sentences:  The flight of the "Question Mark" inspired a rash of projects to break the endurance record.In 1929 alone 40 flights were attempted, all by civilians, and nine succeeded in surpassing "Question Mark"'s record.At the end of 1929 the record stood at over 420 hours, established by Dale "Red" Jackson and Forest E. "Obie" O'Brine in the Curtiss Robin "Greater St.