Details
1360/0/10008
01-DEC-05
CRUDWELL
KEMBLE BUSINESS PARK
Buildings M1 and 2 (Type D hangars),
Main Site
GV
II
Two aircraft storage hangars. 1938/9, to Air Ministry Directorate of Works and Buildings drawings Nos 3212-1313/36. Reinforced concrete walls and roof, asphalt covering; annexes in rendering on block or brickwork, some corrugated asbestos sheet roofing.
PLAN: Except for small side annexes the hangars are identical, set in line but at a slight angle to each other, separated by a manoeuvring area, to the S of which is a third hangar (Type C, qv); the group lies close to the main entrance to the base. Plain rectangular plan, in 15 bays, internal dimensions 300 x 150 x 30ft (clear) (91.4 x 45.7 x 9.1), with full width and height doors at each end sliding to external gantries. Basic form a plain cuboid, with segmental roof.
EXTERIOR: The long side walls are in plain in-situ cast concrete, with large steel lights at the upper level, in 6 over 9 horizontal panes separated by a concrete transom; above these is a deep concrete canopy projecting approx 1m, and above this high plain parapet continues in the wall plan, approx 1.5m high. This parapet returns to the short ends for a short run before merging with the segmental pediment above a horizontal projecting rail carrying the head track to the doors; this track is continued beyond the ends of the hangar as a gantry supported at the outer ends by a plain concrete post. At each end are 6 full-height steel doors, each with full-width lights in 6 over 6 horizontal panes separated by a shallow transom. To enhance blast protection, the doors originally had sand or gravel fill between inner and outer sheeting in the lowest of panels of the doors.
The westernmost hangar (M1) has a short annexe range in the centre bays to the N, and to the S a shallow range to bays 2-7, and deeper range bays 10-14, these with corrugated asbestos sheet roofs, and steel casement lights. The second hangar (M2) has one small, later addition on the N side, and to the S side a deep range in bays 2-7, with 4-pane lights and 2 doors, also doors direct to the hangar in bay 8.
INTERIOR: In 15 bays, with plain concrete floor. Concrete piers at 20ft (6.1m) centres are expressed internally, with plain cast concrete walling up to sill height. Each pair of piers carries one of the bow-string roof trusses, in square concrete sections of straight bottom chord and segmental upper; these are separated by a series of square vertical suspenders, with a longitudinal bar stiffener to the central sections. At the pier supports are short lengths of solid bracing, and at about 2m from the wall is a purlin ring running the full length each side. Horizontal wind-bracing is set to the bay immediately adjacent to the doors each end. Roof decking is in-situ concrete following the segmental profile.
HISTORY: There are two further examples on Side D at Kemble (qv), which differ only in the window treatment to the long flanks. The Type D hangar, which combines concrete construction with bow-string trusses, owes its origin to developments in French engineering (as for example at the historic Montaudron airfield at Toulouse). A total of 34 examples of these all-concrete designs were used on Aircraft Storage Units such as Kemble (there being two further examples on Site D), these being included because of their integral relationship to this uniquely important site.
Kemble, by virtue of its range of 5 different hangar types including structurally advanced ones of parabolic form, is the most outstanding and strongly representative of the 24 Aircraft Storage Units planned and built by the Air Ministry for the storage of vital reserve aircraft in the period 1936-1940. The ASUs were all administered by Maintenance Command and were sited to the W of the principal bomber stations and fighter belt, and their function was to receive and store aircraft before they were made ready to be sent to operational bases: some, such as Hullavington to the south, were grafted onto existing Flying Training Schools. Apart from a cluster of 3 hangars on the Main Site, the hangars were planned in pairs around the flying field. The planners of ASUs thus exercised, for the first time, the principle of 'dispersal' in the planning of military airfield landscapes as opposed to fabric, the planning of domestic and technical sites having integrated these requirements from the 1920s. The dispersal of aircraft around the flying field, instead of being concentrated in the hangars, provided further protection against air attack (particularly crucial for the vital supplies of reserve aircraft to front line units) and had a profound influence on airfield layout during the Second World War. This principle also had an effect on hangar design in ASUs, in the use of both concrete and roofs of parabolic form - the latter originally turfed over for additional protection - which housed aircraft in the 'tails-up' position hung from their roofs. The genesis of the parabolic Lamella type of hangar is the Lamellendach technique, produced by Junkers in Germany from the early 1920s, which utilised a structural grid of short and small-scale steel sections in a diagonal grid in order to create a parabolic vault. This type of hangar was built in England under licence from 1929, and there are four at Kemble (Sites A and B). In addition there are two variants in construction, using the same overall form and dimensions but developed differently: Type L uses close-spaced concrete ribs formed in pressed steel members (Sites F (not included) and C) and Type E uses ribs of small-section steel to support concrete slabs curved to the arc of the frame (Site E). These steel and concrete rib hangars most clearly relate to contemporary experimentation elsewhere in Europe, especially Pierre Luigi Nervi's Lamella-derived forms built for the Italian air force, the Zeiss-Dwidag concrete-ribbed vaults used for side-opening hangars in Germany and the concrete hangars developed for the French air force from the 1920s. All these hangar buildings stretched existing engineering technology in order to clear wide spans, forming the basis for developments in the post-war period. The existence of such a variety of these types of hangars at Kemble, also relating to an advanced type airfield landscape, is certainly unique in a British context, and no such group survives in France or Germany.
RAF Kemble was officially opened in June 1938, but construction continued into 1939 and a Station HQ was not formed until October 1940, under 41 Maintenance Group. By November over 900 personnel were involved, many of them civilians, staffing the Maintenance Unit: most were accommodated off-site, and others were in hutted units, mostly in Kemble Wood to the E. The daily amount of aircraft stored in October was 330, from antiquated Hawker Harts to Bristol Beauforts, Blenheims and Hurricanes. Two runways were built between September 1941 and April 1942, the main one being extended in 1943 in order to accept heavy bombers and accompanied by the building of new taxiways. The station survived aerial attack in 1940/1, it going on to play an important role in the readiness for D-Day with work on Horsa gliders and Typhoons in early 1944. The Fosse Way crosses the site.
(The Royal Air Force Builds for War: A History of Design and Construction in the RAF, 1935-1945, 1956, republished by HMSO in 1997, pp.290-302; Operations Record Book, Public Record Office AIR 28/218; Christopher Ashworth, Action Stations 5 (Military Stations of the South-West), Cambridge, 1982, pp. 115-7; J.S. Allen, 'A short history of 'Lamella' construction', Transactions of the Newcomen Society, 71 (1999-2000), pp. 1-29).
