 Later, on 6 July 1944, he reached a speed of in the Me 163B V18 bearing the "Stammkennzeichen" code of VA+SP, nearly losing the complete rudder surface in the process to flutter.It is unclear, however, if sufficient altitude was attained to make this a true supersonic flight.Dittmar died in a crash in 1960 while test-flying a light aircraft of his own design, the HD-153 Motor-Möve, near Essen/Mülheim airport.