Daimler L20

Daimler L.20
Role	Two-seat light aircraft
National origin	Germany
Manufacturer	Daimler aircraft and Klemm Flugzeugebau
Designer	Hanns Klemm
First flight	c.1924
Variants	Klemm L.25

The Daimler L20, later known as the Klemm-Daimler L20, was one of the first light aircraft to be built in significant numbers. 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.

Hans Klemm's first light aircraft was the Daimler L15 and the L20 had much in common with it. Both were cantilever monoplanes with twin open, tandem cockpits and engines of very low power. The L20's low wing distinguished it from its predecessor and had the advantage of providing a low centre of gravity and better view during the landing approach as well as better protection for occupants in case of crash landings. The low-set wing also allowed a shorter undercarriage on the L20, which was otherwise like that of the L15 with the wheels independently mounted on pairs of centrally hinged V-struts and with vertical shock absorbing legs to the wing underside. Wheels were sometimes replaced by floats. 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. The fuselage was wooden framed with canvas covering. The overall strength of the structure, which had a safety factor of 12, was emphasised.

The wing was tapered in planform and was built around two spars, though there were two variants of the internal wing structure. The first three aircraft, type L20 A1, had wings stiffened against torsion by internal wire bracing but later aircraft, type L20 B1, used a torsion box formed by plywood skin ahead of the rear spar. 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. On early examples these flaps were roughly square, with a side less than a half of the chord at the tip, but at some later time they were reshaped to produce wing curved tips. 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.

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Wikipedia