The Forty-Fifth Wilbur Wright Memorial Lecture, “Advanced Education and Academic Research in Aeronautics” was given before the Society by Dr. Clark B. Millikan, Hon.F.I.A.S., F.R.Ae.S., on 13th September 1957, at the Institution of Civil Engineers, Great George St., London, before a large and distinguished audience which included H.R.H. The Prince of the Netherlands and a number of the Americans who had attended the Sixth Anglo-American Aeronautical Conference. Sir George Edwards, C.B.E., B.Sc, F.R.Ae.S., President of the Society, presided. As has now become customary the principal awards of the Society awarded by the Council for the year were presented before the lecture (see July and October 1957 Journals). This year they included Honorary Fellowship of the Society which was accepted by His Royal Highness, The Prince of the Netherlands.

Introducing the Lecturer, Sir George Edwards said:–Dr. Millikan was born in Chicago in 1903, he graduated from Yale University in 1924 with the degree of Ph.B. and received a Ph.D. degree in physics and mathematics at the California Institute of Technology in 1928. In that year he was appointed Assistant Professor at the California Institute, in 1934 he became Assistant Professor, and since 1940 he has been a full Professor in the Aeronautics Department. He was a member of the Executive Committee of the Institute from 1945 to 1947 and was appointed Director of the Guggenheim Aeronautical Laboratory in 1949. He has been Director of Wind Tunnel Testing at the California Institute since 1935, and Director of the Southern California Cooperative Wind Tunnel since it began operations in 1945. He is Chairman of the C.I.T. Trustees Jet Propulsion Laboratory Committee.

A Fellow of the Royal Aeronautical Society and an Honorary Fellow of the Institute of the Aeronautical Sciences, of which he was President in 1937, he is also a member of a number of other Societies. In 1948 the British Government awarded him the King's Medal for Service in the Cause of Freedom, and in 1949 he received the United States Medal for Merit.

Dr. Millikan is currently serving as Chairman of the Scientific Advisory Committee to the U.S. Secretary of Defense and as Chairman of the Aircraft and Guided Missiles Panel of the U.S.A.F. Scientific Advisory Board. He is also a member of the Army's Ballistic Research Laboratories' Scientific Advisory Committee, Chairman of the Sub- Committee on Fluid Mechanics and a member of the Aerodynamics Committee of the National Advisory Committee for Aeronautics.

It has been normal in discussion of helicopter operations to assume that the aircraft will operate at low altitudes. In particular, the commercial operation of helicopters on “inter-city” routes is usually assumed to take place between altitudes of 1,000 and 2,000 ft. with the appeal of the view of the countryside adding to the attractions of this means of transport.

It is intended to show in this paper that there are considerable advantages to be gained from flying very much higher than these low altitudes, and in using flight paths very similar to those of conventional air liners.

Judging by the number of present-day aircraft which have suffered changes of fin shape, it is clear that there is still some difficulty in estimating the size and shape of fin required on a new project. In this paper some of the principles on which fin design is based will be explained, and some of the difficulties involved described.

It is necessary to have some sort of fin to provide weathercock, or directional, stability. This is illustrated in Fig. 1. This shows the balance of yawing moments, due to sideslipping. In general, the side force acting on the fuselage, represented by the black arrow, has its c.p. ahead of the e.g. of the aircraft, and hence it produces a destabilising moment about the e.g. Sufficient fin area must be provided for the yawing moment due to the fin side force, represented by the white arrow, to at least equal the destabilising fuselage moment. Otherwise, when disturbed laterally due to, say, a gust, the aeroplane will tend to swing still further out of wind, making it difficult to fly accurately. The minimum permissible fin area can, in fact, be fixed simply by this requirement for weathercock stability.

This note describes the design and operation of the rig used to test and develop the Canadair CP 107 “Argus” hydraulic systems. The Argus is a maritime reconnaissance version of the Bristol Britannia, redesigned and built in Canada for the R.C.A.F. by Canadair Ltd., Montreal.

It is common practice on both sides of the Atlantic to test as thoroughly as possible before flight the various systems of a new aircraft. This is usually accomplished by the construction of space frames on which the systems are assembled and subjected to simulated flight conditions.

It was decided during the early stages of the design of the Canadair Argus that the deviations from the original Britannia hydraulic systems were great enough to warrant a full scale hydraulic systems test rig, in as compact a form as possible, which would give the desired test conditions and results.

It is shown that when heavily curved circular beams of constant cross section are subjected to a compressive load along the “open” diameter, the load for the start of significant deformation as indicated by the reduction in diameter along the line of action of the load, may be estimated by the use of rectangular plastic stress blocks based on the yield stress of the material. Comparison of the experimental values obtained on specimens of duralumin and mild steel with those predicted theoretically are, on the whole, only slightly underestimated.

The dimensionless thrust generated by supersonic flow through a convergent-divergent nozzle is given by Ref. 1,

1

which takes its optimum value, bmax when pe = pa.

For ideal one-dimensional flow, the relationship between Ae and pe is given by

2

and the optimum dimensionless thrust by

3

Where4

From equations (2) and (3), the constant D in equation (1) can be evaluated and thence the thrust of an ideal nozzle at any pressure ratio provided that no separation occurs.

Equations (2) and (3) are tedious to evaluate and it is not easy to estimate the effect of changes in γ.