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Japan's Imperial Navy flag

Japan's Yokosuka R2Y Keiun (blue cloud) reconnaissance


  • Yokosuka R2Y Keiun reconnaissance
  • Yokosuka R2Y1 Keiun reconnaissance



In 1942 the Imperial Japanese Navy released the 17-Shi specification for a reconnaissance aircraft with the following specifications:

  • 414 mph / 360 knots at 19,685' / 6,000 m
  • Long range
  • Land based

The Dai-Ichi Kaigun Koku Gijitsusho was tasked with coming up with a design. It was to use a Mitsubishi 24 cylinder (2,500 HP) liquid cooled engine then under development. As the delivery was expected much later than initially planned for two Mitsubishi MK10A radials were used. This design, the R1Y1 Seiun (blue cloud), didn't meet the specifications of the 17-Shi and was abandoned.

Then the Imperial Japanese Navy released an 18-Shi specification in early 1943. This lead to a design that was inspired by an Heinkel He 119V4 that was purchased by the Navy in 1940 by Commander Hideo Tsukada. The design had two engines behind the cockpit that would drive a single propeller. This was to become the R2Y1 Keiun (beautiful cloud).

In 1944, with the worsening war situation the Navy decided to transform the R2Y1 into a jet attack bomber. A Ne-330 turbojet was intended to be placed under each wing. This became the R2Y2.


In April 1945 the R2Y1 prototype was completed and testing was to be made at Kisarazu. On May 8, 1945, Lieut-Commander Kitajima flew the R2Y1 for the first time. The flight was cut short due to rising oil temperatures. A few days later the prototype was destroyed by American bombers.


  • Yokosuka R2Y1 prototype: 1
    • Manufacturer: Dai-Ichi Kaigun Koku Gigitsusho
    • Production: April 1945


  • Yokosuka R2Y1: Long range reconnaissance.
  • Yokosuka R2Y2: Jet attack bomber. Design never completed.


Type Long Range Reconnaissance
Crew Pilot, Radio Operator / Navigator
Engine (Type) 1: Aichi Ha-70 10 (two Aichi Atsuta 30)
Cylinders Radial 24
Cooling Liquid
Net HP 3,400
Propeller blades 6 Metal
Span 45' 11 3/16"
14 m
Length 42' 9 25/32"
13.05 m
Height 13' 10 15/18"
4.24 m
Wing area 365.972 sq ft
34 sq m
Empty 13,261 lb
6,015 kg
Loaded 17,857 lb
8,100 kg
Maximum 20,723 lb
9,400 kg
Speed at 32,810' / 10,000 m 447 mph
388 knots
Speed - Cruising at 13,125' / 4,000 m 288 mph
250 knots
Climb to 32,810' / 10,000 m 10 minutes
Service Ceiling 38,385'
11,700 m
Range 2,244 statute miles
1,950 nautical miles
Armament None
Type Attack
Crew Pilot, Radio Operator / Navigator
Engine (Type) 2: Ne-330 axial-flow turbojets
Thrust 2,910 lb
1,320 kg
Nose Cannons
Bombs 1: 1,764 lb
1: 800 kg


  1. Japanese Aircraft of the Pacific War, René J Francillon, 1970
20th Century American Military History Crucial Site