With the advent of thrust vector control and post stall manoeuvrability affecting the design of modern combat aircraft, there still remains a shortage of performance metric tools available to the conceptual designer. The need for such a tool is highlighted, and a suitable metric is introduced. Using the metric, the effects of thrust vector control and post stall manoeuvrability are investigated quantitatively for a 180° heading change in the horizontal plane, in terms of time to complete the manoeuvre, final Specific Excess Power, energy change over the manoeuvre and turn diameter. The extension of the metric to investigate different manoeuvres and the impact of other new technologies is briefly discussed.

Experiments assessing the effectiveness of passive control involving a porous surface and cavity underneath for reducing the level of surface pressure fluctuations in reattaching flows are reported. Measurements are made on a generic axisymmetric body, representative of a launch vehicle configuration, in the Mach number range of 0·8 to 1·2. The measurements consist of distributions of mean surface pressure and unsteady surface pressure fluctuations in the boat-tail separated region. The passive control significantly reduces the peak surface pressure fluctuations in the reattachment zone, even in the absence of a strong shock wave. The spectra of pressure fluctuations reveal that with passive control the energy is appreciably reduced over a wide range of frequencies.

Noise reduction in the inlet of stationary gasturbines or aeroengines is usually achieved by passive absorbers (acoustic liners) the efficiency of which is limited due to the confined length. Higher sound level reductions can be obtained — in particular for the tonal components -by using additionally active noise control techniques (ANC): The rotorspeed-coherent tonal components of the primary sound field are superimposed with an anti-phase sound field which is produced by secondary acoustic sources.

Computational fluid dynamics (CFD) tools are an integral part of the processes within design and performance assessment offices in the aerospace industry. As timescales from initial concept to design-freeze become shorter, there is an increasing need for the CFD process to be timely and cost effective and for confidence in the predictive capability of the CFD tool to be high. Only in this way will the impact of CFD be maximised. The CFD software development and support team plays a key role in achieving this goal. This paper describes how the team at ARA has met the challenge of delivering to industry what it requires in terms of both the CFD tools and the people who supply them. The qualities needed to do this extend beyond the ability to achieve technical advancement, although prime emphasis is still placed on this aspect. In particular, the importance of developing a close relationship between CFD team and end user — an integrated team approach — is stressed. This leads to a precise and unambiguous understanding of customer needs and the delivery of the required product and its maintenance. The demonstration of recent technical achievements and the discussion of supporting team attributes exemplify these points.

The compressive stability of anti-symmetric angle-ply laminated plates with particular reference to the degrading influence of membrane-flexural coupling is reported in this paper. A specific configuration of anti-symmetric laminate is dealt with in the paper and this takes the form [θ/-θ]n whereby 2n is the total number of plies in the laminated stack. With regard to compressive buckling the paper gives an indication that anti-symmetric laminates with 8 plies or more will yield performance levels which are almost identical to their symmetric counterparts. The degree of membrane-flexural coupling in the laminated composite plates is varied, essentially, by changing the ply angle and also by altering the number of plies in the laminated stack, for a given composite material system. The coupled compressive buckling solutions are determined using the finite strip method of analysis. In order to provide an adequate level of flexibility in the analysis procedure and to ensure a high level of accuracy of solution, the buckling displacement fields of the strip formulation are those which are described in a multi-term form.

Results are given for anti-symmetric angle-ply laminated plates subjected to uniaxial and biaxial compression and these have been obtained from fully converged finite strip structural models. Validation of the finite strip formulation is indicated in the paper through comparisons with exact solutions where appropriate. The natural half-wavelength of the compressive buckling mode of the composite plates is shown to be significantly influenced by variation in the ply angle. Increasing the number of plies in the laminated system is seen to reduce the degree of coupling and the critical stress levels are noted to tend towards the plate orthotropic solutions. The ply angle corresponding to the optimised, compressive buckling stress for any particular laminate is noted in the paper to be influenced by the support boundary conditions at the plates unloaded edges.

An aeroelastic formulation of 2D lifting surfaces in an incompressible flow field via the use of aerodynamic indicial functions is presented. The approach carried out in time and frequency domains yields the proper aerodynamic loads necessary to the study of the subcritical aeroelastic response and flutter of lifting surfaces, respectively. The expressions of the unsteady lift and aerodynamic twist moment in the frequency domain are given in terms of the Theodorsen’s function, while in the time domain, these are obtained directly with the help of the Wagner’s function. Closed form expressions of unsteady aerodynamic derivatives, helpful in an unified approach of response and flutter analyses, and results related to aeroelastic response to gust and blast loads are supplied. In this context, a novel representation of the aeroelastic response in the phase - space was supplied and pertinent conclusions on the implications of some basic parameters have been outlined.

A novel, non-intrusive, high spatial and temporal resolution thermal imaging system, based on the fluorescence properties of a dysprosium doped yttrium-aluminum-garnet (Dy3+:YAG) thermographic phosphor, has been developed. In this system, the phosphor coating on the test surface is excited by a pulsed Nd:YAG laser. The resulting fluorescent emission of the temperature sensitive 456nm transition and that of the temperature independent 496nm transition, are acquired using a pair of image-intensified charged coupled device cameras. The ratio of the acquired emissions is then correlated to temperature. The Dy:YAG phosphor displays temperature sensitivity in the range of 295–l,350K (with possibility up to 1,800K). Temperature measurements obtained from the surface of a disk heated by an impinging jet, demonstrate the feasibility of this technique for general heat transfer studies involving significant unsteadiness and transient phenomena.

