From Nighthawk to Spitfire

by John K Shelton

  British tactics had also to take account of the fact that the cooling of the S6s was so critical that a water temperature of 95° had not to be exceeded. So it was decided that Waghorn would fly as fast as possible, consistent with keeping to a safe engine temperature; that Atcherley, in the second S6, would risk a higher temperature if the performances of the two preceding Italians made it necessary to go faster than Waghorn; and that Greig, in the slower S5, would provide additional back-up.

  In the event, Waghorn began with a slower than expected first lap owing to a rather wayward flight path, as vessels on the course had made it hard for him to identify the ship-borne pylon marking the second turn. Then the Italian in the first M67 retired on lap two as he had been nearly blinded and suffocated by fumes from his exhaust.

  Atcherley also had a visibility problem caused by spray from a long take-off run; he tried to replace his goggles with a substitute pair but these were swept away in his slipstream. He carried on, but nearly killed himself when at the very last moment he saw the first pylon and had to swerve sharply to avoid it. As his evasive action had taken him inside the pylon, he was disqualified. Meanwhile, the pilot of the second M67 was also experiencing fume problems and was then forced to make a hasty landing when steam and nearly boiling water began blowing back from the engine.

  In the end, Waghorn took first place with an average speed of 328.63mph, Dal Molin in the M52 was second with an average speed of 284.2mph and Greig came a close third with an average speed of 282.11mph. Atcherley was compensated for not being placed in the competition by achieving the World’s Closed Circuit Speed Records for 50km and 100km at 332.49 and 331.75mph. respectively, on his sixth and seventh laps.

  Press coverage and eulogy was sustained by an ensuing competition to establish a new World Absolute Air Speed Record between the S6 and the Gloster VI, whose fuel supply problems had now been overcome. The latter achieved 336.3mph three days after the Schneider contest, but Orlebar, as the CO of the High Speed Flight, fittingly took the record with 355.8mph. The existing Italian record of 318.62 was further exceeded two days later, on 12 September, when the S6 reached 357.7mph.

  Waghorn’s winning S6.

  With the possibility of a third win in 1931, and therefore the outright capture of the Schneider Trophy, Supermarine and Rolls-Royce began discussions with the Air Ministry in respect of a predicted increase of 25mph on the Schneider course, assuming that the S6 machines would be loaned back for uprating and that they would be piloted by High Speed Flight pilots. The cost of a successful defence of the trophy was estimated to be in the region of £100,000 and involved the production of two improved machines and engines to support them but, in view of the worsening economic climate, the government now declined any help whatsoever.

  The response, especially in aviation circles, was outrage – but to no avail. Fortunately, the formidable and extremely wealthy Lady Houston was approached and she promised what was then the enormous sum of £100,000 to sponsor Britain’s entry and, incidentally, to embarrass the Labour Prime Minister and his government. By the time some political points had been scored and the necessary money allocated, there was less than a year left for all the work required in time for the competition in the coming September.

  Because of this time constraint and the finite funds available, the British hopes would be concentrated upon uprating the current Rolls-Royce engine and upon modifying the existing S6 design to handle an expected increase in power. Derby had, once more, to put up with the noise of the engine testing and its mayor had to appeal to the patriotism of its citizens. The tests ran from 1 April–12 August before the uprated engine could run for an hour at full power – by which time the 1900hp of the 1929 engine had been increased to 2350hp.

  The S6B

  In view of this power increase, Supermarine estimated that the new aircraft would have to dissipate ‘something like 40,000 BT units’ every minute – the equivalent of over 300 modern fan heaters operating at full power. Mitchell had, therefore, to provide additional radiator surfaces on the floats right down to their chines so that almost half of the 948sq. ft of the aircraft’s available surface area was now to be used for cooling. It is understandable why Mitchell, in a radio broadcast after the competition, described his new aircraft as a ‘flying radiator’.

