Fundamental Propositions

THIS issue opens with a paper on the theory of blade motion and of the static and dynamic stabilities of single‐rotor helicopters by Mr Zbrozek of the Royal Aircraft Establishment, which we publish by permission of the Ministry of Supply. It summarizes a considerable amount of work that has been done on this abstruse subject which hitherto had been scattered among a number of reports, many of them unpublished. We believe it to be of a most important character and of a nature that is destined to make it a worthy successor to the classic papers of Glauert and Lock that are quoted in the author's list of references together with Dr Bennett's well‐known series of articles on the general theory of rotorcraft which appeared in Aircraft Engineering in 1940 and have as yet not been superseded in their field.