specifications issued by the Air Ministry meant that no aircraft could be completed and tested in time to be entered. Two Supermarine S.5 seaplanes were entered for the 1927 contest, which was held in Venice. Mitchell understood that a monoplane on twin floats produced lower drag than any other aircraft type of its day, and was convinced by wind tunnel tests at the NPL that the cantilever wing design was too heavy and should be abandoned. The NPL had demonstrated that flat-surfaced skin radiators reduced drag better than the corrugated variety preferred by American designers, so Mitchell used them to improve the S.5. He reduced the fuselage cross section area so that it was 35 per cent less than the area of the S.4—and complained about the RAF’s pilots being too large to fit into the resulting S.5's cockpit. The fuselage skin thickness was decreased by using duralumin. Witnessed by the Italian dictator Mussolini, along with a huge crowd gathered along Venice's Lido, the two Supermarine S.5's alone finished the race, coming first and second. The third British entrant, a Gloster IV, along with the three Italian competitors flying Macchi M.52s, were forced to drop out of the race. Mitchell had been elected to the RAeS in 1918. In 1927 he was awarded the society's Silver Medal. At the end of the year, he became the Technical Director at Supermarine. When the company was taken over by Vickers Ltd in 1928, he remained as Supermarine's chief designer—one of the conditions of the takeover was that he stay as a designer for the next five years. Supermarine S.6 (1929) Interest in the competition waned after the 1927 race. There was no competition the following year, as the Fédération Aéronautique Internationale was persuaded by the Royal Aero Club to hold races every two years in the future. Mitchell was among those who could see a more powerful engine than the Napier Lion was required for any aircraft that competed in future contests. The Air Ministry invited Rolls-Royce Ltd to design a new engine specifically for Supermarine’s new seaplane, now designated the S.6. Rolls-Royce, under pressure to produce an engine in time and that matched S.6's streamlined shape, adopted the partially-developed Buzzard. Mitchell in turn had to amend some of his design to accommodate the increase in total weight caused by introducing a larger engine, for instance by repositioning the forward float struts,