Heinkel He 51
The He 51 originated from three prototype He 49 biplanes designed by Walter and Siegfried Gunter. Although unarmed, there could be no doubt that the He 49a, a small machine with a 750-hp BMW VI engine, had basic fighter potential, with a top speed of approximately 320 km/h (200 mph).
The high performance of all these aircraft during tests prompted a fourth prototype, refined even further and lighter in weight by Walter and Siegfried Gunter, and this received the new designation He 51a. It was a single-seat open-cockpit fighter, retain-ing the same powerplant as the He 49 and of an all-metal framework with a mainly fabric covering. Armament comprised two 7.9-mm (0.311-in) MG 17 machine-guns in a fairing over the engine, firing through the disc of the two-blade propeller. Its potential so impressed the German air ministry that an initial order for ten pre-production aircraft was placed before the end of 1933.
The He 51 was of unequal-span single-bay biplane configuration. The single seat for the pilot was in a cockpit just aft of the wings, and a cutout in the centre-section of the upper wing was made to enhance the pilot's field of view. Power plant comprised a BMW 12-cylinder in-line engine, and adoption of a minimum cowled section provided a bluff, square look to the fuselage nose. Wheel landing gear of the He 51A was neat and functional, that of the He 51B clean for a float installation.
The first of nine He 51A-0 pre-production fighters flew in May 1934. These were followed from April 1935 by the He 51A-1 initial production model, which in mid-1935 formed the first He 51 unit of the new Luftwaffe, I/JG 132 'Richthofen'. A total of 150 A-1s were built for squadron service (75 each by Heinkel and Arado).
In January 1935 the structurally improved He 51B-0 appeared, of which 12 were built for pre-production trials. They had a more robust wheeled landing gear and were able to carry a 170-litre (37-Imp gal) auxiliary drop--tank under the fuselage. From 1936 the similar He 51B-1 with a jettisonable ventral tank 450 including 46 He 51B-2 floatplanes), and the He 51C ground-attack fighter 79 C-1 and 21 C-2 variants with improved radio).
As early as 6 August 1936 an initial batch of six He 5lBs arrived by sea at Cadiz, Spain, and eventually some 135 such aircraft were delivered to Spain for use by German ‘volunteer’ pilots, Nationalist pilots and finally by the Legion Condor, created in November 1936 as the parent organisation for German air assets in Spain, including Jagdgruppe 88 with two He 51 B Staffeln. By Au-gust 12, the Heinkels were flying from Seville with German pilots, and by Au-gust 18, with Spaniards as well. When German air components in Spain were consoli-dated as the Condor Legion in Novem-ber 1936, the Heinkel He 51B fighters were formed into JagdIgruppe 88, in four StaffeIn, each with 12 aircraft: 1st Staffel (Marabou Stork); 2nd Staffel (Top Hat); 3rd Staffel (Mickey Mouse); 4th Staffel (Ace of Spades). The German fighter was successful against the miscellany of mainly French fighters flown by the Republicans in 1936 and early 1937, but during 1937 was steadily outclassed by the 1-15 and 1-16 fighters supplied by the USSR. Thereafter the He 51 B was relegated to ground-attack with the Germans and the Nationalists’ 1-G-2 and 4-G-2. Messerschmitt Bf 109s gradually replaced the He 51Bs in Jagdgruppe 88; the Germans sent the withdrawn aircraft to Nationalist squadrons who formed Attack Group 1G2 (Squadrons 1E2 and 2E2).
By June 1938, the few surviving Heinkels were combined with newly arrived He 51C-1s (which could carry 200 kilograms of bombs) in Attack Group 4G2, which served until the war's end.
A further 100 were ordered from Fieseler, adapted to carry six 10-kg (22-lb) bombs. Designated He 51C-1 (79 built) and C-2 (21 built) they suffered some loss of performance due to the extra weight and drag of the bombload, but continued to show an ability to take considerable punishment in combat. The Luftwaffe also switched its He 51s to the ground-attack role during the late stages of their service life, arming them with four or six small fragmentation bombs. From 1937 onwards, these aircraft were used to develop ground-attack tactics which were later employed by the Luftwaffe during the Second World War. Some He 51s, mainly the land-plane versions, served into the war years as fighter trainers, but were finally phased out during 1942-43.
Considerably hotter than types the still undercover Luftwaffe pilots were used to, the He 51 was never overly successful, its service career being cut short due to combat experience gained in Spain and by the appearance of Arado's Ar 68. Kustenjagdstaffeln, coastal defence fighter units, began taking delivery of float-equipped He 51B-2s in 1936.
A total of 725 were built.
Engine: 1 x BMWVI 7.3Z, 559kW (750 hp).
Span: 11m (36ft 1 in)
Length: 8.4m (27 ft 6.75 in)
Height: 3.20 m / 10 ft 6 in
Wing area: 27.20 sq.m / 292.78 sq ft
Max T/O weight: 1900 kg (4,189 lb)
Empty weight: 1460 kg / 3219 lb
Max speed: 205 mph / 330 km/h at sea level.
Operational range: 354 miles / 570 km
Ceiling: 7700 m / 25250 ft
Armament: 2 x 7.92-mm (0.312-in) mg, up to 6x10-kg (22-lb) bombs external