Gloster IVB
The Gloster IVB was the short-span, geared-engine member of the three Gloster IV racing floatplanes built by the Gloster Aircraft Company for Britain's 1927 Schneider Trophy team. Flown by the RAF High Speed Flight, it was the only Gloster to start the Venice race, lapping faster than one of the Supermarine S.5s before a cracked propeller shaft forced its retirement; it later served as a high-speed trainer until a landing accident ended its career in December 1930.
Why It Mattered
The Gloster IVB was Gloster's racing floatplane for the 1927 Schneider Trophy contest at Venice. It flew in the first British Schneider effort to have the full backing of the government and the Royal Air Force, whose High Speed Flight was asked to represent Britain. Gloster's chief designer, Henry Folland, decided to persist with the biplane configuration, following an extensive study of speed, wing rigidity and application to service requirements. At Venice the IVB lapped faster than the direct-drive Supermarine S.5, though slower than the geared S.5, before a cracked propeller shaft put it out of the race. The NACA's contemporary judgement was that in speed there was little to choose between the biplane and the monoplane.
Design Notes
The IVB was one of three Gloster IVs built for the race, the variants differing in wing surface area and tail arrangement; the IVB itself, serial N223, had reduced-span wings and a geared Napier Lion VIIB engine of 885 hp. The type was a development of the Gloster III, which had finished second in the 1925 race. Folland's team reshaped the fuselage and floats to cut their head resistance by 45 per cent against the 1925 aircraft, and blending the wings smoothly into the fuselage raised lift by 15 per cent. The fuselage was built of narrow spruce planks laid at about 45 degrees in two skins, the boatbuilders' double-diagonal system. Surface radiators were fitted on both wings and on the decks of the floats, and the duralumin floats were slender single-step units tapered to reduce drag. All controls ran internally, and a variable-gearing device let the pilot adjust the ratio between column and surface movement, suiting the controls to both high and low speed.
Operational History
The three Gloster IVs were first flown in July and August 1927, and the two short-span aircraft, the IVA and the IVB, were shipped to Venice in August. The IVB was finally chosen to race with the two S.5s after the Short Crusader crashed in practice, its control cables having been crossed on re-assembly. On 26 September 1927 the IVB, flown by Flight Lieutenant Samuel Kinkead, was the first aircraft to take off, and it completed five laps before retiring. On inspection the propeller shaft was found to be seriously cracked, and it would probably have failed if Kinkead had not retired when he did. The race was won by Flight Lieutenant Sidney Webster flying the Supermarine S.5. The three aircraft remained with the RAF High Speed Flight, which flew them as trainers for several years.
Afterlife
Back in the United Kingdom, the IVA and IVB were modified to improve the pilot's view by raising the upper wing, and both were used as high-speed trainers. They trained pilots for the 1929 race, and the IVA served as a trainer again for 1931. The IVB's flying ended in December 1930, when it crashed in a landing accident. The original long-span Gloster IV was sold to be converted into a landplane for an attempt on the world air speed record, but these plans came to nothing. None of the three aircraft is known to survive.