Supermarine S.6b
The world’s fastest machine in its time, the S.6b laid some of the groundwork for the later Spitfire
The racing plane origins of the Spitfire
Designed by a team led by the legendary Reginald J. Mitchell, the Supermarine S.6b float plane was built with a single purpose in mind – speed. It was a development of the S.6, winner of the 1929 Schneider Trophy, an international maritime air race.
The S.6b was to enter the 1931 competition. After victories at the previous two races, if the
British team (under the auspices of the RAF High Speed Flight) could win for a third time they would get to keep the trophy and the competitions would come to an end.
The S.6b was built with an improved Rolls Royce R engine and numerous modifications to the airframe. It pushed the boundaries of technology in many ways, from aerodynamics to construction techniques, while the engine also broke new ground. R. J. Mitchell would estimate that the pressure of the competition pushed forward development at three times the normal peacetime rate, and certainly allowed him to hone the skills and knowledge that he would later pour into his masterpiece, the Supermarine Spitfire.
Not only did the S.6b permanently win the Schneider Trophy for Britain, it would set, break and re-set the World Speed Record in its short but spectacular life.
“IT PUSHED THE BOUNDARIES OF TECHNOLOGY IN MANY WAYS, FROM AERODYNAMICS TO CONSTRUCTION TECHNIQUES, WHILE THE ENGINE ALSO BROKE NEW GROUND”
“THE S.6B’S FLOATS WERE EXTENDED SO THEIR BULK COUNTER-BALANCED THE MASSIVE ENGINE”
DESIGN
Everything about the S.6b was aimed at speed, a task complicated by the size of the Rolls Royce R engine. The cross-section was reduced to a minimum. The floats were an obvious source of drag, but even these were put to good use.
The S.6b’s floats were extended so their bulk counter-balanced the massive engine. They also contained fuel tanks. The starboard float’s tank was over twice the size of the port one, with its added weight counteracting the engine’s torque.
Most incredible was the engine’s water cooling system. Heated water was pumped from the engine through channels against the skin of the fuselage, wings and floats, while air was diverted into the wings to also blow across them. This total of 43.7 square metres (470 sq ft) of radiator surface rapidly cooled the water.
ENGINE
The Rolls Royce R 12 cylinder, supercharged, water-cooled engine was a ground breaking piece of machinery. Based on the Rolls
Royce Buzzard, design started in November 1928, specifically aimed at powering the Supermarine S.6 in the September 1929 Schneider Trophy. After helping the S.6 achieve a new world air speed record at 355.8mph (572.6kmh), development continued. It pushed the boundaries in terms of materials, supercharging, and cooling as well as fuel types. The 1931 version could reach powers of 1700Kw (2,300hp), and again set new records. After the Schneider Trophy, modified versions of the R were also used in world land and sea speed record attempts, while much of the science and engineering learned was poured into a new aero engine, the Rolls Royce Merlin.
COCKPIT
The cockpit of the S.6b was sparse and functional. Pilot protection in the open cockpit was minimal, with just an inadequate windshield in front. Spray easily coated the pilot’s goggles, further compounding what was already a poor view. The controls were simple, with rudders in the usual places, a simple stick for steering, and throttle controls on the left side wall of the cockpit. Instruments were also basic, with very little needed for an aircraft only intended for short range and limited duration flights.
“AFTER THE SCHNEIDER TROPHY, MODIFIED VERSIONS OF THE R WERE ALSO USED IN WORLD LAND AND SEA SPEED RECORD ATTEMPTS”
SERVICE HISTORY
Two Supermarine S.6s were built for the 1929 Schneider Trophy (serials N247 and N248). Then, within months of winning that competition (and setting a new world speed record), the government withdrew official backing for the 1931 race. However in January 1931 aviation enthusiast Lady Houston stepped in with £100,000 to sponsor the RAF
High Speed Flight. In the eight months until the competition, two improved S.bbs were built (S1595 and S1596) and the two existing S.6S modified to the same standards but designated S.6as.
On 13 September 1931, S.6b S1595, flown by Flight Lieutenant John Boothman, won the Schneider Trophy for Britain for the third time. Later that day, Flight Lieutenant George Stainforth set a new world air speed record in S1596, at 379.05mph (610.02kmh). On 29 September Stainforth took S1595 up again to break his own record, reaching 407.5mph (655.8kmh) – the fastest any human had ever gone, and survived.