Akaflieg Darmstadt D-39

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

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.

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 (174 mph; 151 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

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.