft carried two guns in the wings and two in the upper fuselage.
The first prototype Ki-44 (serial number 4401) was completed in the summer of 1940, and was rather heavier than expected. The new aircraft handled well, but its performance was not quite good enough. A series of modifications were tried out on the three prototypes, and eventually a top speed of 389mph at 13,120ft was achieved (although with all guns removed). With the guns installed the aircraft was expected to reach 360mph, and the new design was accepted by the Japanese army.
Compared to the Ki-43 the new aircraft was heavier, slightly shorter and had a 4ft narrower wingspan. As a result the Ki-44 had a higher wing loading than the Ki-43, and was thus less manoeuvrable, but its top speed and rate of climb were both better. The Ki-44 entered production as the Army Type 2 Single-Seat Fighter Model 1, and a total of 1,225 were built by the time production ended late in 1944.
The designation Ki-44 was given to the three prototypes and seven pre-production aircraft. All ten of these aircraft were armed with two 7.7mm and two 12.7mm machine guns.
A small batch of production aircraft were built early in 1942, armed with the same guns as the prototypes. These aircraft became the Ki-44-Ia later in the year after the appearance of the Ki-44-Ib (some sources suggest that these aircraft were actually the pre-production aircraft).
The Ki-44-Ib entered production later in 1942 and was armed with four 12.7mm machine guns.
A small number of Ki-44-Ics were produced, carrying the same guns as the Ib but with a modified mainwheel fairing. Only forty -Ib and -Ic aircraft were built before production moved onto the -II series, with more powerful engines.
The Ki-44-II was the designation given to five prototypes and three pre-production aircraft powered by the Nakajima Ha-109 (Army Type 2 radial engine). This provided 1,450hp but had the same diameter as the Ha-41 and so could easily be installed in the Ki-44.
A small number of Ki-44-IIas were built, with two 12.7mm machine guns in the wing and two 7.7mm machine guns in the fuselage.
The Ki-44-IIb was the main production version of the -II, and was armed with four 12.7mm machine guns.
The Ki-44-IIc was a cannon armed version of the aircraft. Most were armed with four 20mm Ho-3 cannon, although some were given two 40mm Ho-301 cannon or two 37mm Ho-203 cannon and two 12.7mm machine guns but this was a less effective configuration. The Ki-44-IIc was more effective against the B-29s than the earlier machine-gun armed versions.
The Ki-44-III was the final version of the aircraft, and was powered by the 2,000hp Nakajima Ha-145 radial engine. The Ki-44-IIIa was armed with four 20mm Ho-5 cannon.
The Ki-44-IIIb was armed with two 20mm Ho-5 cannon and two 37mm Ho-203 cannon. Production of the Ki-II and Ki-III came to an end late in 1944 when it was replaced on the production lines by the Nakajima Ki-84.
At first the Ki-44 was unpopular with the JAAF pilots, who preferred the more manoeuvrable Ki-43. As they got more used to the new aircraft most changed their opinion, coming to like the fast sturdy fighter.
The first unit to use the Ki-44 was a purpose-formed service-test unit, the 'Kingfisher' company, or 47th Dokuritsu Hiko Chutai (Independent Air Company). This unit received its aircraft in Japan before in November 1941 moving to Canton. It then moved to Indo-China, from where it took part in the invasion of Malaya. After initial problems with reliability the aircraft was a success, claiming its first victory early in January 1942 when a Brewster Buffalo was shot down over Johore. The unit was then upgraded to become the 47th Fighter Regiment, before being recalled to Japan to defend the Tokyo area.
After this successful combat debut the Ki-44 was ordered into production. Forty aircraft were ordered in January 1942, and was accepted later in the year as the Army Type 2 Single-seat fighter Model 1. The aircraft was given the name Shoki, after a demon that was said to defend the Japanese Home Islands against threats. This acceptance came after the aircraft had taken part in comparative trials, against an imported Messerschmitt Bf 109E, a captured Curtis P-40E, a Nakajima Ki-43-II and an early Kawasaki Ki-61. The Ki-61 was judged to be the best aircraft, but was still under development, and the Ki-44 outperformed all of the other competitors. It was already clear that more power was needed, but a suitable engine was available, and the Ki-44-II entered production.
During the summer of 1942 more units began to convert to the Ki-44. The 9th Sentai was posted to Nanking, where it remained for the rest of the war. The 85th was originally posted to the same area, while the 87th moved to Manchuria. This was a short posting, and early in 1943 the unit was moved to Palembang in the Dutch East Indies, to defend the oil refineries on Sumatra.
The units based in China were able to hold their own until 1945. At first the Ki-44 was faced with American P-40s and P-38s, aircraft that it could out-manoeuvre. This changed with the arrival of the P-51 Mustang early in 1944. This aircraft was faster and had a tighter turning circle than the Ki-44. Late in 1944 the China based Ki-44s came face-to-face with the B-29 Superfortress for the first time, and the results were at best discouraging. The Japanese fighter struggled to shoot down the American bomber, and the fighter units suffered heavy losses in the attempt. During 1945 the Americans gained control of the air over China, although the B-29s moved away as more suitable island bases became available.
The 87th Sentai at Palembang had a rather less successful introduction to combat. At first the area was quiet, but in January 1944 the Royal Navy launched two raids on Palembang. The first, on 4 January, caught the Japanese entirely by surprise and returned to the carriers unscathed. The second, on 24 January, saw the 87th Sentai lose several aircraft on the ground and more in the air. One Ki-44 shot down to Avengers, but the 87th lost twelve aircraft and seven pilots in the action. During the rest of 1944 the pressure on Sumatra increased, and towards the end of the year the 87th was pulled back to Japan.
The Ki-44 took part in the defence of the Philippines. The 22nd Sentai moved to the area in September 1944 and was joined by the 29th and 246th Sentais after the American invasion in October 1944. The three Ki-44 Sentais were overwhelmed by the massive American invasion force, losing most of their aircraft on the ground. The survivors were then ordered back to Japan.
At the start of 1945 seven Sentais were allocated to the defence of Japan, six based on the Home Islands and one on Formosa. By this time it had become clear that the Ki-44 was little use against the B-29s, which cruised at the very upper limit of its operational range. The heavy defensive firepower of the B-29s also caused great problems. One response was the introduction of ramming attacks, starting on 24 November 1944 when a pilot from the 47th Sentai flew into a B-29. The 47th formed a special suicide squadron, but the numbers of aircraft involved were too small to make any real difference in the skies over Japan. Other counter-measures were proving more effective, and the B-29s moved from high altitude day raids to low altitude night raids. The Ki-44 units were not short of opponents, for in February 1945 the British and American navies came within striking distance of Japan, and their carrier-borne fighters began to appear in increasing numbers over Japan. They were soon joined by long range P-51s and from July Japan was under constant daylight attack. The number of Ki-44s available dropped dramatically, and by the end of the war only three Sentais were still reasonably well equipped with aircraft.
Engine: Nakajima Ha-109 radial
Wing span: 31ft 0in
Length: 28ft 10.5in
Height: 10ft 8in
Empty Weight: 4,641lb
Maximum take-off Weight: 6,603lb
Max Speed: 376mph at 17,060ft
Service Ceiling: 36,745ft
Range: 1,056 miles
Armament: Four 12.7mm machine guns