Franz Zeno Diemer was a bold daredevil. On 17 June 1919, the 230 hp powering the BMW IV aero-engine took the test pilot to an altitude of 9760 metres within the space of one and a half hours – a world record-breaking achievement for BMW. The pilot flew in an open cockpit, and both he and the machine kept going despite low oxygen levels and temperatures of minus 50 degrees.