Heinkel He 70
|Role||Mail plane, Passenger|
|First flight||1 December 1932|
|Retired||1954 Spanish Air Force|
|Primary users||Luft Hansa|
Royal Hungarian Air Force
|Number built||324 + license-built in Hungary|
The Heinkel He 70 is a mail plane and fast passenger aircraft of the 1930s designed by German aeronautics firm Heinkel Flugzeugwerke, which was also used in auxiliary bomber and aerial reconnaissance roles. It had a relatively brief commercial career before it was replaced by types which could carry more passengers. The He 70 was a leading design for its day, setting eight world speed records by the beginning of 1933.
Design and development
The Heinkel He 70 Blitz (lightning) was designed in the early 1930s to serve as a mailplane for Deutsche Luft Hansa in response to a request for an aircraft faster than the Lockheed Vega and Orion used by Swissair) to service short routes.
It was a low-wing monoplane, with the main characteristics of its design being an aerodynamically efficient elliptical wing, twin propellers driven by a single engine, and small, rounded control surfaces.
In order to meet the demanding speed requirements, the design minimised drag, with flush rivets giving a smooth surface finish, and a retractable landing gear. It was powered by a BMW VI V12 cooled by ethylene glycol rather than water, allowing a smaller radiator to further reduce drag. The pilot and radio operator were seated in tandem, followed by a cabin seating four passengers in twos facing each other.
He 70s were flown abroad from Stuttgart to Seville between 1934 and 1936. The route was part of the South America mail service provided by Luft Hansa that continued via Bathurst, The Gambia to Natal, Brazil, using Junkers Ju 52/3m and Dornier Wal flying boats.
Remaining aircraft were transferred to the Luftwaffe in 1937.
The Luftwaffe operated He 70s from 1935, initially as a light bomber and reconnaissance aircraft. As soon as purpose built designs became available, it was relegated as a liaison and courier aircraft.
Twenty-eight aircraft were sent in the late 1930s to Spain with the German-manned Legion Condor, where they were used during the Spanish Civil War as fast reconnaissance aircraft. There they were known as the Rayo, Spanish for "lightning".
The He 70K (later He 170) was a fast reconnaissance airplane variant used by the German air force. Fitted with a new WM-K-14 radial engine, it was used by the Royal Hungarian Air Force as the He 170A early in World War II during 1941–42.
The main weakness of the He 70 in military use was that crews considered it a fire risk. Elements of the airframe were made out of an extremely flammable magnesium alloy called "Elektron", though the majority of the monocoque fuselage was Duralumin. Elektron is very light yet strong, but burns readily when ignited and is difficult to extinguish. Moreover, each wing contained a non-self-sealing 47-gallon fuel tank, which may have further added to the aircraft's reputation for catching fire. A single hit from a light machine gun is reputed to have often set the entire aircraft ablaze. The Hungarian He 170A fleet was retired for this and other reasons, including poor defensive armament, short range and poor view from the cabin, and replaced with vintage, high-wing He 46 monoplanes, until modern Bf 109 fighter-reconnaissance and specialized Fw 189 "Uhu" medium altitude observation aircraft could be introduced.
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While the He 70 saw only limited service in training capacities during World War II, it was the Luftwaffe's first Schnellbomber and served as the antecedent for the majority of bombers involved in both the Battle of Britain and the attack on Pearl Harbor.
The He 70 is known mainly as the direct ancestor of the Heinkel He 111, which had the distinctive elliptical wings and streamlined fuselage in a twin-engine configuration. One can also see the close similarity of the designs in the tail section and cockpit of the early He 111. The He 111, which began service with the Luftwaffe in 1936, went on to become the most numerous bomber type of the Luftwaffe – with just over 5,600 examples produced during the war in total – in the early years of World War II, before the growing numbers of Junkers Ju 88 bomber variants (the -A and -S subtypes) overtook it later in World War II.
Heinkel's pioneering design was also a model for the He 112 fighter which competed unsuccessfully against the Messerschmitt Bf 109 to become the Luftwaffe's first monoplane fighter. The He 112 was nonetheless built in small numbers, and its performance proved once again the strength of the He 70's original design.
The He 70 was exported to Japan for study and inspired the Aichi D3A ("Val") carrier-launched light bomber. This aircraft shared the He 70's distinctive low-mounted elliptical wing and was one of several collaborations between Heinkel and the Japanese aviation industry.
It has been said that the He 70 was an inspiration or influence for the Supermarine Spitfire's elliptical wing,[by whom?]. The He 70 used as an engine test bed by Rolls-Royce did not arrive in the UK until three weeks after the Spitfire's first flight.
In addition to this, we recently investigated the effect that installing certain new British fighter engines would have on the He 70, We were dismayed to find that your new aircraft, despite its larger measurements, is appreciably faster than our fighters. It is indeed a triumph.
However, Beverley Shenstone, RJ Mitchell's aerodynamic advisor denied that the Spitfire wing was copied from the He 70. Shenstone said:
It has been suggested that we at Supermarine had cribbed the wing shape from that of the He 70 transport. This was not so. The elliptical wing had been used on other aircraft and its advantages were well known. Our wing was much thinner than that of the Heinkel and had a quite different section. In any case it would have been simply asking for trouble to have copied a wing shape from an aircraft designed for an entirely different purpose.
Shenstone said that the He 70's influence on the Spitfire design was limited to use as a benchmark for aerodynamic smoothness.
- He 70a
- First prototype.