  Enlarging the cooling area was assisted by an increase in the size of the floats, as the anticipated fuel consumption of the new engine required their capacity to be enlarged, as did a modification to the competition rules – the aircraft were now required to take-off and land immediately prior to the start of the race proper, instead of the navigability and seaworthiness tests being carried out with minimal fuel the day before.

  Wind tunnel testing at the National Physical Laboratory and tank testing at Vickers, nevertheless, led to a narrower float design, although of increased length. The side plating was extended knifelike by ¾in below the chines and as far as the step, to improve running and to inhibit spray. The elevators no longer had a ‘v’ cut-out close to the fuselage but were now made to operate with minimum clearance in order to reduce turbulence at this point.

  The revised design was accordingly designated S6B and it was possible to afford two, with the serials S1595 and S1596. Additionally the two 1929 machines, N247 and N248, were uprated and, as such, they were redesignated S6A. The only noticeable difference between the two pairs of machines was that the latter had its original floats, which were 2ft shorter than those of 1931.

  As there were now four Supermarine racers available, Flying Officer L.S. Snaith was added to the High Speed Flight, already consisting of Flight Lieutenants J.N. Bootham, E.J.L. Hope, F.W. Long and G.H. Stainforth. Flying with the contest machines began when N247 arrived on 20 May, but an alarming oscillation of the rudder developed during an early high speed run, causing the buckling of rear fuselage plates, stress cracks around some of the rivet holes and stretched control wires. In the short time available, Mitchell had streamlined weights on forward projecting brackets fitted to both sides of the rudder and the ailerons – in order to bring the centre of gravity of these surfaces to coincide with their hinge lines and so to dampen any future oscillations which might occur. The last bay of the fuselage was also strengthened.

  Weights were also needed in response to some instability on take-off and during turns. Mitchell decided that the problem here was due to the centre of gravity being too far back and so he had about 25lb of lead placed in the nose of each float and reduced the amount of oil (which was, again, carried all the way back to a tank in the fin). However, Orlebar had also reported nose-heaviness during level flight, and Mitchell (before the developing use of trim tabs) ‘produced a splendid gadget to cure the trouble’ – metal strips were fitted to the trailing edge of the elevators and bent downwards by about one degree, thus using the slipstream at high speed to deflect the elevator upwards slightly and to counteract any load on the stick.

  Additionally, the engines were prone to cutting out because of choked fuel filters. This was found to be the result of the engine’s exotic fuel mixture causing the excess compound used to seal the joints in the fuel system to come adrift. Mitchell’s response was both practical and blunt: ‘You’ll just have to bloody well fly them until all this stuff comes out.’

  There was another problem previously experienced in 1927 – the first new S6B, which had arrived on 21 July, could not be made to fly as it also gyrated in ‘a very good imitation of a kitten chasing its tail’. In the course of these rotations, S1595 hit a barge and had to be returned from Calshot for repair. As a new reason for its unwillingness to take off was suspected, the smaller 8ft 8in diameter propeller of the S6B was fitted to N247, which then behaved like its younger sister. This suggested that the slipstream from this diameter propeller was producing a side pressure that the rudder was unable to counteract. When S1595 was returned on 29 July, a larger diameter unit was fitted and the new machine then took off with little difficulty.

  In view of the peculiar
take-off requirements mentioned earlier, the increased speed, and the extra weight of the new aircraft, it is not surprising that the British team now began to have accidents. Mitchell had to watch the pilots of his machines flying at previously unattained speeds, virtually at sea level, often in hazy conditions, and taking off and landing without the aid of flaps or variable pitch propellers, among the busy shipping lanes off Calshot.

  The first of the S6Bs at Calshot. (Courtesy of E.B. Morgan)

  Hope virtually wrote off one of the S6A machines. A piece of the cowling from N248 worked loose in flight and, while managing an emergency landing, he encountered the wash from a passing ship, which caused the sensitive machine to cartwheel and sink. The pilot survived, but was withdrawn from the team because of a punctured eardrum. (He was the son of the influential hull designer mentioned in Chapter 2; as Group Captain Linton Hope, AFC, he was killed in action in August 1941.)

