An experimental study has been performed manipulating a fully developed turbulent channel flow, by means of blade manipulators known as outer layer devices (Olds). A large amount of investigation has been performed for boundary layer flow, whereas little research is available for internal flow manipulation. The influence on drag reduction for different configurations (single and tandem) and for some geometric parameters (distance from the wall and blade gap), have been analysed. Reynolds number effect has also been investigated. Some of the mechanisms involved in the skin friction reduction process are examined, in terms of time-space integral scales, Reynolds stresses and spectral analysis. Results show better efficiency for tandem configurations. These give high local skin friction reductions, up to 20%, which are strongly dependent on the manipulator distance from the wall, but have very little dependence on the blade gap and Reynolds number. Turbulence analysis displays reduced fluctuations in all three directions — as with space-time integral scales. Evidence of suppression for the large structures is also shown by spectral analysis. From a global balance it has been verified that no net drag reduction is obtained due to the additional drag introduced by the manipulators.

The loss of torsional or flexural stiffness due to thermal stresses in a thin solid wing is now well known and has been considered by a number of authors, e.g. Dryden and Duberg, Vosteen and Fuller, Bisplinghoff, Hoff, Budiansky and Mayers, Argyris, and the present author. Exact analyses are available only for the “one-dimensional” case of a wing of infinite aspect ratio with arbitrary chordwise distribution of wing thickness and temperature. The loss of stiffness in a similar wing of finite aspect ratio is not as great and, in particular, the proportional reduction in flexural stiffness in a low aspect ratio wing will tend to be less than the proportional reduction in torsional stiffness.

In Ref. 1, Professor D. W. Holder describes a very interesting experiment pertaining to shock wave position and boundary layer separation in supersonic nozzles at low Mach numbers (M ⩽ 1·4). A closer examination of this experiment indicates that the results may only be applicable in the Mach number range of M < 1·48, not in the range of M> 1·48.

The results of the subsonic doublet lattice method (DLM), i.e. generalised unsteady aerodynamic forces (GAFs) at a set of reduced frequencies, are often used as input to the solution of the flutter equation. Solutions of the flutter equation are usually required at many more reduced frequencies than GAFs are calculated for by the DLM and some form of interpolation is therefore required. In the p-k formulation of Rodden, Harder and Bellinger, the imaginary part of the GAFs appear as QI/k, i.e. the imaginary part of the GAFs divided by the reduced frequency. In the case of real (i.e. non-oscillatory) roots of the flutter equation, the solution is determined entirely by the steady GAFs and the limiting value of QI/k at zero frequency. This is also true of the g-method of flutter solution as the two formulations are equivalent at k = 0. Expressions are derived for calculating the limiting values of QI/k directly from the DLM, thereby making the real roots independent of the interpolation of the GAFs. The exact way in which the low frequency DLM results are interpolated has a small effect on the interpolation quality in the case of the p-k flutter equation, whereas it has a significant qualitative effect on the results of the g-method of flutter solution of Chen.

A Fast and efficient method has been developed to obtain the equilibrium composition of a flame at a given temperature, pressure and mixture strength. The Newton-Raphson iteration technique enables one to solve a set of simultaneous non-linear equations and in the present problem these are the equations relating the equilibrium partial pressures and equilibrium constants for the particular reaction and the conservation of atomic species in reactants and products. A trial solution is used to check the energy balance for the flame at the assumed temperature. The temperature is then suitably altered and the whole procedure is repeated till a reasonable agreement is obtained.

Airbus and Boeing are cooperatively presenting this topic dealing with transport aircraft stalls. The paper will begin by defining a stall, followed by a review of requirements, predictive validation and flight testing. There are various ways of designing modern jet transports for the stall regime such as aerodynamic approaches, flight deck indications, and augmentation control laws to deal with the high angle-of-attack (α) arena. The goal of augmented control laws for high α is common – no full aerodynamic stall or loss of climb performance should occur in the operational flight envelope, in Normal flight control modes. The validation techniques employed in preparation for a flight test campaign will follow. These include flight characteristic predictions based on wind-tunnel data as well as pilot-in-the-loop simulation rehearsals. The preparation for flight testing will be reviewed from both the engineer and pilot viewpoints. This will be followed by a review of various flight testing that has been conducted. The paper will close with a brief foray into what the future of transport stalls could be – perhaps protection features in degraded flight control modes? What are the benefits as well as drawbacks to increased augmentation for high α?

