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Klemm L.25, later Klemm Kl 25
was a successful German light leisure, sports and training monoplane
aircraft, developed in 1928. More than 600 aircraft were built,
and manufacturing licenses were sold to the United Kingdom and
the United States. With a low cantilever wing, fixed landing
gear, and two open cockpits, the aircraft was developed by Hanns
Klemm who used his previous design, the Klemm Kl 20, as a starting
point. It first flew on a 20 hp (15 kW) Mercedes engine. About
30 different versions of the Kl 25 were made, and these were
equipped with engines ranging from 32 to 70 kW (43 to 94 hp).
The fuselage was covered with plywood. Depending on the model,
the aircraft's weight was 620 to 720 kg (1,367 to 1,587 lb),
and it had a 10.5 to 13 m (34 to 43 ft) wingspan. Takeoff was
achieved at only 50 km/h (31 mph) and the maximum speed was between
150 to 160 km/h (93 to 99 mph). In relation to similar aircraft
of the time, assembly was very easy, and this made it a very
popular aircraft. According to the sales brochures, only 25%
of the engine's power was needed to keep the aircraft flying,
compared to biplanes of the period, which required 50% engine
power. About 600 were built in Germany between 1929 and 1936,
serving with various flight training organizations, with either
wheels, skis, or floats.
15 were sold to Britain before
the Second World War, being fitted with a variety of domestic
engines, while 28 more were built by British Klemm Aeroplane
Company as the B.A. Swallow. The British dealer for the L.25,
Major E.F Stephen, set up the "British Klemm Aeroplane Company"
at London Air Park, Hanworth, Middlesex to produce a version
of the L.25 under license. The prototype of the licensed version,
known as the B.K. Swallow, first flew at Hanworth in November
1933. It was an all-wooden cantilever monoplane, with tandem
cockpits accommodating two persons, and was powered by a 75 hp
(56 kW) Salmson 9 or 85 hp (63 kW) Pobjoy Cataract radial engine.
It differed from the German original with its more powerful engines
and local strengthening to meet British airworthiness requirements.
In 1935 a revised version of the Swallow was introduced, with
the curved wing tips, rudder and tailplane inherited from the
Klemm original being made straight and with revised fuselage
top decking. At this time the company changed its name to the
British Aircraft Manufacturing Co., so the revised version was
known as the B.A Swallow II. Swallow IIs were produced powered
either by the Cataract or the Cirrus Minor inline engine, production
continuing until 1938, with a total of 107 Swallow IIs produced,
following on from the 28 Swallows I.
Production in the United States
was carried out by the Aeromarine-Klemm Company which enjoyed
moderate success, as well as developing models for the American
market, in isolation from the parent company, with about 120
built of all models. |
