The Royal Aircraft Factory S.E.4 was a single engine, single seat biplane designed and built at the Royal Aircraft Factory just prior to the start of the First World War.
Intended to be as fast as possible, it recorded a speed of 135 mph (217 km/h), which made it the fastest aircraft in the world in 1914, but no production followed and it was soon written off in a crash.
In April 1913, Henry Folland, one of the talented pool of designers assembled at the Royal Aircraft Factory started the design of a high-speed development of the earlier Royal Aircraft Factory S.E.2 (designed by Geoffrey de Havilland), the S.E.3.
The S.E.3 was abandoned in favour of the S.E.4, a more advanced aircraft intended to break the world air speed record.
The S.E.4 was a tractor biplane powered by a closely cowled 14-cylinder, two-row Gnome rotary engine.
The aircraft’s fuselage was of wooden construction, and was carefully streamlined to reduce drag.
Although it has been sometimes claimed to be of monocoque construction, the fuselage was in fact built around a wooden box girder, with formers fitted around the box girder to give the desired shape and skinned with plywood.
The pilot sat in a cockpit under the trailing edge of the upper wing, unusually for the time, a transparent canopy made out of celluloid to fit the cockpit was made, but pilots refused to fly with it fitted and the canopy was never used.
The aircraft had single-bay wings, of equal span and unstaggered.
The wings were braced with a single “ɪ” section strut on each side, and were fitted with full span control surfaces on both the upper and lower wings.
These could be moved differentially as ailerons or together as camber changing flaps, with the gaps between the wings and control surfaces covered in elastic netting to further reduce drag.
The aircraft had a Conventional landing gear with a tail skid, and the main wheels carried on each side of a leaf spring held on an inverted tripod.