A study was conducted to identify possible improvements to the current certification and operational procedures for turboprop powered aircraft operating in icing conditions. Information was gathered through a series of interviews with airframe and engine manufacturers and also, operators and aircrews in Europe and Canada. The significant issues raised during the interviews are discussed, and a number of recommendations are made for future research and development activities in die area of aircraft icing. These recommendations identify the need for improved ice protection methods, enhanced thermodynamic models in ice prediction computer codes, and development of an ice prediction probe to warn aircrew that they will soon be entering icing conditions. Recommendations also include improvements to pilot training, and the need to make weather forecasts of icing more accurate and specific.

Metal adhesives have been known to the Aircraft Industry for at least ten years, the Chrysler Cycle Weld process being among the earliest. Since then metal-to-metal bonding has been the subject of many papers, but no member of a firm of aircraft constructors is known to have lectured on the subject.

It is hoped, therefore, that this paper may prove a useful contribution to the workshop aspects of the method. The fundamentals of adhesion will be avoided and only brief reference will be made to the strengths of structures assembled by that means; those are matters for the physicist and aircraft designer.

This paper presents an improved algorithm for foreign object debris (FOD) detection on the runway with several innovative techniques. The detection scheme incorporates four steps of geometric adjustment, background subtraction, clutter suppression and camouflage elimination. After geometric adjustment, the background model is built for each pixel with a set of RGB colour values taken in the past at the same location or in the neighborhood in the step of background subtraction. The background model samples are substituted randomly with an unfixed update period. Furthermore, the steps of clutter suppression and camouflage elimination are added to modify the segmentation map after background subtraction in order to increase the detection probability and decrease the false alarm rate. The overall algorithm is applied to the test data and real data on the runway. The results show that the RGB-based algorithm performs better than the classical gray-based techniques.

Targeting higher efficiencies and lower fuel consumption of turbomachines, heat transfer and profile loss are research topics of particular interest. In contrast to that, the interaction of both was, so far, rarely investigated, but gains in importance in recent research activities. The profile loss of engine components can be characterised by the airfoil wakes at the blade rows utilising established measurement and evaluation methods for which an adiabatic flow is typically supposed. To enable the investigation of the influence of heat transfer at the blade on the loss characteristics, a novel evaluation procedure was set up. In addition to the pneumatic data, the total temperature in the airfoil wake at a linear cascade was measured by means of a five-hole probe with an integrated thermocouple. For the evaluation and analysis of these data, different definitions of the loss coefficient were investigated and, finally, extended to account for thermal aspects. Furthermore, established techniques to average the local wake data were applied and compared with special focus to their suitability for non-adiabatic cases. Moreover, an extended version of the mixed-out average as defined by Amecke was utilised applying not only a far-reaching consideration of a temperature gradient but also the inclusion of the third spatial dimension to enable the evaluation of field traverses in addition to single wake traverses. These techniques were applied to wake measurement data from a linear compressor cascade gained in a special test set-up in the high-speed cascade wind tunnel for different operating points and different blade temperatures. The suitability of the new methods could be proven, and initial steps of the aerodynamic analysis of the resulting data are presented. Thereby, the acquired techniques turned out as powerful methods for the evaluation of wake traverses on compressor and turbine cascades under non-adiabatic conditions.

A new method for system stability analysis, the weight functions method, is applied to estimate the longitudinal and lateral stability of a Hawker 800XP aircraft. This paper assesses the application of the weight functions method to a real aircraft and a method validation with an eigenvalues stability analysis of the linear small-perturbation equations. The method consists of finding the weight functions that are equal to the number of differential equations required for system modelling. The aircraft’s stability is determined from the sign of the total weight function – the sign should be negative for a stable model. Aerodynamic coefficients and stability derivatives of the mid-size twin-engine corporate aircraft Hawker 800XP are obtained using the in-house FDerivatives code, recently developed at our laboratory of applied research in active controls, avionics and aeroservoelasticity LARCASE. The results are validated with the flight test data supplied by CAE Inc. for all considered flight cases. This aircraft model was chosen because it was part of a research project for FDerivatives code and continued with weight function method for stability analysis in order to develop a design tool, based only on the aircraft geometrical parameters for subsonic regime. The following flight cases are considered: Mach numbers = 0·4 and 0·5, altitudes = 3,000m, 5,000m, 8,000m and 10,000m, and angles-of-attack α = –5° to 20°.

