Two Lamella Hangars, Site B

Two aircraft storage hangars built in 1938-39 to Air Ministry Directorate of Works and Buildings drawing number 6953/36. The hangars have a pressed steel framework with a concrete roof on pressed metal sheeting and a coated profiled steel sheet roof covering. The end walls are constructed of in-situ concrete.

Plan and Location

The hangars are identical and set nearly parallel to each other, just to the north of the west end of the main runway. Each forms a plain rectangle with internal dimensions of 300 feet by 167 feet and a maximum height of 36 feet (91.4 by 50.8 by 11.1 metres). They create a low parabolic vault springing from ground level. Wide pairs of doors are set within the diaphragm walls at each end. At the outer end of each hangar are two small annexes flanking the door opening, one of which contained a boiler room. Small personnel doors are set in the end walls.

Exterior

The broad expanse of corrugated sheeting covering the low-profile parabolas is completely unbroken. The west end of each hangar has a wide central opening containing a high panel with a central roller-shutter door below a range of lights arranged in a 4:5:4 pattern vertically. To each side is an external annexe with a monopitch roof of corrugated sheeting; the one to the left is taller than the other and formerly housed the boiler. The inner end of each hangar has a plain pair of steel doors in a near-square opening. Inside one of the doors to the northernmost shed is a cast panel recording: "Lamella, by Horseley and Thomas Pigott. Pat 243363". The parapets to the end walls are flared out at the bottom, and a continuous wide concrete trough-gutter runs at ground level along each side.

Interior

The floor is smooth finished concrete. The structure consists of a diagonal lattice of pressed steel members in a small grid. These carry steel sheeting as formwork for the poured concrete roofing. A series of longitudinal steel members running the full length of the hangar is suspended below the structure at the centre and to the sides.

Historical Context

The Lamella hangar is a form developed in Germany in 1929 and originally built in Britain under licence by the Horseley Bridge Engineering Company. The structure can be realised in concrete, timber or steel, but steel was always used in Royal Air Force examples. It utilises the extra structural strength generated by the larger cross-section of a diagonal member, plus the ease of prefabrication of relatively small steel units easily assembled on site.

The first British arched hangar featuring this form of construction was erected for Henleys (1928) Ltd at Heston Airport between May and June 1930. Taking just five weeks to complete, it had a maximum span of 82 feet, a length of 149 feet and a door opening 62 feet wide with a clear height of 18 feet.

Another version had an arched roof with wall plates carried on girders supported by stanchions. Three hangars were supplied in this form. One at Liverpool Airport is now a Grade II* listed building. The others were built as part of the Cunliffe-Owen aircraft factory at Southampton Airport. Lamella construction took the form of a large net-like framework of shallow channel-section standard steel pressings with ends bent to the correct angle and bolted together in pairs (a right and left to a left and right). This formed a diamond-shaped web and a lattice arch when assembled with others. Tooling for the manufacture of Lamella roof components was installed in the factory at Tipton. No provision was made for tails-up storage, so aircraft were simply packed together.

There are two further Lamella hangars at Kemble (Site C), but the remaining hangars, although externally similar, use other means of construction. Originally the roofs were covered with earth finished in turf. This provided some extra protection against bomb blast but also created excellent camouflage from above. Turf-covered versions may be seen at Hullavington airfield in Wiltshire, about 10 kilometres south from Kemble.

Kemble, by virtue of its range of five 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 Aircraft Storage Units were all administered by Maintenance Command and were sited to the west of the principal bomber stations and fighter belt. 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 three hangars on the Main Site, the hangars were planned in pairs around the flying field.

The planners of Aircraft Storage Units 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 Aircraft Storage Units, 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 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). 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. 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 and Type E uses ribs of small-section steel to support concrete slabs curved to the arc of the frame.

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.

Royal Air Force Kemble was officially opened in June 1938, but construction continued into 1939 and a Station Headquarters 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 east. 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 1940-41, going on to play an important role in the readiness for D-Day with work on Horsa gliders and Typhoons in early 1944.