In co-operation with the University of Bremen and the German Aerospace Center (DLR), the Corporation from Bremen, Germany developed the weightlessness demonstrator "Gravity Jumper" based on a trampoline. Due to the acceleration during the jump, an acceleration force takes effect in addition to the usual gravitational force. Both forces add up and the person on the trampoline seems to become heavier. As soon as the jumper leaves the trampoline, he is under a free fall condition, which means that the jumper seems weightless and does not feel the acceleration due to gravity. Every person receives a three-axis acceleration sensor, fastened to them with a belt. The sensor transmits the data of the flight path to a monitor; a monitor shows the course of the acceleration, including the weightless phase. The interplay of acceleration due to the trampoline and weightlessness becomes apparent.