This analytical treatment gives general considerations concerning “ true rolling ” of a rolling body in a circular path : firstly, for constant speed of its centre of gravity, and, secondly, for acceleration of its centre of gravity. From these are derived the relations of the dimensions, as function of the conditions, and the corresponding constructions for both taper roller bearings and ball bearings, which are essential to produce “ true rolling” at constant and variable shaft speeds.

Results of numerical simulation of inviscid compressible flow around a generic satellite launch vehicle (SLV) with strap-on boosters using a commercial computational fluid dynamics (CFD) code named Star-CD are experimentally evaluated. Governing equations of flow around the SLV with two and two strap-on boosters were solved in three dimensions using the SIMPLE algorithm in an unstructured tetrahedral mesh, to determine longitudinal aerodynamic coefficients and surface pressure distribution at Mach numbers from 0·6 to 2·0, and angles-of-attack from 0° to 16°. To evaluate the numerical results, 1:100th scale models of the SLV were tested in a trisonic wind tunnel in the same configurations and flow conditions as those analysed numerically. Comparison of results shows reasonable agreement between numerical and experimental values, however, drag coefficients had to be corrected to compensate the effects of base flow and the struts connecting the boosters to the core rocket. This evaluation shows that a relatively simple simulation of flow using a commercial CFD code can be considered an efficient tool for prediction of aerodynamic characteristics of a multi body satellite launch vehicle with a level of accuracy acceptable in the process of preliminary aerodynamic design.

To investigate the control effect of the synthetic jet on the aerodynamic characteristic of rotors, a numerical simulation procedure for the rotor flowfield is established. First, a moving-embedded grid method and an unsteady Reynolds Averaged Navier–Stokes (URANS) solver are established for predicting the complex flowfield of rotors. A velocity jet boundary condition over the jet actuator orifice is constructed, and a numerical method for simulating the active flow control on rotors is developed. Then, the effectiveness of the simulation method is validated by comparing the numerical results of jet control on NACA 0015 aerofoil with the experimental data. At last, the aerodynamic characteristic of rotors with synthetic jet actuators located on the suction surface of the blade in forward flight is calculated. The results indicate that the synthetic jet has the capability of improving the aerodynamic characteristic of rotors, especially in inhibiting the flow separation over the surface. In addition, the increase of the jet momentum coefficient and the jet angle can both enhance the lift coefficient in the retreating side. Compared with a single jet, jet arrays have better control effects on improving the aerodynamic characteristic of rotors in forward flight.

Aero engine designs can have a life time of over 45 years, which is long enough for the understanding of environmental problems to change significantly. This places the aero engine designer in a position of uncertainty, as unforeseen environmental problems could affect the viability of a design. ‘Risk’ is used to describe future uncertainties that can lead to undesirable consequences. This paper presents a framework for environmental risk management that allows the designer to answer the question: what is the risk to a design from its environmental impacts over the life cycle? The framework provides a process for turning complex environmental business hazards into a form that can be used to develop mitigating actions within the design process. The paper demonstrates the framework through two examples and discusses findings, leading to conclusions on what is required to implement the framework into a business.

The unmanned aerial vehicle (UAV) flocking among obstacles was transferred to a velocity-controllable UAV flocking problem, which means that multi-UAV gradually form and maintain the $\alpha$ -lattice geometry as they track the desired flocking velocity, and can be applied to tasks such as obstacle avoidance and velocity tracking. Velocity-controllable UAV flocking problem is a multi-objective flocking controller parameters optimisation problem, for which we design flocking velocity and geometry objective function, and solve them using a multi-objective particle swarm optimisation algorithm (MOPSO). On this basis, to address the problem that MOPSO has random results and long computation time, we propose to use a neural network (NN) to approximate the mathematical relationship between the UAV flocking state and the flocking controller parameters. We simulate the flight process of 5 and 49 UAVs performing obstacle avoidance and velocity tracking tasks, respectively. The results show that the proposed UAV flocking controller has better convergence performance, obtains reproducible results, reduces computation time, and can be used for large-scale UAV flocking control.

