Question Mark (aircraft) Question Mark (aircraft) Question Mark (""?"") was a modified Atlantic-Fokker C-2A transport airplane of the United States Army Air Corps. In 1929, commanded by Major Carl A. Spaatz, it was flown for a flight endurance record as part of an experiment with aerial refueling. "Question Mark" established new world records in aviation for sustained flight (heavier-than-air), refueled flight, sustained flight (lighter-than-air), and distance between January 1 and January 7, 1929, in a non-stop flight of more than 150 hours near Los Angeles, California. Following the record-setting demonstration, the C-2A was returned to transport duties. In 1931 more powerful engines replaced
The Airplane Factory Sling 2 endurance at standard cruise of approximately 24 hours. The aircraft cruised at 89 knots Indicated airspeed (IAS) (98 knots True airspeed (TAS)) with almost full fuel. When more nearly empty, it would cruise at 96 knots IAS (105 knots TAS). With full fuel, fully loaded with crew the Sling weighed approximately 1,984 Lbs (900 kg), or about 600 pounds overweight. At sea level the aircraft would climb slowly, at a rate of 350 feet per minute. The Airplane Factory Sling 2 The Airplane Factory Sling 2 is a South African two-seater light aircraft designed and produced by The Airplane Factory