The use of aerospikes at the nose of a hypersonic vehicle can substantially reduce its drag; however, the associated heat flux at the reattachment point is very high for turbulent flows. In this paper, the aerothermodynamics of a generic projectile model represented by a hemisphere- cylinder, fitted axisymmetrically with an aerospike at the nose is investigated numerically with a commercially available Navier Stokes Solver. The base model is a hemisphere-cylinder with a diameter of 40mm and an overall length of 70mm. An aerospike protrudes axisymmetrically at the nose of the base model and has a hemispherical cap from which another aerospike protrudes which again has a hemispherical cap, thus forming a double-disk aerospike. Compressible, axisymmetric Navier-Stokes Equations are solved for turbulent hypersonic flow of thermally perfect air with free stream conditions of Mach No 6·2 at standard sea level atmospheric conditions. The results for the model with double-disk aerospikes are compared with those of hemisphere-cylinder without aerospike. The results suggest that the use of double-disk aerospike can favourably reduce the turbulent reattachment heat flux along with suitable drag reduction of the main body.

Results of a comparison of dynamic stall onset are presented, as assessed from low Mach number windtunnel data contained in the University of Glasgow's database and that from the well established Beddoes’ model. The model, which was originally developed to reconstruct higher Mach number dynamic stall characteristics, exhibited a lower stall onset incidence than that assessed from the windtunnel data. The differences and speculations on the physical reasoning underlying the two assessments are discussed. An addition to the Beddoes model is proposed which yields an improved reconstruction of the Glasgow windtunnel data.

Following on from the LUMINA and HERMES elements discussed in TN’s 11 and 12, this note analyses two further three-dimensional elements outlined in ref. 1. These new elements possess the desirable features of completeness and consequent invariance of the polynomials for the displacement fields. It has been shown in ref. 2 and stated in ref. 1 that third order complete polynomials yielding a second order or parabolic strain distribution fit into a tetrahedron element with 20 nodal points and 60 degrees of freedom, denoted within ASKA as TET 20 (Fig. 1).

A brief survey is made of the way the flow develops about wings with leading edges swept at about 50° as the stream Mach number rises from a subsonic to a supersonic value. The shock pattern which occurs may be complex. Three aspects of the wing flow are discussed in more detail, including the possible conditions for shock-induced separation of the surface boundary layer. The effect of the changing flow pattern on the overall wing lift, drag and pitching moment is commented upon.

This paper reviews the research on Gurney flaps and related high lift trailing edge devices. It investigates aerofoil performances at Reynolds numbers Re ≅ 105 and below, both with the clean configuration and various Gurney flap sizes. The device height is optimised, and a semi-empirical formula linking flap height to free stream speed and aerofoil chord is proposed. The analysis shows that the optimal size of the device is always below the boundary-layer thickness at the trailing edge. Discussion of results includes analysis of hysteresis loops occurring in the L/D performances. These are mostly due to large changes in drag and small changes in lift, which occur when the aerofoil is restored to the reference angle of attack.

With changes in the availability and quality of existing aviation fuels anticipated in the next 30 years it is timely to assess how changes in fuel properties would affect the range payload performance of aircraft. The effects on range and payload of a wide range of candidate fuels for aviation are investigated, including changes to the blends of conventional hydrocarbon fuels. Lighter fuels tend to be more desirable for commercial flights, where the flight is as close to the maximum payload as possible. Flights favouring range over payload are better suited by a more dense fuel. The hydrocarbon blends suggest for each aircraft, an optimum fuel may exist for the maximum payload and allowing the maximum range. Specific flight plans below the maximum range of the aircraft may be met with a lower specific energy fuel.

A procedure is developed for the analysis of plane stress problems when yielding occurs locally. The region is divided into triangular elements and the deformation is analysed on a step-by-step basis, using the matrix notation developed by Argyris. The simple expressions which are derived for the element properties are applicable with any stress-strain relations which are stable and time-independent. Simple numerical examples are given.

In order to ensure low-altitude safety, a tracking and recognition method of unmanned aerial vehicle (UAV) and bird targets based on traditional surveillance radar data is proposed. First, several motion models for UAV and flying bird targets are established. Second, the target trajectories are filtered and smoothed with multiple motion models. Third, by calculating the time-domain variance of the model occurrence probability, the model conversion probability of the target is estimated, and then the target type is identified and classified. The effectiveness and robustness of the algorithm is demonstrated by several groups of Monte Carlo simulation experiments, including setting different recognition steps, different model transformation probability, filtering and smoothing algorithm comparison. The algorithm is also successfully applied on the ground-truth radar data collected by the low-altitude surveillance radar at airport and coastal environments, where the targets of UAVs and flying birds could be tracked and recognised.

In choosing the title, “The Development of All–Wing Aircraft,” as the subject of my lecture I run some risk of being accused of writing a company history rather than a paper of the broad scope ordinarily presented before this time–honoured institution. This is far from my intent, but being sincerely convinced that the all–wing aeroplane is a valuable step in the development of aeronautics, and desiring to contribute a maximum amount to the available data in the limited time at my disposal, my paper must be confined largely to experience gained by our company in its work on this subject.

