Inside ImageAir Spring Systems in Airborne Observatory

Air Spring Systems for Industrial Applications

Developers and engineers at ContiTech Air Spring Systems have succeeded in building an air suspension system that will assume a key role in future astronomic research.


The system provides for vibration-free working conditions on board the flying observatory SOFIA (Stratospheric Observatory for Infrared Astronomy). This marks a completely new application case for air spring technology. A joint project of the American space agency NASA and the German Aerospace Center (DLR), SOFIA is a Boeing 747 SP that has been converted into a laboratory. Operating at an altitude of 14 kilometers above the earth, it looks for answers to basic questions concerning the genesis of the stars and planetary systems as well as the origin of the solar system.

At the heart of SOFIA is the world’s biggest infrared telescope, peering out at space through a hatch in the rear of the aircraft. The 17-tonne telescope rests on a vibration-isolation system (VIS) consisting of an air spring system and silicon-oil-filled dampers. The air suspension system guarantees the functionality of the telescope in many ways. It absorbs any vibrational interference emanating from the aircraft itself or from the windflow when the hatch is open. Assisted by control electronics and sensors, the air spring system holds the telescope exactly in position. The highly-sensitive instrument thus remains directed at the observation target at all times, enabling it to supply perfect images. It does so under extreme conditions. In the telescope chamber the temperature plunges as low as minus 60 degrees when the hatch is open; air pressure just one fifth the normal level. The air pressure varies with fluctuations in the aircraft’s altitude. The air suspension system makes sure that the telescope remains fixed in its original position nonetheless.

The air suspension system is a complex structure consisting of 24 single- and double-convolution air springs plus sensory controls. A specific solution also had to be found in terms of material. The air spring bellows are made of a self-extinguishing elastomer and satisfy NASA’s incombustibility requirements. ContiTech sales partner CFM Schiller GmbH, from Roetgen in the German state of North Rhine-Westphalia, assumed full engineering responsibility, from design calculations through to final assembly at the American NASA base.

In spring 2007 SOFIA successfully completed initial test flights. Research is to be launched in 2008 and is expected to run for 20 years. In October 2007, ContiTech Air Spring Systems introduced the air suspension system as part of the SOFIA project presentation at the Stuttgart’s New Trade Fair Center.


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