Page 49 - Demo

This cover commemorates the First Flight of Operation Hourglass, a flight-endurance demonstration of the Allison Transmission Company%u2019s 501-D13 prop-jet engine and its Aeroproducts 606 turbopropellers. The test involved a YC-131C Convair, flown for 1,000 hours, and the demonstration was completed in an unprecedented short amount of time%u2014just 84 days. By averaging 12-hours of flight time each day, the airplane covered a distance equivalent to ten trips around the world. During the 1,000 hours of operation, the crews landed in 50 cities in 24 states, and cruised at 20,000 feet while flying at a speed of 360 miles-per-hour. This was about 100 mph faster than a standard Convair outfitted with conventional piston engines.The test was carried out in a manner consistent with a typical airline%u2019s operating schedule, so the individual flights varied in length, and there were 20-minute shutdowns to simulate passenger loading and unloading. Following the successful demonstration, the engines and propellers were torn down and inspected, then reassembled for a nation-wide tour to operators of military and commercials airlines. The new engine and propellers were designed for use on Lockeed Electra airplanes.There were three complete crews involved, and this cover is signed by pilot R.F. Petercheff and copilot R.C. Wendling. The final leg of the demonstration was piloted by John M. Cyrocki and Joseph A. Thomas, and it landed at Indianapolis%u2019 Weir Cook Airport on January 23, 1958. First Flight of Operation Hourglass, cancelled in Indianapolis on October 30, 1958, approximately a week after the initial takeoff.