The Kawanishi E15K Shiun (Violet Cloud) was a reconnaissance float-plane designed to be able to operate in areas dominated by enemy fighters, and that would thus be too dangerous for more conventional float-planes.
The E15K was designed in response to a 14-Shi specification which called for a two-seat reconnaissance float-plane capable of out-performing contemporary land-based fighters. The idea was that it would be able to operate in areas where the enemy had air superiority, using its speed to escape from interception.
Kawanishi's design used a number of innovative features, but the failure of these new ideas would doom the project. The most important innovation was the use of a jettisonable main float. The aircraft could reach 291mph with the float attached, but gained 59mph when the float was dropped, giving it a speed of 350mph. The stabilizing floats at the wing tips were given an inflatable upper section which could be used as a floatation device after the main float had been dropped. The aircraft also used a contra-rotating propeller, the first to be installed on a Japanese aircraft, and rare elsewhere in 1941. The rest of the aircraft was fairly conventional, and it was a low-wing monoplane with a circular fuselage and a greenhouse canopy over its long cockpit.
The aircraft took two years to complete, and didn't make its maiden flight until 5 December 1941. The aircraft handled well in the air, but all of its new features caused problems. In early tests there were problems with the pitch control for the propellers and with the retractable stabilisation floats. The first prototype was badly damaged late in 1942 after the floats failed to lower. The inflatable section was removed and eventually fixed stabilisation floats were used. At the same time a 1,850hp Mitsubishi MK4S Kasei 24 engine.
A total of fifteen aircraft were produced, as the Navy High-speed Reconnaissance Seaplane Shiun (Violet Cloud). Six were prototypes or service trails aircraft and nine were production aircraft.
Six aircraft were sent to Palau Island for front line trials, but this was a disastrous failure. The main float failed to jettison, leaving the aircraft vulnerable to allied fighters. All six were shot down and as a result production came to an end in February 1944.
Engine: Mitsubishi MK4D Kasei 14 fourteen cylinder air cooled radial engine
Power: 1,500hp at take-off, 1,620hp at 6,890ft, 1,480hp at 18,045ft
Wing span: 45ft 11 3/16in
Length: 38ft 0 3/14in
Height: 16ft 2 7/8in
Empty Weight: 6,978lb
Loaded Weight: 9,039lb
Max Speed: 291mph at 18,700ft with float attached
Cruising Speed: 184mph at 8,205ft
Service Ceiling: 32,250ft
Range: 2,095 miles
Armament: One flexibly mounted rear firing 7.7mm machine gun
Bomb-load: Two 132lb bombs