This might be Terrafugia's boldest claim. To qualify as "light sport," the Transition will have to weigh around 1,300 pounds. That's 500 pounds less than a Smart car, but the Transition will be as long as a Suburban and, in places, just as tall. That calls into question whether it can survive a strong breeze, never mind a head-on collision with an SUV. In trying to be both an automobile and an aircraft, the Transition could wind up a mediocre version of both. "You look at the set of rules for designing a car and those for an airplane, and they're not all that similar," says Virginia Tech University aerospace engineering professor James Marchman, who in 1999 led a yearlong academic project to design a roadable aircraft.
Dietrich believes his design circumvents those rules. Take the assumption that only heavy cars are stable. With a low center of gravity, a long, wide wheelbase, a center of mass close to the front, and the canard wing, which generates downforce, Dietrich says that the featherweight Transition will stay glued to the pavement.