Professor and department head for the School of Aeronautics and Astronautics at Purdue University Bill Crossley answers questions about airplanes and aerospace engineering from Twitter. How do airplane wings generate the necessary amount of lift to achieve flight? Can a plane fly with only one engine? Could electric airplanes replace fuel-burning ones? Is severe turbulence still safe to fly through? Why do commercial planes fly at 35,000 feet? Are planes safer than cars statistically? How much does it cost to build an airplane? Answers to these questions and many more await on Airplane Support.