In 1934, the Imperial Japanese Navy issued a specification to Mitsubishi, Aichi and Kawanishi for a replacement for its Nakajima E8Nfloatplanes, which were used for short-ranged reconnaissance and observation missions from the Navy's warships.[1] Mitsubishi's design, the Ka-17, given the short system designation F1M1 by the Japanese Navy, was a small all-metal biplane powered by a single Nakajima Hikari 1 radial engine rated at 610 kilowatts (820 hp), the same engine as used by Aichi's competing F1A. It had elliptical wings and great care had been taken to reduce drag, with the number of interplane struts and bracing wires minimised. The first of four F1M1s flew in June 1936.[2][3]
While the F1M1 had better performance than the Aichi aircraft, it had poor stability both on the water and in the air, so the aircraft was redesigned to resolve these problems. The wings were redesigned, with straight tapered leading and trailing edges and rigged with greater dihedral, and the vertical fin and rudder were enlarged. The aircraft's floats were enlarged to increase buoyancy, and the Hikari engine was replaced by a 652 kilowatts (875 hp) Mitsubishi Zuisei 14-cylinder radial, giving better forward visibility. As modified, the aircraft's handling characteristics were greatly improved, and the modified aircraft was ordered into production as the Navy Type 0 observation seaplane Model 11 (rei-shiki kansokuki ichi-ichi-gata, Reikan in short), with the short designation F1M2.[4][5] 940 series aircraft were built in total (342 by Mitsubishi and 598 by Sasebo Arsenal and 21st Arsenal) in addition to 4 prototypes (older publications present higher production figures, i.e., 1,016 or 1,118).[notes 1]
The F1M2 had a maximum speed of 368 km/h (230 mph) and operating range of up to 1,072 km (670 mi) without external stores. An F1M airframe had a projected operational life of 350 flight hours, after which it needed replacing.[6]
The F1M was armed with a maximum of three 7.7 mm (.303 in) machine guns (two fixed forward-firing and one flexible rear-firing) with provision for two 60 kg (132 lb) bombs.
The F1M was originally built as a catapult-launched reconnaissance float plane, specializing in gunnery spotting. The "Pete" took on a number of local roles including convoy escort, bomber, anti-submarine, maritime patrol, rescue, transport, and anti-shipping strike; for example sinking Motor Torpedo Boat PT-34 on 9 April 1942. The type was also used as an area-defense fighter and engaged in aerial combat in the Aleutians, the Solomons and several other theaters. In the New Guinea front, it was often used in aerial combat with the Allied bombers and Allied fighters.
Personnel of 80 Squadron RAF amongst parts of a Japanese F1M, bearing Indonesian markings, at an airfield and seaplane base in Surabaya, Java. January 1946
^Number of 940+4 is quoted by Wieliczko (2017), p. 19-21 (in Polish) derived from the latest Japanese research.
Bibliography
Claringbould, Michael John (2022). IJN Floatplanes in the South Pacific 1942-1944. Pacific Profiles. Vol. 8. Kent Town, Australia: Avonmore Books. ISBN978-0645246940.
Francillon, R.J. Japanese Aircraft of the Pacific War. London:Putnam, 1970. ISBN0370000331.
Green, William. War Planes of the Second World War, Volume Six: Floatplanes. London: Macdonald & Co., (Publishers) Ltd., 1962.
Wieliczko, Leszek A. (2017). "Mitsubishi F1M (Pete)". Technika Wojskowa Historia (in Polish). No. Special 6(36)/2017. Magnum X.
1 X as second letter is for experimental aircraft or imported technology demonstrators not intended for service,
2 Hyphenated trailing letter (-J, -K, -L, -N or -S) denotes design modified for secondary role, 3 Possibly incorrect designation, but used in many sources
