When World War I ended, the German Air Force was disbanded under the
Treaty of Versailles, which required the German government to abandon all
military aviation by October 1, 1919. However, by 1922, it was legal for
Germany to design and manufacture commercial aircraft, and one of the first
modern medium bombers to emerge from this process was the Heinkel He
111, the first prototype of which an enlarged, twin-engine version of
the single-engine mail-liaison He 70, which set 8 world speed records in 1933
flew in February of 1935. The second prototype, the He 111 V2,
had shorter wings and was the first civil transport prototype, capable of
carrying 10 passengers and mail. The third prototype, He 111 V3 also
had shorter wings and was the first true bomber prototype. Six He
111 C series airliners were derived from the fourth prototype,
the He 111 V4, and went into service with Lufthansa in 1936,
powered by a variety of engines, including BMW 132 radials. The first
production models had the classic stepped windshield and an elliptical wing,
which the designers, Siegfried and Walter Gunter, favored. As a military
aircraft, it took longer to gain favor, because military load requirements and
underpowered engines kept its cruising speed down to less than 170 mph.
However, in early 1936, the plane was given 1,000 hp Daimler Benz DB 600A
engines which improved performance dramatically enough to bring in substantial
orders. The first two mass-production versions, He 111 E and He
111 F experienced great success during the Spanish Civil War,
where they served with the Condor Legion as fast bombers, able to outrun many
of the fighters sent against them.
