Glaser-Dirks DG-400

The Glaser-Dirks DG-400 is a single-seat self-launching motorglider that was produced by Glaser-Dirks between 1981 and 1992. It was the first self-launching motorglider with retractable engine and propeller to be produced in large numbers.

DG-400
Role 18 metre class sailplane
National origin Germany
Manufacturer Glaser-Dirks
Designer Wilhelm Dirks
First flight May 1981
Introduction 1981
Number built 290
Developed from Glaser-Dirks DG-200
External image
DG-400 self-launching

Development

The cost of carbon-fibre had fallen enough in the late 1970s to allow its use in the wing spars of high-performance gliders. Glaser-Dirks introduced a carbon wing variant of the DG-200 about this time. Designer Wilhelm Dirks realised that the span, strength and very low weight of this wing allowed for a self-launching engine to be carried in the glider without an unacceptable penalty when soaring in weak conditions. The DG-400 was created as a result. It first flew in May 1981.

The DG-400 uses the wings and most systems of the DG-202. It has a modified fuselage with a slightly enlarged tailcone and carbon fibre reinforcements to accommodate the engine, which is a relatively large unit with electric starter and electric retraction. This powerful installation, with a user-friendly engine control unit, made the DG-400 easier to operate than other self-launching gliders.

As was typical for the time, the engine, propeller and supporting pylon constitute a single unit that extends into the airflow (in more recent self-launchers the engine usually stays inside the fuselage). The type may be flown either with 15 metre or 17 metre wingtips.

The DG-400 was not aimed at competitions, but rather at leisure flying. Nevertheless, several World Gliding Records have been achieved flying this type.

Specifications (17 metre wings)

Data from [1]

General characteristics

  • Crew: 1
  • Length: 7 m (23 ft 0 in)
  • Wingspan: 17 m (55 ft 9 in)
  • Height: 1.4 m (4 ft 7 in)
  • Wing area: 10.57 m2 (113.8 sq ft)
  • Aspect ratio: 27.3
  • Airfoil: root:Wortmann FX-67-K-170-17; tip Wortmann FX-60-K-126
  • Empty weight: 305 kg (672 lb)
  • Max takeoff weight: 460 kg (1,014 lb)
  • Fuel capacity: 20 l (5.3 US gal; 4.4 imp gal)
50 l (13 US gal; 11 imp gal) with optional tanks in lieu of water ballast
  • Water ballast: 90 l (24 US gal; 20 imp gal)
  • Powerplant: 1 × Rotax 505 two-stroke retractable pylon mounted air-cooled piston engine, 32 kW (43 hp)
  • Propellers: 2-bladed Hoffman fixed pitch propeller, 1.29 m (4 ft 3 in) diameter

Performance

  • Cruise speed: 130 km/h (81 mph, 70 kn) economical
140 km/h (76 kn; 87 mph) max
  • Stall speed: 63 km/h (39 mph, 34 kn)
  • Never exceed speed: 270 km/h (170 mph, 150 kn) in smooth air
190 km/h (100 kn; 120 mph) in rough air
190 km/h (100 kn; 120 mph) on aero-tow
130 km/h (70 kn; 81 mph) on winch launch
  • Range: 400 km (250 mi, 220 nmi) level flight
750 km (400 nmi; 470 mi) cruise/soar
  • Service ceiling: 5,000 m (16,000 ft)
  • g limits: +6 -4
  • Maximum glide ratio: 45 at 110 km/h (59 kn; 68 mph)
  • Rate of climb: 3.90 m/s (768 ft/min) at 80 km/h (43 kn; 50 mph)
  • Rate of sink: 0.5 m/s (98 ft/min)
  • Wing loading: 43.5 kg/m2 (8.9 lb/sq ft)
  • Power/mass: 0.0714 kg/kW (0.0433 hp/lb)

References
  1. John W.R. Taylor, ed. (1988). Jane's All the World's Aircraft 1988-89. London: Jane's Information Group. pp. 620–621. ISBN 0-7106-0867-5.
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