Akaflieg Darmstadt D-39

The Akaflieg Darmstadt D-39 was a single-seat motor glider derived from the D-38 sailplane. Built in Germany in the late 1970s, it was not intended for production and only one was constructed.

DF-39
Role Motor glider
National origin Germany
Manufacturer Akaflieg Darmstadt
First flight 28 June 1979
Number built 1
Developed from Akaflieg Darmstadt D-38

Design and development

The D-39 was a motorised version of the D-38 sailplane, with wings moved down from the latter's shoulder-wing position to the bottom of the fuselage. A Limbach SL 1700 flat four engine was conventionally mounted in the nose; the propeller could be removed but not folded away in flight. The wings, with 4° of dihedral, tail and monocoque fuselage were formed from glass fibre balsa sandwiches and the ailerons from glass fibre/Klégécel foam sandwiches. The D-38 had an all moving T-tailplane, fitted with a Flettner tab. It landed on a retractable monowheel, fitted with a drum brake and assisted by a small, fixed tailwheel.[1]

The D-39 was first flown on 28 June 1979.[1] By July 1982 it had been modified into the D-39b, with a greater span, revised wing roots and fitted with a three-bladed Hoffmann Propeller airscrew with three blades and three pitch positions. The D-39 was not further developed nor put into production.[2]

Variants
D-39
Original version
D-39b
Same aircraft modified with greater span, revised roots and a new propeller.

Specifications (D-39)

Data from Jane's All the World's Aircraft 1981/2[1]

General characteristics

  • Crew: 1
  • Length: 7.15 m (23 ft 5 in)
  • Wingspan: 15.00 m (49 ft 3 in)
  • Height: 1.02 m (3 ft 4 in) over fuselage, not tail
  • Wing area: 11.00 m2 (118.4 sq ft) gross
  • Aspect ratio: 20.5
  • Airfoil: Wortmann FX-61-184 at root, FX-60-126 at tip
  • Empty weight: 370 kg (816 lb)
  • Max takeoff weight: 470 kg (1,036 lb)
  • Fuel capacity: 35 L (9.25 US gal; 7.7 Imp gal)
  • Powerplant: 1 × Limbach SL 1700E flat four, 51 kW (68 hp)
  • Propellers: 2-bladed

Performance

  • Maximum speed: 280 km/h (170 mph, 150 kn)
  • Stall speed: 80 km/h (50 mph, 43 kn)
  • Maximum glide ratio: 36 best, without propeller at 84 km/h (52 mph; 45 kn)
  • Rate of sink: 0.7 m/s (140 ft/min) minimum, without propeller at 105 km/h (65 mph; 56.5 kn)
  • Wing loading: 42.0 kg/m2 (8.6 lb/sq ft) Maximum

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References
  1. Taylor, John W. R. (1981). Jane's All the World's Aircraft 1981-1982. London: Jane's Information Group. pp. 575, 598–9. ISBN 0710607059.
  2. Taylor, John W. R. (1985). Jane's All the World's Aircraft 1985-1986. London: Jane's Information Group. p. 734. ISBN 0-7106-0821-7.


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