This special issue is one of a number of activities taking place this year to celebrate the founding of the Royal Aeronautical Society in 1866. The decision to form the Society was taken on 12 January 1866 at a meeting of distinguished people held in London and chaired by the Duke of Argyll. One of those present, James Glaisher, addressed the gathering and it is interesting to revisit an extract from his statement: “The first application of the balloon as a means of ascending into the upper regions of the atmosphere has been almost within the recollection of men now living but with the exception of some of the early experimenters it has scarcely occupied the attention of scientific men, nor has the subject of aeronautics been properly recognised as a distinct branch of science. . .”. The meeting resolved “that it is desirable to form a Society for the purpose of increasing by experiments our knowledge of Aeronautics and for other purposes incidental thereto and that a Society be now formed under the title of the ‘Aeronautical Society of Great Britain’ to be supported by annual subscriptions and donations.”

The paper presents the results of the aerodynamic optimisation of an Unmanned Aerial System's wing using a morphing approach. The shape deformation of the wing is achieved by placing actuator lines at several positions along its span. For each flight condition, the optimal displacements are found by using a combination of the new Artificial Bee Colony algorithm and a classical gradient-based search routine. The wing aerodynamic characteristics are calculated with an efficient nonlinear lifting line method coupled with a two-dimensional viscous flow solver. The optimisations are performed at angles of attack below the maximum lift angle, with the aim of improving the Hydra Technologies UAS-S4 wing lift-to-drag ratio. Several configurations of the morphing wing are proposed, each with a different number of actuation lines, and the improvements obtained by these configurations are analysed and compared.

Efforts to develop the next generation of aircraft with ever-increasing levels of performance – higher, farther, faster, cheaper – face great technical challenges. One of these technical challenges is to reduce structural weight of the aircraft. Another is to look to aircraft configurations that have been unrealizable to date. Both of these paths can lead to a rigid flex coupling phenomenon that can result in anything from poor flying qualities to the loss of an aircraft due to flutter. This has led to a need to develop an integrated flight and aeroelastic control capability where structural dynamics are included in the synthesis of flight control laws. Studies have indicated that the application of an integrated flight and aeroelastic control approach to a SensorCraft high-altitude long-endurance vehicle would provide substantial performance improvement(1,2). Better flying qualities and an expanded flight envelope through multi-flutter mode control are two areas of improvement afforded by integrated flight and aeroelastic control. By itself, multi-flutter mode control transforms the flutter barrier from a point of catastrophic structural failure to a benign region of flight. This paper discusses the history and issues associated with the development of such an integrated flight and aeroelastic control system for the X-56A aircraft.

This application paper describes a novel, cluster-based, semi-automatic, stream surface placement strategy for structured and unstructured computational fluid dynamics (CFD) data, tailored towards a specific application: The BLOODHOUND jet and rocket propelled land speed record vehicle. An existing automatic stream surface placement algorithm(8), is extensively modified to cater for large unstructured CFD simulation data. The existing algorithm uses hierarchical clustering of velocity and distance vectors to find potential stream surface seeding locations. This work replaces the hierarchical clustering algorithm, designed to work with small regular grids, with a K-means clustering approach suitable for large unstructured grids. Modifications are made to the seeding curve construction algorithm, improving the smoothness and distribution of the discretised curve in complex cases. A new distance function is described which allows the user to target particular characteristics of simulation data. The proposed algorithm reduces the required memory footprint and computational requirement compared to previous work(8). The performance and effectiveness of the proposed algorithm is demonstrated, and CFD domain expert evaluation is provided describing the value of this approach.

The aerodynamic and structural design of a pitching blade tip with a double-swept planform is presented. The authors demonstrate how high-fidelity finite element (FE) and computational fluid dynamic (CFD) simulations are successfully used in the design phase. Eigenfrequencies, deformation, and stress distributions are evaluated by means of a three-dimensional (3D) FE model. Unsteady Reynolds-averaged Navier-Stokes (RANS) simulations are compared to experimental data for a light dynamic stall case at Ma = 0.5, Re = 1.2 × 106. The results show a very good agreement as long as the flow stays attached. Tendencies for the span-wise location of separation are captured. As soon as separation sets in, discrepancies between experimental and numerical data are observed. The experimental data show that for light dynamic stall cases at Ma = 0.5, a factor of safety of FoS = 2.0 is sufficient if the presented simulation methods are used.

