First Edition. pp. 168, illusts #230122 S.E.5 (Fighter plane) World War I
The Royal Aircraft Factory S.E.5 is a British biplane fighter aircraft of the First World War. It was developed at the Royal Aircraft Factory by a team consisting of Henry Folland, John Kenworthy and Major Frank Goodden. It was one of the fastest aircraft of the war, while being both stable and relatively manoeuvrable. According to aviation author Robert Jackson, the S.E.5 was: “the nimble fighter that has since been described as the “Spitfire of World War One“.[2]

In most respects the S.E.5 had superior performance to the rival Sopwith Camel, although it was less immediately responsive to the controls. Problems with its Hispano-Suiza engine, particularly the geared-output H-S 8B-powered early versions, meant that there was a chronic shortage of the type until well into 1918. Thus, while the first examples had reached the Western Front before the Camel, there were fewer squadrons equipped with the S.E.5 than with the Sopwith fighter.

Together with the Camel, the S.E.5 was instrumental in regaining allied air superiority in mid-1917 and maintaining it for the rest of the war, ensuring there was no repetition of “Bloody April” 1917 when losses in the Royal Flying Corps were much heavier than in the Luftstreitkräfte. The S.E.5s remained in RAF service for some time following the Armistice that ended the conflict; some were transferred to various overseas military operators, while a number were also adopted by civilian operators.

The S.E.5 (Scout Experimental 5) was designed by Henry Folland, John Kenworthy and Major Frank Goodden of the Royal Aircraft Factory in Farnborough. It was built around the new 150 hp (112 kW) Hispano-Suiza 8, a V8 engine that, while providing excellent performance, was initially underdeveloped and unreliable. The first of three prototypes flew on 22 November 1916. The first two prototypes were lost in crashes (the first killing the chief test pilot at the Royal Aircraft Factory, Major Frank Goodden, on 28 January 1917) due to a weakness in their wing design. The third prototype underwent modification before production commenced; the S.E.5 was known in service as an exceptionally strong aircraft which could be dived at very high speed – the squarer wings also gave much improved lateral control at low airspeeds.[3]

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, but it was also quite manoeuvrable. It was one of the fastest aircraft of the war at 138 mph (222 km/h), equal at least in speed to the SPAD S.XIII and faster than any standard German type of the period. While the S.E.5 was not as agile and effective in a tight dogfight as the Camel it was much easier and safer to fly, particularly for novice pilots.[4] According to “Dodge” Bailey, Chief Test Pilot of the Shuttleworth Collection, it had “somewhat similar handling characteristics to a de Havilland Tiger Moth, but with better excess power”.[5] The Royal Aircraft Factory S.E.5 was a conventional tractor biplane fighter aircraft. The fuselage was a wire-braced box girder structure while the wings were furnished with wooden spars and internal ribs. The fuselage was narrower than many contemporary aircraft, which provided the pilot with good all-round visibility.[12] The aircraft had considerable structural strength, which was credited with improving the type’s crashworthiness and survivability. It could also withstand high-g manoeuvres and was relatively resistant to battle-damage.[12][8]

Unlike many of its peers, which were highly agile but unforgiving, the S.E.5 was comparatively stable and easy to fly; its stability enabling pilots to more readily fire upon enemies from further away with a greater degree of accuracy. It had a noticeably lower accident rate than comparable aircraft.[13] The exception to its generally stability was an excessive amount of adverse yaw. The yaw could be compensated for by balanced application of the aileron and rudder, whilst adjustment of the elevator trim made it possible to fly in a ‘hands off’ manner.[13]

The S.E.5 was powered by various engines, initially adopting a Hispano-Suiza 8 V8 engine. The Hispano-Suiza engine was advanced for the era, incorporating such features as an aluminium cylinder block with steel liners, dual ignition and forced lubrication that aided cooling; especially compared with contemporary rotary engines, it had the advantage of being easy to operate by most pilots. An expansion tank for the cooling system was integrated into the leading edge of the upper wing’s centre section.[13] One of its greatest advantages over the Sopwith Camel was its superior performance at altitude, making it a much better match for the Fokker D.VII when that fighter arrived at the front.[4]

The S.E.5 was armed with a single synchronised .303-inch Vickers machine gun in contrast to the Camel’s two, but it also had a wing-mounted Lewis gun fitted on a Foster mounting, which enabled the pilot to fire at an enemy aircraft from below.[8][9] This armament configuration was much appreciated by the pilots of the first S.E.5 squadrons as the new hydraulic-link “C.C.” synchronising gear for the Vickers machine gun was unreliable at first. The Vickers gun was mounted on the forward left dorsal surface of the fuselage with the breech inside the cockpit, at a slight upwards angle. Typically, spare magazines for the Lewis gun would have been placed within most of the free space in the cockpit including the forward areas, such as the instrumentation panel.[13]

The standard instrument panel included a compass, altimeter, tachometer, oil pressure indicator, airspeed gauge, radiator temperature dial, fuel air pressure indicator, fuel selector, and air exchange; these were somewhat difficult to view due to their low-set position in the cockpit.[5] According to “Dodge” Bailey, Chief Test Pilot of the Shuttleworth Collection, the S.E.5’s cockpit was “the best of the bunch from the era”.[5] It was set amidships, making it difficult to see over the long front fuselage, but otherwise visibility was good.[4]

Individual in-service S.E.5s would often receive customisations and user-specified tweaks at the request of their pilots.[12] Popular changes included reducing the dihedral of the wings in order to increase its manoeuvrability and the removal of the head fairing to increase the pilot’s visibility to the rear. James McCudden, an ace pilot and former RFC mechanic, was famous for his prolific fine-tuning of his aircraft in order to produce improved performance from it; McCudden was able to increase the top speed by 9 mph and to raise the service ceiling from the standard 17,000 ft to 20,000 ft. His adaptions included replacing the standard pistons with high compression versions, shortening the exhaust (saving weight and improving exhaust scavenging), and changes to mixture, ignition and other engine settings as well as fitting a salvaged German propeller spinner (which he himself credited as gaining 3 mph alone).[12]

Aviation authors Donald Nijboer and Dan Patterson describe the S.E.5 as “arguably the best British-built fighter of World War I”.[8] Australia received 35 S.E.5a under the Imperial Gift in 1919, and the type went on to be the newly formed R.A.A.F.’s main fighter type until the late 1920’s.