Sandwich composites are widely used in aerospace materials thanks to their low weight and high strength properties. The purpose of this study is to observe the effects of polyurethane foam filling on honeycomb core structures produced by additive manufacturing in terms of mechanical strength and moisture absorption properties. Within the scope of the study, honeycomb structures were produced by a 3D printer using polylactic acid (PLA) filament. Then, the honeycomb core was filled with polyurethane foam, which is supplied in liquid form. After the core material was given its final form, it was combined with an epoxy and carbon fibre facesheet material using the vacuum infusion technique. After the sandwich composite production was completed, in-plane compression, three-point bending, shear, and moisture absorption tests were applied. The polyurethane foam filling greatly increased the mechanical strength, but slightly more moisture absorption occurred in this structure compared to a hollow honeycomb structure.

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.

This paper presents a mathematical approach for the simulation of rotor-fuselage aerodynamic interaction in helicopter aeroelasticity and flight dynamics applications. A Lagrangian method is utilised for the numerical analysis of rotating blades with nonuniform structural properties. A matrix/vector-based formulation is developed for the treatment of elastic blade kinematics in the time-domain. The combined method is coupled with a finite-state induced flow model, an unsteady blade element aerodynamics model, and a dynamic wake distortion model. A three-dimensional, steady-state, potential flow, source-panel method is employed for the prediction of induced flow perturbations in the vicinity of the fuselage due to its presence in the free-stream and within the rotor wake. The combined rotor-fuselage model is implemented in a nonlinear flight dynamics simulation code. The integrated approach is deployed to investigate the effects of rotor-fuselage aerodynamic interaction on trim performance, stability and control derivatives, oscillatory structural blade loads, and nonlinear control response for a hingeless rotor helicopter modelled after the Eurocopter Bo105. Good agreement is shown between flow-field predictions and experimental measurements for a scaled-down isolated fuselage model. The proposed numerical approach is shown to be suitable for real-time flight dynamics applications with simultaneous prediction of structural blade loads, including the effects of rotor-fuselage aerodynamic interaction.

Prediction of stall before it occurs, or detection of stall is crucial for smooth and lasting operation of fans and compressors. In order to predict the stall, it is necessary to distinguish the operational and stall regions based on certain parameters. Also, it is important to observe the variation of those parameters as the fan transitions towards stall. Experiments were performed on a contra-rotating fan setup under clean inflow conditions, and unsteady pressure data were recorded using seven high-response sensors circumferentially arranged on the casing, near the first rotor leading edge. Windowed Fourier analysis was performed on the pressure data, to identify different regions, as the fan transits from the operational to stall region. Four statistical parameters were identified to characterise the pressure data and reduce the number of data points. K-means clustering was used on these four parameters to algorithmically mark different regions of operation. Results obtained from both the analyses are in agreement with each other, and three distinct regions have been identified. Between the no-activity and stall regions, there is a transition region that spans for a short duration of time characterised by intermittent variation of abstract parameters and excitations of Fourier frequencies. The results were validated with five datasets obtained from similar experiments at different times. All five experiments showed similar trends. Neural Network models were trained on the clustered data to predict the operating region of the machine. These models can be used to develop control systems that can prevent the stalling of the machine.

I have, for the second time, the honour of addressing you. Four years ago I told you how I had had the good fortune to discover a new method of flying with characteristics altogether different from the conventional aeroplane.

To-day, taking advantage of your kind invitation, I come to tell you of how the crude experimental autogiros of 1925 have been developed into practical flying machines. I will also deal with a number of theoretical points in justification of the assertions I have often made about the qualities of the autogiro and in answer to the criticisms of which my system has been made the object from time to time.

‘Active Control Technology’ (ACT) is a jargon of the last few years describing the technological requirements which permit the earlier concept of the Control Configured Vehicle (CCV). The CCV idea was that by suitably driving specially arranged controls, various desirable aircraft characteristics, notaby stability and good handling, could be provided synthetically and as a result the tail and fin sizes could be reduced and the wing mounted in a more advantageous position on the fuselage: more freedom of choice was thus given the designer in settling his configuration. The technology to do this was barely ready at the time but meanwhile has been progressing apace in the form of minicomputers, electrical signalling, digital control systems and a deeper analysis of what is involved in a total system.

