S. E. 5a
The S.E.5/5a, rival of the Sopwith "Camel" for the title of the most successful British fighter of the First World War, was designed by H. P. Folland, J. Kenworthy and Major F. W. Goodden of the Royal Aircraft Factory. Stable and very effective at high altitude, it made even a mediocre pilot look good. Though not as maneuverable as the Camel or the Fokker DR.1 Triplane, it could outdive anything the Germans flew.
The prototype S.E.5, A4561, appeared in December 1916; it had the new 150 h.p. Hispano-Suiza engine with a car-type radiator and short exhaust manifolds. The wings had wire-braced spruce spars; in place of compression struts, some ribs were of solid construction. The tail-plane incidence could be changed in flight. A wire-braced wooden box girder, the fuselage was fabric-covered except for plywood sides from the nose to the front spar of the lower wing, with plywood round the cockpit. The main fuel tank was behind the engine, and there was a gravity tank to port of the center section.
In January 1917 the wings of the prototype collapsed in flight, and Major Goodden was killed. The main planes of subsequent machines were strengthened, their span was reduced and blunter tips were fitted. A few of the early production aircraft, however, retained the wing plan of the first two prototypes.
A Vickers gun fixed on the port side of the fuselage with its breech inside the cockpit, fired through the air screw by means of the Constantinesco synchronizing gear. A Lewis gun on a Foster mounting could be fired ahead over the top wing or directly upwards.
The type first went to France on April 7th, 1917, with No. 56 Squadron. The early machines had celluloid 'greenhouses' over the cockpits; these were liable to be dangerous in a crash, so Major Blomfield, the C.O., had them replaced by flat Triplex windscreens. The gravity tank was soon moved from the top of the wing to a position inside the center section. A few S.E.5s had faired head-rests.
A modified version, the S.E.5a, powered by the 200 h.p. geared Hispano-Suiza engine, was introduced in June 1917. It had a rather deeper nose than that of the S.E.5, radiator shutters and long exhaust pipes. The standard faired head-rest was frequently removed to improve the rearward view. From December 1917, the front struts of the undercarriage vees were strengthened.
The geared 200 h.p. engine suffered from manufacturing faults, and there were frequent failures; in addition, engine construction lagged behind airframe manufacture, and the S.E.5a was not available in quantity until well into 1918. Eventually the Wolseley W.4a Viper 200 h.p. engine, based on the Hispano-Suiza, became standard and there were no more engine difficulties. The Viper's radiator was square and bulky, with short horizontal shutters.
Both friend and foe recognized the S.E. as a formidable fighting machine; it was fast, extremely strong and easy to fly. Superior to the Albatross D-III and D-V, the Pfalz D-III and the Fokker Dr-I, it was not outclassed when the excellent Fokker D-VII appeared in May 1918. It is significant that the S.E.5a was the mount of Mannock (seventy-three victories), Bishop (seventy-two), McCudden (fifty-seven) and Beauchamp-Proctor (fifty-four).
Some machines of No: 24 Squadron were rigged with reduced dihedral to improve their maneuverability.
Country: Great Britain
Designation: S. E. 5a
Service date: April 7, 1917
Wingspan: 27' 7"
Length: 20' 11"
Production: 5, 205
1 Vickers machine gun and 1 Lewis gun
Engine: Wolseley W.4a Viper in-line 200 h.p.
Climb rate: 8 min. to 6,500 ft.
Ceiling: 19,500 ft
Max speed: 138 mph
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