Ladies and Gentlemen

The subject of the opening paper for our 1948/49 Lecture Session is, I am sure you will agree, of prime importance to all of us in the helicopter industry To my mind there is no point in spending time, money and energy designing and constructing helicopters unless they can be operated economically, although for any specialized application economy may not be so important

MR WIGDORTCHIK has put a great deal of work in the preparation of this paper, and although he will only have time to read a summary this afternoon, examination of the full paper, which will be published in the Association’s Journal, will be well worth while

MR WIGDORTCHIK is an A F R Ae S, and was a Wakefield Scholar to the College of Aeronautical Engineering in London He was commissioned in the Technical Branch of the R A F in 1940, and from 1943 was engaged in Research and Development in connection with aircraft, and subsequently helicopters, holding an appointment in the Ministry of Supply in this respect

From the very beginning of helicopter development the designer has had two major problems, one associated with the balancing of the torque reaction on a mechanically driven rotating system, and the other one that of mechanical difficulties associated with the transmissions ISACCO for instance realized right at the beginning that what he wanted was some jet reaction device on his blade tips, but there was no jet reaction device which was efficient, and he had to have recourse to individual engines, each driving its own propeller on to his blade tips Other designers, such as BRENNAN, in this country, and BLEEKER in America, had recourse to a single engine rotating, with the system This was only half the solution, because they still had to face all the mechanical difficulties From then onwards, many people have tried jet propulsion You will realise that because we have tip speed limitations as we go on to bigger sizes our torque reaction problem becomes worse and worse

This afternoon we are about to hear a lecture entitled ‘Some Speculations on the Aeroelastic Problems of Rotary Wing Systems’ This sounds a terrifying title—rather like the sub-titles of Victorian novels—but I suggest the short title, ‘Collar on Blade Flutter’ I have the pleasant task of introducing to you the lecturer In view of Professor COLLAR’S reputation, I am really not sure whether I should introduce the lecturer to the Association or the Association to the lecturer I shall therefore do both without, I hope, imposing upon your patience

Professor COLLAR is easily introduced, because he is one of those people who hold their jobs After taking his degree in Cambridge, he served for 12 years on the staff of the N P L, and for 4 years at the R A E, before being invited to become the Sir George White Professor of Aeronautical Engineering in the University of Bristol