The Chairman, in opening the meeting, said that the first part of the Paper would be presented by Mr J D Sibley, who for the past 10 years had been Chief Aerodynamicist at the Helicopter Division, Bristol Aircraft Ltd, Weston-Super-Mare Mr Sibley would discuss the aerodynamic aspects The second part, relating to the dynamical aspects, would be presented by Mr C H Jones, who had been Dynamics Engineer at the Helicopter Division, Bristol Aircraft Ltd, since 1955 Afterwards there would be a short film

The paper discusses a number of aerodynamic aspects which have appeared during the development of the Bristol Helicopters I have deliberately avoided excessive comparisons of the advantages and disadvantages of tandem helicopters versus the single main rotor helicopters, as this subject has been covered by numerous authors

The subject matter covers information on performance, control and stability, which has been obtained in the course of development work on Bristol Tandem Helicopters Some of this information is directly applicable to other types of helicopter

The Chairman, in opening the meeting, said he was very glad indeed to see so many members present at the first meeting of the new Session, especially as, some of them had, no doubt, been up half the previous night watching the television programme (to hear the election results)

It was a pleasure to welcome tonight’s lecturer, Mr Newberry, who, since 1951, had been in charge of the rotorcraft work within the Directorate of Engine Research and Development at the Ministry of Supply Mr Newbery had obtained his B Sc degree in 1932 at London University with first-class honours in mechanical and civil engineering and his subsequent career included working in the Airworthiness Department at the Royal Aircraft Establishment and as Resident Technical Officer at de Havilland’s, Stag Lane Since 1942, he had been at Ministry headquarters, where he was responsible particularly for transmissions With his long experience of mechanical systems and in establishing requirements for both rotors and propellers, Mr Newbery was an authority on the subject of his lecture— “The Programme of Development Testing for a Helicopter”

Attempts at human flight go a long way back into history First success did not come by use of man’s own power for propulsion but by the use of balloons for lifting Later gliders were made for descending flight It was only when a much greater source of power than man’s own was developed that flight with heavier than air machines became really successful It was not until the 1930s that much serious attention was given to man-powered aircraft flight With the aeronautical knowledge that was then available successful man-powered aeroplanes were developed and built which flew a few hundred yards Little attention appears to have been given to the possibility of a manpowered helicopter, possibly because it did not appear to be as promising a line of development as the aeroplane

The present interest in man-powered flight has led to the consideration of whether man-powered flight can be accomplished by rotary wings If this could be done, it would be extremely convenient and in many ways much more attractive than man-powered flight by fixed wings or even semi-fixed flapping wings Support in the air by a rotor enables the forward speed to be as small as zero and, one would hope, as fast as a bicycle Not only it is attractive from this point of view, but such a machine could be small and compact and it is initially imagined as something on the lines of the small one-man helicopters under development in the U S A and France and possibly in other countries

Study of the problem involves two basic considerations Firstly, it must be made clear exactly what power can be made available from the human body to drive the rotor Secondly, it must be discovered how this power can best be applied in order to get the most out of it, in the hope that it will be sufficient for free flight by man-power