The Royal Aircraft Factory S.E.5 was a British biplane fighter aircraft of the First World War. Like the Hurricane compared to the Spitfire in the Second World War, the S.E.5 was not as glamorous as the Sopwith Camel, nor did it achieve the same iconic status, but it was one of the most important and influential aircraft of the war. The S.E.5 was instrumental in ensuring that the period of German dominance known as Bloody April 1917 was not repeated.

The S.E.5 (Scout Experimental 5) was designed by Henry P. Folland and J. Kenworthy of the Royal Aircraft Factory in Farnborough. It was built around the new 150-hp (112 kW) Hispano-Suiza 8a V8 engine which, while it provided excellent performance, was under-developed and unreliable. The first of three prototypes flew on 22 November 1916. The first two prototypes were lost in crashes and the third underwent modification before production commenced.

Only 77 original S.E.5s were built before the improved S.E.5a model took over. In total 5205 S.E.5s were built by six manufacturers including Austin Motors and Vickers. A few were converted as two-seat trainers and there were plans for Curtiss to build 1000 S.E.5s in the United States but only one was completed before the end of the war.

The introduction of the 200-hp (149 kW) Hispano-Suiza or Wolseley Viper (a high-compression version of the Hispano-Suiza) resolved the engine problems and added nearly 30 mph (45 km/h) to the S.E.5s top speed.

Like the other significant Royal Aircraft Factory aircraft of the war (B.E.2, F.E.2 and R.E.8) the S.E.5 was inherently stable, making it an excellent gunnery platform. It was also one of the fastest aircraft of the war, at 138 mph (222 km/h) equal in speed to the SPAD S.XIII. The S.E.5 was not a great dog fighter, lacking the agility of the Camel, but was a benign aircraft that did not bite novice pilots the way the Camel was known to.

The S.E.5 had only one synchronised .303-in Vickers machine gun to the Camel's two however it did have a wing-mounted Lewis gun which enabled the pilot to fire at an enemy aircraft from below. The Vickers gun was mounted on the left side of the fuselage with the breech inside the cockpit. The cockpit was set amidships, making it difficult to see over the long front fuselage, but otherwise visibility was good.

The S.E.5 entered service with No. 56 Squadron RFC in March 1917 although the squadron did not deploy to the Western Front until the following month, flying its first patrol with the S.E.5 on 22 April. The S.E.5a entered service in June 1917.

By 1918 the S.E.5 equipped 21 British Empire squadrons as well as two U.S. squadrons. Many of the top Allied aces flew the S.E.5 including Billy Bishop, Raymond Collishaw, Edward Mannock and James McCudden. Legendary British ace Albert Ball was initially disparaging of the S.E.5 but in the end scored 17 of his 44 victories flying it. McCudden wrote of the S.E.5 "It was very fine to be in a machine that was faster than the Huns, and to know that one could run away just as things got too hot."

Sholto Douglas, who commanded No. 84 Squadron RFC which was initially equipped with the S.E.5, listed the plane's qualities as:

• Comfortable, with a good all-round view.
• Retaining its performance and manoeuvrability at high level
• Steady and quick to gather speed in the dive.
• Capable of a very fine zoom.
• Useful in both offence and defence.
• Strong in design and construction.
• Possessing a reliable engine.

Specifications (S.E.5a)

Operators

• Australia (AFC, RAAF), Canada, Poland, South Africa, United Kingdom (RAF, RFC), United States

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Royal Aircraft Factory S.E.5 | Royal Aircraft Factory S.E.5 | Royal Aircraft Factory SE.5