| Summary : Aircraft Assembly Hall, now commonly known as the Brabazon Hangar, built for the construction of the Bristol Type 167 passenger airliner, Brabazon Mark I. Erected between March 1946 and September 1949 and designed by Bristol Aeroplane Company architect, Eric Ross, in association with David Aberdeen and P N Taylor. Brian Colquhoun and Partners acted as consulting engineers, with T P O'Sullivan. The building is rectangular on plan and divided into three bays. The central bay, which projects forward to the north, is deeper than the flanking bays. The drawing and supervising offices, toilets and stores are arranged as a series of galleries along the back (north) and side walls of each bay. To the north-east corner of the central bay is the visitors' entrance, which consists of an entrance hall leading to a staircase and the reception hall and offices at first-floor level. It is constructed using a structural steelwork frame which spans each bay in the form of two-pin arch latticed ribs tied at the haunches and set at 15m centres. This building, and a circular petrol pump house to the east, were assessed for listing in 2012 but failed to meet the required criteria. |
More information : The Brabazon Hangar, originally known as the Aircraft Assembly Hall, was built for the production of the Bristol Type 167 passenger airliner, the Brabazon Mark I. The idea for the aircraft was conceived in 1942 by the aviation pioneer, Lord Brabazon of Tara, when he became chair of the Brabazon Committee. The aim of the committee was to review and make recommendations to the government on the future of civil aviation in Britain. In February 1943 Lord Brabazon recommended to the Cabinet Office that the Brabazon Type I should be given priority in design and production. It was to be the largest civil airliner in the world, providing a luxury service between London and New York.
BAC took occupation of the Aircraft Assembly Hall in March 1947. The building consisted of three bays and was originally designed to house the fabrication, assembly and testing of the aircraft. The testing bay, to the west end, was taken over as the maintenance bay in November 1947 as the British Overseas Airways Corporation (BOAC) transferred its principal maintenance base from Montreal, Canada to Filton. An additional wing of offices and workshops were built for BOAC between April 1948 and August 1949. The central bay was then used for aircraft assembly, and the east bay for final fabrication and assembly as well as flight testing. The maiden flight of the Brabazon Mark I occurred on the 4th September 1949.
Despite the Brabazon Mark I achieving its aim of being the largest civil aeroplane in the world, with a wingspan of 230ft, it did not find commercial success, and no orders were received. The last flight of the Brabazon was on the 20 September 1952. Its design, however, led to a number of innovations within the aviation industry; for example, the high power electrical systems first used in the Brabazon are now standard. The versatility of the Aircraft Assembly Hall has enabled other planes to be produced here including the Britannia and, most notably, Concorde. All British Concorde aeroplanes were built and flown from the Aircraft Assembly Hall at Filton.
The Aircraft Assembly Hall was well-regarded at the time of its construction and was reviewed in a number of architectural publications. The features of the design singled out for note included the three bays which could house three Brabazon aircraft side by side; the three pairs of folding doors to the south elevation which were powered by electric motors and designed so that the whole length of the building could be opened within two minutes; the glazed north elevation that provided natural light for daylight working; the electric crane system to the steel frame roof which enabled a 12 ton load to be delivered anywhere in a bay; and the steel framework which was designed by the engineer, T P O’Sullivan, to carry loads over that required. O’Sullivan made provision for future increases in loading and consequently extended current steel and design theory. His work led to a paper, ‘The Strengthening of Steel Structures Under Load’, for which he was awarded a Telford Premium by the Institution of Civil Engineers.
The Aircraft Assembly Hall employed a subtle colour scheme to its external elevations to define the different elements of the building. The folding doors were painted pale green with a white border; the wall area above the doors was painted pink, and the concrete asbestos sheets to the side elevations were painted cream. The purpose of the colour scheme was to help to define the shape of the hall preventing it from appearing as a single mass which would overpower the ancillary buildings.
The ancillary buildings were grouped together to form reasonably-sized units, so as not to be dominated by the assembly hall. They included the boiler house, the inflammable stores, the canteen and the petrol pump house to the east end, and the electric sub-station, fire station and various workshops to the north. These were primarily constructed of reddish brown brick to contrast with the assembly hall and also employed rubble stone for decorative effect.
