After a journey by sea and road that lasted over two weeks, the world's largest research autoclave has reached its destination at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in Stade. Road signs had to be taken down and motorways closed to transport the cylinder, measuring 27 metres in length and with a diameter of 6.5 metres, to the DLR Center for Lightweight Production Technology (Zentrum für Leichtbauproduktionstechnologie; ZLP). The autoclave will be used to cure composite aircraft components at elevated pressures and temperatures – much like the principle employed by pressure cookers.
The lid alone weighs 16 tons, and the actual autoclave 165 tons. This new 27 metre long autoclave will enable DLR to conduct research on large aircraft components. "The proportion of components made of carbon-fibre reinforced composites used in aircraft is constantly increasing, which means that we need to raise our production facilities to a new dimension," says Matthias Meyer, the head of ZLP.
Carbon-fibre reinforced composites are very strong and light materials. For the aircraft of the future, this translates to less weight, which in turn cuts fuel consumption and reduces pollutant emissions. The new autoclave at DLR will assist with research in this field. "It works much like a pressure cooker, or like an oven, in which the materials that make up a compound combine with one another under the influence of temperature and pressure," explains Meyer. This huge appliance for manufacturing fibre-composite materials is equipped – in contrast to conventional industrial autoclaves – with additional sensors and control technology that permits substantially more influence over all processes. "We can now manufacture and analyse complete fuselage components, wings or control surfaces." The research autoclave is able to operate at temperatures of up to 420 degrees Celsius and at a maximum pressure of 10 bar – the equivalent of the pressure found at a water depth of 100 metres.
Travelling by ship and transporter
Before the autoclave could be brought into service, it needed to complete the journey from Coesfeld to Stade, which lasted several weeks. This journey began on 26 May 2011, when a special transporter carried the autoclave from the manufacturing plant to the port of Coesfeld. The size of the pressure vessel prevented it from completing its entire journey on public roads, so the autoclave and its lid were loaded onto two different ships. Through the Dortmund-Ems Canal and along the Rhine, the ships, 'Indian' and 'Adriana', travelled to the Dutch Ijsselmeer and, from there, via the rivers Ems and Weser, the Mittelland Canal and the River Elbe, to Stade. After being unloaded from their ships, traffic lights had to be rotated and road signs had to be taken down to enable the heavy-duty transporter to complete its journey. A main obstacle that had to be dealt with was the A26 autobahn; it was closed to all other vehicles on Sunday, 12 June 2011. The transporter with its gigantic load travelled along the motorway, extending right across both carriageways on its way from one slip road to another. "DLR's Stade-based ZLP will now be able to install the research autoclave and operate on an industrial scale," states Matthias Meyer. By November 2011, the installation of the autoclave will have been completed and it will undergo trials before entering operational service. In the first experiments, researchers at DLR will examine the curing characteristics of wing surface skins.
At ZLP, two DLR institutes work together: the Institute of Composite Structures and Adaptive Systems (Institut für Faserverbundleichtbau und Adaptronik) and the Institute of Structures and Design (Institut für Bauweisen- und Konstruktionsforschung). ZLP has two sites, located in Stade and Augsburg.