Design and development Daimler L15

the l15 in glider configuration

by end of first world war, hanns klemm had moved dornier aircraft branch of daimler motors , had designed 2 prototype fighters, daimler l11 , l14. military aviation ended terms of versailles treaty, turned developing low-power light aircraft. 1919 daimler l15 high cantilever wing aircraft 6 kw (7.5 hp) indian motorcycle engine. rather little detailed information on seems have survived; had unusual rotating wingtips roll control instead of ailerons , single axle undercarriage. suffered serious propeller damage in 1919, in testing programme. on daimler , klemm abandoned aviation; klemm remained daimler, concentrating on streamlined racing cars , locomotives.

during 1920 german aviation enthusiasts realised that, though germany forbidden allies build aeroplanes, gliders not included in category, resulting in series of competitions on wasserkuppe became known rhön contests. perhaps stimulated these events, klemm proposed in 1922 l15 should rebuilt glider , obtained approval daimler management. engine demounted , replaced long, smooth nose, deliberately designed removable engine reinstalled if desired. pilot sat @ wing leading edge in cockpit within removable nose , there passenger cockpit between 2 wing spars @ 1 third chord. fuselage formed 4 longerons, positioned formers , wire-braced rectangular section, rounded upper , lower fairings. smooth fuselage , cantilever wing, empennage had no external bracing, made aerodynamically clean time.

the fabric-covered, tapered wings built around 2 box spars. 1919 machine had single piece wing gliders need transportable , wings rebuilt in 3 pieces. rudder , elevators removable , outer parts of tailplane hinged upwards, again ease of transport.

at point during reconstruction fixed axle undercarriage replaced more refined arrangement wheels separately mounted on hinged , faired v-struts fuselage underside , vertical shock absorber struts wing underside, allowing larger wheel deflections on landing less half wheel-diameter allowed end-sprung rigid axle mountings. unusually, wheels, had three-ply centres, ash-tyred because rubber expensive in postwar germany.

given limitations of relatively low aspect ratio (about 7.5), l.15 performed satisfactorily glider. in summer of 1922 made flights of 13 minutes, estimated l/d of 16.

towards end of 1923 l15 received second-hand, 9 kw (12.5 hp) harley-davidson motorcycle engine, mounted cyliders exposed cooling , driving two-bladed propeller though 3:1 epicyclic reduction gearing. there again 2 open cockpits in tandem, since nose shorter pilot occupied cockpit used passenger on glider , passenger sat close behind him @ wing trailing edge.

during tests, powered l15 reached altitude of 2,150 m (7,050 ft) pilot on board , 1,100 m (3,610 ft) passenger; solo flight lasting 185 minutes made , 1 passenger-carrying flight lasted 122 minutes. other flights covered 190 km (118 mi) solo , 190 km (118 mi) passenger. in autumn of 1924 l15 fitted floats , took off water successfully, @ first carrying pilot , passenger. takeoff took 12 seconds in both cases, 12.5 hp. in these tests new engine, uncowled daimler-versuchmotor f7506 flown first time. unusual small, two-stroke, six-cylinder, air-cooled radial engine, fitted roots blower, had been designed light aircraft , produced 15 kw (20 hp), not developed produce higher powers , abandoned in favour of harley-davidson.

the last new engine power l15 more powerful (30 kw (40 hp)) salmson. in place, l15 considerably refined flaps, slats , pneumatic, rubber-tyred wheels.

the flights low-powered harley-davidson engine attracted attention , launched klemm on path led him, after designing @ least 2 more daimler light aircraft, set own light aircraft company in 1926. in 1924 l15 refitted motorcycle engine , put on display in deutsches museum placard first light aircraft , destroyed during world war ii.