Heinkel He 70 Blitz
The Heinkel He 70 Blitz was a German single-engined monoplane designed as a fast four-seat airliner for Deutsche Lufthansa and first flown on 1 December 1932. Its elliptical wing, smooth flush-riveted skin and retractable landing gear made it one of the fastest airliners of its day; the prototypes set eight international speed records and Heinkel built 324 in all. The Luftwaffe adapted it as a light bomber and reconnaissance aircraft, it served in Spain with the Condor Legion, and a licence-engined variant, the He 170, served Hungary. Its wing and streamlined form fed into the later He 111, but no example of the type survives today.
Why It Mattered
The He 70 was Heinkel's answer to a Deutsche Lufthansa demand for a mail plane that could outperform the American-built Lockheed Orion then entering service with Swissair. When it appeared, its speed set it apart: it reached 234 mph on a timed flight in 1933, and the prototypes set eight international records for speed over distance. It was that speed that earned the aircraft its name, Blitz — lightning. It was also the first aircraft in German commercial aviation with retractable landing gear, a feature that soon became essential to military design. Its elliptical wing and streamlined fuselage carried into Heinkel's later military aircraft, above all the He 111. Heinkel built 324 He 70s in all.
Design Notes
The He 70 was designed by the Günter brothers as a low-wing cantilever monoplane built around an elliptical wing. History of War describes that wing as an inverted gull form, with the retractable main gear set into its lowest point. The fuselage was assembled from panels riveted edge to edge rather than overlapped, which gave the aircraft a very smooth surface. A single BMW VI V-12 powered it, cooled by a compact radiator that retracted in flight to reduce drag. Pilot and radio operator sat in tandem ahead of a cabin for four passengers. On the early aircraft the cockpit sat offset to the left of the fuselage; later versions moved it to the centre line. History of War also notes the wing was similar in plan to the Supermarine Spitfire's.
Operational History
The prototype first flew on 1 December 1932 at Travemünde. Lufthansa received twenty-eight He 70s, putting them on airmail work from March 1933 and on its fast Blitz-Dienst passenger routes from June 1934. The airline also flew the type from Stuttgart to Seville, collecting mail for its South America service. Larger twin-engined airliners then displaced it, and the last Lufthansa aircraft were withdrawn in 1938. The Luftwaffe took the design over as a military aircraft: deliveries of the He 70E light bomber began early in 1935, and the He 70F reconnaissance version followed later that year. On 3 June 1936, General Walther Wever, the Luftwaffe's first chief of staff, was killed when his He 70 crashed on take-off. Eighteen He 70F-2s went to Spain in the autumn of 1936 with A/88, the Condor Legion's reconnaissance element, where they were named Rayo. Replaced there by the Dornier Do 17F, the twelve survivors passed to the Spanish Nationalist Air Force and remained in service into the 1950s. By September 1939 the remaining German aircraft had been relegated to liaison and training duties. Hungary's eighteen licence-engined He 170s, delivered in 1937–38, flew reconnaissance on the Eastern Front from 27 June 1941 but were withdrawn from the front line that July.
Afterlife
One He 70 was exchanged for Rolls-Royce Kestrel engines and reached Britain, where it remained in use as an engine test bed until 1944. Fitted there with a Peregrine engine, it reached 298 mph in October 1938, faster than any German version of the type. Heinkel scaled the Blitz down into the He 112 fighter, which lost its competition to the Messerschmitt Bf 109. A single aircraft sent to Japan was studied by the Aichi Aircraft Company, and lessons from it were applied to the Aichi D3A dive bomber. The Spanish aircraft outlasted the Second World War, but no example of the He 70 family survives today.