Royal Aircraft Factory S . E . 4 The Royal Aircraft Factory S . E . 4 was a single - engined , 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 . Development and design . 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 cowelled 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 grider 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 " " 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 tailskid , and the main wheels carried on each side of a leaf spring held on an inverted tripod . Operational history . The prospective design , although yet to fly , was mentioned at a February 1914 meeting of the Royal Aeronautical Society by Brigadier General David Henderson , who said : " If anyone wants to know which country has the fastest aeroplane in the world - it is Great Britain " . The S . E . 4 was first flown in June 1914 , demonstrating performance every bit as good as hoped , with a maximum speed of 135 mph ( 217 km / h ) , making it the fastest aircraft in the world . The novel mounting of the mainwheels proved unstable during taxiing , and was replaced by more conventional V - struts . The engine was prone to overheating , so the propeller spinner had an opening cut into it and a fan installed inside the spinner to help cool the engine . Although it was praised by its pilots , including John Salmond , later to become Chief of the Air Staff , its landing speed of 52 mph ( 84 km / h ) was considered too fast for operational use , and the engine was still too unreliable , being replaced by a 100 hp ( 75 kW ) Gnome Monosoupape rotary engine . With this engine , speed fell to a less impressive 92 mph ( 148 km / h ) . The S . E . 4 was badly damaged in a landing accident on 12 August 1914 , with the type being abandoned . Although the Royal Aircraft Factory S . E . 4a had a similar designation , it was effectively a completely different aircraft .