- He 70b
- Second prototype with the crew of 2 and 4 seats for passengers.
- He 70c
- Third prototype armed with machine gun for trials of versions for light bomber, reconnaissance and courier duties.
- He 70d
- Fourth prototype built in 1934 for Luft Hansa, powered by BMW VI 7,3 engine.
- He 70e
- Fifth prototype built in 1934 for Luftwaffe as light bomber, powered by BMW VI 7,3 engine.
- He 70A
- Passenger version for Luft Hansa.
- He 70D
- Passenger version for Luft Hansa, 12 examples built.
- He 70E
- Light bomber version for Luftwaffe, later converted to F version.
- He 70F
- Reconnaissance / courier version for Luftwaffe.
- He 70F-1
- Long-range reconnaissance version.
- He 70F-2
- Similar to the He 70F-1
- He 70G
- Passenger version built for Luft Hansa, after 1937 converted to F versi on.
- He 70G-1
- One aircraft fitted with a 604 kW (810 hp) Rolls-Royce Kestrel piston engine.
- He 70K (He 170A)
- License-built Hungarian fast reconnaissance variant equipped with a licence-made 746 kW (1,000 hp) WM-K-14 radial engine.
- He 270 V1 (W.Nr. 1973, D-OEHF)
- Prototype with DB-601Aa inline engine.
- Deutsche Luft Hansa received the first two prototypes in 1933 and 1934 as well as three He 70D in 1934 and 10 He 70G in 1935.
- Imperial Japanese Navy Air Service received one aircraft for test.
- Swissair received a few Heinkel He-70s for express trans-alpine flights between Zurich and Milan in 1934.
- Rolls Royce acquired one He 70G from the RLM in exchange for 4 Kestrel engines. It was used as an engine test bed.
- Royal Hungarian Air Force received 18 domestically license-built He 170A aircraft.
Specifications (He 70F-2)
Data from The Beautiful Blitz
- Crew: 3 (pilot, radio operator and dorsal gunner)
- Length: 11.70 m (38 ft 4⅔ in)
- Wingspan: 14.80 m (48 ft 6⅔.75 in)
- Height: 3.10 m (10 ft 2 in)
- Wing area: 36.50 m² (392.9 sq ft)
- Empty weight: 2,360 kg (5,203 lb)
- Loaded weight: 3,386 kg (7,450 lb)
- Max. takeoff weight: 3,500 kg (7,700 lb)
- Powerplant: 1 × BMW VI 7.3 Z water-cooled V12 engine, 750 PS (552 kW)
- Propellers: metal, two-bladed
- Maximum speed: 360 km/h (195 knots, 224 mph) at sea level
- Cruise speed: 295 km/h (159 knots, 183 mph)
- Range: 2,100 km (1,135 nmi, 1,305 mi)
- Service ceiling: 5,300 m (17,390 ft)
- Climb to 1,000 m (3,300 ft: 2.5 min
- Climb to 4,000 m (13,125 ft): 15 min
- Guns: 1 × 7.92 mm (.312 in) MG 15 machine gun aimed from rear cockpit
- Bombs: 6 × 50 kg (110 lb) or 24 x 10 kg (22 lb) bombs internally
Aircraft of comparable role, configuration and era
- "Historical Listings: Spain, (SPN) Archived 2011-07-20 at the Wayback Machine.."] World Air Forces. Retrieved: 10 June 2011.
- Smith and Kay 1972, p.233.
- Smith and Kay 1972, p.234.
- Donald 1999, p.494.
- "Transatlantic". Flight. 1934-12-10. pp. 1349–1350. Retrieved 2011-05-18.
- Regnat, Karl-Heinz (2004). Black Cross Volume 4: Heinkel He 111. Hersham, Surrey, UK: Midland Publishers. p. 74. ISBN 978-1-85780-184-2.
- Mark Peattie, Sunburst: The Rise of Japanese Naval Air Power, 1909–1941, p. 94
- Price 1977, pp. 33—34.
- "Landing Wheels Vanish Into Wings During Take Off" Popular Science, June 1933
- Green and Swanborough Air International January 1991, p. 28.
- Donald, David (ed.) The Encyclopedia of Civil Aircraft. London:Aurum Publishing. 1999. ISBN 1-85410-642-2.
- Green, William and Gordon Swanborough. "The Beautiful Blitz". Air International, January 1991, Vol 40 No 1. Stamford, UK:Key Publishing. pp. 25–33. ISSN 0306-5634.
- Nowarra, Heinz. Heinkel He111 A Documentary History. Jane's Publishing Co Ltd. 1980. ISBN 0-7106-0046-1.
- Smith, J.R. and Kay, A.L. German Aircraft of the Second World War. London: Putnam. 1972. ISBN 0-85177-836-4.
- Price, Alfred. Spitfire: A Documentary History. London: Macdonald and Jane's, 1977. ISBN 0-354-01077-8.
- Townend, David, R. Thunderbolt & Lightning—The History of Aeronautical Namesakes. AeroFile Publications. 2009. ISBN 978-0-9732020-2-1.
- Green, William. "Warplanes of the Second World War – Bombers and Reconnaissance Aircraft, Volume Nine" Macdonald: London, 1967.
|Wikimedia Commons has media related to Heinkel He 70.|
- Photograph of a Heinkel He 70 Luftwaffe ashtray taken from Halle airfield in May 1945
- Heinkel He 70 EADS. Retrieved 16 February 2008.
- LuftArchiv.de (German-language site)