With this survey paper, the author proposes a new ‘tao’ – a new way of understanding – of how pilots do what they do. Research into the control of purposeful action in the natural world suggests that very rapid, efficient and ‘instinctive’ techniques have evolved based on the time to close on a goal, or close a gap, τ(t), and its derivatives. Purposeful actions involve the closure of one or more physical gaps, each with its own time to close, varying with time. Maintaining a constant rate of change of τ(t) with time (< 1) during an approach will ensure a successful arresting when the gap is closed, but an animal’s strategy can be adapted to the circumstances to achieve either a hard stop (aggressive action with ṫ > 0·5), or a soft stop (gentle action with ṫ < 0·5). Synchronous coupling of two motions, x(t) and y(t), such that the times to close are coupled, τx = kτy, results in the motion gaps x(t) and y(t) being related through a power law, x = Cy1/k, and closing smoothly together; examples of such coupling in the form of pursuit tracking in the natural world abound. Research has also shown that gaps can be closed by following ‘intrinsic’ guides, or self-generated mental models of desired motion, that have particular forms; for example, constant deceleration or constant acceleration. The gathering evidence from research into animal behaviour in the natural-world forms a background for the exploration of flight control in the man-made world. The implications for control theory, flight control developments and flight handling qualities, are considered to be profound. τ-theory suggests that natural control has a particular non-linear, albeit very simple, time varying form and that pilots learn control strategy skills by developing mental models, or internalised schemata, in the form of what are described as ‘τ guides’. In this context the author presents his perspective on flight control, briefly reviewing τ-theory and providing examples from research conducted at The University of Liverpool during the period 1999-2011, including the work of several PhD students. Concepts for guidance algorithms suitable for augmented manual or autonomous control are discussed and the implications for handling qualities developments, particularly relating to flight in degraded visual conditions, are presented. Some outstanding questions pointing directions for future research are raised.

The planar librational motion of a dumb-bell satellite has been studied by several authors. In most cases the analysis has been restricted to circular or nearly circular orbits. In an elliptic orbit, the variation of the angular velocity of the satellite around the central body together with the change in the local gravity gradient provides the satellite with a mechanism for exchanging energy between the librational and orbital modes. In general, this imposes a limit on the orbit eccentricity for which stable (non-tumbling) librational motion is possible. This note investigates the bounds that must be placed on a disturbance applied to a slender gravity gradient stabilised satellite so that it will librate and not tumble. The determination of the stability boundary as presented here was arrived at by the numerical solution of the exact equation of motion, obtained using an IBM 7040 computer.

The analysis of axisymmetrical thin shells has always been an important part of the theory of structures, and recently the problem of the cooling tower has aroused considerable interest for practical engineering reasons. Various solutions have been obtained, using either the finite difference or the finite element methods, with varying degrees of success. Amongst the latter, elements such as the TRIB 3c from the ASKA library and the axisymmetrical elements from the SABOR programme, with either a straight or a curved meridian line, have given reasonable displacements. But, by the nature of these elements, the stress distributions are discontinuous across element boundaries. Other existing elements, e.g. the arbitrarily curved triangular shell element SHEBA developed by Professor Argyris's team at the ISD in Stuttgart, are also suitable for the purpose and yield an excellent estimation of the stresses.

The trailing vortex wake shed by large transport aircraft not only has detrimental effects on their aerodynamic efficiency through the production of induced drag but can cause a considerable safety hazard to smaller following aircraft. This hazard is a major factor in determining the minimum allowable spacing between aircraft during airport operations with separations of up to five nautical miles being required between heavy aircraft and smaller aircraft following them on the approach for landing. It has been estimated that the minimum safe operating distance based on considerations other than vortex wake hazard is approximately two nautical miles’. The potential economic saving from the reduction in operating times at busy airports as well as the improvement in aerodynamic efficiency has led to the investigation of many schemes for the alleviation of these trailing vortices.

The GOAHEAD (Generation of an Advanced Helicopter Experimental Aerodynamic Database for CFD code validation) consortium was created in the frame of an EU-project in order to create an experimental database for the validation of 3D-CFD and comprehensive aeromechanics methods for the prediction of unsteady viscous flows. This included the rotor dynamics for complete helicopter configurations, i.e. main rotor – fuselage – tail rotor configurations with emphasis on viscous phenomena like flow separation and transition from laminar to turbulent flow. The wind tunnel experiments have been performed during two weeks in the DNW-LLF on a Mach-scaled model of a modern transport helicopter consisting of the main rotor, the fuselage, control surfaces and the tail rotor. For the sake of controlled boundary conditions for later CFD validation, a closed test section has been used. The measurement comprised global forces of the main rotor and the fuselage, steady and unsteady pressures, transition positions, stream lines, position of flow separation, velocity profiles at the test section inlet, velocity fields in the model wake, vortex trajectories and elastic deformations of the main and tail rotor blades.