This paper relates to a recent project in which the aim was to devise a procedure that could be used to identify the linearised transfer functions of the longitudinal motion of the solar powered airship Lotte from flight test data.

Using a non-linear mathematical model of the Airship, a linearised state space model was derived numerically and this was used to derive the response transfer functions, which formed the theoretical results. A test procedure was then developed to identify the transfer functions experimentally from frequency response data obtained in simulated flight tests. Initially, the linearised model was used and the test procedure was refined until a suitable level of coherence between the experimental and theoretical results was observed. The test procedure was then applied to simulated flight test data from the non-linear model, and finally sensor noise was added in order to represent actual flight test conditions as closely as possible. Unfortunately, the results were inaccurate and in some cases, they were unacceptable. When the test procedure was applied to the non-linear model, significant errors were seen in all the results. The addition of sensor noise led to heavily distorted results and a further degradation of the resulting transfer function estimates.

It was concluded that meaningful results could not be achieved unless frequency response data with a higher resolution could be obtained and the effects of sensor noise could be reduced. Presently, no test procedure has been developed that would be of any use in a practical situation. However, a number of ways of possibly improving the test procedure or otherwise improving the quality of the results were conceived near the end of the project. It is therefore the purpose of this paper to account for the shortcomings that were encountered in the project and to introduce briefly the unexplored remedies, in the hope that these may be of some benefit to future identification studies.

An experimental study of the supersonic vortices from a 75° swept-back delta wing has been carried out in a Mach 2.49 stream. Five-hole conical probe surveys were conducted at the trailing edge of the planform for 7° and 12° angles-of-attack. The main objective was to determine the Mach number and pressure distributions in the primary vortex. A novel approach of utilising a computational flow solver was used to generate the calibration data for the five-hole probe over a range of Mach numbers and pitch angles. Measurements indicate significant static and total pressure deficits in the vortex core. Both the magnitude and the spatial scale of these deficits increase with the higher incidence angle. The swirl profiles have supersonic peak magnitudes and resemble the low speed Lamb-Oseen vortex. Similar to the case of supersonic wing tip vortices, and contrary to the experimental results from transonic and low speed leading-edge vortices, the axial Mach number distribution in the vortex core is found to have strong wake-like profile.

This paper discusses selected aviation human factors challenges in the air transport environment. Because of the authors’ background, much of this paper will be based upon the growth of human factors and airline training in transport aviation in the United States. However, parallel growth and advancements have been made in other parts of the world from the beginning of air transport and are being made in many parts of the world today. This is certainly true of Great Britain. One should never forget that air transport is a world enterprise and has been since its beginning. While it is important to recognise that cultural and other differences should be considered if they are relevant, it is equally important in air transport to recognise that common problems are solved by common solutions and can be addressed by, but are not limited to, common approaches.

It is recognised that the behavioral aspect of aviation human factors deserves considerable attention, particularly in the area of training and evaluation. We have also learned that previous training criteria are not satisfactory for operation with increasingly complex aircraft being operated in an increasingly complex environment. Human errors occur with greater frequency than is often believed and can be made by anyone — even an airline captain. An inevitable consequence of this entirely human characteristic is that the role of the co-pilot has been considerably enhanced. Furthermore, the monitoring function of the pilot-not-flying, whether he/she is the captain or co-pilot, is now recognised as a critical safety function by virtually all serious operational experts.

A detailed numerical study has been performed to investigate the origin and mechanism of the formation of windward shocks that have been observed on inclined slender bodies at supersonic speeds inside the bow shock wave around the body. It is shown that the feature is associated with the virtual double cone-like deflection of the supersonic stream by the primary vortices and, as such, can be named the ‘vortex shock’.

Customers demand reliable products and such demands are reflected in the product specification and requirements documents. Indeed, contractual obligations are being introduced to ensure that the supplier meets the cost of unreliability. Thus, equipment suppliers must design products to perform reliably for the required product life. Moreover suppliers must provide sufficient evidence that their product will meet reliability requirements. This evidence is termed the reliability case. The main instigator for the use of the reliability case is the British Ministry of Defence (MoD) under the guise of Defence Standard 00-42 Part 3 but the concept is also becoming accepted in the commercial field as one of the key criteria for selecting products.

This paper describes the work carried out under a collaborative project funded by the UK Department of Trade and Industry (CARAD) entitled reliability enhancement methodology and modelling (REMM). More specifically it will concentrate on demonstrating the methodology in the form of providing the necessary guidance for building a reliability case. It will also discuss the challenges associated with design for reliability and demonstrate how the REMM tool will encourage designers to consider what might go wrong.

The REMM tool encompasses a reliability assessment model and this paper will describe and discuss the advantages of this Bayesian model with particular reference to decision making aspects during the design stage of a project.