Inverse dynamics is investigated as an efficient means of generating large angle satellite attitude slew manoeuvres. The required slew manoeuvres are specified using high order polynomials which result in a smooth control torque profile. Such smooth torque profiles are of importance in avoiding excitation of elastic modes of the satellite structure. In addition, the polynomial functions may be used to define a slew trajectory between arbitrary initial and final states allowing track-to-track manoeuvres. To compensate for uncertainties in the satellite dynamics, the inverse control is extended to include feedback linearisation about the nominal reference trajectory. It is shown that for rest-to-rest slew manoeuvres the resulting composite control is robust to uncertainties in the satellite inertia matrix and to actuator degradation. In addition, it is shown that complex paths may be generated through the use of high order polynomial functions which contain all the information required to enforce user defined constraints and boundary conditions in a compact, computationally efficient form.

Aspects of numerical simulation of aircraft program flight along a predetermined trajectory are presented. An emphasis is laid on the problem of describing the required trajectory by means of a succession of defined points. A spline function method is used for interpolation and smoothing routines. Some numerical illustrations of aircraft trajectory flight simulation (only planar motion) are demonstrated and discussed.

A survey is presented of results obtained from experiments in the RAE 5m low-speed pressurised wind tunnel. The tunnel is capable of operation over a range of pressures (from one to three atmospheres) so that the effects of Mach and Reynolds number may be separated. This decoupling of scale and compressibility effects has made possible reliable extrapolation of test results to full-scale conditions (where this is necessary) as well as giving greater insight into the underlying flow mechanisms. The large size of the tunnel, combined with pressurisation to three atmospheres, has enabled some tests, on small combat/trainer aircraft and on bomb-like stores, to be carried out at full scale.

Three facets of the work of the 5m tunnel are described — work aimed at predicting or improving the high-lift performance of specific aircraft, work of a more fundamental nature concerned particularly with the optimisation of high-lift devices on generalised research models, and work on the drag of stores carried externally on combat aircraft.

A symmetric Mach 12·76 hypersonic flow in a 90° corner, formed by 30° swept back intersecting 8° wedges, was investigated in detail through numerical simulation using locally conical Navier-Stokes equations. Three different numerical schemes for spatial discretisation, MacCormack central differencing, van Leer’s flux vector splitting and Osher’s flux difference splitting, were studied to compare their capabilities to capture both strong shock waves and thin shear layers. Comparison with experimental data was made to validate the simulation. The numerical simulation provided further insight into the flowfield and a pair of counter-rotating vortices were discovered near the junction of the corner.

The 48th Wilbur Wright Memorial Lecture, “Mathematics and Aeronautics” was given by Mr. M. J. Lighthill, F.R.S., before a large and distinguished audience at the Institution of Mechanical Engineers, 1 Birdcage Walk, on 19th May 1960. Dr. E. S. Moult, C.B.E., B.Sc, F.R.Ae.S., M.I.Mech.E., President of the Society, presided.

As has become the custom, before the lecture was delivered the President presented the awards made by the Council for 1960 for outstanding contributions to aeronautics. In the unavoidable absence of the Secretary he was assisted by Miss E. C. Pike, M.A., A.F.R.Ae.S., Secretary of the Medals and Awards Committee and Editor of The Aeronautical Quarterly. The list of the awards presented on this occasion was published in the June 1960 Journal—(p. XXXII).

The President, introducing the lecturer, reminded the audience that the Wilbur Wright Lecture commemorated the first manned, powered controlled flight by Wilbur Wright at Kitty Hawk, North Carolina on 17th December 1903. The first Wilbur Wright Memorial Lecture was held in 1913 and they had been held each year ever since, through two World Wars; in itself a wonderful record. The custom had been, and would continue to be, to have alternately a lecturer from the United Kingdom and a lecturer from the United States; last year the lecture had been by Mr. McCarthy of Chance Vought and next year again it would be by an American.