  Hope was replaced by Lieutenant G.L. Brinton who, on 18 August and on his first take-off in N247, was killed. D’Arcy Greig had explained how, if porpoising developed during take-off and with the stick held well back, it was imperative to close the throttle and start again; otherwise, the pitching of the aircraft invariably increased until the machine was eventually thrown into the air in a stalled condition and an accident was inevitable. Like the pilot of the Sea Lion III before him, Brinton apparently did not fully appreciate the importance of this advice, and Time magazine reported that:

  The plane slid along the surface of the Solent until it was going about 200mph. It cleared the water for a second and then dropped back to it. A tower of spray shot up. The S6 bounced 40ft in the air and then plunged down into the Solent, nose first. When Lieut. Brinton’s fellow officers reached the ship in a speedboat, it had risen again, upside down, with wings and tail torn off. The wreckage was towed ashore and the dead body of Lieut. Brinton removed from the tail of the fuselage, where the shock had wedged it.

  Flight Lieutenant Long on his return from a test run. (Courtesy of P. Jarrett)

  The writer did not elaborate on the fate of Brinton’s body. It was first assumed to have been lost at sea and only later was it found jammed into the rear of the fuselage. It is not recorded how news of the actual discovery of the body was received by Mitchell but, in view of his well-known concern for the pilots of his machines, an explanation of the need to cut into the damaged machine for its recovery must have required considerable tact.

  At about the same time, a French aircraft was considerably damaged in a landing accident and another was completely destroyed, killing its pilot. Meanwhile, Macchi were developing their M67 layout into a new machine, which was also to kill one of its pilots. The main feature of the new aircraft was the advanced engineering of contra-rotating propellers, but the revolutionary power plant was plagued with problems, especially carburation, and during a fly-past to demonstrate its erratic behaviour, it crashed, also killing its pilot.

  As a result of such accidents and other setbacks, the French and Italian teams jointly requested a postponement of at least six months. As some government assistance in the matter of RAF support had eventually been won with difficulty, as funds had already been spent in preparations for a competition that was virtually only days away and as Lady Houston’s generous donation had been used up, the due date of the event was insisted on. As a result, the Air Ministry was informed on 5 September that neither France nor Italy felt able to compete.

  In the end, the only postponement of what was expected to be a fly-over for Britain was for one day owing to bad weather, and the following day was almost perfect with visibility of over 10 miles. In view of there being no external competition, it was decided that S1595 was to fly the course without putting undue strain on the engine – the increase in propeller diameter had resulted in too high an engine temperature and, again, Mitchell had had to accept a slightly lower airspeed than his design was capable of. If S1595 were to fail, then Hope’s repaired S6A would be sent off to finish the course and, therefore, to win the trophy outright. The second S6B would also be available to make trebly sure of a win, but it was hoped to retain this aircraft to give the crowds the additional thrill of seeing the setting of a new world speed record.

  The commanding officer, Orlebar, gave his senior pilot, Stainforth, first choice and he opted for the proposed attempt on the speed record. The next most senior man, Boothman, then chose to fly first in the competition itself and, it was hoped, to have the honour of winning the trophy. And so, just before 1 p.m. on 13 September, Boothman taxied out in S1595, which he had never flown in practice for longer than twenty-seven minutes. Nor had it been considered wise to practice the landing, as the 1931 rules required, with the full load of fuel for both the 350km of the competition course and for the required preliminary navigation manoeuvres.

