Imagine an aircraft that will take off and land like a helicopter but fly as fast and high as some light private jets. If all goes according to plan, a prototype of such an aircraft will fly in the fall and could be in customer hands by 2023. The six-seat, $6.5 million TriFan 600 being built by XTI Aircraft in Denver holds the promise of dramatically cutting travel times between major city centers and offering the ultimate in private, secure transport. “It affords you utmost privacy as it eliminates the need for an airport,” said XTI CEO Robert LaBelle. When...