Flying Boat Hangar

Summary

Flying Boat Hanger or Shed built 1917 to 1918 and designed by HM Office of Works under Sir Frank Baines.

Reasons for Designation

The Flying Boat Hangar at Hythe is designated at Grade II for the following principal reasons:
* Design interest: it is an important development in hangar design, directly attributable to the notable architect Sir Frank Baines;
* Rarity: the hangar is an early, largely intact example of an unusual type of flying boat factory shed, and its sawtooth-profile northlight roof appears to be unique in the context of World War I flying boat factory hangars;
* Structural interest: the roof construction of this enormous hangar displays a stage in the development of hangars, reflected in other manufacturing workshops, solving the problem of spanning large surface areas without the need for intervening columns and freeing up a large floor area;
* Historic interest: as the site of production of flying boats such as Southamptons, Supermarine Seagulls and Walruses which mark the high point of flying boat aviation between the wars, and for its association with the introduction of the air mail service to Britain;
* Context: it stands on Southampton Water, an area with particularly strong associations with flying boats, and is close to the related complex at Calshot.

History

The hangar was built during the First World War for the construction of flying boats for the Royal Naval Air Service (RNAS). During the First World War the company of May, Harden & May of Hythe occupied a ship building yard at Shore Road Hythe, and were building Felixstowe flying boats for the Royal Naval Air Service and subsequently for the RAF. On the southern side of the shipyard was a large private house called Winterton Hall, which the War Office took over and demolished, and the Admiralty built what became the Hythe Flying Boat Depot. The Depot was constructed by John Mowlem and Co. between 1917 and 1918, and consisted of a large construction hangar, concrete apron, and a slipway into Southampton Water.

The National Archive (NA MUN4/997) shows that the flying-boat factory was designed in the office of the distinguished architect Sir Frank Baines (1877-1933), from 1914 Principal Architect of HM Office of Works, and was overseen by him. Sir Frank Baines entered the Office of Works in 1895, and by 1920 had risen to be its Director. Baines' personal association with the hangar is illustrated by the fact that he used it as one of his examples in a lecture he gave at the Royal Institute of British Architects in April 1919 on the subject 'War factories and sheds - their construction and adaptation to future needs'. Sir Frank Baines is famous for the design of Thames House (1929-1930 and listed Grade II) in London, for some years now the headquarters of MI5. In the 1920s he was involved in pioneering engineering work to repair and conserve the roof structure of Westminster Hall, Palace of Westminster, amongst other major conservation projects, and it is now clear that he was also deeply involved in the war factories programme of the First World War. Sir Lionel Earle (1866-1948) was Permanent Secretary to the Office of Works from 1912 until his retirement in 1933. His recollections in his book 'Turn Over The Page' informs us that Baines worked tirelessly for the war effort in a civilian capacity; Baines' now known personal involvement in the flying-boat factory underscores this.

A number of the most famous flying boats produced in Britain between the wars were constructed in this hangar. The large size of the shed at Hythe is important because it demonstrates a trend towards building bigger aircraft. This is illustrated by the fact that May, Harden & May soon took over the management of the facility for the construction of the large Felixstowe flying boats and subsequently the Fairey Atalanta. There are early seaplane hangars at Calshot, not far from Hythe and near the mouth of Southampton Water, which form an outstanding group dating to 1914 -18, most of which are now listed Grade II*. The Calshot hangars, however, appear to have been for the 'garaging' of seaplanes, not for the production of aircraft. In September 1925 the Hythe hangar was taken over by Supermarine; the Southampton firm famous for the racing aircraft which won the Schneider Trophy between the wars and for the development of the Spitfire which played an important part in the Battle of Britain in the Second World War. Supermarine produced the Mark 1 Southampton and Supermarine Southampton flying boat here which were based on a design by the famous designer of the Spitfire R J Mitchell; the large hangar was refurbished, and Mark 1 and Mark 2 Southamptons, Supermarine Seagulls and Walruses (the last also designed by Mitchell) were assembled here, names significant in the history of flying-boat aviation.