The effort required to produce very accurate supersonic nozzles has suggested the need for criteria from which the order of accuracy required for quantitative experiments can be deduced. The purpose of this note is to indicate a way of obtaining such criteria for measurements of aerodynamic forces, but also to point out that “ sufficiently accurate ” nozzles for such measurements are indeed very difficult to produce and to suggest that a remedy might first be sought in interference corrections.

This paper attempts to develop an efficient online algorithm for terrain following in completely unknown rough terrain environments while incorporating aircraft dynamics in the guidance strategy. Unlike most existing works, the proposed algorithm does not generate the flight path directly. The algorithm employs acquired information from the vehicle onboard sensors and rapidly issues appropriate Guidance Commands (GCs) at every point along the way. A suitable dynamic model is developed which takes the lags in the vehicle dynamics into account. The flight path forms gradually as a result of applying the GCs to the vehicle dynamics. Terrain-conforming capability afforded by this approach allows for autonomous and safe low-level flight in unknown mountainous areas. It considerably enhances the autonomy level of the vehicle and in the case of manned aircraft could significantly lead to pilot workload reduction. The proposed scheme is proven to be promising for online applications.

The Sixteenth British Commonwealth Lecture, The Story of Indian Air Transport, by Mr. J. R. D. Tata, Chairman of Air-India International, was given before a distinguished audience on 18th November 1960 at the Institution of Mechanical Engineers, Birdcage Walk, London, S.W.1.

The President of the Society, Dr. E. S. Moult, C.B.E., B.Sc., F.R.Ae.S., M.I.Mech.E., presided at the meeting. Before introducing the Lecturer the President explained that hitherto the election of Fellows had been initiated by the Council and announced once a year but, under the new By-Laws, Fellowship was to be regarded as a position which could be attained by any qualified member who had reached a position of eminence and responsibility in the profession of aeronautics. At the same time it had been decided that the announcement of such elections should be made not just once a year, but on occasions such as this.

The names of 22 members who had been elected to Fellowship since May 1960 were then read out by the Secretary. (These names were published in the December Journal–Ed.)

After congratulating the new Fellows, Dr. Moult said that the British Commonwealth series of lectures started at the end of the War in 1945, and had continued annually until the present day. Throughout the years they had had a series of outstanding lectures on subjects associated with aeronautics in the Commonwealth, given by most distinguished lecturers. The stature of this lecture was set for all time in 1954 when His Royal Highness The Duke of Edinburgh addressed them on “Aviation and the Development of Remote Areas”. Now they were to hear about the growth of aviation in one of the great members of the Commonwealth. Air Transport in India was now thirty years old1 and there was no one more suited to tell the story of that thirty years than their lecturer, Mr. J. R. D. Tata.

Mr. Tata had been actively associated with this development all his working life. Indeed, it was true to say he had had a major part in it. He learned to fly in 1929 and personally flew the first scheduled transport service in India in 1932. He had been associated with aviation throughout all these years and a few years ago was president of I.A.T.A., the International Air Transport Association; he was now Chairman of Air-India International. He had great pleasure in asking Mr. Tata to give the Sixteenth British Commonwealth Lecture, “The Story of Indian Air Transport.”

Alec Young spent over 30 years in academic life. He has been active, not only in nurturing the teaching of and research in aeronautical engineering, first in the Aerodynamics Department at Cranfield College of Aeronautics, and then in the Department of Aeronautical Engineering at Queen Mary College, but also in participating in wider academic developments as Vice Principal of Queen Mary College and as Senator of the University of London. Hence, it is appropriate that in such a tribute, there should be an article on an academic topic. A review of undergraduate aeronautical engineering education, its past, present, and future, has been chosen. Such a review is timely as a contribution to the current debate on engineering education in general, initiated by the newly formed Engineering Council.

