Airship Hangar

The hangar, 306 m long, 220 m wide and 107m high, is probably the largest hall in Europe. It was designed for the construction ofthe CargoLifter airship, a kind of flying crane that can lift loads of up to 160 t and transport them over distances up to 10,000km. The hangar was conceived as a minimum volume toaccommodate two airships. The central section of the hall consists of five four-chord arched steel girders at 35 m centres with a membrane system between them. Constructed with tubular members, the girders are 8 m deepand are made up of 17 straight segments each more than 18 m in length. Wind bracing is fixed to the lower chords; torsion bracing to the upper chords The feet of the arches are anchored in reinforced concrete plinths nearly 9m high. The gates at the two ends consist of six movable and two fixed elements. They can be opened by means of dollies on rails, and pivot about a huge pin 1 m in diameter at the crest. Between each of the arches is a free-spanning system of membranes over 31 m wide which transmits snow and wind loads to the upper chords of the girders. The membrane system consists of four layers of polyester fabric in the form of a double air cushion. The main loads are borne by the uppermost layer – the outer skin of the upper air cushion, which is fixed to the top edge of the top chords. The second, lighter air cushion is fixed to the underside of the top chords. This form of construction achieves a U-value of less than 1 Wm2/K, whilemaintaining the translucent effect of the fabric. A daylight transmission of two per cent over a membrane area of 35,000 m2 helps to reduce the use of artificial lighting. The inner membrane cushion also allows the outer weather layers to be replaced. The outer cushion is fixed at the crest and along the arched girders on both sides. A cable on the undersidealong the middle of each bay prevents the membrane whipping up and down, and the hollow thus formed serves to channel rainwater into tanks at the base. Over the arched girders and the ridge girder are glass strips with an in-built louvred ventilating system. The strips serve to improve the daylighting andalso form a firebreak between the membrane bays.