A two-seater with an engine of only 20 hp (15 kW), it demonstrated the ability of a small aircraft to cope with flights over the Alps in winter and to make transcontinental journeys of over 36,000 km.

Intended from the start for serial production, the L20's structure was simplified, with a pentagonal cross-section fuselage lacking the L15's rounded upper and lower surfaces.

[1] Like the later version of the L15, the L20 used a combination of conventional ailerons and unusual wingtip flaps, rotating about an axis well ahead of mid-chord.

The ailerons were directly controlled from the cockpit as normal and the tip flaps were linked to them with external rods and cranks.

The wings could be detached at the root in about five minutes, reducing the width of the L20 to 1.7 m (67 in) for road transport on a trailer pulled by a car.

Flight Magazine hailed this as the "Vindication of the Light 'Plane", in the sense that it showed small aircraft to be a practical vehicle for travel over difficult terrain and in uncertain weather.

The return journey reached eastwards, skirting the Alps via Budapest and Vienna and arriving home at Sindelfingen on 16 March.

From there he and the L20 crossed to North America by sea but flew across the United States, arriving in New York City on 3 September 1929 after travelling 36,000 km (22,369 mi) from Berlin.