It is, of course, a very great honour and pleasure for me to act as Honorary President of the Royal Aeronautical Society in its Centenary Year. This would be true even if I did not know the first thing about aviation but for someone who enjoys flying and takes a close interest in the whole subject of aeronautics this is a very special experience.

I have already been able to extend a very warm and cordial welcome to all the delegates attending this Congress but I want to repeat how delighted the Society is to have so many distinguished guests from abroad. Aeronautics is one of the few truly international activities right through from research and development to the carriage of passengers and freight all over the world.

For centuries, scientists and engineers dreamed of going to the moon or the planets, but the more they learned about the problems involved, the more improbable space flight appeared.

While there were many difficult questions, the principal problem overshadowing all others was how to propel the vehicle free of the earth's gravitation.

When serious attention finally was devoted to the magnitude of the thrust required and the means for obtaining it, space flight became a real possibility. This assurance of adequate propulsion marked the true beginning of the space age, and continues to be the prerequisite for the more ambitious space flights planned for the future.

The military tactics of vertical envelopment require the transport of 8000 pounds of payload to a radius of 100 nautical miles at a speed of 150 knots. The aircraft should be able to hover at 6000 feet on a standard day and with one engine inoperative maintain level flight in turbulent air. The helicopter should be readily convertible to carry cargo or troops.

The CH-53A meets these requirements. Additional design constraints, including emergency water landing, rear loading, self-contained navigation system and weight and dimensions compatible with aircraft carriers have been imposed.

With special attention having been given to the vibrational environment two General Electric T-64 engines have been installed. The 72-foot diameter main rotor is equipped with six blades with 26 inch chord and a NACA 0012 aerofoil modified to improve the characteristics at high Mach number. To achieve low drag and interference the fuselage and rotors have been developed in the wind tunnel. Tail surfaces have been especially developed to provide good handling qualities. An automatic stabilisation system was provided to relieve the pilot of various flight duties and to permit him to give more attention to the military situation.

Special design procedures have been followed to control weight, drag, reliability and vibration. The final helicopter is within 3-7 per cent of the desired weight and the performance is in substantial accord with predictions. The vibration level is generally about ±0-10 g throughout the cockpit and cabin.

During the flight development phase the control system was modified to provide appropriate coupling to relieve the pilot and automatic flight control system of any unnecessary compensating control motions. The structural integrity tests revealed the need for improvement of the main rotor blade attachment spindle. The engine-to-transmission shafting required a damped support.

The finally developed version of the CH-53A meets the mission requirements already stated. The hovering ceiling on a standard day Is over 5000 feet. The maximum level flight speed is 170 kt. The handling qualities and vibration are superior to any helicopter previously built by Sikorsky Aircraft. The reliability and maintenance features have been demonstrated by extensive testing. The overhaul periods will be 1200 hours in early service operation; 5-5 direct maintenance man-hours per flight hour are required to accomplish all maintenance except overhaul of repairable components. The dynamic components have been developed to such a high degree of reliability that they will be overhauled “on condition” only and continued in service throughout the normal military usage.

In terms of commercial service, the CH-53A (S-65) will have a direct operating cost of approximately 4c per seat mile.

This paper relates the advantages of centrifugal, mechanically-driven fuel pumps and quotes their ability to operate with hot contaminated fuel. It also shows the substantial weight saving when compared with positive displacement pumps. The poor part load efficiency of the conventional centrifugal pump at its design speed, giving considerable temperature rise in the fuel, has resulted in the development of the vapour core principle where flow regulation is effected by a throttle at the eye of the impeller.

Reference is made to the associated control and distribution equipment which, although not peculiar to the vapour core pump must be made compatible with a pump having an inherent pressure-raising capability which decreases with engine speed. The inlet throttle feature permits adequate control of the temperature rise to be maintained over the whole working range of the gas-turbine fuel systems.

