While flying, she gave me the feeling of great stability, and when not flying low, the slow revs. of the engine gave me the impression that I remember I got when I flew a Horsley [bomber] after having just left the seat of a Gamecock [fighter]. On turns she was delightful. Perhaps she was a little heavier laterally than the S.5 and the Glosters, but then she was a much bigger and heavier machine. There was no noticeable torque effect against a left-hand turn which had been so tiring in the S.5, and, generally speaking, gave me a feeling of great trust and confidence, and I never had cause to change my opinion. . . The S.6 appeared to stall about 3 mph slower than the S.5, but air speed indicators are not infallible at such a speed. However, it can be taken that she stalled in the region of 95 and was certainly no faster than the S.5 She was extraordinarily stable at the stall. The S.5 would quiver at the stall and flick over either side at the slightest provocation. The S.6 showed no tendency to drop either wing, but would sink on an even keel. On one such occasion, while testing the stalling speed, I found the machine on an even keel sinking at about 87 mph. When one considers the behaviour of her elder brother at a similar speed it is all the more interesting, especially when you realise the extra top speed of the S.6.Two years later, the S.6 airframe was strengthened to take account of greater fuel loads and a power increase from 1900 to 2350 hp. The two new S.6Bs built with these various features were given the serials S1595 and S1596 and the two 1929 machines, N247 and N248, were modified accordingly as they were also to have the new, more powerful, engine. As such, they were redesignated S.6As. In 1931, both the S.6As went to the bottom of the Solent but with little reflection upon Supermarine’s build or modifications. A piece of the cowling from N248 worked loose in flight and, as the pilot was managing a successful emergency landing, the wash from a passing ship caused the machine to cartwheel and sink. The pilot survived but was withdrawn from the team because of a punctured eardrum. [Incidentally, he was the son of the influential hull designer associated with the early days of Supermarine. As Group Captain Hope, AFC, he was killed in action in August, 1941.] He was replaced by Lieutenant G. L. Brinton who, on his first take-off in N247, seemed not to get the recommended take-off technique right – at a height of about ten feet, it would appear that he had pushed the stick forward too soon and the machine hit the water, bounced back at a sharper angle of attack, hit the water again, and then, from about thirty feet, dived in, with fatal consequences.
Linton Hope’s machine was recovered and was readied for the Trophy contest. As neither France nor Italy could provide a challenge in time, it was decided that S1595 was to complete the course without putting undue strain on the engine or airframe – and, in any event, Mitchell’s valiant efforts to prevent engine overheating could not quite cope with prolonged full throttle flying. If this aircraft were to fail for any reason, then the repaired S.6A would aim to finish the course and win the Trophy outright. S1596, would be available to make trebly sure of a win but it was hoped that it would be retained – to give the crowds the additional thrill of seeing the setting of a new World Speed Record. The Commanding Officer gave the senior pilot, Fl. Lt. G. H. Stainforth, first choice and he opted for the proposed attempt on the speed record; the next most senior man, Fl. Lt. J. N. Boothman, then opted to fly first in the competition itself and, hopefully, to have the honour of winning the trophy.
Events turned out as hoped and Stainforth later became the first man to exceed 400 mph – this time in S1595, as during a test flight in the other S.6B, his foot jammed under the rudder bar on landing and another machine went under the waves. N248 can be seen at the Solent-Sky Museum, Southampton, and S1595 at the Science Museum, London. [n.b. Was S1596 broken up??]
This brief account of the perils and pitfalls of flying at the limits of current technology reflect well on the basic soundness of Mitchell’s S.6 design, despite the accidents.
There remains the question of the other S racer which went into the Solent. Did Kinkead’s S.5 crash in 1928 because of a structural fault or pilot error? Julian Lewis’ admirable book on the pilot leads one to seriously question the inquest finding of stall while landing; misjudging the machine’s height above the water in the hazy conditions prevailing is much more likely although I lean towards the possibility of a structural failure at the tail, similar to that which nearly terminated one of the S6s – the subject of a later Blog, I hope.
For reference sources see my "Blog Subjects, Sources and References".
Fuller account of the above in my forthcoming 2nd Edition of Schneider Trophy to Spitfire.