The Wilbur Wright Lectures had been a most distinguished series by distinguished lecturers, and he was sure that the lecture that night would be in keeping. His pleasant duty was to introduce Professor Lighthill—or as they had to call him Mr. Lighthill now that he was Director of the Royal Aircraft Establishment, which was an even greater distinction. Mr. Lighthill was the youngest Director that the R.A.E. had ever had—that alone was a tribute to Mr. Lighthill's ability and his high standing in the profession. Before joining the Royal Aircraft Establishment Mr. Lighthill was Professor of Applied Mathematics at Manchester University, and for a time, after leaving Cambridge, had worked at the National Physical Laboratory where he applied the mathematics of Cambridge to the problems of aerodynamics. His lecture was on “Mathematics and Aeronautics” he would ask Mr. Lighthill to deliver the 48th Wilbur Wright Memorial Lecture.

There is very little information on the stress concentration which is caused by a notch on one side of a plate in tension and the authors are not aware of any published data based on experiment. The theoretical solutions due to Neuber are for notches of hyperbolic or elliptic form and only give an approximate result for U-notches of varying depth.

The effectiveness of any braking system is ultimately limited by the point at which the wheels lock and slide over the surface on which the stop is being made. When surfaces are clean and dry the adhesion with a rubber tyre is high enough to meet most requirements of braking without risk of skidding. In wet, or in icy conditions, however, adhesion may be reduced to such an extent that, even with efficient brakes, stopping distances are greatly increased and dangerous conditions can arise. Under wet conditions there are special difficulties. Different surfaces may have very different skid-resisting properties and, in addition, when surfaces are wet, the adhesion with a tyre depends on speed, generally diminishing as speed is raised.

This paper describes an evaluation of the longitudinal flying qualities of a generic blended-wing-body (BWB) transport aircraft at low speed flight conditions. Aerodynamic data was obtained from several sources and integrated into the equations of motion of a typical BWB configuration in order to provide a reasonable basis for flying qualities assessment. The control requirements to trim are enumerated for a representative range of cg position and static margin over the typical range of approach speeds for both stable and unstable configurations. The linear dynamic characteristics of the unaugmented airframe are also described for the same range of stability margin. Subsequent work describes the development of a rate command-attitude hold command and stability augmentation system configured to comply with representative modern handling criteria. Finally, the flight dynamics of the augmented aircraft are described after refinement of the control law by means of piloted simulation in a fixed base flight simulator.

Airports have been frequently affected by different internal and external disruptive events, which generally deteriorated their planned/regular performances. Their resilience is defined as the ability to withstand and maintain a certain level of functionality of performances compared to their reference regular/planned level during the impact of disruptive events and to recover reasonably rapidly afterwards. Robustness is defined as the level of saved functionality of performances compared to their planned/regular level, enabling continuous operations during the impact of disruptive events. The level of deteriorated functionality compared to that of the planned/regular functionality of performances represents their vulnerability. This paper develops a methodology for assessing resilience, robustness and vulnerability of airports affected by a given disruptive event(s). The methodology consists of analytical models of indicators of operational, economic, social and environmental performances of airports and other main actors/stakeholders involved. These indicators are used as figures-of-merit in analytical models for assessing their cumulative and time-dependent resilience, robustness, and vulnerability. The methodology is applied to assess resilience, robustness and vulnerability of two large airports – LHR (London Heathrow, UK) and NYC JFK (John F. Kennedy, US) – affected by a global and lasting external disruptive event – the COVID-19 pandemic disease. Based on the indicators of operational and economic performances, the results indicate very low resilience and robustness and very high vulnerability of both airports and their other main actors/stakeholders involved. Their resilience and robustness based on the indicators of social and environmental performances were not substantively different from the corresponding vulnerability. In absolute terms, LHR airport has been affected stronger than its NYC JFK counterpart. Savings in costs/externalities during the observed period under the given conditions have modestly compensated for total losses of both airports and their main actors/stakeholders involved.