In 1928 Vickers took over Supermarine, but did not start producing aircraft again until 1935 when it manufactured Supermarine Stranraers for the RAF. This work lasted until 1938, and was followed by work on the Walrus flying boats until the operation was transferred to the Woolston works in 1939 and the aircraft production at the Hythe Works ceased.

In addition to the production of famous aircraft, the Hythe depot, including the hangar, was also involved in the introduction of the air mail service. In 1937 part of the Hythe Works had been leased to Imperial Airways as a maintenance depot for their Empire Flying Boats, and as Supermarine gradually used less of the site, Imperial Airways progressively took over more until, with the closure of the Works in 1939, they took control of the whole site. Imperial Airways had, through negotiations with the British Government, established the Empire Air Mail Scheme, which was an intercontinental air service linking the countries of the British Empire. This Scheme began in 1937, and the Supermarine hangar and other buildings were used for the maintenance of the new fleet of flying boats. Even when, with the advent of the Second World War, the Empire Service was transferred to Poole Harbour, maintenance of the flying boats was retained at Hythe.

During the Second World War the Hythe site undertook work under contract for the War Department which included the repair, maintenance and modification of four Heinkel 115s which were used to take agents into German occupied areas.

When the war finished the British Overseas Air Corporation, the successor to Imperial Airways, brought their commercial flying operation to Hythe, but the company changed to land-based aircraft and in December 1949 the BOAC flying boat services ceased and the Hythe base was closed down.

In 1953 the base was taken over by the Royal Navy as a care and maintenance base for the minesweeper HMS Diligence, and remained as such until 1963 when it was closed again.

When France left the military structure of NATO in 1966, the US army facility near La Rochelle was closed, and HMG offered the Hythe depot to the US army, an offer it accepted. The US Field Army Support Brigade/Combat Equipment Battalion - Hythe began occupation of the Hythe site in 1967, and used the base mainly for small boat repairs. This use continued until 2006. For administrative purposes all American bases in the UK need to have a British name, and the Hythe base became RAF Hythe.

Details

Flying Boat Hanger or Shed built 1917 to 1918 and designed by HM Office of Works under Sir Frank Baines. The area covered by the hangar is nearly 7,000 square metres. There are a number of later additions which include a re-clad brick building extension at the east end

EXTERIOR: the hangar has colour-coated corrugated steel cladding, replacing the original steel cladding, with a saw tooth profile roof of four apexes with northlight glazing. It has, on its south, east and west elevations, raking angle-iron buttresses. In some cases the light angle-framed buttresses have been reinforced by adding short horizontal or sloping sections of rectangular-section steel tube site-welded to the original angle-framing. Sliding doors open the whole of the north long axis of the hangar to the apron. Door apertures formerly embodied in the rear (south) elevation appear to have been overclad, modified or removed to achieve a different arrangement of smaller doors. Vertical glazing in the external walls and the sliding doors of the north elevation, as well as the glazing of the northlights, is of double or triple-wall polycarbonate sheet, replacing original glazing. The later extensions including the re-clad brick building extension at the east end are not of special interest.

INTERIOR: the saw-tooth-profile roof is supported on deep lattice trusses with stanchions and steel rakers. Small-section channels have been bolted to the undersides of one of the two original angles which make up the tie-beams of the lateral steel trusses to stiffen the small-section tie beams. The former unitary volume of the hangar has been subdivided to accommodate different work areas. These changes have included the installation of a broad mezzanine floor extending along the interior’s south side which is supported on independent ‘goalpost’ steel-joist portals, bolted down to the concrete ground-floor through holding down plates. The individual uses to which the building is now put are accommodated in a simple orthogonal arrangement of the space between the rear mezzanine and the north-elevation sliding doors. Some uses require complete containment which has been achieved through free standing structures sitting within the former unitary space. The mezzanine structure and modern inserted subdivisions of the hangar are not of special interest.

Sources

Books and journals
Francis, P, British Military Airfield Architecture From Airships To The Jet Age, (1996)
Earle, L, Turn Over The Page, (1935), 101

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