Triple Hangar at ST 60 806, Filton Airfield

Triple Hangar at Filton Airfield

A group of four paired aircraft hangars in line, built in 1918 by the War Office's Directorate of Fortifications and Works to drawing number 417/17. The structures are constructed from brick walls, buttresses, central piers and door pylons, with curtain walls of half-brick thickness in cheaper bricks. The roofs employ softwood Belfast roof trusses with corrugated steel door cladding and later profiled steel roofing.

The buildings form a triple-span shed arrangement, with each span divided by a central row of brick piers. Low single-storey sets of stores or offices flank the longer sides of each shed.

The exterior presents triple segmental gables to the east and west elevations. A series of raking buttresses runs along the side walls, which incorporate brick workshop annexes with steel casement windows. Outside the outer bays stand brick pylons in red brick, designed to accommodate sliding doors. These pylons consist of three sets of paired piers carrying thin brick stiffening diaphragms with straight tops but segmental lower edges, mirroring the internal construction.

The interior hangars are divided by a central row of paired brick columns, two bricks square with a clear gap between them. These carry a longitudinal thin brick stiffening diaphragm on a segmental arch. The outer faces of each column support a concrete spreader, corbelled in three courses, which carries a strut formed from three small scantling timbers spliced into the doubled bottom chord of the Belfast trusses. These trusses, commonly used from 1916 onwards for aircraft hangars, have their bearing ends plated in diagonal boarding to the point where the strut is taken in, then a close-set diagonal grid of small struts. The doubled upper chord, in a flat segment, carries close-set purlins and lined profiled roof sheeting. Vertical X-bracing runs between bays, with horizontal bracing in the bays adjoining the main doors.

The Bristol Aeroplane Company, founded by Sir George White, was established in 1910 as one of Britain's first aircraft manufacturers. It also established training schools for civilian and military flyers, with hangars at Larkhill in Wiltshire surviving from this period. By the Second World War, Bristol supplied engines for nearly half the world's airlines and more than half the world's air forces, and during the war it provided a third of the RAF's engines.

Sited to the north of Sir George White's aircraft factory of 1910 (converted from tram manufacturing sheds built in 1908), this part of Filton was developed as an Aircraft Acceptance Park for the reception and final assembly of aircraft from factories, their flight testing, storage and distribution to operational squadrons. The buildings, which survive as the most complete on any of these types of sites in existence, numbered 27 in November 1918. They were retained for use by the Bristol Aeroplane Company after the war, and from 1929 became part of an operational fighter base. Following the disbanding of 501 (County of Gloucester) Squadron in 1957, the hangars reverted to use by the aircraft factory, now British Aerospace.