Wildly expensive and with unproven demand, venture capitalists, automakers and aerospace firms are racing for a piece of what soon may be a $1 trillion market.

If you consider some European flying machine experimenters in the ... That's the way they stepped toward the invention of the airplane. NOVA: What does December 17, 1903, represent for you?

Throughout his lifetime, Leonardo da Vinci designed many fantastical flying machines, self-driving carts and even a tank! Explore 3D models of these wonderful designs. In the mid-1480s ...