The pace at which new technologies are assimilated into society is driven by trends in the regulatory, budgetary, and societal environments in addition to the pace of technology development itself. This study merges trends in these areas to develop an integrated forecast of the levels to which unmanned aviation can be expected to emerge in the military, air cargo, business, general aviation, and airline aviation segments over the coming 40 years. One out of every 80 aircraft on an instrument flight rules (IFR) flight plan over the US are anticipated in this forecast to be unmanned by 2025 and two out of nine (18 of every 80) by 2050. Portions of this study were originally researched in 2005 in support of the Federal Aviation Administration’s (FAA’s) Joint Planning and Development Office (JPDO) for planning the Next Generation (NextGen) air traffic system and later presented at the 23rd Bristol UAV Systems Conference.

The transient motion of a shock wave is investigated during its passage through ducts containing various area convergences. The method of characteristics has been used to follow the unsteady motion of the shock wave in an inviscid, non-conducting gas. The strength of the shock is taken to be large enough so that initially both sets of characteristics face downstream. The results are found to be in good agreement with unsteady and quasi-steady theories. A comparison is made between the characteristics results and experimental results obtained in a 1 ft (0·305 m) diameter shock tube. This shock tube incorporates a 3·75:1 linear area change in the low pressure section length. Good agreement is found between experiment and theory. A comparison is also made with other experimental work.

Whereas a body of theoretical research is available on the conditions of supersonic flow through Laval nozzles and around aerofoils, such is lacking for turbo-machinery in general, with the exception of some researches by Stodola, confined to axial steam turbines. The present paper investigates some important questions relating to the flow at supersonic velocity through centrifugal machines of the general type.

Numerical simulations have been carried out for a 32.16-ft-diameter rotor in autorotational forward flight. Coupled flapping and rotational equations were solved using the transient simulation method (TSM) to ascertain the quasistatic torque equilibrium conditions. The Pitt/Peters inflow theory was adopted in the simulations, and an airfoil look-up table made by a compressible Navier-Stokes solver was used. The adverse cyclic and collective pitch inputs were introduced in a similar fashion to helicopter control in that the cyclic lever is pulled back and the collective lever is pushed down for increasing airspeeds. The simulation results showed that the longitudinal cyclic pitch input combined with a lowered collective pitch increases the rotating torque for a low shaft angle and an advance ratio greater than one, producing both high lift and a high lift-to-drag ratio. Upon introducing the adverse cyclic and collective pitch inputs, the control range broadened, and a torque equilibrium condition was detected at 414.7kt (700ft/s) of airspeed in the simulation.

Boost-gliders offer the possibility of rapid long distance travel (e.g. England-Australia in 75 minutes) and boosters using similar technology offer the possibility of “everyday” travel between the earth and space stations. This paper uses simple parametric methods to assess conditions for boost-gliders to be commercially competitive and to discuss their evolution in relation to other boosters and advanced aircraft. It is concluded that booster-gliders using a similar state of the art to presently-projected aerospace transporters (i.e. winged, two-stage, hydrogen-fuelled vehicles) would be reasonably economical given cheap hydrogen fuel and a market large enough to support about 50 aircraft each making 5 antipodal flights per day. In addition, numerous problems would be involved in developing this type of vehicle to an acceptable level of design and operational familiarity but, at first sight, none of these appears to be insurmountable.

This paper considers two-dimensional flow past flexible membranes whose supports are aligned at right angles to the flow. Unlike a previous study of bluff impervious membranes, the present membranes are slightly porous having a porosity similar to that of parachutes. The drag and base pressure have been measured for various lengths and for a variety of fabrics. The results have been correlated by two theories which are extensions of those already published. When the porosity is not too small the results are shown to depend only on the total volume flow through the membrane. The tendency for the membrane to oscillate in harmony with regular vortex shedding is reduced by the porosity and increased by the length of the membrane. Above a certain porosity oscillation is inhibited for all membrane lengths.

According to the Plowden report, the American worker has weekly earnings of 2 to 2 times those of the British worker. The report also stated that, for the same production run (of 100 aircraft), the average cost in the USA would be between 105 and 115 per cent of the British cost for the same aircraft. This means that the number of man-hours expended in Britain is of the order of 2 to 2 times the number of man-hours taken in the USA for the same job. Or, it means that, if we could make an aircraft in Britain for the same man-hours as in the USA, it could sell at only 40 to 50 per cent of the American equivalent. But bear in mind that the man-hours I refer to are for all employees, not just those usually charged direct.

