The Caspar U.1 (sometimes known as the Caspar-Heinkel U.1) was a 1920s German patrol seaplane designed by Ernst Heinkel and built by Caspar-Werke.[1] The U.1 was designed to fit into a cylindrical container to allow it to be carried, then launched from a submarine.[1]

Caspar U.1
Caspar U-1.jpg
U.1 under test by the US Navy
Role Submarine-launched patrol seaplane
National origin Germany
Manufacturer Caspar-Werke
Designer Ernst Heinkel
First flight 1922
Primary user Reichsmarine
Number built 3


The U.1 was designed to meet a requirement to fit inside a cylindrical container 7.40 metres (24.3 ft) long with a diameter of 1.70 m (5 ft 7 in); this allowed the aircraft to be carried by a submarine.[1] To reduce the time to launch the aircraft, it was built as a cantilever biplane to remove the need to rig struts and wires on assembly.[1] The U.1 had two single-step floats and was powered by a front-mounted 55-horsepower (41 kW) Siemens radial piston engine.[1] The pilot had an open cockpit behind the upper wing which gave a clear view forward.[1] It is claimed that during tests, four men could remove the U.1 from the container and erect it in 1 minute 3 seconds.[1] Two aircraft were bought by the United States Navy for evaluation;[1] these were delivered to Naval Air Station Anacostia in late 1922, and were tested during 1923; one of the aircraft was damaged beyond repair whilst mounted on a truck for a parade.[2]


  United States


Data from Flight, June 1923[3]

General characteristics

  • Crew: Two
  • Length: 6.20 m (20 ft 4 in)
  • Wingspan: 7.80 m (25 ft 7 in)
  • Height: 2.34 m (7 ft 8 in)
  • Wing area: 14 m2 (150 sq ft)
  • Empty weight: 360 kg (794 lb)
  • Gross weight: 510 kg (1,124 lb)
  • Powerplant: 1 × Siemens 5-cylinder radial engine, 37 kW (50 hp)
  • Propellers: 2-bladed


  • Maximum speed: 145 km/h (90 mph, 78 kn)
  • Cruise speed: 121 km/h (75 mph, 65 kn)
  • Time to altitude: 7 mins to 1,000 m (3,300 ft)
  • Landing speed: 75 km/h (47 mph; 40 kn)

See alsoEdit

Aircraft of comparable role, configuration, and era

Related lists



  1. ^ a b c d e f g h Orbis 1985, p. 1060
  2. ^ Treadwell, Terry (February 1983). "Submarine Aviation". Naval Aviation News. Washington, DC: Naval Air Systems Command. 65 (2): 9. ISSN 0028-1417.
  3. ^ "The Caspar sport seaplane". Flight. XV (24): 315–6. 14 June 1923.


  • The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing.
  • Passingham, Malcolm (February 2000). "Les hydravions embarqués sur sous-marins" [Submarine-carried Seaplanes]. Avions: Toute l'aéronautique et son histoire (in French) (83): 7–17. ISSN 1243-8650.