The dream of flying is as old as mankind itself. However, the concept of the airplane has only been around for two centuries. Before that time, men and women tried to navigate the air by imitating the birds. They built machines with flapping wings called ornithopters. On the surface, it seemed like a good plan. After all, there are plenty of birds in the air to show that the concept does work. The trouble is, it works better at bird-scale than it does at the much larger scale needed to lift both a man and a machine off the ground. So folks began to look for other ways to fly.