Multipurpose flying boat
H5Y. The design of a flying boat, designated H5Y1 or "Type 99" Model 11, was ready at the end of 1935, and at the end of 1936 two prototypes were made at the 11th arsenal in Hiro. The tests took place throughout 1937 and 38, and the results were downright disappointing.
Power plant. Two 14-cylinder radial air-cooled engines with three-blade variable pitch propellers, whose power is 2400 hp. was clearly not enough for a heavy vehicle. The aircraft had to be lightened as much as possible, but all the measures taken did not bring a noticeable improvement in flight data. There were simply no more powerful engines in Japan at that time.
Armament. In an attempt to lighten the vehicle, the armament was significantly weakened compared to the specification requirement and consisted of only two 7.7-mm machine guns. One of them was located in a glazed tail turret. The second machine gun was located in the bow cockpit and fire from it could be conducted from the side windows or the upper hatch located in front of the cockpit, which housed two pilots, a bombardier and a radio operator. Sometimes a third portable machine gun, located in the cockpit, was also included in the armament. Any of the free crew members could fire from it through the windows in the cockpit canopy. The bomb load did not exceed two 250-kg bombs on an external sling under the wing.
Combat use. Most of the produced aircraft of this type entered service with Yokohama kōkūtai, where they served until December 1941 as an anti-submarine patrol. The crews greeted the new materiel without enthusiasm and by the beginning of hostilities in the Pacific Ocean they gladly switched to 4-engine Kawanishi Н6К. By this time, two H5Y boats had already been lost in accidents. Allied intelligence believed that the fleet of H5Y flying boats was significantly larger and assigned it the code designation "Cherry". There is practically no evidence of H5Y combat use. One "Cherry" was transferred to the Central Meteorological Observatory in Yokohama, where he served until the end of 1942 as a weather scout. Four more worked as transport workers in Yokohama kōkūtai, the fate of the rest is unknown. Probably, in 1943, not a single H5Y remained.
The production of Type 99 flying boats was limited to only 16 units produced at the 1st Yokosuka Arsenal, two at the Kawanishi plant and two prototypes. Production was discontinued in 1940. In total, taking into account prototypes, 20 aircraft were built.
|Wing area, m²
|2 × PE Mitsubishi MK1A Shinten 21
||MK1A Shinten 21
||1200 (890 kWt)
|Maximum speed at altitude 700m, km/h
|Maximum rate of climb, m/min
|Service ceiling, m
|Service range, km
|Three machine guns of 7.7 mm caliber, bombs, kg
||2 × 250
- "Encyclopedia of military engineering " /Aerospace Publising/
- "Japan Warplanes of World War II" /Oleg Doroshkevich/
November 24, 2019
Failures of a flying boat in its design were initially laid down in the very task of development. For a twin-engine power plant set by the fleet (at that time its total power could not exceed 2400 hp), the requirements for the project were extremely high. The maximum speed in the specification was set at 463 km / h, and the flight range was supposed to reach 7200 km (or 3700 km with a bomb load of half a ton). The armament was to consist of a 20-mm cannon and four 7.7-mm machine guns, and the maximum bomb load was 1600 kg or two aircraft torpedoes.