Determination of runway orientation is a prime factor affecting the layout of airport facilities. This paper presents a new computer model called TORO (Tool for Optimum Runway Orientation) which is developed with an approach different from that of the Federal Aviation Administration's (FAA) wind rose method. All models previously developed are based on this traditional method. In the new model, each wind observation is evaluated individually in the computations without grouping them. Thus, the errors arising from the partial coverage problem and the FAA's assumption related to distribution of winds in each cell of wind rose are eliminated. The new model is written in CSharp (C#) programming language and the wind data tables are prepared in Access format. The accuracy, reliability and flexibility of the model are tested with three numerical examples. The results demonstrate that the TORO model may be a valuable tool for airport planners and designers.

Helicopter downwash impact on ship airwake is addressed from a three-pronged approach: (1) Analysis of one-point statistics of autospectrum and two-point statistics of cross-spectrum and coherence from a Computational Fluid Dynamics database of flow velocities effected by helicopter downwash and shipboard airwake; (2) Development of a mathematical framework for extracting interpretive turbulence models in closed form from these autospectral statistics; and (3) Simulation through white-noise-driven filters for the extracted models. The framework begins with an earlier-exercised perturbation-type series expansion of the autocorrelation for all three velocity components, where the first term of the series has a form of the von Karman longitudinal or lateral correlation function. After transformation into equivalent series of autospectrum, the coefficients in the series are evaluated by satisfying theoretical constraints and fitting a curve on a set of selected autospectral data points generated from the database. The framework represents a sensible combination of series expansion, exploitation of a database, and theoretical constraints to provide a foothold on airwake-downwash phenomenon for engineering analysis. It ensures that the extracted model and the autospectral data points have the same time scale, mean square value, and asymptotic decay according to the Kolmogorov –5/3 Law. The framework's strengths and weaknesses, and its major advancement over the earlier series-expansion schemes are also addressed. Finally it is shown that downwash increases airwake energy (mean square value) by one order of magnitude, and almost all of this airwake-downwash energy is concentrated within the bandwidth (0.16 < f(Hz) < 1.6) that affects flight mechanics.

In France, the very first ideas on flow control were developed by Philippe Poisson-Quinton from the Office National d'Etudes et Recherches Aérospatiales (ONERA) in the 1950s. There was some renewal of this research topic in the early 1990s, first in the United States with scientists like Wygnanski and Gad-El Hak, and also in France at the initiative of Pierre Perrier from Dassault Aviation, who triggered a lot of research activities in this field both at ONERA and in the French National Centre for Scientific Research (CNRS) laboratories. The motivation was driven by the applications on Dassault Aviation military aircraft and Falcon business jets in order to contribute to the design, while facilitating performance optimisation and multi-disciplinary compromise. A few examples of flow control technologies, such as forebody vortex control, circulation control, flow separation control or boundary layer transition control using hybrid laminar flow control (HLFC), are presented to illustrate the applications and to explain the methodology used for the design of the flow control devices. The author also emphasises the current reaction of industry with respect to the integration of flow control technologies on an aircraft programme. The conclusion is related to the present status of the French research on this topic and to the next challenges to be addressed.

The effects of aspect ratio on elliptical sonic jet decay at different levels of under-expansion has been studied experimentally. Elliptical sonic jets from orifices of same area with aspect ratios (AR) 2, 4 and 6 at nozzle pressure ratios 2 to 5 in steps of 1 have also been studied. A circular jet from an orifice with an area equal to that of elliptical orifice was also studied for comparison. Jet centreline pressure decay, spread and waves present in the jet core were analysed. The results show that the mixing of the elliptical jet is superior to the circular jet, at all the nozzle pressure ratios of the present study. Also, the aspect ratio of the elliptical orifice has a strong influence on the jet mixing. Elliptical jets of aspect ratio 4 and 6 experience a significantly higher mixing than the aspect ratio 2 jet, till the under-expansion level corresponding to Mach disk formation. For higher under-expansion levels, the mixing of AR 4 and 6 jets become inferior to that of the AR 2 jet.

In this work, we qualify and quantify the advantages of using SODAR (sonic detection and ranging) from current scenarios of Aeronautical Meteorology, with the goal of establishing a conceptual model for runway change procedures at Guarulhos International Airport (São Paulo, Brazil). The methods consist of analysing data from the Department of Airspace Control (DECEA) and Brazilian Airport Infrastructure (Infraero) about the reports of runway changes in Guarulhos in addition to SODAR data from September 2011 and December 2013. It is noted that in 234 analysed cases of runway change, there were significant periods of weak-intensity wind on the surface as well as the anticipated modification wind direction at altitude detected by sonic detection and ranging (SODAR), indicating future changes in levels closer to the surface. By examining the intersection of both scenarios, it is possible to observe that there is enough time for the air traffic controller to anticipate the needed runway change while minimising the impact on the aircraft flow, and this period has an average duration of 1 hour and 24 minutes. This confirms that the preliminary analysis of the information provided by SODAR can help predict alterations in wind direction, requiring redirection and bringing advantages in economic and security terms.

