Supermarine S.5
A British racing floatplane designed by Reginald Mitchell and built by Supermarine for the Schneider Trophy. Three were built, one with a direct-drive Napier Lion and two with geared Lions; at Venice in September 1927 they finished first and second, Webster's N220 averaging 281.65 mph. A modified S.5 also took third place in the 1929 contest behind the newer S.6. None of the originals survives; a full-scale replica flew in 1975, and another airworthy example is being built.
Why It Mattered
The Supermarine S.5 was built for one contest: the Schneider Trophy, the seaplane race that had become the leading international test of aircraft speed and technical development. At Venice in September 1927 the type took the first two places, with every Italian entry withdrawing during the race. The win opened a run of three consecutive British victories — the S.6 followed in 1929 and the S.6B in 1931 — and under the contest rules three wins in a row kept the trophy in Britain permanently. History of War credits the S.4 to S.6B series with giving its designer, R. J. Mitchell, his grounding in high-speed stressed-skin monoplanes, experience that fed into the Spitfire.
Design Notes
Mitchell designed the S.5 after the loss of the S.4, chasing lower drag: History of War puts the new aircraft's frontal area 35 percent below its predecessor's. The fuselage was metal — Wikipedia describes it as entirely metal, primarily duralumin, of semi-monocoque construction — but the development window was short, so the wing was built of wood rather than metal. Wing surface radiators replaced the S.4's Lamblin radiators, a change History of War calculates was worth 24 mph. All the fuel sat in the starboard float, which was set 8 inches nearer the centreline than the port float, helping to counter the Napier Lion's torque. Three aircraft were built: N219 with a direct-drive 900 hp Lion, and N220 and N221 with geared 875 hp Lion VIIBs.
Operational History
The first S.5 made its maiden flight on 7 June 1927. In trials that July, N219 averaged 284 mph, and it was then shipped to Italy with N220 for the contest at Venice. On 26 September 1927, Flight Lieutenant Sidney Webster won the race in N220, averaging 281.65 mph and setting a 100 km world speed record of 283.66 mph along the way. Flight Lieutenant Oswald Worsley finished second in N219 at 272.91 mph, and the Italian Macchi entries all withdrew during the race. On 12 March 1928 the third aircraft, N221, crashed during an attempt on the world air speed record, killing its pilot, Flight Lieutenant Samuel Kinkead. In November 1928 an S.5 set a British speed record of 319.57 mph with Flight Lieutenant D'Arcy Greig at the controls, although the world record eluded him. The type raced once more: for the 1929 contest the High Speed Flight entered the modified N219 beside the two new S.6s, and Greig flew it to third place at 282.11 mph, behind Waghorn's winning S.6.
Afterlife
None of the three original aircraft survives; Vintage Aviation News states the point directly. The type's afterlife has instead run through a replica: Ray Hilborne's full-scale S.5, built of wood and powered by a Continental IO-360, first flew on 28 August 1975. Vintage Aviation News records that the replica flew for eight years before suffering major damage in 1982, and that a further airworthy example is now being built by Will Hosie, son of the replica's second owner. A separate project, a full-scale flying reproduction by the Supermarine Seaplane Charity, is now aimed at 2031, after a workshop fire forced the team to abandon its original 2027 centenary target. The original's standing rests on the racers around it: Museums Victoria notes that Mitchell went on to design the Spitfire, which first flew in 1936.