Häfeli DH-3

The Häfeli DH-3 was an 1910s Swiss two-seat reconnaissance aircraft, built by the aircraft department of the Federal Construction Works (Eidgenoessische Konstruktionswerkstaette, (K+W)) at Thun, Switzerland.

Development and design

Following the poor performance of the DH-2, August Häfeli designed an improved version the Häfeli DH-3. It was basically the same airframe as the DH-2, the upper wing had a cut-out to give a greater field-of-fire for the pivoted machine-gun. It was a two-bay of wood and fabric construction, powered by a 120 hp (89 kW) Argus As II water-cooled inline engine. Initial problems with the landing gear and the engine cooling system led to modifications. Further developments were the re-engined and improved DH-3a, and the DH-3b used for engine trials. Following successful trials with an installation of the Handley Page slats all surviving DH-3as were modified in 1932.

Operational history

On 8 January 1919 a DH-3 inaugurated the firsts Swiss air mail service between Zurich and Berne. A DH-3 aircraft failed a structural test in 1923 which caused the DH-3 to be withdrawn from service. The DH-3a following modification remained in service until 1939.

Variants

DH-3

Initial production version with Argus As II engine, 24 built.

DH-3a

Improved version with Hispano-Suiza HS-41 8Aa engines, four aircraft ordered in 1919. A second order of 30 aircraft was placed in 1919 with licence built engines, a third order for 49 aircraft was placed in 1925. Survivors were modified at Thun in 1932 with Handley Page slats and changes to allow crew to wear parachutes.

DH-3b

Three aircraft powered by the indigenous 150 hp (112 kW) LFW 0 engine developed by the Swiss Locomotive and Machine Works were built in 1918.

Operators

Cutaway replica of a Häfeli DH-3

  Switzerland

• Swiss Air Force

Specifications (DH-3a)

Data from The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985)

General characteristics

• Crew: Two
• Length: 26 ft 1 in (7.95 m)
• Wingspan: 41 ft 0 in (12.50 m)
• Height: 10 ft 2 in (3.10 m)
• Wing area: 409.04 m² (38 m²)
• Empty weight: 1,587 lb (720 kg)
• Max. takeoff weight: 2,447 lb (1110 kg)
• Powerplant: 1 × Hispano-Suiza HS-41 8Aa 8-cylinder Vee piston engine, 150 hp (112 kW)

Performance

• Maximum speed: 90 mph (145 km/h)
• Range: 249 miles (400 km)
• Service ceiling: 14,765 ft (4500 m)

• one pivoted machine-gun in the rear cockpit

References

• The Illustrated Encyclopedia of Aircraft (Part Work 1982-1985). Orbis Publishing. 

External links

Konstruktion Häfeli DH-3 in Thun

See also