Glaser-Dirks DG-400

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Glaser-Dirks/
DG Flugzeugbau DG-400
A 17-metre span DG-400
Type designation	DG-400
Competition class	18 metre
Number built	290
Crew	1
Length	7 m
Height	m
Cockpit width	0.62 m
Cockpit height	0.81 m
Wingspan	17 m
Wing area	10.57 m²
Aspect ratio	27.34
Wing profile	FX 67-K-170
Empty mass	ca. 310 kg equipped
Water ballast	90 kg
Maximum mass	460 kg
Wing loading	ca. 37 - 43.5 kg/m²
Maximum speed	270 km/h
Maneuver speed	190 km/h
Minimum sink	ca. 0.54 m/s
Glide ratio	45
Roll rate	ca. 3.5 - 4 s (-45º to +45º)
Engine type	Rotax 505 2 cylinder 2 stroke
Engine power	ca. 43 hp
Fuel tanks	20 litres (50 as option)
Take-off run	ca. 170 m (460 kg, ISA)
Distance to clear 15 m obstacle	ca. 270 m (460 kg, ISA)
Climb rate	m/s (sea level) m/s (at 3000 m)
Best climb speed	90 km/h
Range in 'saw-tooth' operation	380 km with 20 l

The Glaser-Dirks DG-400 is a single-seat motorglider produced by Glaser-Dirks between 1981 and 1990. It was the first self-launching motorglider with retractable engine and propeller to be produced in large numbers.

[edit] History

The cost of carbon-fibre had fallen enough in the late 1970's to allow its use in the wing spars of higher-end 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 unnacceptable penalty in weak weather soaring ability. Thus was born the DG-400, whose first flight took place in May 1981.

The DG-400 uses the wings and most systems of the DG-202. A modified fuselage with a slightly enlarged boom and carbon fibre reinforcements was required for the engine, which is a relatively large unit with electric starter and electric retraction. This powerful installation, associated with a user-friendly engine control unit - a field where DG Flugzeugbau continues to lead up to this day - ensured that the DG-400 was significantly safer and easier to operate than other self-launching gliders, ensuring its success.

As was typical for the time, the engine, propeller and supporting pylon constitute a monolitic 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. Although superseded by more modern self-launching sailplanes, the DG-400 is still very popular, being one of the favorites in the second-hand market.