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HD 25
Heinkel HD 25 of the Imperial Japanese Navy
Role Reconnaissance seaplane
National origin Germany
Manufacturer Heinkel, Aichi
First flight 1926
Primary user Imperial Japanese Navy
Number built ca. 18

The Heinkel HD 25 was a reconnaissance seaplane developed in Germany during the 1920s for production in Japan. It was intended to provide a spotter aircraft for warships, to take off from a short ramp since shipboard catapults had not yet been invented. The HD 25 was a conventional biplane with staggered wings and twin pontoon undercarriage. The pilot and observer sat in tandem, open cockpits. Two prototypes were built by Heinkel in Germany, with the first flying in 1926.[1] Following trials, the Navy officially accepted the type in March 1928 and gave it the designation Type 2 Two-seat Reconnaissance Seaplane. 16 were built by Aichi and saw brief service aboard the cruisers of the Imperial Japanese Navy.

A single example of a modified demilitarised version was built by Aichi as the AB-1, and three surplus Type 2 Two-seat Reconnaissance Seaplanes were converted with two seat cabins aft of the open rear cockpit, to seat three passengers, for use by the Kouchi Shimbun newspaper.


Heinkel HD 25
Heinkel Doppeldekker 25, two prototypes designed and built in Germany.[1]
Heinkel Large Reconnaissance Seaplane
Unofficial designation for the Heinkel built prototypes[1]
Heinkel-Type Warship Seaplane
Initial unofficial designation for the Aichi produced aircraft[1]
Aichi Type 2 Two-seat Reconnaissance Seaplane
Production aircraft built by Aichi in Japan with modifications to allow operations from turret platforms[1]
Aichi Type 2 Transport
Conversions of three surplus Type 2 Two-seat Reconnaissance Seaplanes with cabins seating three passengers, used by the Kouchi Shimbun newspaper.[1]
Aichi AB-1
A single aircraft derived from the HD 25 for use as a transport aircraft and enterred in the Japanese Aviation Bureau of the Department of Communications competition for a home grown transport aircraft. Modifications included: increaesed dimensions, N-type inter-plane struts, a four seat enclosed cabin forward of the two pen cockpits and a Lorraine W-12 engine.[1]

Specifications (Aichi-built)

General characteristics

  • Crew: Two, pilot and observer
  • Length: 9.70 m (31 ft 10 in)
  • Wingspan: 14.88 m (48 ft 10 in)
  • Height: 4.27 m (14 ft 0 in)
  • Empty weight: 1,700 kg (3,750 lb)
  • Gross weight: 2,570 kg (5,650 lb)
  • Powerplant: 1 × Napier Lion, 334 kW (450 hp)


  • Maximum speed: 203 km/h (127 mph)
  • Range: 910 km (570 miles)
  • Rate of climb: 3.3 m/s (645 ft/min)


  • 1 × flexible, rearward-firing 7.7 mm (.303 in) machine gun for observer
  • 300 kg (661 lb) of bombs
  • References

    1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Mikesh and Abe 1990, p.63.
    • Mikesh, Robert C.; Abe, Shorzoe (1990). Japanese Aircraft 1910-1941. London: Putnam. ISBN 0-85177-840-2. 
    • Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. pp. 499. 

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