In this paper I have endeavoured to give an account of the various methods which have been employed in the past ten years to alter—for better or worse— the conditions in the boundary layer of a body in turbulent flow. I have refrained from speaking of “ control ” in reference to the-boundary layer, since in the minds of most people, this implies an amelioration of the flow and a reduction of drag. As will appear in what follows, some of the devices in which I and other experimenters have been concerned have just the opposite effect. Nevertheless, following the principles current in clinical research in medicine, I think we should find both what conditions will cause “ deterioration ”—if one may use the term—as well as those which will cause “ improvement ” of the flow round a body, if we are to progress in our knowledge of the state of affairs in the boundary layer. Working rather on my own in aerodynamics and not being committed to any rigid programme of research, I have followed my bent to explore unorthodox paths of experiment, the results of which I present with some diffidence in the hope that engineers may pursue them further with better equipment. I am afraid I have not gone deeply into the vexed question of the efficiency—in the engineering sense—of the devices I am going to describe to you, since, as a physicist that—nevertheless, important—aspect of the question does not interest me.

This paper presents a short account of the flight control systems used in commercial transport, military combat and general aviation aircraft. The effects of aircraft safety, reliability and weather delays on satisfactory aircraft operations are shown to be significant reasons for the extensive use of flight control systems. The principles of flight control, the sensors and actuators required and the various modes which can be selected are treated, together with a short account of the primary flying controls and the use of manual reversion in emergency situations. The paper concludes with a consideration of the fly-by-wire (FBW) and fly-fby-light concepts, and covers relaxed static stability, carefree manoeuvring and the use of canards before discussing some FBW flight control systems which are used in passenger aircraft.

Research on propeller performance has been reinvigorated by the development of new classes of vehicles, ranging from electrically powered fixed-wing aircraft, to multi-rotor electrical Vertical Take-off/Landing (eVTOL) vehicles and tilt-rotor aircraft. These types of aircraft utilise a range of modern propellers, often with more advanced planforms and features such as anhedral, and operate in flight envelopes that are outwith the traditional bands of performance. The use of advanced materials (mostly composites), high geometrical sweeps and variable angular velocities are the source of unsteady aerodynamics, that is often coupled with the blade’s structural response. Data from experimental investigations is mostly historic, with the majority of studies conducted before 1960, when aviation shifted rapidly towards jet propulsion. These studies lack in flutter boundary assessment. Modern propellers are likely to be pushed toward their flutter boundaries, but the experimental database published to-date is insufficient to provide flutter boundary assessment. This review examines the value of the available experimental research and the status of the state-of-the-art numerical methods, in order to establish the requirements for modern research on propeller stall flutter.

In this paper, we present a new force-feedback side-stick which has been developed and integrated into a research flight simulator. The developed 2 Degrees of Freedom (DOF) force-feedback joystick, as a kind of haptic device, provides two-way communication in both position and force, and allows users to interact with the simulation system. It has been designed by considering the main factors in designing a general use force-feedback device. Thus, the design must allow the restitution of aerodynamic forces onto the hand of the pilot. This is an important feature, which gives the pilot the ‘natural feel’ of traditional mechanical aircraft control. In order to provide the force feedback to enhance the realism of the simulation, we added the necessary software using Commercial-Off-the-Shelf (COTS) solutions (Microsoft Flight Simulator Software (MSFS)) and built-in data structure and methods. Thus, the main contribution of this paper concerns the design and implementation of an automatic controller based on fuzzy logic systems. It is not simply designing a force-feedback stick for flight simulation: we proposed a novel control principles and more importantly completely new approach to compute in real-time force feedback on the stick based on pilot knowledge that avoids the use of complex aerodynamics equations with unknown parameters. To our best knowledge, this work is the first to propose the integration of fuzzy logic force controller in flight simulation for creating force feedback. Results using the overall simulation are presented and evaluated and interesting sensations have been recorded.

Sensed data from high-value engineering systems is being increasingly exploited to optimise their operation and maintenance. In aerospace, returning all measured data to a central repository is prohibitively expensive, often causing useful, high-value data to be discarded. The ability to detect, prioritise and return useful data on asset and in real-time is vital to move toward more sustainable maintenance activities.

We present a data-driven solution for on-line detection and prioritisation of anomalous data that is centrally processed and used to update individualised digital twins (DT) distributed onto remote machines. The DT is embodied as a convolutional neural network (CNN) optimised for real-time execution on a resource constrained gas turbine monitoring computer. The CNN generates a state prediction with uncertainty, which is used as a metric to select informative data for transfer to a remote fleet monitoring system. The received data is screened for faults before updating the weights on the CNN, which are synchronised between real and virtual asset.