Civil aircraft that fly long ranges consume a large fraction of civil aviation fuel, injecting an important amount of aviation carbon into the atmosphere. Decarbonising solutions must consider this sector. A philosophical-analytical feasibility of an airliner family to assist in the elimination of carbon dioxide emissions from civil aviation is proposed. It comprises four models based on the integration of the body of a large two-deck airliner with the engines, wings and flight surfaces of a long-range twin widebody jet. The objective of the investigation presented here is to evaluate the impact of liquid hydrogen tank technology in terms of gravimetric efficiency. A range of hydrogen storage gravimetric efficiencies was evaluated; from a pessimistic value of 0.30 to a futuristic value of 0.85. This parameter has a profound influence on the overall fuel system weight and an impact on the integrated performance. The resulting impact is relatively small for the short-range aircraft; it increases with range and is important for the longer-range aircraft. For shorter-range aircraft variants, the tanks needed to store the hydrogen are relatively small, so the impact of tank weight is not significant. Longer range aircraft are weight constrained and the influence of tank weight is important. In the case of the longest range, the deliverable distance increases from slightly over 4,000 nautical miles, with a gravimetric efficiency of 0.3, to nearly 7,000 with a gravimetric efficiency of 0.85.

A theoretical and experimental investigation has been made into the effect of swirl on a supersonic jet. In certain circumstances a core of reversed flow can occur along the axis of symmetry and the jet mixes much more quickly with the ambient air than does the corresponding non-rotating jet. A characteristic calculation has been performed for the first cell in the case where the axial flow is not reversed. This indicates a shortening of the cell length and the formation of shocks nearer the nozzle.

A three-dimensional integral formulation for the solution of the full potential equation and the associated numerical algorithm, the field-integral method, are presented. The method is a direct extension of a two-dimensional method and in particular retains the simple grid generation requirements noted in that method. Results are presented for the flow over body shapes and a complex winglet configuration, and are compared with existing transonic methods and experiments with good agreement. The further work necessary to provide a fast, robust method for use in design is outlined.

Wind tunnel tests have been made on the effect of bottom wall and sidewall fences of various sizes and combinations in reducing the swirl of an S-duct at high angle of attack. It is shown that large reductions can be made: in some cases the swirl is eliminated or even reversed. Fences of modest size can be chosen to combine a large swirl reduction with an improvement of the total pressure distortion at high incidence and only a small effect on mean pressure recovery at low incidence. Some further observations are made on the nature of the general swirl phenomenon.

In this paper, helicopter rotor blades are analysed in hover using computational fluid dynamics (CFD) coupled with a structural model. The method relies on a mesh deformation algorithm that allows for exchange of forces and deformations between a beam-based finite-element model and the fluid flow volume mesh. The method is demonstrated against experimental data, and the aerodynamic predictions appear to improve when the aeroelastic model is used. For all employed cases the flexibility of the method allows the CFD mesh deformation to be spread over the computational domain in a controlled fashion. The influence of the aeroelastic deformations on the blade loads was limited yet evident on the rotor performance. The lack of adequate test cases and experiments for validation of CFD/CSD methods is also highlighted.

In this paper we present a Bayesian belief network (BBN) socio-technical model for investigating the accident rate for multi-crew civil airline aircraft. The model emphasises the influence of airline policy and societal behaviour patterns on the pilots within the piloting system. The main claim of this paper is that a BBN can be used to bring most aviation safety-critical elements into a common quantitative safety assessment despite the unique problems posed by the very low probability of accidents. We support this claim by replicating certain phenomena such as the low accident rate, the difference between the ‘more’ and ‘less’ safe airlines and other statistical factors of civil aviation. In particular, the model succeeds in explaining the large gap of six to seven orders of magnitude between in-flight measurements of pilots’ error and accident rate.

Flow separation results in many problems to single expansion ramp nozzle (SERN) and hypersonic vehicle. However, little research has been conducted on the separation patterns and their effects on SERN’s performance. In the present paper, the numerical simulation is adopted to get the intuitive results and help to analyse the separation phenomena in SERN thoroughly. The main separation pattern is the restricted shock separation (RSS) in SERN, and the free shock separation (FSS) only appears in a small range of the nozzle pressure ratio (NPR), which is much different from the axisymmetric rocket nozzle. Further CFD results show that the separation pattern transition makes great effects on the performance of SERN, especially the lift. Moreover, the performance of SERN has an extreme in the separation pattern transition because of the main jet impinging on the expansion ramp. The transitions occur in both the startup and shutdown processes but the critical nozzle pressure ratios of the separation pattern transitions are different, which leads to a hysteresis loop of SERN performance.

