[MOC] Schneider Trophy - Supermarine S.6 (Calshot 1929)

Hod Carrier · April 13

<-- Supermarine S.5 (Venice 1927)

The amount of time needed for research and development required to design a high-speed racing aircraft and their engines was now so great that staging the Schneider Trophy annually was no longer realistic. Therefore, it was agreed unanimously that the competition would run every two years, with the winner being the nation that won three out of five successive events. This meant that it was 1929 before Britain could mount its defence of the title. Once again, the contest would be held over the waters of the Solent, but this time the event would be based at Calshot using the facilities of the RAF’s seaplane base.

After an absence of several years, France decided it was time to stage a return. Sadly, none of its contenders were ready in time, mostly due to engine development difficulties, and so they withdrew. The USA once again was relying on private enterprise and the wit of Lt. Alford J. Williams, but his Williams Mercury monoplane proved reluctant to take to the air and, when it did, the engine overheated almost immediately forcing it back down again. They also were compelled to withdraw.

In Italy, Mario Castoldi had been busy further refining his racing monoplane design. The biggest change was a switch from FIAT power to the Isotta-Fraschini Asso 18-cylinder “broad arrow” engine producing 1,800hp. The Italian team struggled to make these engines run smoothly at full throttle in flight and eventually opted simply to reduce the maximum revolutions, even though this would also reduce performance. Three Asso powered Macchi M.67s were built for the contest and delivered to the new Italian high-speed centre at Desenzano on Lake Garda, but one was lost, along with its pilot, Capt. Guiseppe Motta, in a practice flight. The cause of the crash was attributed to exhaust fumes entering the cockpit. Its place in the team would be taken by a Macchi M.52R, an improved version of the aircraft previously entered at Venice two years before.

The Italians had not been idle, as it was not just Macchi who had been building racing seaplanes. A number of different designs were brought to Calshot, including the tiny FIAT C.29. This diminutive racer was powered by a 1,000hp FIAT AS.5 engine and should have been fast, but a series of testing mishaps meant that it was not ready. Also at Calshot was the Savoia S.65, an unconventional twin-engine design that was also not quite ready for competition.

The British had also been busy working on different designs. The Gloster VI was a very streamlined monoplane powered by the venerable Napier Lion, now producing 1,320hp, but the Glosters were withdrawn as the engine could not be made to run reliably in flight.

Supermarine, on the other hand, had decided that the Napier unit was reaching the end of its developmental life and turned instead to Rolls-Royce, who had been working on a 12-cylinder vee racing engine. This engine promised more power and reduced fuel and oil consumption from a lightweight design with a small frontal area and, when it was ready for installation, produced 1,850hp. Testing of the engines had been done in a wind tunnel to replicate the conditions during high-speed flight and included running the engine at full power for an hour to ensure reliability. As the Rolls-Royce R engine was larger than the Napier Lion, the resulting aircraft, the Supermarine S.6, was also larger than the preceding S.5 but shared a lot of the same design features. Two aircraft were built and delivered to the RAF High Speed Flight for testing.

The race teams were Lt. Giovanni Monti and Lt. Remo Cadringher in the Macchi M.67s, with W.O. Tommaso Dal Molin in the Macchi M.52R, against Flg Off. H. R. D. Waghorn and Flg Off. R. L. R. Atcherley in the Supermarine S.6s, and Flt Lt. D. D’Arcy Greig in a Supermarine S.5.

With the race underway, it became clear that the cockpits of the Macchi M.67s were still filling with exhaust fumes despite the additional ventilation provided following Motta’s fatal crash in testing. Cadringher lasted only two laps before being overcome and could not even overtake Dal Molin in the slower M.52R, so opted to retire. Monti in the second of the M.67s showed better pace and was challenging the Supermarine S.6s, but he was also suffering the effects of exhaust fumes and only lasted two laps before the cooling system failed, badly scalding him with steam and boiling water and forcing him out of the race. Misfortune of a slightly less dramatic nature struck the British team, as Atcherley, in an attempt to clear his goggles, lost them in the slipstream and was unable to put on his spare set. Unsighted, he turned inside a marker and was disqualified.

This left the battle between the two old warhorses, Dal Molin in the Macchi M.52R and D’Arcy Greig in the Supermarine S.5. Although both aircraft were slower than the others it became imperative to stay ahead in case the other S.6 of Waghorn failed to finish. It looked as though this might be possible, as Waghorn’s S.6 started to lose power and misfire. He climbed in the hope of being able to glide to the finish line, but the engine finally cut out as he rounded the final turn and he was forced to alight. He was initially distraught, but a motor launch came alongside to give him the news that he had won. Like Webster in 1927, he had miscounted his laps and flown an additional lap, running out of fuel as he did.

Waghorn’s victory very nearly did not happen, and it was only thanks to an attentive Rolls-Royce engineer that it did. During routine maintenance of the engine on the night before the race, a fleck of metal was found on a spark plug as it was removed, which warned the engineer of an impending problem. As changing the whole engine was not permitted in the rules, the only solution was to change the cylinder block. This was not a simple job, but luckily there were several hundred Rolls-Royce engineers who had come down to watch the race, billeted in hotels and boarding-houses across Southampton. A team was quickly assembled and the cylinder block was changed and the engine test run by 8am on the morning of the contest.

(A piece of trivia that I particularly like also relates to Rolls-Royce. Because the run-time between overhauls for the R engine was only 5 hours, it was necessary to shuttle the engines between Calshot on the south coast and the Rolls-Royce factory in Derby in the industrial Midlands. To do this, Rolls-Royce converted a Phantom I motorcar into a lorry, and the engines would be ferried overnight. Clearly the competitive spirit of the Schneider Trophy had rubbed off on the transport crews, as each vied to complete the journey in the fastest time. On one night, the Police caught the Phantom as it sped through a sleepy Hampshire village at around 80mph.)

Supermarine_S.6_L'A%C3%A9rophile_September,1929.jpg