The Yokosuka H5Y, also known as the Yokosuka Navy Type 99 Flying Boat Model 11 and designated Cherry by the Allied forces, was a flying boat utilized by the Imperial Japanese Navy Air Service (IJNAS) from 1938.
The H5Y was developed by Yokosuka to fulfill the IJNAS’s requirement for a twin-engine maritime reconnaissance flying boat that could match the performance of contemporary four-engine flying boats, while being more cost-effective and easier to maintain.
Two prototypes were constructed at the 11th Naval Arsenal in Hiro in 1936.
The H5Y was a parasol wing aircraft with twin engines, resembling a scaled-down version of the Kawanishi H6K “Mavis”.
However, the aircraft’s performance was deemed inadequate due to underpowering and structural issues, which resulted in production delays.
Only 20 H5Ys were built between 1936 and 1941, with Yokosuka Naval Air Arsenal constructing the aircraft at the Dai-Juichi Kaigun Kokusho facility.
Despite being accepted for production in 1938 as the Type 99 Flying Boat Model 11, production was swiftly terminated due to the H5Y’s subpar performance, with only 20 units being produced.
Although some H5Ys were deployed for coastal anti-submarine patrols early in World War II, they were quickly re-assigned to secondary duties such as transport or training.
Variants
H5Y
2 Prototypes constructed at the Hiro Naval Arsenal
H5Y1
Production model, 18 built.
Yokosuka Navy Type 99 Flying Boat Model 11
The long formal designation of the H5Y.
Specifications
Crew
6
Length
20.53 m (67 ft 4 in)
Wingspan
31.57 m (103 ft 7 in)
Height
6.71 m (22 ft 0 in)
Wing area
107.7 m2 (1,159 sq ft)
Empty weight
7,070 kg (15,587 lb)
Gross weight
11,500 kg (25,353 lb)
Powerplant
2 × Mitsubishi MK1A Shinten 21,
14-cylinder air-cooled radial piston engines,
890 kW (1,200 hp) each
Propellers
3-bladed variable-pitch propellers
Performance
Maximum speed
306 km/h (190 mph, 165 kn) at 700 m (2,297 ft)
Range
4,800 km (3,000 mi, 2,600 nmi)
Endurance
26 hours
Service ceiling
5,200 m (17,100 ft)
Time to altitude
3,000 m (9,843 ft) in 24 minutes
Armament
Guns
3× 7.7 mm (.303 in) machine guns
Bombs
2× 250 kg (552 lb) bombs.
Sources Japanese Aircraft, 1910-1941-Robert Mikesh & Shorzoe Abe The Mainichi Newspapers Co Ltd Yushukan War Memorial Museum Japanese Aircraft of the Pacific War-Rene Francillon, Japanese Aircraft-John Stroud, Japanese Military Aircraft Illustrated.