Results show the successful detection of a known in-flight engine fault and the collection of data related to high novelty pre-cursor events that were previously unrecognised. We demonstrate that data related to novel operation are also identified for transfer to the fleet monitoring system, allowing model improvement by retraining. In addition to these industrial dataset results, reproducible examples are provided for a public domain NASA dataset.

The data prioritisation solution is capable of running in real-time on production-standard low-power embedded hardware and is deployed on the Rolls-Royce Pearl 15 engines.

In recent years, there has been an increasing interest in the research and development of hybrid airships for various applications. Airship design involves multiple design parameters from various disciplines that interact mutually. Existing design methodologies, however, are often limited to fixed shapes and geometry. This paper provides a comprehensive parametric design approach for the sizing of multi-lobed hybrid air vehicles for low- and high-altitude applications. The proposed design techniques are robust so that the designer has the freedom to change the number of lobes, the relative location of lobes, the envelope profile, and the optimiser for the design optimisation process. The outcomes of the proposed methodology are envelope volume, wetted surface area, length and span of the envelope, sizing and layout of the solar array, and sizing and layout of the fins. The modeling techniques highlighted in this paper are very efficient for the design and optimisation of multi-lobed airships in the conceptual design phase with a large design exploration space. The robustness of the shape generation algorithms is tested on some of the standard envelope profiles of airships. The effect of the shape and geometry of the multi-lobed envelope on added mass is demonstrated through the added mass estimation using Boundary Element Method.

In the early era of aviation, Frederick Lanchester was both an inventor and a theoretician driven by the need for a theory of flight that would reduce the guesswork in designing new aircraft. His book Aerodynamics in 1907 laid down the early foundations of such a theory. The theory with contributions from others, notably Ludwig Prandtl, was refined to become the basis for the sleek designs of WWII aircraft brought about with little guesswork. New technology changed aircraft design radically with the increased speed of jet propulsion reaching into the transonic range with nonlinear aerodynamics. In the late 1940s and early 1950s substantial guesswork returned to aircraft design. The legacy of Lanchester et al., however, lived on with the development of computational fluid dynamics (CFD) that could guide designers through nonlinear transonic effects. This article presents a historical sketch of how CFD developed, illustrated with examples explaining some of the difficulties overcome in the design of the first-generation swept-wing transonic fighters. The historical study is forensic CFD in search for the likely explanation of the designer’s choice for the wing shape that went into production a long time ago. The capability of current CFD applied to the aerodynamics of aircraft with slender wings is surveyed. The cases discussed involve flow patterns with coherent vortices over hybrid wings and wings of moderate sweep. Vortex-flow aerodynamics pertains to understanding the interaction of concentrated vortices with aircraft components. Modern Reynolds-Averaged Navier-Stokes (RANS) technology is useful to predict attached flow. But vortex interaction with other vortices and breakdown lead to unsteady, largely separated flow which has been found out of scope for RANS. Direct simulation of the Navier-Stokes equations is out of computational reach in the foreseeable future, and the need for better physical modeling is evident. Both cruise performance and stalling characteristics are influenced by strong interactions. Two important aspects of wing-flow physics are discussed: separation from a smooth surface that creates a vortex, and vortex bursting, the abrupt breakdown of a vortex with a subsequent loss of lift. Vortex aerodynamics of not-so-slender wings encounter particularly challenging problems, and it is shown how the design of early-generation operational aircraft surmounted these difficulties. Through use of forensic CFD, the article concludes with two case studies of aerodynamic design: how the Saab J29A wing maintains control authority near stall, and how the Saab J32 mitigates pitch-up instability at high incidence.

In this paper, we investigate the constrained attitude control problem of hypersonic vehicles (HVs). An improved prescribed performance dynamic surface control method is proposed based on an adaptive scaling strategy. Because of the uncertain time-varying disturbances, the controlled state may violate the constraint in the prescribed performance control (PPC) framework. An adaptive scaling strategy is introduced in the PPC method to avoid state violation. The performance function is scaled with respect to the state adaptively. Moreover, a nonlinear disturbance observer is used to compensate the sum of external and other internal disturbances of the system. The proposed method improves the system dynamic performance while ensuring the system robustness. Furthermore, the stability of the closed-loop system is proved by Lyapunov analysis. Finally, numerical simulations are implemented to verify the effectiveness of the PPC method and superiority over other methods.