The sky’s the limit

Since the Wright brothers first looked for somewhere to park, hangar design has been restricted to box-like sheds. Today, new technology for large span roof structures is allowing designers’ imagination to soar.

Kitty Hawk, North Carolina, will be celebrating the 100th anniversary of the world’s first powered aeroplane flight on 17 December. Here, in 1903, Orville Wright’s machine rose 3m and travelled 36m. Man could fly.
This new mode of transport brought the need for somewhere to house and maintain its vehicles, but for much of the following century hangar design remained the domain of engineers, who calculated bending moments and point design while architects took a back seat.
Hangar design was restricted by the sheer size of structure required to house aircraft as large as the B52, with its wingspan of 56m. Today, new materials and a greater understanding of conventional ones gives designers much more freedom. Four practices taking advantage of that are HOK, Reid Architecture, Feilden Clegg Bradley and Atelier Volkmar Burgstaller.
Of the four designs, the most spectacular is Atelier Volkmar Burgstaller’s design for Hangar-7,  home to the Flying Bulls aerobatics team at Salzburg Airport. Its curving steel skeleton supports 380 tonnes of glass and spans 95m over a footprint of 4100m².
Each of the 1754 panes of glass in this crystalline spider’s web differs slightly in shape and contour from the next. Without computer aided design and manufacturing techniques, this type of architecture would be unaffordable.
‘The technique can be used on any structure,’ says practice principal Volkmar Burgstaller. ‘But the results can be no better expressed than in a building of this form. We have been able to create a single span, transparent building that connects the planes within it to their domain, the sky outside.’

In the UK, the Imperial War Museum’s outpost at Duxford in Cambridgeshire continues its experimental approach to hangar design. In 1997 Foster & Partners designed the American Air Museum. Today HOK is working on The Air Space, another exhibition hangar, complete with conservation and education centres. The new building is being built around and over an exhibition hangar erected in 1986.
The scheme doubles the floor area of the building to 12000m² by extending out each side and adding five bays to its length, plus two interior mezzanine levels. Brian Fishenden, project manager for HOK, says: ‘Our challenge was to treat what is otherwise a very large shed as a piece of architecture. The design is sensitive to what was a landmark hangar, while incorporating new technology to fulfil our architectural and engineering aspirations.’

The original hangar’s structural frame has been retained as it is perfect for suspending large aircraft from. Considerably over-designed, its 65m span features 4.9m deep trusses. In the new end sections HOK has been able to reduce this to 2.2m by using tapered curved hollow steel columns supporting lightweight N trusses.
HOK’s new side aisles relieve the hangar of its boxy shed aesthetic, producing a distinct aerofoil shape. Lightweight hollow steel columns and bow trusses provide a frame for the cladding and an elegant contrast to the heavy original structure. The issue of weight also comes into play at the transparent north wall of the hangar.
‘The wall is made entirely of ETFE pillows,’ says Fishenden. ‘The cushions are extremely light and will span large areas giving considerable savings on structural supports required when compared with glass. And, as a bonus, they are effectively self cleaning.’

Innovation on a budget
Reid Architecture’s design for TAG Aviation’s hangars at Farnborough in Hampshire also takes the issue of weight seriously, both in relation to the structure design and its cost. This is the only building of the four that will operate as a commercial hangar. Its design includes numerous innovations in order to minimise the cost to the client.
Eric Guibert of Reid Architecture says: ‘The fact that we had to design and build the hangar to a sum that would be competitive with more standard solutions has been a challenge, but it also made us examine and refine every aspect to produce the best possible result.’

Originally the brief was for three hangars but the architects realised immediately that one building would drastically cut labour and materials costs on the foundation and external envelope. The design emerged as one huge 290m long structure of three bays, capable of housing six Boeing 737s.
This simple triple-arched building hugs the ground, with no vertical side elevations. This isn’t purely the whim of the designer. Reducing the building’s height also reduces wind loading, lowering the strength requirements of the structural frame and saving on steelwork costs. Because the roof is one expanse, the Kalzip standing seam covering was nearly all rolled on site and very simple to install.
‘From an engineering point of view, the tolerances were obviously greater due to the size of the building,’ says Guibert. ‘But, architecturally it didn’t make the design more complex. We have been able to design a striking building that performs better than the standard solution but which is competitive in terms of cost.’

Feilden Clegg Bradley Architects is designing the new Cold War and Transport Aircraft Museum at RAF Cosford in Shropshire. The concept originates from the exhibition title ‘Divided World - Connected World’. Two triangular volumes butt together but are split by a dramatic ‘fault line’ of rooflights running down their adjoining edges.
It is not an expensive design. The building, which is virtually all roof, is clad with a standing seam roof, on proprietary structural metal decking, laid on a simple triangular steel frame.
This frame is the perfect apparatus for hanging large aircraft from. Suspended from the narrow ridge, the downward force of the plane’s weight is counteracted and redistributed through the structural members of the roof and down to the ground. And, because the roof narrows towards the apex, smaller planes do not look lost against a huge flat ceiling.
Hangar architecture is no longer constrained by its proportions. The multitude of materials, technologies and techniques available make almost any size or shape possible. All that limits the ambitious architect today is know-how - and, of course, the budget.