Fallturm Bremen

The Bremen drop tower of the Center for Applied Space Technology and Microgravity ( ZARM ) at the Department of Production Engineering at the University of Bremen is a unique in Europe Bremen drop tower, which offers the possibility to ground-based experiments under short-term weightlessness.

The Bremen drop tower has a 110 -meter-high, evacuated tube case, in which a drop capsule is dropped 4.74 seconds long. During this time there in the capsule weightlessness. The duration of the capsule in zero gravity can be extended using the catapult built in 2004 to over 9 seconds. The capsule has a diameter of 800 mm and a length of 1.6 meters or 2.4 meters, depending on the space required for the respective experiment. She falls into an 8 meter high collection container, which is filled with pinhead-sized foam polystyrene beads. The entire tower is comprised of a cylindrical concrete shaft with a conical tip is 146 meters. Inside the tower is a freestanding steel tube of the actual event space that is decoupled from the wind- induced fluctuations of the outer shell. This case space is evacuated for the case experiments to about 10 Pa.

Vacuum

Instead of dropping the capsule in a vacuum, the air friction could be compensated by an additional drive, to achieve exactly the acceleration due to gravity. Even a plant with no mechanical components, in the sense of a perpendicular magnetic levitation, but had the problem generated by the wind noise and vibrations which would interfere with sensitive experiments.

In principle it would be sufficient to aerate only the lower and upper part in the pre-and post-processing of the experiments. However, it is re- evacuated the entire 123 -meter-long tube for each experiment. For this purpose, 18 pumps are required with a Nennsaugleistung of 32,000 m3 / h. Is a vacuum of 10 Pa (1 Pa = 10-5 bar) is reached, the experiment can be run. This low residual pressure in the drop tower, a residual acceleration of 10-6 g0 is achieved, which exceeds the weightlessness quality of manned orbital platforms. Before the capsule recovered and the experiment can be evaluated, the drop tower is flooded with pre-dried air. This process takes 20 minutes.

The catapult

A catapult, which 12 meters below the drop tower, hurls the experimental capsule up to the spire. Catapult table is connected to a piston which is moved by compressed air from large storage containers. A differential pressure of 3 bar between the vacuum of the drop tube and the reservoirs accelerates the catapult table during a quarter of a second on average with twenty times the force of gravity on a top speed of 175 km / h The capsule needs for the high- rise as long as for the subsequent fall. Throughout the rise and fall phase prevails in the capsule weightlessness. The time available for experimentation time can be approximately doubled when using the catapult.

History

The completion of the shell lasted from 6 April 1988 to 29 April in 1989 and cost about 24 million DM carrier of the drop tower in 1989 were the Federal Ministry for Research and Technology, the Federal Ministry of Education and Science, the state of Bremen, the air and aerospace company MBB ERNO, the electronics company Krupp Atlas Elektronik and the space company Otto hydraulic Bremen ( OHB system).

After commissioning in September 1990 about 400 experiment bombings were carried out annually in the Bremen drop tower. It was up to three times daily achieved for less than 5 seconds, the state of weightlessness. With the commissioning of 4.2 million euro expensive catapult from 2nd December 2004, this time has doubled.