The Mitsubishi F1M 'Pete' was designed as an observation float plane, but saw service as an impromptu fighter, diver bomber and patrol aircraft. The F1M had a rather long development period. It was produced in response to a 10-Shi specification of 1934 for a catapult launched short-range observation sea plane, which was to replace the Nakajima E8N1 on units of the Japanese fleet. Aichi, Kawanishi and Mitsubishi were each asked to produce a design. Aichi responded with the AB-13 and Mitsubishi with their Ka-17, designed by Joji Hattori.
The Ka-17 was a biplane, with a single large central float and stabilising floats at the end of the lower wing. The prototype was powered by the 820hp Nakajima Hikari 1 nine-cylinder radial engine. It had an aerodynamically clean fuselage and a minimum number of struts and wing bracing, and was thus rather faster than the Aichi aircraft. The Ka-17 was the basis of four F1M1 prototypes, each with the same engine, overall design and elliptical wings. Unfortunately the F1M1 also suffered from poor directional stability in flight, and was prone to 'porpoise' when on the water.
These problems were solved in the F1M2. This used a more powerful 875hp Mitsubishi Zuisei 13 fourteen-cylinder radial engine, which required a longer cowling. The elliptical wings of the F1M1 were replaced with straight edged wings and the dihedral on the wings was increased, improving stability. The vertical fin and rudder was made larger. This version was much better, and was accepted for service. Mitsubishi built 524 aircraft, and the Dai Nijuichi Kaigun Kokusho (21st Naval Air Arsenal) at Sasebo produced 590, for a total of 1,124 aircraft.
The F1M entered service in 1940 as the Navy Type 0 Observation Seaplane Model 11. It was used on eight battleships (including the Nagato and Yamato), nine cruisers and six aircraft tenders, as well as by a number of shore based units. The battleship and cruiser borne aircraft were used for their original purpose, as an observation and scouting aircraft.
Although the F1M's comparatively low speed made it vulnerable to the best Allied fighters, it could successfully be used as a front line aircraft in secondary theatres (of which there were many in the Pacific), and served as a fighter, a dive bomber in support of amphibious landings, a convoy escort aircraft (although its short range was a limit here) and for coastal patrols. Its main strength here was its manoeuvrability, which allowed it to escape the attentions of any second-line Allied aircraft it met.
This was the designation given to the first prototype and the early development versions, with the 820hp Nakajima Hikari engine and elliptical wings.
F1M2 (Navy Type 0 Observation Seaplane Model 11)
The F1M2 was the only production version of the aircraft, with a more powerful Mitsubishi Zuisei 13 radial engine, a modified wing and much better handling and characteristics on the water.
F1M2-K was the designation given to a number of F1M2s that were converted into advanced two-seat training aircraft.
Engine: Mitsubishi Zuisei 13 radial engine
Wing span: 36ft 1in
Length: 31ft 2in
Height: 13ft 1.5in
Empty Weight: 4,251lb
Maxiumum take-off weight: 5,662lb
Max Speed: 230mph at 11,285ft
Service Ceiling: 30,970ft
Range: 460 miles
Armament: Two fixed forward firing 0.303in machine gun, one flexibly mounted 0.303in machine gun
Bomb-load: Two 132lb bombs