The fundamentals of the pump are explained and the development progress reviewed for application to main and reheat fuel systems. Reference is also made to control methods that are being currently developed for combined engine and reheat systems supplied from a common pump.

The spill nozzle, which was developed specifically for use with hot contaminated fuel, possesses satisfactory characteristics for use with the vapour core pump. The temperature rise data associated with combination of vapour core pump and spill nozzle are quoted, and temperature rise data are also given where the pump is used either for reheat supply or for both combined reheat and main engine fuel systems.

When one talks of the difficulties of the aerospace industry in this country, it is all too easy to point a finger westwards to the United States. It then seems right to talk of long production runs and large home markets. One can then turn to our own industry and to its output since the last War, and perhaps forgive.

But should we?

In this short paper, a young author intends to examine professional education and manpower in aeronautics, because herein must be the reason for any future success or failure of the products of the industry, and the pointer to the future level of expertise in the art.

As I come to the end of five years’ training as an Aeronautical Engineer, several thoughts come to mind, both about my training up to the present time and the future of the aerospace industry in which I am about to serve.

During the past ten years, the aerospace industry has seen many changes, not only in the form of amalgamations and project cancellations, but also in the way it must face the future. More recently it has seen the publication of the Plowden Report with all its implications. Although for many the future paints a gloomy picture, at no time has the thought of leaving the world of aeronautics been farther from my mind than it is now.

The present re-look at compressible flow graphs arose during extensive testing of jet blowing models in low speed tunnels. In these tests, it is often necessary to calculate such quantities as jet thrusts, mass flow rates and velocities assuming isentropic expansion to the tunnel static pressure from the measured values of the stagnation pressure and temperature. These jet flows are usually compressible but subsonic and, in order to make these calculations, use has to be made either of Bernoulli's compressible flow equation or, alternatively, the extensive compressible flow graphs that are now available.

For the analysis of sandwich panels it is necessary to know the shear and flexural properties of the sandwich. For some of the more common sandwich constructions theoretical solutions exist. However, in the majority of cases, it is necessary to determine these properties experimentally. This note, based on work done for the Royal Aeronautical Society's Structures Committee in which the major British aircraft companies interested in this subject were consulted, describes and evaluates the various test methods commonly in use. Particular reference to the accuracy of results obtained and to the relative economics of the test methods is made.

In preparation for the wind tunnel testing of a series of aerodynamic research models a strain-gauged balance was sought which could be successfully made without the use of sophisticated tools. The principal requirements which influenced the design of the balance were:

1. (a) It must enable lift, drag and pitching moment to be measured.

2. (b) Deformation of the balance under the aerodynamic loads to be small.

3. (c) Use of only basic workshop tools.

4. (d) Short manufacturing time.

Further, the models were to be sting mounted at one end of the balance with their span vertical. The other end of the balance was to be rigidly fixed to a supporting stand which would be mounted on the wind tunnel turntable to permit incidence variation (Fig. 5).

The Holzer method is widely used in the solution of the modes and frequencies of lumped parameter torsional systems. Basically the method consists of assuming an approximate value of the required frequency and, starting from one end of the system, determining the amplitudes of vibration station by station. Since the assumed frequency is an approximate one there will be a residual (torque or displacement) at the last station. The true frequency to be determined is that for which the residual is zero. Among the special advantages of the method are that any natural frequency may be obtained directly without a knowledge of the lower modes and, with the use of transfer matrices, the method may be readily adapted for the solution of complex vibration problems using a computer.

In this paper we are restricting our attention to those cases of circumferential inlet distortion where the distortion of the velocity profile is too large to be described as a small perturbation. Thus any theory describing the flow must use a mathematical model which is non-linear.

Exact expressions for deflection, swept volume and the ratio of the balancing force to the total thrust due to pressure are given for the case of a flat circular plate subjected to a uniform normal pressure and held fixed both in displacement and slope on the periphery and at an inner radius.