Type L Hangars, Site E

Two aircraft storage hangars built in 1939 to Air Ministry Directorate of Works and Buildings drawing numbers 5163-5/39. They feature steel rib framework with a concrete roof on pressed metal sheeting, finished with an asphalt roof covering, and in-situ concrete end walls.

Plan and Setting

The hangars are identical structures set roughly parallel but staggered, located approximately 730 metres south of the western end of the main runway. Each forms a plain rectangle with internal dimensions of 300 by 167 feet and a maximum height of 36 feet (91.4 by 50.8 by 11.1 metres). They create low parabolic vaults springing from ground level, with wide doors at each end. Attached to the inner ends are annexes, one containing the boiler room, with small personnel access doors.

Exterior

The broad expanse of asphalt covering the low-profile parabolic vaults is completely unbroken. The outer end walls reduce in thickness at about half-height with an external offset. They contain four wide steel doors within a plain rectangular opening. Above the centre of each opening rises a steel tube ventilator or stack.

The inner ends show a similar reduction in wall thickness at half-height and contain matching wide doors. To the left, a shallow boiler-house annex is attached parallel to the wall, with a square stack rising just above parapet height. A smaller shallow annex stands to the right. The parapet ends flare outward at the bottom. 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 series of triangular-section fabricated steel ribs carrying profiled sheet steel, which served as formwork for the poured concrete roof. A series of continuous longitudinal steel rails is suspended from the ribs.

Historical Development

This form of hangar evolved from the earlier Lamella type (found at Sites A and B at Kemble), maintaining the same overall dimensions but employing easily prefabricated steel ribs set in parallel to carry the concrete roof. Originally these roofs were covered in earth finished with turf, which provided extra protection against bomb blast while creating excellent camouflage from above. Turf-covered versions may be seen at Hullavington Airfield in Wiltshire, about 10 kilometres south of 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 between 1936 and 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 for despatch 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 had integrated these requirements from the 1920s. The dispersal of aircraft around the flying field, instead of concentrating them in 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 affected hangar design in Aircraft Storage Units through the use of both concrete and roofs of parabolic form. The latter, originally turfed over for additional protection, 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 seen at the historic Montaudron airfield at Toulouse. The genesis of the parabolic Lamella type of hangar lies in the Lamellendach technique, produced by Junkers in Germany from the early 1920s. This utilised a structural grid of short and small-scale steel sections in a diagonal grid to create a parabolic vault. This type of hangar was built in England under licence from 1929, and there are four at Kemble on 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 and E), while Type E uses ribs of small-section steel to support concrete slabs curved to the arc of the frame (Site C). These steel and concrete rib hangars most clearly relate to contemporary experimentation elsewhere in Europe, especially Pier Luigi Nervi's Lamella-derived forms built for the Italian air force, the Zeiss-Dywidag 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 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 of 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 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, while others were in hutted units, mostly in Kemble Wood to the east.

The daily number of aircraft stored in October was 330, ranging 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 to accept heavy bombers, accompanied by the building of new taxiways. The station survived aerial attack in 1940 and 1941, going on to play an important role in readiness for D-Day with work on Horsa gliders and Typhoons in early 1944. The Fosse Way crosses the site.