In March 1928 the three men visited the Wasserkuppe, a mountain which had become the center of German gliding to investigate the possibility of fitting rockets to an aircraft.

In June von Opel, Sander, and Valier returned and bought one of his aircraft, the Ente, a canard design.

A counterweight system was also devised and placed under the cockpit floor which would automatically adjust the aircraft's center of gravity as the fuel of the rockets was consumed.

The rockets were intended to be fired one after the other, to provide continuous thrust for as long as possible, and each had a burn time of around 30 seconds.

Stamer was nevertheless able to bring it down from a height of around 20 metres (65 ft) before hastily abandoning the Ente, which was burned beyond any hope of repair.