It was the first self-launching motorglider with retractable engine and propeller to be produced in large numbers.

The cost of carbon-fibre had fallen enough in the late 1970s to allow its use in the wing spars of high-performance gliders.

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.

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).