This work aims to describe a mathematical model and a numerical method to simulate a thin anisotropic membrane moving and deforming in 3D space under a dynamic load of an arbitrary time and space profile. The anisotropic continuum medium model described in the article can be used to model a membrane made of composite material using its effective elastic parameters. The model and the method allow the consideration of problems when the quasi-static approximation is not valid and elastic waves caused by the impact should be calculated. The model and the method can be used for numerical study of different processes in thin composite layers, such as shock load, ultrasound propagation, non-destructive testing procedures and vibrations. The thin membrane is considered as a 2D object in 3D space, an approach that allows a reduction in the computational time compared with full 3D models, while still having an arbitrary material rheology and load profile.

Measured characteristics of compressible constant pressure adiabatic turbulent boundary layers are correlated in an incompressible frame of reference with the aid of a modification of the well known Mager compressibility transformation. Quite good data collapse is obtained although the transformation is shown to be deficient in the outer regions of the boundary layer. The results will be used to produce data sheets of constant pressure adiabatic turbulent boundary layer properties.

Ladies and Gentlemen, tonight we pay homage to Frederick William Lanchester, Doctor of Laws, Fellow of the Royal Society who, having become interested in mechanical flight at the age of 21, while studying at South Kensington in 1889, entered the field of aeronautics in 1892 and continued to aid its development until his death in 1946. His great contributions to aeronautics were the discovery of the theory of the vortex motion of the lifting wing and that the key to successful flight lay in reducing the skin friction, which was far from being the negligible quantity that others such as Langley, whose name is forever remembered through NASA Langley Field, had stated earlier. All this was in 1893 to 1894 some ten years before the first flight of the Wright brothers. When asked later how he had successfully derived his great and momentous theory Lanchester simply stated; ‘it was a matter of logical deduction helped by experiment’. He vigorously defended his work as not being empirical but was soundly based on hydrodynamic theory.

A stiffened shear web, consisting of a thin plate (referred to simply as the web) attached to longitudinal members (or flanges) and supported by a series of transverse stiffeners, buckles in a mode involving both the web and stiffeners, at a shear stress which also depends on the restraint between the web and flanges. With increasing stiffener size changes in the mode of buckling occur until, at a certain critical value of the flexural stiffness of the stiffener, buckling is largely confined to the web between stiffeners, and the buckling coefficient is then practically constant. The buckling coefficient reduces to that of an unstiffened flat plate with decreasing stiffener size.

Engineering Sciences Data Item 02.03.02 plots buckling coefficients for long shear webs with uniform, equally-spaced stiffeners. The curves are based on work by Stein and Fralich, for stiffeners of zero torsional rigidity and simply-supported longitudinal edges, and on a more recent series of papers by Cook and Rockey (listed in the Data Item) which extend the analysis to clamped, as well as simply-supported, webs and also include the torsional rigidity of the stiffeners.

The feasibility of using a single effective on-line control law to regulate the dynamic response of a jet engine throughout its flight envelope is of considerable importance. In this paper, a study was made to find such a single effective control law, which was able to regulate the dynamic responses of the linear, and ultimately the non-linear, model, throughout the engine’s entire operating range. This effective control law was obtained from solving a Linear Quadratic Problem (LQP) to obtain an optimal control law, a linear state feedback control.

Approximate solutions are given for the lowest natural frequency of flexural vibration of isosceles triangular plates which have the equal edges simply-supported and the base clamped. The results are presented graphically to allow rapid determination of a desired fundamental frequency.

A practical application of two-dimensional subsonic bluff body flow research can be seen in the design, construction and positioning of tall slender buildings. Similarly, from a three-dimensional viewpoint, drag reduction and vortex control is an important factor in the latest road vehicle designs. From just these two examples it can be seen that the problem of flow about a bluff body is one of major practical importance, while at the same time being of great theoretical interest. However, despite many years of extensive testing, there has been little progress made on the theoretical investigation of turbulent base flows since the foundations laid down by Kirchhoff and von Karman. The non-steady processes in the wake, in particular the complex dynamics of vortex formation, have proved to be problems of formidable size.

Curie and Skan have modified the approximate methods of Thwaites and Stratford to predict separation properties of laminar boundary layers for flow over an impermeable surface. The work of Curie and Skan has been extended by Curle to include the estimation of laminar skin friction for the whole flow. The purpose of the following note is to compare the approximate methods of Curie and Skan and Curle with the numerical results given by the author for flow past a circular cylinder. It is found that there is remarkable agreement between these approximate methods and the exact numerical solutions. This indicates that these methods can be used widely, both on account of their simplicity and their accuracy.