For many years, deceleration systems developed in an evolutionary fashion. This evolution needed flight test and experimental data. Concurrently, payload became much more expensive and needed to be safer. Today, there are a variety of methods employed to recover airborne bodies such as bio-capsules, reentry satellites, carrier missiles' boosters, reentry satellites, etc. Most of these methods make use of a parachute landing system in which recovery occurs in multiple phases. This paper studies the final phase of the subsonic recovery scenario for which a multi-phase deceleration system has been designed. To observe and evaluate system performance, a test projectile is designed that accelerates the payload to a certain velocity in order to test the recovery system. Finally, theoretical and test results are compared to indicate the appropriate design and reliable deceleration velocity in a space payload recovery.

The imperfection sensitivity of cylindrical panels under compression loading is shown to be not only reduced but effectively eliminated using stiffness tailoring techniques. Shells are designed with variable angle-tow (VAT) laminae, giving their laminates variable-stiffness properties over the surface co-ordinates. By employing an asymptotic model of the non-linear shell behaviour and a genetic algorithm, the post-buckling stability was maximised with respect to the VAT design variables. Results for optimised straight-fibre and VAT shells are presented in comparison with quasi-isotropic designs. In the straight-fibre case, small improvements in the post-buckling stability are shown to be possible but at the expense of the buckling load. In the VAT case, on the other hand, considerable improvements in the post-buckling stability are obtained and drops in axial stiffness and load associated with buckling are reduced to negligible levels. The improvements are shown to be a result of a benign membrane stress distribution prior to buckling and a localisation of the buckling mode. The asymptotic results are compared with non-linear finite-element analyses and are found to be in good agreement. Potential future multi-objective optimisation studies are discussed.

Data mining is an iterative process in which progress is defined by discovery through either automatic or manual methods. A data cleaning procedure is proposed to improve the quality of classification tasks in the knowledge discovery process by taking into account both redundant and conflicting data. The redundancy check is performed on the original dataset and the resultant dataset is preserved. This resultant dataset is then checked for conflicting data and, if any are found, they are corrected and updated on the original aircraft dataset. This updated dataset is then classified using a variety of classifiers such as Bayes, functions, lazy, MISC, rules and decision trees. The performance of the updated datasets on these classifiers is examine, and the result shows a significant improvement in the classification accuracy after redundancy and conflicts are removed. The conflicts after correction are updated in the original dataset, and when the performance of the classifier is evaluated, great improvement is observed. This paper aims to address how data mining techniques can be used to understand complex system accidents in the aviation domain. Decision trees are considered to be the one of the most powerful and popular approaches in knowledge discovery and data mining. The objective is to develop a classification model for aviation risk investigation and reduction using a decision tree induction method that enhances the ability to form decision trees and thereby proves that the classification accuracy of decision trees is greater. Different feature selectors are used in this study in order to reduce the number of initial attributes.

Within an immunity-based architecture for aircraft fault detection, identification and evaluation, a structured, non-self approach has been designed and implemented to classify and quantify the type and severity of different aircraft actuators, sensors, structural components and engine failures. The methodology relies on a hierarchical multi-self strategy with heuristic selection of sub-selves and formulation of a mapping logic algorithm, in which specific detectors of specific selves are mapped against failures based on their capability to selectively capture the dynamic fingerprint of abnormal conditions in all their aspects. Immune negative and positive selection mechanisms have been used within the process. Data from a motion-based six-degrees-of-freedom flight simulator were used to evaluate the performance in terms of percentage identification rates for a set of 2D non-self projections under several upset conditions.

The article includes study on the influence of a LEX (leading-edge extension) and wing tip plates on aerodynamic characteristics of the Rocket Plane in tailless configuration for manned suborbital flights. The research was conducted only for the low speed regime in the wind tunnel at the Warsaw University of Technology. Tests were carried out for a few configurations of the Rocket Plane. Moreover, two shapes of LEX were investigated. Analysis of results was focused on the aerodynamic synergism effect only. The influence of LEX and the wing tip plates of the Rocket Plane on the aerodynamic coefficients was identified.

