The bridge engineer

Hanns Klemm did not set out to build aeroplanes. Born in Stuttgart in 1885, he trained as a civil engineer and worked on reinforced concrete and bridges. Only in April 1917 did he answer a newspaper advertisement from Zeppelin and find himself under Claude Dornier, learning to build in metal. He moved to Ernst Heinkel at Hansa-Brandenburg, then in 1918 to Daimler at Sindelfingen as chief designer. There, working with wood for the first time, he formed the idea that would make his name: a light, cheap wooden aeroplane that needed only a tiny engine.

A motorcycle engine and a Porsche

His first try, the Daimler L15 of 1919, flew on a 12 hp Harley-Davidson motorcycle engine and once stayed up for 185 minutes. The L20 that followed had a square, easy-to-build fuselage and a 20 hp engine designed by Ferdinand Porsche; more than 100 were built. In 1926 Klemm set up on his own at Böblingen. His designers were a remarkable line: Martin Schrenk, then Robert Lusser, the future father of the V-1 flying bomb, under whom the L25 was born. It could take 14 different engines and about 720 were built, including licence-built aircraft in the United States and Britain.

Round the world in a Klemm

Klemms flew astonishing journeys. In 1928 Friedrich Karl von Koenig-Warthausen set off for Moscow in an L20 and kept going, circling the world in a 20 hp aeroplane and winning the Hindenburg Cup. In January 1930 Mohamed Sidki flew an L25a from Berlin to Cairo, landing on 26 January in defiance of the British authorities and becoming a national hero. Elly Beinhorn flew a Kl 26 to Australia in 1931–1932, and in 1937 Maude Bonney flew a Kl 32 from Brisbane to Cape Town, the first flight from Australia to South Africa.

The Luftwaffe’s trainer

The Nazi air ministry wanted mixed construction and trainers, and Klemm adapted. The Kl 35 prototype broke up at Rechlin in 1935, officially from a material defect, more likely from overstressed wings. Once revised, the Kl 35 became the Luftwaffe’s standard elementary trainer, built at Böblingen, by Fieseler and at Zlín, about 2,000 in all, and under licence in Sweden. A ministry-imposed branch works at Halle became the Siebel company. Klemm himself joined the NSDAP in 1933.

Into Bölkow

After the war German aircraft building was banned until 1955. The firm was refounded in 1952, run by Klemm’s son Hanns-Jürgen, and revived the wartime Kl 107 two-seater, which flew again in mid-1956; 54 were built in the 1950s. In April 1959 Bölkow took over Klemm, and the Kl 107 grew into the Bölkow Bo 207. Hanns Klemm died in 1961, his name gone from the aircraft registers two years earlier.

Factories

• Böblingen works · Böblingen, near Stuttgart — Main plant and attached flying school
• Halle branch · Halle an der Saale — Set up in 1934 at the ministry’s demand; became Flugzeugwerk Halle, later Siebel

People

• Hanns Klemm · founder — 1885–1961; civil engineer turned light-aircraft pioneer
• Robert Lusser · designer — Led the L25 design; later the V-1’s designer
• Elly Beinhorn · pilot — Flew a Kl 26 to Australia and round the world; Hindenburg Cup
• Friedrich Karl von Koenig-Warthausen · pilot — Round-the-world flight in an L20, 1928–1929

Records and firsts

• Round-the-world flight in a 20 hp Klemm L20, Koenig-Warthausen, 1928–1929
• First flight from Australia to South Africa, Maude Bonney, Klemm Kl 32, 1937