The present paper continues the work of Zhu et al. The closed-form expressions for the evaluation of forces on a body in compressible, viscous and rotational flow derived in the previous paper have been extended to different forms. The expressions require only a knowledge of the velocity field (and its derivatives) in a finite and arbitrarily chosen region enclosing the body. The equations are implemented on three-dimensional inviscid flows over wings and wing/body combinations. Further implementation on three-dimensional viscous flows over wings has also been investigated.

An experimental investigation was carried out of the incompressible boundary layer flow along a flat plate, in the presence of an adverse pressure gradient that corresponds to a linear retardation of the free stream velocity. The turbulence level in the free-stream was 0·12% and transition occurred with the laminar boundary layer being close to separation. For three values of the Reynolds number (2·56, 3·11 and 4·09 million based on the reference length that is defined as the reciprocal of the nondimensional-velocity gradient) the laminar, transitional and turbulent regions were studied by single (normal) hot-wire surveys at several streamwise positions. This allows the fluctuations of the streamwise velocity component to be followed from the amplification of laminar instability waves, through breakdown in the intermittency region, and the subsequent development towards a more or less developed turbulence structure. The study reveals that within the transition region fluctuation levels are reached throughout a large part of the boundary layer that are significantly higher than those in fully developed turbulent flow, which is partly a direct consequence of the intermittent character of the flow. For the highest Reynolds number additional cross-wire surveys were carried out in the turbulent region to observe the development of the turbulent stresses following transition. The data are interpreted in terms of structural coefficients, eddy viscosity and mixing length. Also, these results indicate that the transition process can be associated with turbulence levels well in excess of those occurring in fully developed turbulence, and reveal the relaxation of the outer region turbulence structure.

This short paper is confined to a discussion on one aspect of the Structural Design of Supersonic Transports. It is chosen because it covers the area in which the impact of supersonics is probably most critical from the structural point of view, i.e. kinetic heating.

It is of utmost importance that the significance of kinetic heating is not exaggerated. Adequate attention must be paid to assessing the degree to which past experience is relevant if excess weight is to be avoided.

It is in this direction that the discussion is aimed.

In view of the need to keep the paper short, attention is concentrated on the Mach 2 class of aeroplane constructed largely of aluminium alloy. Much of what is said will also have relevance to the Mach 3 class of aeroplane.

Attention is confined to civil aviation and the present scope of investigating procedures is outlined on a world-wide basis. Deficiencies in these procedures are noted and some suggestions are made for possible future developments of technique. In particular it is suggested that there can be little progress in air safety without the assimilation of “ human engineering data” by investigators and the Industry alike. Opinions expressed are entirely personal to the author and are not associated in any way with the official views of The British Aviation Insurance Co. Ltd.

A new methodology is described to identify aircraft dynamics and extract the corresponding aerodynamic coefficients. The proposed approach makes use of fuzzy modelling for the identification process where input/output data are first classified by means of the concept of fuzzy clustering and then the linguistic rules are extracted from the fuzzy clusters. The fuzzy rule-based models are in the form of affine Takagi-Sugeno models, that are able to approximate a large class of nonlinear systems. A comparative study is performed with existing techniques based on the employment of neural networks, showing interesting advantages of the proposed methodology both for the physical insight of the identified model and the simplicity to obtain accurate results with fewer parameters to be properly tuned.

There appear in the literature some discrepancies in the various mathematical expressions for the upwash constituting the wall interference on a small lifting wing placed symmetrically in a rectangular tunnel with closed side-walls and open floor and roof. The representation of the interference field as that of a doubly infinite array of image doublets is shown to lead to divergence. An independent calculation by relaxation confirms the correctness of an analytical solution by expansion in Fourier series. The discrepancies are found to arise from incomplete flow conditions at the open boundaries, and it is shown in this paper how the various theories are reconciled.

