The Evolution of the Rotor Blade: A review of helicopter blade construction with a survey of possible future developments in this field

THE helicopter presents a classic case of a device for which there is an insatiable world demand that cannot be met because the current state of engineering development prohibits an economic product. The overriding factor in any airborne vehicle is the necessity of achieving a viable payload and performance at an acceptable cost with dependable standards of safety and reliability. Sensible figures are difficult to quote but it would not be far wrong to indicate that existing helicopters carry an all in cost penalty of 5 to 1 compared with fixed wing aircraft of the same all up weight. It is not surprising therefore that, apart from prodigal military usage and small specialist operations as with offshore drilling rigs, progress over the last decade has been slow. Indeed it would be more realistic to say that in terms of basic design there has been what is more like stagnation, as at least three major projects in the U.K. alone have been dropped after many millions of pounds had been spent on them.