Fluidic flight controls enable forces and moments for flight vehicle trim and manoeuvre to be produced without use of conventional moving surface controls. This paper introduces a methodology for the design of Circulation Control (CC) and Fluidic Thrust Vectoring (FTV) as fluidic controls for roll and pitch. Work was undertaken as part of the multidisciplinary FLAVIIR project, with the goal of providing full authority fluidic flight controls sufficient for a fully flapless flight of an 80kg class demonstrator aircraft known as DEMON. The design methodology considers drag, mass, volume and pneumatic power requirements as part of the overall design cost function. It is shown that the fundamental flow physics of both CC and FTV are similar, and hence there are strong similarities to the design approach of each. Flight ready CC and FTV hardware has been designed, manufactured and ground tested. The CC system was successfully wind tunnel demonstrated on an 85% scale half model of the DEMON. The design condition of a control ΔCL of 0·1 was achieved with a blowing coefficient of 0·01, giving a useable control gain of 10. The FTV system was static tested using a micro gas turbine source. The control characteristic was ‘N’ shaped, consisting of an initial high gain response in a negative sense (gain = −30) followed by a low gain response in a positive sense (gain = +3) at higher blowing rate. CC and FTV control hardware directly contributes to around 6% to the overall mass of the flight vehicle, however provision of pneumatic power carries a significant mass penalty unless generated as part of an integrated engine bleed system.

The lecture recalls great Manchester traditions in the mechanics of fluids and in related areas of mathematics which were brilliantly renewed from 1945 onwards through Sydney Goldstein’s work as Beyer Professor of Applied Mathematics. Goldstein brought to this important task not only his own personal distinction in those fields but also his great experience in leading interacting groups working in experimental and theoretical fluid dynamics with largely aeronautical objectives. The University has continued strongly to maintain these traditions.

The lecture celebrates also two fine pieces of research where gifted biologists have successfully used certain key mathematical ideas and methods in the mechanics of fluids to solve problems of importance in the field of animal locomotion. The first example is the work of C. J. Pennycuick, J. M. V. Rayner and G. R. Spedding in determining the character of the vortex wake behind a steadily moving bird in horizontal flapping flight. Typically, this takes the form of a “concertina wake” of fluctuating width but approximately constant circulation, exerting forces which are greater in the downstroke (which sheds a wide wake) and less in the upstroke (which sheds a narrower wake). Some notable advantages of the concertina wake are indicated.

Finally, work by Sir Eric Denton, Sir John Gray and Dr J. H. S. Blaxter on schooling behaviour in herrings and other clupeoid fishes is described. These fishes’ mechanisms for advantageously maintaining well coordinated motion of the school as a whole depend not only on eye vision but also on certain specialised organs admirably fitted to the sensing of hydrodynamic pressure fields (associated with the motions of other fishes) and of their lateral and longitudinal gradients.

An unusual philosophical approach is proposed here to decarbonise larger civil aircraft that fly long ranges and consume a large fraction of civil aviation fuel. These inject an important amount of carbon emissions into the atmosphere, and holistic decarbonising solutions must consider this sector. A philosophical–analytical investigation is reported here on the feasibility of an airliner family to fly over long ranges and assist in the elimination of carbon dioxide emissions from civil aviation.

Backed by state-of-the-art correlations and engine performance integration analytical tools, a family of large airliners is proposed based on the development and integration of the body of a very large two-deck four-engine airliner with the engines, wings and flight control surfaces of a very long-range twin widebody jet. The proposal is for a derivative design and not a retrofit. This derivative design may enable a swifter entry to service.

The main contribution of this study is a philosophical one: a carefully evaluated aircraft family that appears to have very good potential for first-generation hydrogen-fuelled airliners using gas turbine engines for propulsion. This family offers three variants: a 380-passenger aircraft with a range of 3,300nm, a 330-passenger aircraft with a range of 4,800nm and a 230-passenger aircraft with a range of 5,500nm. The latter range is crucially important because it permits travel from anywhere in the globe to anywhere else with only one stop. The jet engine of choice is a 450kN high-bypass turbofan.

A non-linear mathematical model for the study of the dynamics of an extensible cable subjected to aerodynamic forces generated by a uniform flow field is formulated. Solutions are found considering large displacement caused by suddenly applied loads (i.e., gusts, shock waves, turbulence) for a range of flow speeds and cable lengths. Transition from overdamped to oscillatory motion is observed when flow speed and cable length are increased and decreased respectively. The stability of the system is discussed.

Coupling an unsteady flow-solver with a structural model offers the opportunity to simulate aeroelastic behaviour of wings and rotor blades. The moving and deforming surfaces resulting from unsteady simulations require deforming meshes during the simulation, and it is common to use simple interpolation of surface displacements and velocities onto the initial undisturbed mesh. However, aeroelastic simulations can result in large displacements and deformations of solid surfaces, and simple interpolation of perturbations results in poor grid quality and possible grid crossover. A new interpolation technique is presented which is still simple in that it is driven solely by surface motion, but represents rotational effects near the solid surface, to maintain grid quality there. Furthermore, the scheme is fully analytic, so is very cheap computationally and results in grid speeds also being available analytically. Results, in terms of unsteady grid motion and flow solution, show the scheme to be effective and efficient.