1.1 Looking Back
1.1.1 Early Years
The first foray into rotary-winged flight occurred around 400 BC with a toy known as the Chinese top. It was constructed with a central shaft to which was attached wings consisting of feathers or flat blades inclined to the rotation plane normal to the shaft. This was spun between the hands and by generating thrust flew for a short period of time. Jumping forwards to AD 1325, a Flemish manuscript contained the first known illustration of a helicopter rotor which was operated by the pulling of a string.
Just over 150 years later we encounter probably one of the most influential milestones in the work of Leonardo da Vinci. His famous design of a rotary-wing vehicle, see Figure 1.1, forms an ideal illustration of the origin of the term ‘helicopter’. It is commonly considered to be the combination of the words ‘helix’ and ‘pteron’ giving the concept of the ‘helical wing’.
In 1784, Launoy and Bienvenu built a mechanical model with two rotors. It was effectively the Chinese top but extended to a pair of rotors on the same axle but rotating in opposite directions. It was powered by a leaf spring and strings. It is similar to the coaxial configuration of more modern times.
In 1810, Sir George Cayley wrote an aeronautical paper preparing the ground for future helicopter development. ...