This paper assesses the financial performance of 35 European airports for the decade 1990 to 2000, comparing those subject to partial or full privatisation with those still in public ownership. In contrast to earlier research, the outcomes of partial factor productivity (PFP), financial ratio (FRA) and data envelopment analysis (DEA) are evaluated, in order to investigate differences attributable to the degree of privatisation. Changes in performance after a change in ownership structure are reviewed. The analysis of sample data reveals economically meaningful and statistically significant differences between publicly owned and privatised airports. The major differences lie in operating efficiency, capital productivity and capital structure. Although partially and fully privatised airports operate more efficiently, this does not translate into significantly higher returns on shareholders’ funds. Due to their at least indirectly government-backed credit standing, publicly owned airport companies can assume more debt relative to their respective equity. This results in considerably higher gearing and financial leverage, which compensates for the comparatively low return rate on assets.

Automated manufacturing of thermoplastic composites has found increased interest in aerospace applications over the past three decades because of its great potential in low-cost, high rate, repeatable production of high performance composite structures. Experimental validation is a key element in the development of structures made using this emerging technology. In this work, a $750\times640\times240$ mm variable-stiffness unitised integrated-stiffener out-of-autoclave thermoplastic composite wingbox is tested for a combined shear-bending-torsion induced buckling load. The wingbox is manufactured by in-situ consolidation using a laser-assisted automated tape placement technique. It is made and tested as a demonstrator section located at 85% of the wing semi-span of a B-737/A320 sized aircraft. A bespoke in-house test rig and two aluminium dummy wingboxes are also designed and manufactured for testing the wingbox assembly which spans more than 3m. Prior to testing, the wingbox assembly and the test rig were analysed using a high fidelity finite element method to minimise the failure risk due to the applied load case. The experimental test results of the wingbox are also compared with the predictions made by a numerical study performed by nonlinear finite element analysis showing less than 5% difference in load-displacement behaviour and buckling load and full agreement in predicting the buckling mode shape.

This paper presents a novel method for quantifying the effect of ambient, environmental and operating conditions on the progression of degradation in aircraft gas turbines based on the measured engine and environmental parameters. The proposed equivalent operating time (EOT) model considers the degradation modes of fouling, erosion, and blade-tip wear due to creep strain, and expresses the actual degradation rate over the engine clock time relative to a pre-defined reference condition. In this work, the effects of changing environmental and engine operating conditions on the EOT for the core engine booster compressor and the high-pressure turbine were assessed by performance simulation with an engine model. The application to a single and multiple flight scenarios showed that, compared to the actual engine clock time, the EOT provides a clear description of component degradation, prediction of remaining useful life, and sufficient margin for maintenance action to be planned and performed before functional failure.

Numerous military platforms (land, sea and air) feature serial data bus technology based on the US MIL-STD-1553B data bus standard for integration of their digital systems. Many of these platforms have 15-20 years of operational life remaining, but the installed 1553B data buses (data networks) having only a 1Mbit/sec transfer rate are unable to meet many of the future data networking requirements. Research into new, higher performance data networks has concentrated on modern alternatives with throughput increases of two to three orders of magnitude (100Mbit/sec to 1Gbit/sec). These are generally based on modern commercial-off-the-shelf (COTS) standards, good examples being Ethernet and Fibre Channel. Some are already being employed in military platforms having been ruggedised for the harsh physical and electro-magnetic environment. However these COTS systems while being a natural choice for new platforms may not be cost effective for upgrading older platforms. This paper plots the history of MIL-STD-1553, possibly the most successful military platform standard of all time, and discusses some of the options for increasing its performance and economically extending its life into the future.