The Problem of Vertical Flight: An Examination of the Characteristics of the Helicopter in Comparison with the Autogiro and Cyclogiro

MUCH time and money have been devoted to the development of the helicopter, but the achievement of a practical machine is apparently not yet in sight. Some of the problems, indeed, have been solved; others await solution. In any discussion of the helicopter the subject naturally divides itself into five headings. First, there is the problem of the provision of adequate lift. This has for many years been solved, and an airscrew can now be designed that will give its predicted lift with a certain degree of confidence. On the practical side, helicopters have demonstrated that they can be built with a sufficiently light structure weight that modern power plants are adequate to lift the aircraft vertically upwards. The problem has also been investigated theoretically, and a relationship between disc loading and pounds per horse power established which should permit of any designer producing a helicopter that will lift itself. This fact cannot be too strongly emphasised in view of the fact that many inventors consider that the major problem is one of lift.