Aircraft Hangar, Shackleton Barracks, Ballykelly, Limavady, Co Londonderry

Aircraft Hangar at Shackleton Barracks

This aircraft hangar is situated to the east of the runways and close to Spallan Road on flat terrain. It is a substantial structure measuring 220.7 by 48.3 metres overall.

The building comprises eight cantilevered steel frames, each with a clear span of 39.2 metres from the front of the doors to the main upright. The frames are of identical fabrication and designed both to prevent collapse under their own weight and to counteract the uplifting force of wind on the roof. Each main upright consists of a 660 millimetre square welded steel box with a triangulated truss bolted to the top front and a braced anchor leg at the back. The main components of the trusses and anchor legs are of I-profile rolled steel measuring 610 by 305 millimetres. Secondary framing comprises braced lengths of L-profile steel. The main frames are set at 27.4 metre centres, with triangulated steel lattices running between them to carry the roof, which slopes slightly towards the rear to facilitate rain run-off.

Externally, the building has a 1.5 metre high skirting wall in brickwork on three sides, with continuous strip glazing rising to 2.4 metres, above which profiled aluminium panels form the upper walls. The south elevation is broken up by three large areas of aluminium curtain walling with bands of continuous glazing and blue coloured infill panels. The roof and deep fascias are clad in profiled aluminium. The roof itself comprises felt on cork on aluminium decking, with sides of troughed aluminium sheeting resting on brick walls 660 millimetres wide by 1.5 metres high.

Three catwalks run the entire length of the building within the cantilever frames. Along the entire length of the north wall are seven banks of horizontally-moving steel-clad doors, varying from 20.7 to 28.3 metres in width, stepped back on either side of the central door to allow unimpeded movement and enable either the entire length or individual bays to be opened. These were formerly activated by manual winches on metal rails and are no longer operational.

The anchor legs are secured to piles driven into the ground some 7.3 metres beyond the south wall. These piles began to move shortly after the building was completed, probably as a result of a change in the local water table. To counteract the magnified movement caused by the cantilever, dead weights were added to the tops of the piles in the form of mass-concrete blocks of cruciform plan, each measuring 10.5 by 4.3 by 1.2 metres overall.

For interior illumination, artificial rather than natural light was paramount as the interior needed to be usable 24 hours a day. However, windows are positioned along the rear pitch of the roof and in bays on the south wall. Access doors are located in the front doors (as picket gates) and along the south wall. Underground heating pipes, probably low pressure water, run around the internal perimeter of the hangar and underneath the floor. Heating steam is generated in a small brick boiler house located a short distance beyond the middle of the south wall.