The Heinkel He 111 was a German aircraft designed by Siegfried and Walter Günter at Heinkel Flugzeugwerke in the early 1930s. It has sometimes been described as a "wolf in sheep's clothing" because it masqueraded as a cargo plane though its actual purpose was to provide the nascent Luftwaffe with a fast medium bomber. (Germany had been prohibited by the 1919 Treaty of Versailles from having an air force.)
Perhaps the best-recognised German bomber due to the distinctive, extensively glazed "greenhouse" nose of later versions — in effect, a "stepless cockpit", with no separate windscreen panels for the pilot and co-pilot apart from the streamlined shape — the Heinkel He 111 was the most numerous and the primary Luftwaffe bomber during the early stages of World War II. It fared well until the Battle of Britain, when its weak defensive armament, relatively low speed, and poor manoeuvrability were exposed. Nevertheless, it proved capable of sustaining heavy damage and remaining airborne. As the war progressed, the He 111 was used in a variety of roles on every front in the European theatre. It was used as a strategic bomber during the Battle of Britain, a torpedo bomber during the Battle of the Atlantic, and a medium bomber and a transport aircraft on the Western, Eastern, Mediterranean, Middle Eastern, and North African Fronts.
Although constantly upgraded, the Heinkel He 111 became obsolete during the latter part of the war. It was intended — along with almost every other twin-engined bomber in Luftwaffe service — to be replaced by the winning design from the Luftwaffe's Bomber Bdesign competition project, but the delays and eventual cancellation of the project forced the Luftwaffe to continue using the He 111 until the end of the war. Manufacture ceased in 1944, at which point, piston-engine bomber production was largely halted in favour offighter aircraft. With the German bomber force virtually defunct, the He 111 was used for transport and logistics.
Production of the Heinkel continued after the war as the Spanish-built CASA 2.111. Spain received a batch of He 111H-16s in 1943 along with an agreement to licence-build Spanish versions. Its airframe was produced in Spain under licence by Construcciones Aeronáuticas SA. The design differed significantly in powerplant only, eventually being equipped with Rolls-Royce Merlin engines. The Heinkel's descendant continued in service until 1973.
Design and development
Heinkel He 111 in flight.
After its defeat in World War I, Germany was banned from operating an air force by the Treaty of Versailles. German re-armament began in the 1930s and was initially kept secret because it violated the Treaty. Therefore, the early development of military bombers was disguised as a development program for civilian transport aircraft.
In the early 1930s Ernst Heinkel decided to build the world's fastest passenger aircraft, a goal met with scepticism by Germany's aircraft industry and political leadership. Heinkel entrusted development to Siegfried and Walter Günter, both fairly new to the company and untested.
In June 1933 Albert Kesselring visited Heinkel's offices. Kesselring was head of the Luftwaffe Administration Office: at that point Germany did not have a State Aviation Ministry but only an aviation commissariat, the Luftfahrtkommissariat. Kesselring was hoping to build a new air force out of the Flying Corps being constructed in the Reichswehr and convinced Heinkel to move his factory from Warnemünde to Rostock and turn it over to mass production with a force of 3,000 employees who would produce the first He 111. Heinkel began a new design for civil use in response to new American types that were appearing, the Lockheed 12, Boeing 247 and Douglas DC-2.
The first single-engined Heinkel He 70 Blitz ("Lightning") rolled off the line in 1932 and the type immediately started breaking records. In its normal four-passenger version its speed reached 380 km/h (230 mph), powered by a 447 kW (600 hp) BMW VI engine. The elliptical wing that the Günther brothers had already used in the Bäumer Sausewind sports plane before they joined Heinkel became a feature in this and many subsequent designs they developed. The design drew the interest of the Luftwaffe, which was looking for an aircraft with dual bomber/transport capabilities.
The He 111 was a twin-engine version of the Blitz, preserving the elliptical inverted gull wing, small rounded control surfaces and BMW engines, so that the new design was often called the Doppel-Blitz ("Double Blitz"). When the Dornier Do 17 displaced the He 70, Heinkel needed a twin-engine design to match its competitors. Heinkel spent 200,000 hours developing it. The fuselage length was extended to just over 17.4 m/57 ft (from 11.7 m/38 ft 4½ in) and wingspan to 22.6 m/74 ft (from 14.6 m/48 ft).