Heinkel HD 20
| Heinkel HD 20 | |
|---|---|
| |
| Role | Three seat photographic survey and mapping aircraft |
| National origin | Germany |
| Manufacturer | Heinkel Flugzeugwerke
|
| First flight | c.1926 |
| Number built | At least one |
The Heinkel HD 20 was a twin engine, three seat German biplane built in 1926 for civil survey work.
Design and development
The Heinkel HD 20 was one of the early products of post-World War I aircraft companies after the Allies aviation ban was lifted.[1] HD stood for German: Heinkel Doppeldecker or Heinkel biplane.
The HD.20 had unswept wings of mixed construction with wooden spars, two in the upper wing and one in the lower, and steel ribs; they were
It was powered by two 150 kW (200 hp) Wright R-790 Whirlwind nine cylinder radial engines, mounted in streamlined cowlings with the cylinder heads protruding for cooling. They were fed from fuel tanks in the upper wing; oil tanks were in the cowlings. Each engine was bolted to a frame formed of the interplane struts, a nearly horizontal V-strut to the upper fuselage and an N-form strut from the lower wing to the upper fuselage.[1]
The square cross-section fuselage was formed with steel tubes and covered with fabric, with a light, rounded, wooden upper decking. There were three open cockpits: one in the nose, another under the upper wing and the last, from which it was flown, just behind the upper trailing edge which had a shallow, rounded cut-out to aid the pilot's forward view. The tail surfaces were conventional and straight-edged, with angled leading edges and unswept trailing edges. The tailplane, mounted on the upper fuselage, was braced from below to the fuselage with a single strut on each side. Both the rudder and elevators were balanced; the latter were separate, their inner corners cut away for deflections of the deep rudder.[1]
The HD.20 had a conventional tailskid undercarriage. Each mainwheel was mounted on a group of three struts, two to the lower fuselage longeron at points on the wing leading edge and at mid-chord and the third to the upper longeron. There was a solid rubber shock absorber in each hub. The wheels could be replaced with floats.[1]
Operational history
Rather little is known about the history of the HD 20. From the January 1927 date of the Les Ailles article[1] the first flight was probably in later 1926. The number built is also not known. One (D-1157), which appears on a reconstructed civil register, was owned by the Epro advertising agency and was destroyed on 21 November 1929.[2] The HD.20 is also mentioned as a photographic survey aircraft in a 1930 review of the topic, though it does not show the camera positions.[3]
Specifications
Data from Les Ailes, 6 January 1927[1]
General characteristics
- Crew: Three
- Length: 9.45 m (31 ft 0 in)
- Upper wingspan: 12.80 m (42 ft 0 in)
- Lower wingspan: 8.80 m (28 ft 10 in)
- Height: 3.52 m (11 ft 7 in)
- Wing area: 39.80 m2 (428.4 sq ft)
- Empty weight: 1,315 kg (2,899 lb)
- Gross weight: 1,965 kg (4,332 lb)
- Fuel capacity: 340 L (75 imp gal; 90 US gal)
- Powerplant: 2 × Wright R-790 Whirlwind 9-cylinder radial, 150 kW (200 hp) each
- Propellers: 2-bladed metal, Reed Propellers
Performance
- Maximum speed: 195 km/h (121 mph, 105 kn) at 500 m (1,600 ft)
- Cruise speed: 180 km/h (110 mph, 97 kn)
- Minimum control speed: 85 km/h (53 mph, 46 kn)
- Endurance: 4.5 hr
- Service ceiling: 6,000 m (20,000 ft)
- Time to altitude: 35 min to 5,000 m (16,000 ft)
References
- ^ a b c d e f "L'Avion de 'Travail' Heinkel". Les Ailes (290): 3. 6 January 1927.
- ^ "Golden Years of Aviation". Retrieved 2 November 2015.
- ^ Hay, Alfred (1930). Handbuchen Wissenschaftlichen und Angewanten Photographie - Vol VII - Photogrammetrie und Luftbildwesen. Vienna: Verlag der Julius Springer.