THE CHAIRMAN: This afternoon I take the Chair with great pleasure for the occasion is marked by the presence of our friend, Major G. P. BULMAN, President of the Royal Aeronautical Society, and also other .members of the Society, who have come along to hear Captain LIPTROT. I know that you will support me in extending to Major BULMAN a very warm welcome. It is the second occasion on which we have been able to meet on common ground, and I know that we shall enjoy listening to Captain LIPTROT on this particular subject.

We have been told that certain of our lectures in the past have been far too technical and above the understanding of some of the more youthful of our membership, and I must say that sometimes even I have viewed with apprehension the mass of mathematical formulae presented by some of our more advanced lecturers, but today I am heartened because our old friend Captain LIPTROT is the lecturer and he is one of those who, although accomplished technically, is able to present his subject in an exciting and yet easily understandable manner, having a style which brings the subject well within my own comprehension.

This paper examines the problems involved in designing the combustion system of a ram-jet motor for mounting on the tips of helicopter blades. Although sufficient knowledge is not yet available for such a motor to be completely designed on the drawing-board, a principle of construction is suggested which should require the minimum of experiment and development. The principle is illustrated by consideration of a 60 h.p. motor for a tip-speed of 650 ft./sec.