The problem of designing a composite laminated plate subject to multiple loading cases is addressed using the methodology of heuristic redesign. Lower bounds on extensional stiffnesses together with a maximum strain first ply failure criterion constitute the design constraints. The general theory of heuristic redesign and its application to this particular problem are described. Results for different combinations of loading cases and redesign strategies are presented.

Cycloidal rotors are a novel form of propulsion system that can be adapted to various forms of transport such as air and marine vehicles, with a geometrical design differing significantly from the conventional screw propeller. Research on cycloidal rotor design began in the early 1930s and has developed throughout the years to the point where such devices now operate as propulsion systems for various aerospace applications such as micro air vehicles, unmanned air vehicles and compound helicopters. The majority of research conducted on the cycloidal rotor’s aerodynamic performance have not assessed mitigating the dynamic stall effect, which can have a negative impact on the rotor performance when the blades operate in the rotor retreating side. A solution has been proposed to mitigate the dynamic stall effect through employment of active, compliant leading-edge morphing. A review of the current state of the art in this area is presented. A two-dimensional, implicit unsteady numerical analysis was conducted using the commercial computational fluid dynamics software package STAR CCM+, on a two-bladed cycloidal rotor. An overset mesh technique, otherwise known as a chimera mesh, was used to apply complex transient motions to the simulations. Active, compliant leading-edge morphing is applied to an oscillating NACA 0015 aerofoil to attempt to mitigate the dynamic stall whilst maintaining the positive dynamic lift coefficient (Cl) contributions. It was verified that by applying a pulsed input leading-edge rotational morphing schedule, the leading-edge vortex does not fully form and the large flow separation is prevented. Further work in this investigation will focus on coupling the active, leading-edge motion to the cycloidal rotor model with the aim to maximise aerodynamic performance.

The scope of the subject is a challenging, if not a forbidding, one. It is to trace the evolution of routes, capacity, charters, designation and rates from Chicago to the present day. Collectively, these issues encompass the question of governmental regulation of the international air transport market and embrace the total air transport system. However, there is no attempt to catalogue the specific of these policy developments worldwide. Rather, it is attempted to analyse the foundations of international aviation policy, in a shorthand steeplechase through the past, present and into the future and, in this way, to offer some interpretations of the developments over the past thirty years. In so doing, it is hoped to place in perspective the complexity of the international system and the many interrelated factors which must be taken into account by those who bear the heavy responsibility of determining national policies.

Avoiding collisions with other aircraft is an absolutely fundamental capability for semi-autonomous UAVs. However, an aircraft avoiding moving obstacles requires an evasive tactic that is simultaneously very quick to compute, compatible with the platform’s flight dynamics, and deals with the subtle spatio-temporal features of the threat.

We will give an overview of a novel prototype method of rapidly generating smooth flight-paths constrained to avoid moving obstacles, using an efficient trajectory-optimisation technique. Obstacles are described in terms of simple geometrical shapes, such as ellipsoids, whose centres and shapes can vary with time. The technique generates a spatio-temporal trajectory which offers a high likelihood of avoiding the volume in space-time excluded by the predicted motion of each of the known obstacles. Such a flight-path could then be passed to the aircraft’s flight-control systems to negotiate the threat posed by the obstacles. Results from a demonstration implementation of the collision-avoidance technique will be discussed, including non-trivial scenarios handled well within 100ms on a 300MHz processor.

The concept of the manoeuvre margin is discussed, and definitions are suggested which are applicable to all types of configurations. Calculations are presented for the manoeuvre characteristics of simplified flexible models representing conventional and slender integrated aircraft. Linear aerodynamics only are assumed.

Control of agricultural pests and diseases has been attempted for well over one thousand years, but it is only during the present century that the means have been available to combat the problems on a large scale by the use of pesticides. The contribution which pesticides have made to the reduction of crop losses is enormous. However, the fact that significant losses of production still occur shows that they are not a complete or simple answer to the problems.

When used in the broadest sense the term ‘pest' applies to a wide range of plant and animal organisms which adversely affect the crops grown by man. Attention here will be restricted to invertebrate pests and crop diseases.