Vern Raburn is gunning his 500-horsepower Ford Shelby GT on a high desert road behind the airport in Albuquerque, N.M. He hits a pothole but just presses harder on the gas. After all, he has struggled for nine years to get his small-jet startup off the ground--battling skeptics, losing an engine, and burning through nearly $750 million--and he's not about to slow down now. Read more…