In an effort to quantify the feasibility of candidate space architectures for astronauts servicing Geosynchronous Earth Orbit (GEO) satellites, a conceptual assessment of architecture-concept and operations-technology combinations has been performed. The focus has been the development of a system with the capability to transfer payload to and from geostationary orbit. Two primary concepts of operations have been selected: (a) Direct insertion/re-entry (Concept of Operations 1 – CONOP 1); (b) Launch to low-earth orbit at Kennedy Space Center inclination angle with an orbital transfer to/from geostationary orbit (Concept of Operations 2 – CONOP 2). The study concludes that a capsule and de-orbit propulsion module system sized for the geostationary satellite servicing mission is feasible for a direct insertion/re-entry concept of operation CONOP 1. Vehicles sized for CONOP 2 show overall total mass savings when utilising the aero-assisted orbital transfer vehicle de-orbit propulsion module options compared to the pure propulsive baseline cases. Overall, the consideration of technical, operational and cost factors determine if either the aero-assisted orbital transfer vehicle concepts or the re-usable/expendable ascent/de-orbit propulsion modules is the preferred option.

The 150th anniversary of the Royal Aeronautical Society offers an ideal opportunity to reflect on the spirit of innovation and collaboration fostered by the Society and its members over the past century and a half. Dr Jean Botti, an engineer with 31 patents to his name and Chief Technical Officer at Airbus Group, reflects on key innovation milestones for both Airbus Group and the industry as a whole. He also discusses the benefits of collaboration between the RAeS members and industry, and looks forward to an exciting new era of discovery – from electric flight (e-flight) to ‘smarter skies’ and the future development of new modes of flight which can only be imagined today.

Elastomeric and Fluidlastic® absorbers are proposed to be embedded in blade cavity to reduce troublesome second harmonic flap-wise blade loads of rigid rotors. A simple model of a blade with a flap-wise dynamic absorber is derived to investigate centrifugal force effects on the absorber's rotating frequency. The system's dynamic equations of motion indicate that centrifugal force has no effect on absorber's frequency under rotation. Aeroelastic simulation of the coupled rotor and absorber system based on an elastic beam model in generalised force formulation is used to explore load reduction extent and dynamic absorber behaviour. At a forward speed of 200 km/h, the elastomeric absorber reduces the second harmonic flap-wise root-bending moment by 88.8% for unacceptably large stroke; the Fluidlastic® absorber reduces the moment by 78.5% with a stroke 4.26% of blade chord length. Results indicate that placing an embedded Fluidlastic® absorber in the blade's flap-wise direction has potential for reducing load in different flight states with relatively small strokes. Increasing tuning port area ratio or Fluidlastic® absorber mass can distinctly decrease strokes without increasing loads. However, deviation from normal rotor speed significantly lowers Fluidlastic® absorber performance.

The actuation mechanism is a crucial aspect in the design of morphing structures due to the very stringent requirements involving actuation torque, consumed power, and allowable size and weight.

In the framework of the CRIAQ MD0-505 project, novel design strategies are investigated to enable morphing of aeronautical structures. This paper deals with the design of a morphing aileron with the main focus on the actuation technology. The morphing aileron consists of segmented 'finger-like' ribs capable of changing the aerofoil camber in order to match target aerodynamic shapes. In this work, lightweight and compact actuation kinematics driven by electromechanical actuators are investigated to actuate the morphing device. An unshafted distributed servo-electromechanical actuation arrangement is employed to realise the transition from the baseline configuration to a set of target aerodynamic shapes by also withstanding the aerodynamics loads. Numerical investigations are detailed to identify the optimal actuation architecture matching as well as the system integratability and structural compactness.

Wind-tunnel measurements were used to study the characteristics of the unsteady separation bubbles on a NACA 0015 aerofoil with simulated two-dimensional leading-edge glaze ice accretions. The unsteadiness present in the iced-aerofoil flowfield was determined using measurements of the time-dependent aerofoil surface pressure distribution at Reynolds number of 1.0 × 106. Additionally, the unsteady flow features were investigated through the power spectrum of the stream-wise velocity fluctuations using a hot-wire anemometry. The results showed that the highest value of root-mean-square fluctuation of the surface pressure consistently occurred upstream of the mean shear-layer reattachment location. Spectral analysis of stream-wise velocity fluctuations near reattachment location revealed evidence of the regular frequency at Strouhal numbers of 0.5-0.63. Moreover, the low-frequency oscillations associated with shear-layer flapping was also identified in the wake velocity spectra on the order of 10 Hz that resulted in Strouhal numbers of 0.0186-021.