After the failure of the British entrants in the 1925 Schnieder Trophy competition, Air Ministry funding was provided to support a 'High-Speed Flight' aircraft and the development of potential entrants for the 1927 competition. This had been driven by the embarrassment that there had been no British entries in 1926 and the competition had been won by the Italians in a Macchi MC39.
Amongst those rising to the challenge was Vickers Supermarine who had previously taken part in 1922 as The Supermarine Aviation Works Ltd. That year, they had won the Schnieder Trophy with a Supermarine Sea Lion Mk2 and so they had the necessary experience to respond to the task. The design that emerged was the Supermarine S5, which was proposed alongside the Short-Bristow Crusader and the attractive Gloster IV biplane.
The Supermarine S5, designed by Reginald J Mitchell, was of mixed construction with an all-metal fuselage with wooden wings and tail surfaces. Wire bracing was provided to both wing and floats which contributed to a lower structural weight fraction than had been achieved on the Supermarine S4.
Three Supermarine S5's were ordered (N219, N220 and N221) all powered by the Napier Lion engine developed to deliver 900 hp at 3,300 rpm. Further design features introduced for the all-metal Supermarine S5 included a very slim fuselage with fuel stored in the starboard float which helped to counteract the engine torque on take-off. Engine liquid cooling was achieved by wing surface radiators and additional longitudinal oil cooling surfaces, running down the fuselage sides.
The pilot was seated further forward than had been the case with the Supermarine S4, being forward of the wing trailing edge.
Engine developments to achieve sustained high power running included high compression operation with the use of tetra-ethyl lead to suppress premature detonation.
The major contribution of Schneider racing was arguably in engine development including advanced fuels and fuel additives, supercharging, valve cooling and low-drag installation of liquid-cooled engines and their radiator systems.
The first of the Supermarine S5 aircraft (N219) was first flown on 7th June 1927, powered by a direct drive engine.
This was followed by the second and third aircraft (N220 & N221) using a geared engine allowing a reduction in propeller rpm.
Both took part in the race, which was held in Venice on 26th September 1927 and Flt Lt S.N. Webster was placed first at 281.65 mph flying N220, with N219 in second place at 273.01 mph.
|Powerplant||One 900 hp Napier Lion VII engine|
|Span||26 ft 9in|
|Maximum Weight||3,242 lb|
|Maximum Speed||319.57 mph|
|3 Aircraft||N219, N220 & N221|