Measurements of static pressure across the boundary layer on the wall of a circular cylinder with flow parallel to its axis display wall-interference effects which exceed corrections due to turbulence by almost an order of magnitude. Two different types of static pressure probe were investigated and gave different pressure distributions in the same boundary layer.

A commercial aircraft programme has always been an undertaking with significant risk. Accurately estimating potential sales and production costs of these aircraft is an essential part of containing this risk. This paper addresses the cost estimating process and cost management of the latest Boeing programme — the 757.

Substantial resources are required for a new programme. The number of people involved, of course, varies with the stage of production, but Boeing will employ approximately 10,000 at peak production rates. In a typical Boeing programme, a network of over 1000 suppliers of material, parts and equipment will employ another 20 000 people at peak production so that total employment is in the 30 000 range.

The deterioration in the performance of NACA submerged intakes in the presence of a boundary layer has been established in Ref. 12, where a correlation of experimental data, obtained from wind tunnel tests on models, is presented. The purpose of this paper is to provide a prediction method which will allow the efficiency of these intakes to be estimated outside the range for which experimental data exist.

To anyone involved in aeronautics, Formula I cars must seem to be pretty weird devices and so, in order to explain some of the rather unorthodox aspects of FI aerodynamic design, I shall start by retracing the history of aerodynamics in FI a few years to 1968, when it was realised that greater gains could be made by increasing the tyre loads than by trying to reduce the drag. It was the tyre manufacturers who influenced this development more than anyone else, as the width of tyre being developed to generate cornering loads greater than 10 g was making any attempts to reduce drag pretty fruitless. On the average circuit only about one-fifth of the time is spent at around maximum speed and four-fifth is spent cornering, braking and accelerating, when adhesion is far more important than drag.

Recent work on the Head-Up Display (HUD) has shown properties of continuous transition, easy learning and accurate use, when certain design principles are followed. Use of HUD in manual landing has suggested application as a monitor for automatic landing and another use is for the directed take-off.

Developments in display techniques have led to a proposal for an electronic flight instrument display (EFID), suitable for head-down, as well as head-up presentation. Economy in presentation area may result from compressing a number of displays into a single format, and from using the same area for a number of displays presented in sequence.

Similar flexible techniques applied to the topographical map display suggest a general-purpose plan position display, complementing the “front elevation” display of flight instruments. These ideas are combined in a proposal for an advanced cockpit layout.

The flowfield around a supersonic projectile using a pin actuator control method has been predicted using computational fluid dynamics. It has been predicted using both viscous and inviscid methods for a number of positions. Both methods showed that an optimal longitudinal position exists. However, the inviscid model over-predicted the lateral acceleration due to the difference in shock formation around the pin between the two approaches. The optimal location was predicted independent of solver, however the higher-fidelity solver predicted lower achievable lateral accelerations. This is due to the viscous interactions caused by the pin. The effect of projectile orientation has shown that shielding the pin leads to reduced effectiveness due to the wake of the fin enveloping the pin. When the pin is exposed to onset flow, the forces achieved are increased. There is also an increase in the achievable forces and moments with increasing Mach number.

Aircraft yaw control at high angles of attack by tangential forebody blowing has been investigated experimentally. Tests were performed in the University of Bath 21 m x 1.5 m low speed wind tunnel using a 6% scale generic combat aircraft model fitted with blowing slots in the nose cone. Six component strain gauge balance force and moment data were measured for angles of attack up to 90° for various slot geometries and locations. The effect of slot azimuthal location is demonstrated and a slot stall phenomenon described. A geometry dependent forebody/wing flowfield coupling has been identified which can lead to unexpected yawing and rolling moments. The primary source of yawing moment is shown to be the enhanced area of attached flow on the blown side of the forebody rather than direct vortex influence.

The optimum slot extent and location depend on the angle of attack range over which control is required. For regions where steady vortex asymmetry is present, slots near the apex of the forebody produce severe control reversals at low blowing rates. These reversals can be minimised by placing the slots away from the apex. For control in regions where the flow is dominated by periodic vortex shedding, long slots offer efficient control to 90° angle of attack. The most suitable compromise for wide range control would appear to be a short slot placed away from the apex of the forebody.

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

Increased helicopter operational requirements and the consequent advances in operating techniques are producing problems which need early recognition It is true that an increased requirement usually means an improvement in performance, but invariably each advance in performance introduces new handling problems In this short paper I will discuss two such handling problems as they effect the present military use of helicopters

Already the extension of pure helicopter flight for world-wide operation in any reasonable weathers and up to higher ceilings has provided new handling problems which we encounter regularly in our present work These I will discuss under the general headings of high altitude and instrument flight I am considering the problem of high altitude handling as a manufacturers problem, and instrument flight as a users problem