The Heinkel He 51 was the first fighter aircraft to be used by the Luftwaffe after its official formation in April 1935. It was developed from the third He 49 prototype, and was a single bay biplane, with an all-metal framework with fabric covering, and armed with two fixed forward firing 7.92mm MG 17 machine guns mounted above the engine.
The He 51a prototype was produced by rebuilding the He 49c. It was followed by ten pre-production aircraft, the He 51A-0. On these aircraft the raised fairing on the rear fuselage was removed, and there was a revised tail skid and exhaust system. The first of the He 51A-0s made its maiden flight in May 1933.
Deliveries of the He 51A-1 production aircraft began in July 1934. A total of 150 aircraft were built by Heinkel and Arado. Eight of these aircraft were later modified for maritime operations, with the fixed landing gear replaced by floats, racks to carry six 10kg bombs, and the new designation He 51A-2.
The first four He 51A-1s were delivered to Jagdgeschwader 132 'Richthofen', the new Luftwaffe's first fighter squadron, in April 1935. Over the next year the He 51 became the mainstay of the new fighter squadrons, but it was soon out-performed by the Arado Ar 68, and began to be phased out from 1936.
The structurally strengthened He 51B was the main production version. Twelve He 51B-0 pre-production aircraft were built early in 1936, and were followed by 450 He 51B-1s, built by Heinkel, Ago, Eria and Fieseler. These were similar to the B-0, but could carry a 170lt jettisonable fuel tank under the fuselage. As with the He 51A-2, the He 51B-2 was a floatplane fighter produced from the B-1. Thirty eight were built for use on Kriegsmarine cruisers.
The final production versions were the C-1 and C-2, both of which could carry small 50kg bombs. A total of seventy nine were built, with most of the C-1s going to Spain, while the C-2, with superior radio equipment, was used by the Luftwaffe.
A relatively large number of He 51s served in Spain, where a batch of six aircraft was followed by one of thirty six. Much to German embarrassment the He 51 was outclassed by the Soviet I-15, and by April 1937 it had been relegated to a ground attack aircraft, a role it performed with more success. In Germany some front line squadrons retained the He 51 until 1938, but after that it was relegated to the training units.
Engine: BMW V1 12 cylinder inverted-Vee
Wing span: 36ft 1in
Length: 27ft 6 3/4in
Height: 10ft 6in
Empty weight: 3,219lb
Maximum take-off weight: 4,178lb
Max Speed: 205mpg at sea level
Cruising Speed: 174mph at sea level
Service Ceiling: 25,260ft
Range: 354 miles
Armament: Two 7.92mm MG 17 machine guns