  Nevertheless, he took off without any apparent difficulty, made the required landing at well over 100mph without mishap, and took off again after a period of less than two minutes. He then flew the required seven laps, all within about 4mph of each other, slightly throttled back, taking the turns wide and with a gentle bank and finished with an average speed of 340.08mph – just over 11mph faster than Waghorn in 1929. Then, as if to emphasise the superiority of the Rolls-Royce/Supermarine partnership and also to post a more impressive speed, Stainforth took out the other S6B a little later and proceeded to capture the World Absolute Air Speed Record at 379.05mph.

  Lady Houston had attended on her steam yacht to watch ‘her’ machines and, two days later, gave a celebratory lunch on board, attended by Mitchell and his wife and by the High Speed Flight. Cozens recorded that:

  She was afforded the rare privilege of mooring her yacht Liberty on the RAF buoys inside Calshot … In the evenings the Liberty had a string of electric lights from her bowsprit to the mastheads and down to the stern, and this seemed to add just the right touch to the celebration of victory.

  The Air Ministry then set about disbanding the High Speed Flight and restoring the Calshot base to its normal flying boat duties, but Rolls-Royce particularly wanted to have produced the first aero engine to exceed the magic mark of 400mph. Mitchell had indicated the same in an interview with the Southampton Daily Echo, when he said that ‘with a specially tuned up engine, I am very hopeful we may get very near to an average speed of 400mph, which is our ambition’.

  For this special sprint machine, Mitchell had the wing-tip air scoops removed and a newly prepared engine was to be supplied, using a specially blended fuel mixture. After delays caused by the weather, Stainforth squeezed into the cockpit of S1595 and the required runs were photographically measured. There was some concern that bad light and a low evening sun might prevent confirmation being obtained, but eventually, at 4 a.m., the results were telephoned through and Mitchell was informed. It was reported that he was ‘too sleepy to be more than mildly enthusiastic’ that the World Absolute Speed Record had just been raised by nearly 30mph to 407.5mph.

  An invitation to give a talk on the BBC in 1932 indicated recognition by the wider public of his technical achievements, and his name appeared in the New Year’s Honours List of that year. Mitchell particularly disliked having to wear bows on his Court shoes but it was surely impossible for one who had designed so many aircraft for the British armed forces not to accept becoming a Commander of the Order of the British Empire.

  As Mitchell always gave full credit to others in his speeches, there is no reason to suppose that he would begrudge, in this chapter concerning his notable Schneider Trophy successes, a final word about the pilots concerned. Various instances of their skill and courage are to be found in the preceding pages, including flying and alighting at unprecedented speeds, in machines with extremely limited vision, and at altitudes that gave little margins for error and no possibility of survival if things went badly wrong.

  Mitchell greeting Lady Houston at Calshot on the occasion of the 1931 Schneider Trophy Contest. (Courtesy of Solent Sky Museum)

  Undoubtedly, other
pilots would have accepted the challenges of flying beyond the boundaries of previous experience, but it was those mentioned above to whom credit must go. If they had not successfully flown their frankly dangerous aircraft, the Spitfire might not have been ready in time for the Battle of Britain. One notes, at least, D’Arcy Greig’s dedication in My Golden Flying Years ‘to all those involved with the Schneider Trophy races that helped so much in the development of the Spitfire in later years’.

  THE LAST SEAPLANES

  Supermarine Walruses. (From a painting by the author)

  MITCHELL’S AIR YACHTS

  R.J. Mitchell was responsible for two luxury air yachts, although both in fact began as military orders. The first looked backwards to the Southampton reconnaissance flying boat, but the second might very well have led to a Supermarine equivalent of the Catalina, which became the most widely used maritime patrol aircraft in the Second World War.

  The Solent

  The first Air Yacht came about as a request from Denmark for a torpedo-carrying version of the Southampton; it was to be called ‘Nanok’, the Inuit word for polar bear, and first flew in 1927. But all was not well, as the necessary positioning of the torpedoes produced stability problems. As each torpedo was suspended fairly well out from the centre line of the flying boat, the resultant lurches when dropping only one torpedo, necessarily at low level, could hardly have recommended the aircraft to any pilot assessing it.