Habit # 2—Translate the Project Vision into Coherent Requirements

Leonardo Da Vinci is frequently credited with having the first vision of a helicopter, what he called the Helical Air Screw in 1490 a.d. He wrote, “I have discovered that a screw-shaped device such as this, if it is well made from starched linen, will rise in the air if turned quickly.” However, Da Vinci was not the first to have the idea. A book written in China in the fourth century a.d. describes “flying cars with wood from the inner part of the jujube tree with ox-leather straps fastened to returning blades as to set the machine in motion.” The Chinese may have been describing a toy, whereas Da Vinci likely had in mind a more substantive application. Nonetheless, the concept for a helicopter existed as long as 1800 years, and certainly no less than 300 years, before the first working models were built by several different European experimenters between 1750 and 1850. Progress toward a viable design concept continued until the early 1900s when a working prototype was finally demonstrated.1