No. 12811. Bristol Boxkite
Aeroplane Photo Supply (APS) Photo No. 307

Bristol Boxkite

06/30/2015. Remarks by Johan Visschedijk: "The two-seat Bristol biplane of 1910 was an unashamed copy of the Henri Farman, using the same dimensions and scantlings, but introducing the more refined metal fittings, such as steel clips and cast aluminum strut sockets. The quality of French-built Farmans was somewhat variable, but the Bristol biplane, though similar in general appearance, was equivalent to or better than the best that France had produced at that time. Indeed, when the solicitors for Farman Frères proposed to sue the 'Bristol' Directors for infringement of patents, the Directors immediately entered a defense claiming substantial improvements, and no court proceedings ensued.

The first two Boxkites were constructed at Filton to drawings made by George Challenger in June 1910. They differed from all later Boxkites in having rear elevators with straight trailing edges and in having two, instead of one, intermediate vertical struts between each pair of upper and lower front booms. Aircraft No. 7 was at first fitted with a 50 hp Grégoire four-cylinder engine and No. 8 with a 50 hp eight-cylinder E.N.V., both being water-cooled. A further point of difference was that No. 8 had double-surfaced wings whereas No. 7 had a single fabric covering with pockets enclosing the ribs; the latter was standard Farman practice and was adopted on all later Bristol Boxkites, mainly to save weight.

The Grégoire was unreliable and deficient in power, so it was particularly valuable when Émile Stern (Bristol's agent in Paris, France) succeeded in obtaining one of the first 50 hp Gnome rotaries released for export. Fitted with this engine, No. 7 was taken to Larkhill on July 29, 1910, assembled overnight, and flown the next day to a height of 150 ft (46 m) at the first attempt by the French pilot Edmond, to the astonishment of observers who had taken up prone positions on the ground in order to detect the first glimmer of daylight between the grass and the wheels. With the efficiency of the design thus spectacularly confirmed, more Boxkites were laid down at Filton and Nos. 10 and 12 were specially prepared for the Missions to Australia and India, respectively, the latter being the first to have upper wing extensions.

The conditions in India were very severe and No. 12 came to grief on the rock-strewn terrain, with a ground temperature of 100°F, but many flights were made and repairs kept pace with damage. In Australia, No. 10 was flown at Perth, then at Melbourne, where 32 flights were made, many with passengers. The Mission then moved to Sydney, by May 19, 1911, 72 flights totaling 765 mls (1,231 km) had been completed without having had to replace a single bolt or wire.

The Boxkite had by now begun to attract foreign buyers. The outcome of negotiations with the Russian Attaché in Paris, William Rebikoff, was the first Government contract in the world for British aeroplanes, signed on November 15, 1910 for the supply of eight improved Boxkites having enlarged tanks and three rudders, which were called the Military model. The first three of these, Nos. 17, 18 and 19, were at first flown with 50 hp Gnomes, and in April 1911, Nos. 18 to 25 were shipped to St. Petersburg, all fitted with 70 hp Gnome engines.

In February 1911, two special exhibition models were built, having 70 hp Gnome engines, enclosed nacelles and increased span. The first, No. 31, was exhibited at Olympia, London in March 1911, and the second, No. 32, at St. Petersburg in April. The latter was purchased by Russia in addition to the eight already ordered.

On March 14, 1911, the War Office placed a contract for four Military Boxkites with 50 hp Gnomes as described in a specification submitted on 20 October 1910. The first two War Office machines were delivered in May, but then the War Office asked for the other two to be supplied with 60 hp Renault engines for comparison. This required a redesign of the engine mounting and girder, which resulted in a substantial nacelle structure in front of the pilot. The first Renault-powered aircraft was delivered in July, by which time four more had been ordered, two with 50 hp Gnomes and two as spare airframes without engines.

By September 1911 the Boxkite production line had become well established and continued until 1914. In the standard models the wing extensions were retained but the third rudder was deleted. Strict interchangeability of components was maintained, and many later school machines incorporated serviceable parts from earlier aircraft; the 50 hp Gnome remained as the standard engine. Aircraft No. 60 was powered by a 70 hp Gnome engine and also incorporated an enclosed nacelle, longitudinal tanks and a push-pull handwheel control instead of the simple control-stick; this was demonstrated at Cuatros Vientos airfield, Madrid, Spain, in November 1911 and purchased soon afterwards by the Spanish Government, who ordered a similar spare airframe in which they fitted one of their own 70 hp Gnomes. Another machine, No. 139, was supplied to RNAS Eastchurch in April 1913, receiving Naval serial no. 35, and was standard except for a 70 hp Gnome engine.

Including rebuilds which received new sequence numbers, the total number of Boxkites built was 76, all at Filton except for the final six, which were the first aeroplanes constructed at the Tramways Company's Brislington works. Although underpowered and out-dated at the end of their career, they survived mishandling often to the point of demolition, but the pupils emerged more or less unscathed and the mechanics performed daily miracles of reconstruction, so that school machines were constantly reappearing Phoenix-like from their own wreckage. Apart from the nine exported to Russia, three were sold to South Africa, two each to Australia, Germany and Spain, and one each to Bulgaria, India, Rumania and Sweden.

In addition to the proper Boxkite, there were two variants, both for competition work. One had wings of much reduced span and a small single-seat nacelle. This was for Maurice Tétard in the Circuit de l'Europe (racing no. 3) and was first flown on May 30, 1911; in the race it developed engine trouble and Tétard retired at Reims, half-way through the first stage. The other was a redesign in November 1911 by Gabriel Voisin using standard wings, but with the gap reduced and the front elevator and booms deleted; a single large tail plane and a single rudder replaced the normal biplane tail unit. It was sent to Larkhili for tests in February 1912. No photograph of this machine has survived and it was apparently soon rebuilt as a standard school Boxkite, in which form it was crashed at Larkhill by Major Forman on November 3, 1912."

Created June 30, 2015