The Vickers Supermarine S.6 was designed by RJ Mitchell against specification 8/28 for the Schneider Trophy Competition of 1929.
The concept that followed was vastly similar to that of the successful Supermarine S.5, the S.6 in that it was of all-metal construction, using the more powerful and heavier Rolls-Royce 'R' engine. The engine had been developed from the Rolls-Royce 'Buzzard' and it featured the addition of supercharging, as well as increased crankcase and component strengthening.
However, there were still some major engine design trade-offs which revolved around fuel composition, power output, oil and coolant temperatures plus a vastly reduced engine life. Ultimately, 1,900 hp was achieved from the power unit although its duration was limited to just one hour of operation only.
Two Supermarine S.6 aircraft were ordered and built at Woolston (N247 & N248).
They were initially operated by the RAF High Speed Flight who were a unit specifically formed for the purpose of competing in the Schneider Trophy Races. The first of the aircraft (N247), was first flown on 10th August 1929.
Engine cooling required the installation of surface radiators within the floats which also acted as fuel tanks. A greater volume of fuel was carried in the starboard float which helped counter-act the engine torque experienced on take-off.
The 1929 Schneider Trophy Race was held on 7th September, at Calshot in the western corner of Southampton Water. It was won by Flying Officer Waghorn, flying a Vickers Supermarine S.6 (N247) achieving 328.63 mph. The second Vickers Supermarine S.6 aircraft (N248) was disqualified when it turned inside one of the marker pylons in error.
After the race however, it did set the World’s Absolute Air Speed Record of 357.7 mph.
Two new Vickers Supermarine S.6B's (S1595 & S1596) were built whilst the two Vickers Supermarine S.6 aircraft (N247 & N248) were latterly fitted with new engines and modified to a similar standard before being designated Vickers Supermarine S6A. The first of the new builds (S1595) flew for the first time on 29th July 1931 and the uprated 'R' engine passed its one hour type test at 2,300 hp, achieving this only one week before the race.
The Vickers Supermarine S.6B was a more powerful development of the design, built specifically for the 1931 competition in which the British raced (somewhat controversially), with no opposition to win and permanently retain the Schneider Trophy.
The aircraft was flown by Central Flying School Instructor Flt Lt John Bootham (later Air Marshall Sir John Bootham) setting a course speed of 340.08 mph (S1595). The victory certainly would not have happened without the colourful Lady Houston, who donated £100,000 to sponsor the entry after the Air Ministry withdrew financial support after the 1929 victory.
The Vickers Supermarine S.6B was refined in terms of reduced drag, increased fuel and oil capacity. Control mass balancing had to be introduced to ensure protection against flutter. It boasted higher engine power available as a result of the use of Sodium-cooled valves and a rather exotic fuel mix devised by Francis 'Rod' Banks. Banks later became Air Commodore Banks who ended his career as Managing Director at Hawker Siddeley (Commercial Aircraft).
On the same day as the 1931 Schneider Trophy Race, another Vickers Supermarine S.6B (S1596),flown by Flt Lt George Staniforth, set a new Absolute World Speed Record of 379.05 mph and on 29th September 1931 this was increased this figure to 407.5 mph (S1595).
The achievements of RJ Mitchell, his Design Team and the valiant pilots and Schneider Trophy competitors cannot be understated and proved fundamental in the development of one of the world's most iconic aircraft - The Supermarine Spitfire.
|Supermarine S.6A||Supermarine S.6B|
|Powerplant||1,900 hp Rolls-Royce R||2,350 hp Rolls-Royce R|
|Span||30 ft 0 in||30 ft 0 in|
|Maximum Weight||5,771 lbs||6,086 lbs|
|Capacity||Pilot only||Pilot only|
|Maximum Speed||357.7 mph||407.5 mph|
|Supermarine S6A 2 conversions||N247 & N248|
|Supermarine S6B 2 built||S1595 & S1596|