... THE 'VON OPEL FLIGHTS' . ... Raab, with his partner Diploma Engineer Kurt Katzenstein would apply to their lightest aeroplane the solid-propellant Sander rockets that had proven themselves so well in Fritz von Opel's rocket cars. ... The von Opel-Sander-Stamer-Lippisch tests were elevated to a full-scale airplane immediately after the model flights ; in effect, this was to be the first manned rocket flight. ... FRITZ VON OPEL at the controls of the Opel Sander Rak. 1 rocket plane. ...