The Brabazon Hangar has been altered in recent years, including re-cladding of the walls and roof and the removal of the original glazing to the north elevation. The ancillary buildings, save the petrol pump house, have been demolished or extensively altered and absorbed into new buildings. The Brabazon Hangar itself is now vacant and no longer used for the assembly and maintenance of aircraft.
PLAN: the building is rectangular on plan and divided into three bays. The central bay, which projects forward to the north, is deeper than the flanking bays. The drawing and supervising offices, toilets and stores are arranged as a series of galleries along the back (north) and side walls of each bay. To the north-east corner of the central bay is the visitors’ entrance, which consists of an entrance hall leading to a staircase and the reception hall and offices at first-floor level.
The building faces away from the runway onto a seven-acre concrete apron which has been excavated into the grassy slope which forms the southern boundary to the site. The slope curves round to the west and protects the apron from the wind. The apron leads to a taxi-way which curves round the ancillary buildings to the east, crosses the branch railway line, and allows aircraft to be towed to the runway.
MATERIALS: constructed using a structural steelwork frame which spans each bay in the form of two-pin arch latticed ribs tied at the haunches and set at 15 metres centres. Those for the outermost bays are 2 metres wide and those for the centre bay are 1.5 metres wide. To allow for movement and expansion within each bay, the arch ribs carrying the flanking bays are independent of those carrying the centre bay and the two columns rest inside each other at the junction. Movement is allowed for at foundation level by resting the main ribs on steel pins.
The folding doors to the south elevation are of aluminium. The external walls are constructed of brick at ground-floor level with, originally, concrete asbestos sheeting above which has now been replaced with a lightweight corrugated sheeting.
EXTERIOR: three bays, each with a gently curved roof. The roof lights over the main arches have been replaced by glazing strips at right angles to the arches. A rail runs round all sides of the building, except the south, and did carry an electrically-operated chair, to allow for glass cleaning and general maintenance. To the front (south) elevation are three pairs of folding doors with window openings at ground-floor level. Above the doors, at roof height is an external walkway which runs the length of the building. To the rear (north) elevation, the glazing has been replaced with two rows of glazing to match the east and west elevation. The central bay projects forward and includes two viewing stations with glazing at roof level. A canopy runs the length of the central bay above ground level. The visitors’ entrance to its north-east corner has a cantilevered canopy, and a revolving door has replaced the original doorway. This entrance has a rubble stone wall to its south elevation with blocked round windows; the glass block wall to its east elevation has been replaced with a clad wall.
INTERIOR: the internal floor space is clear of services, with pipes running in under floor channels, and raised vertical aluminium heating ducts located to the outer walls of the bays. The offices are arranged as galleries along the side and rear walls of each bay. This allows for the flexible use of space. To the roof space is a complex steel framework with the original crane system in situ.
The visitors’ entrance retains some key features including the staircase, the egg-crate ceiling of steel sheeting and a glass block wall to the upper level.
SUBSIDIARY FEATURES: the petrol pump house is a circular building to the east. Constructed of random rubble stone, it has a set back, glass block, clerestorey and a flat roof. The other ancillary buildings that formed part of the original design have either been demolished or absorbed into new buildings.
The Brabazon Hangar, designed by architect Eric Ross, for the assembly of the Brabazon Mark I, is not recommended for designation for the following principal reasons:
Architectural interest: although an interesting example of an aircraft assembly hall its architectural form is standard, and it has undergone later alteration including the re-cladding and the removal of the north glazing;
Historic association: a number of aircraft were assembled here, including the Brabazon Mark I, Concorde and the Britannia but apart from the Brabazon Mark I, the building’s association with subsequent aircraft is not manifest in the fabric of the building;
Engineering interest: although of importance for the developments in the strengthening of steel structures, this was not particularly innovative and is not of sufficient interest to raise the interest of the building as a whole;
Group value: despite the survival of the apron, taxi-way and runway, as well as the petrol pump house, the losses to the ancillary buildings have affected the context of the site in terms of its legibility and overall setting. (1)
The assembly hall or Brabazon Hangar is visible on numerous oblique aerial photographs as it was being constructed between 1946-1949. The photographs are part of the Aerofilms collection now housed at the Engine Heritage Archives, Engine House, Swindon. The original ancillary buildings referred to above (Source 1) do not seem to be demolished when compared with historical aerial photographs, though some have definitely been expanded or altered. (2-3) |