Royal Aircraft Factory S . E . 2 The Royal Aircraft Factory S . E . 2 ( Scout Experimental ) was an early British single - seat scout aircraft . Designed and built at the Royal Aircraft Factory in 1913 as the B . S . 1 , the prototype was rebuilt several times before serving with the Royal Flying Corps over the Western Front in the early months of the First World War . Development and design . In 1912 , a team at the Royal Aircraft Factory , led by Geoffrey de Havilland , started design of a single seat scout , or fast reconnaissance aircraft , the first aircraft in the world specifically designed for this role . The design was a small tractor biplane , and was named the B . S . 1 ( standing for Blériot Scout ) after Louis Blériot , a pioneer of tractor configuration aircraft . It had a wooden monocoque circular section fuselage , and single - bay wings . Lateral control was by wing warping , while the aircraft was initially fitted with a small rudder without a fixed fin ( a scaled down version of that fitted to the B . E . 3 ) , and a one - piece elevator . It was powered by a two - row , 14 - cylinder Gnome rotary engine rated at 100 hp ( 75 kW ) . The B . S . 1 was first flown by Geoffrey de Havilland early in 1913 , demonstrating excellent performance , with a maximum speed of 91 . 7 mph ( 147 . 6 km / h ) , a stalling speed of 51 mph ( 82 km / h ) and a rate of climb of 900 ft / min ( 4 . 6 m / s ) , despite the engine only delivering about 82 hp ( 61 kW ) instead of the promised 100 hp . De Havilland was not satisfied with the control afforded by the small rudder and designed a larger replacement , but on 27 March 1913 , before the new rudder could be installed , he crashed the B . S . 1 , breaking his jaw and badly damaging the aircraft . Following this accident , it was rebuilt , with an 80 hp single - row Gnome and new tail surfaces , with triangular fins above and below the fuselage , a larger rudder and conventional divided elevators . While the rebuilt aircraft was initially designated B . S . 2 , it was soon redesignated S . E . 2 ( for Scout Experimental ) . It was flown in this form by de Havilland in October 1913 . In April 1914 , the S . E . 2 was again rebuilt , this time under the supervision of Henry Folland , as de Havilland had left the Royal Aircraft Factory to become chief designer of Airco ( the B . S . 1 / S . E . 2 was the last design de Havilland produced for the Factory ) . The tail surfaces were again revised , with a larger fin and rudder , with new tailplane and elevators . The monocoque rear fuselage , which had been criticised as too expensive for mass production , was replaced by a conventional wood and fabric structure . Better streamlined struts were fitted , as well as streamline sectioned bracing wires ( " Raf - wires " ) . It was first flown in this form on 3 October 1914 . This modified version is often referred to as the " S . E . 2a " - this designation was not used at the time , and was probably not official . Operational history . The S . E . 2 was handed over the Royal Flying Corps on 17 February 1914 , with the serial number 609 being issued to No . 5 Squadron , where it made a good impression , and then to No . 3 Squadron before being returned to the Royal Aircraft Factory in April . By the time the rebuilt " S . E . 2a " version was completed , the First World War had broken out , and the modified S . E . 2 was sent across the English Channel to join No . 3 Squadron on 27 October . It was fitted with an improvised armament of a pair of rifles mounted on the side of the fuselage , angled outwards to avoid the propeller , together with the pilot ' s revolver . It was one of the fastest aircraft available in the early months of the war , with it being said that : " Its speed enabled it to circle around the enemy machines and gave it a decided ascendancy . " It remained in use with 3 Squadron until March 1915 , when it was damaged by an exploding bomb and was sent back to England .