Heinkel He 70

Heinkel He 70 on saksalaisen lentokonevalmistajan Heinkelin Deutsche Luft Hansalle suunnittelema ja valmistama matkustajalentokone, joka lensi ensilentonsa 1. joulukuuta 1932.


Koneen sotilasversiota käyttivät Saksan ilmavoimat, sekä Espanjan sisällissodassa Kansallisten puolen lentojoukot, ja myöhemmin Espanjan ilmavoimat, yhteys- ja pommikoneena. 

Unkarin ilmavoimat käytti koneesta kehitettyä tähtimoottorista He 170 -versiota

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The Heinkel He 70 was a German mail plane and fast passenger aircraft of the 1930s, that also saw use in auxiliary bomber and 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.

The Heinkel He 70 Blitz (lightning) was designed in the early 1930s to serve as a fast mailplane for Deutsche Luft Hansa. The He 70 was developed in response to a Deutsche Luft Hansa request for a faster aircraft than the Lockheed Vega and Orion (as used by Swissair) for employment on short routes.

It was a low-wing monoplane, with the main characteristics of its revolutionary design its elliptical wing, which the Günther brothers had already used in the Bäumer Sausewind sports plane before they joined Heinkel, and its small, rounded control surfaces. In order to meet the demanding speed requirements, the design minimised drag, with countersunk flush rivets giving a smooth surface finish and a retractable undercarriage, a novel feature for a German aircraft. It was powered by a BMW VI V-12 engine, cooled by ethylene glycol rather than water, allowing a smaller radiator and therefore reducing drag. The pilot and radio operator were seated in tandem, with a cabin housing four passengers on two double seats facing each other.

The first prototype flew on 1 December 1932, and proved to have excellent performance, setting eight world records for speed over distance, and reaching a maximum speed of 377 km/h (222 mph).

Operational history
Luft Hansa operated He 70s between 1934 and 1937 for fast flight service which connected Berlin with Frankfurt, Hamburg and Cologne, as well as on the Cologne/Hamburg route.
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.

Military use
Twenty-eight aircraft were sent with the Legion Condor, where they were used during the Spanish Civil War as fast reconnaissance aircraft. Their high speed gave them the nickname Rayo (lightning).

The He 70K (later He 170), a fast reconnaissance airplane variant was used by the Royal Hungarian Air Force in early World War II during 1941-42. The Luftwaffe operated He 70s from 1935, initially as a light bomber and reconnaissance aircraft. As soon as purpose build designs became available, it was relegated as a liaison and courier aircraft.

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 so-called "Elektron (alloy)", though the majority of the monocoque fuselage was Duralumin. Elektron is a very light, yet strong, alloy of magnesium, which burns readily when ignited, and is difficult to extinguish. Moreover, the wings contained a 47-gallon fuel tank apiece, which may have further added to the aircraft's reputation for being flammable. 

A single hit from a light machine gun is reputed to have usually set the entire plane ablaze. The Hungarian He 170A (a military version derived from the He-70 with a new WM-K-14 radial engine), 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-recce and specialized Fw 189 "Uhu" medium altitude observation aircraft could be introduced.

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.
Operators
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.
United Kingdom, Rolls Royce acquired one He 70G from the RLM in exchange for 4 Kestrel engines. It was used as an engine test bed.
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Military Operators
Luftwaffe
Royal Hungarian Air Force received 18 domestically license-built He 170A aircraft.
Spanish State
Ejército del Aire received 11 aircraft of the 30 that had served with Legion Condor.

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