The Air Pavilion, an aerial exhibition building, is one of three structures in the former steel foundry, a shed 350m long and 30m high to the ridge.
A cigar-like flattened ovoid, 17m in diameter at its widest point, the pavilion is suspended in space; the viewing platforms that run inside are 20m above the foundry floor. They are supported by four beams spanning 21m and bolted at their ends to the rails of a huge former crane gantry, which occupies one bay of the foundry.
The flattened ovoid enclosure consists of a series of translucent ETFE foil cushions secured at their long edges to curved aluminium purlins that run the length of the pavilion, encircling it to create the ovoid shape.
The purlins are restrained at each end of the ovoid by two elliptical 114mm diameter CHS rings braced by diagonal steel struts.A third, inner ring supports an exhibition structure.
In section the extruded aluminium purlins are trefoilshaped - the two lower lobes secure the edges of adjacent foil cushions; the upper lobe acts as a fixing point for a cable-net structure which pulls the cushions taut. A series of cables, tied back to anchor points in the original steel structure, are connected by means of pulley blocks to six cable-rings. These encircle the ovoid and, in turn, are fixed to the purlins. The cables, which together with the cable-rings are all in tension, are fitted with turnbuckles to achieve an equilibrium with the inflated ETFE foil cushions.
The external envelope package - ETFE cushions, purlins and cable-net structure - was by Vector Special Projects.