Predating the invention of the helicopter by two decades, the Autogiro was the world's first rotary-wing aircraft. The helicopter had the advantageous ability to rise straight up, while the Autogiro/gyroplane could only taxi. Yet the gyroplane was safer and more stable; both aircraft should have had value in market. Why did the helicopter survive and prosper, while the Autogiro became a nearly forgotten historical footnote? Why didn't the Autogiro...