Due to constraints of natural condition, cost and of available time associated with model fabrication and for extensive wind-tunnel tests or flight tests, Computational Fluid Dynamics (CFD) simulation was considered an alternative means of providing air vehicle icing simulation and aeromechanic performance analysis. Full-scale icing experiments and, therefore, certification and cost can be significantly reduced by developing full-numerical simulation methods to evaluate the air vehicle performance for a wide range of icing conditions. This paper summarises helicopter icing simulation methods that include the development of helicopter aerodynamics, calculation methods of helicopter icing, icing protection system performance, icing effects on the helicopter performance, and some challenges in helicopter icing simulation.

The present paper describes a new, agent-based computer model that can simulate the evacuation of narrow body transport aeroplanes in the conditions prescribed by the airworthiness regulations for certification. The input data are extracted from a complete plan view of the cabin. The results include full egress details of all occupants, passengers and crew-members, and the most significant evacuation figures and diagrams. The model has been tuned and verified with real data of narrow body certification demonstrations. Numerical simulations of six narrow body aircraft, representative of current designs, show the capabilities of the model and provide relevant information on the relationship between cabin features and emergency evacuation results. Although the computer model has been developed for helping in the certification process it would be useful too in the design of new cabins.

This paper presents a simulation study of ion thruster plume effects on formation flying spacecraft. Two formation flight applications using micro-ion propulsion are considered: an L2-Halo orbit interferometer formation and a LEO micro-satellite formation. Worst case scenarios in both missions have been investigated. We focus our study on thruster configurations resulting in possible indirect plume impingement on satellites outside of the direct impingement zone. Indirect impingement which cannot be predicted except through plasma simulation or in-flight measurements might expose critical spacecraft elements such as optical sensors to a harsh contamination environment. A high-fidelity electrostatic plasma simulation code for parallel computing platforms was used in the study.

In our study, we found that using miniature scale ion propulsion in both formation missions creates a very low charge-exchange plasma environment which results in tolerable contamination environment for other spacecraft in the formation.

In recent years increasingly pressure has been applied on aircraft component suppliers to reduce design lead-time and design cost of aircraft components. To achieve this reduction in lead-time and cost, advanced automation tools that automate part of the engineering process can be used. Knowledge based engineering (KBE) tools are one such automation tool type and automate part of the engineering process based on existing knowledge within a company. In this paper the development process and use of a KBE application to design machined ribs in an industrial setting is discussed. The development of the KBE tool has resulted in the standardisation of the design methodology. Furthermore it has reduced machined rib design lead-time in a project to develop a bussines jet empennage by 40%.

The estimation from flight data of aerodynamic parameters for vehicle in steady-state conditions, perturbed by an identification manoeuvre, is a well-established technology, whereas system identification from dynamic flight data is a subject of continuous interest. This paper presents a hybrid frequency and time domain technique for identification of vehicle longitudinal aerodynamic model, including the ground effect. Identification is performed in the framework of a multi-step approach, in which, first aerodynamic coefficients are estimated in the frequency domain, using an equation error method; then time domain techniques are applied to identify out of ground effect aerodynamic derivatives and ground effect model parameters. The technique was successfully applied to flight data of an experimental ultra light aircraft. Identification results showed that the proposed method works properly also in the dynamic phases of the flight or when no dedicated identification manoeuvres are executed. Moreover, the identified longitudinal aerodynamic model was used to design the flight control system that successfully performed many autonomous landings.

Experimental and computational investigations have been made to obtain the details of the flow field of a supersonic air-intake with different cowl deflection angles and back pressures at the exit. The flow field obtained with an inviscid computation on the basic configuration, designed for Mach 2·2, shows starting behaviour whereas computation with k-ω turbulence model and experiments indicate unstart characteristics. Both experiments and computations indicate that provision of a small angle at the cowl tip leads to start of the same intake and also improves it’s performance. Results obtained with cowl deflection shows a better performance in comparison to performance achieved with a basic intake and with a bleed of 2·8%. Sustainable back pressure could be obtained through the computations made at different back pressures for different cowl deflection angles. Overall results suggest that provision of small cowl deflection angle itself leads to improvement in performance achieved in comparison to a bleed of 2·8%, even with back pressure at the exit.

Combined Vertical and short take-off and landing, or ‘V/STOL’ capability has been of great demand and interest in the field of aeronautics since the creation of the aircraft. V/STOL capability is a targeted capability for many projected or prototype future aircraft. Past V/STOL aircraft are reviewed and analysed with regard to their performance parameters. This research has found two embedded categories in this class of aircraft based on their propulsion systems, i.e. jet and non-jet propulsion, and highlights the significant performance differences between them. In light of historical experience the performance of a relatively new class of aircraft, the flying cars, has been evaluated.

The miniaturisation of sensors has in recent years led to the ability to provide multiple sensor operations from a single Unmanned Aircraft System (UAS) platform. Multiple UAS platforms can be synchronised to link devices from separate UAS platforms thus proving a powerful capability for data collection, while opening up interesting opportunities in the way data is retrieved and used. A range of new sensors being investigated will be discussed with reference to selected case studies that have taken place. As we move into an increasingly growing, data rich environment, data management, quality and pedigree will become of increasing importance. Operations for both defence and non-defence applications will be discussed with reference to the present capability and what is required in future systems. This paper describes some of the sensors currently being evaluated. In the coming years it is expected that we will see a sharp increase in the use of small tactical sized autonomous vehicles in general and a large growth in the capability of the payloads being used.

Research studies have indicated that the optical flow parameter, time to close tau, is the basis of purposeful control in the animal world, and used by both fixed wing and helicopter pilots during manoeuvring. This parameter is defined as the instantaneous time to close a gap (spatial or force) at the current closing rate. A novel automatic flight control strategy has been developed that makes use of optical flow theory and in particular, the parameter tau. This strategy has been applied to two distinct problems; (1) the landing of a helicopter on a ship and (2) the lateral repositioning of a helicopter. The first is a challenging case because the landing of a helicopter on a ship is one of the most dangerous of all helicopter flight operations. Furthermore, helicopters are often subject to torque oscillations during rapid collective control, which increases pilot workload significantly when operating with low power margins and/or whilst performing tasks that require accurate heave control. The second case demonstrates the generality of the technique. Both automatic manoeuvres were simulated successfully within desired limits, with the novel control strategy creating a ‘natural’, smooth, tau motion.

This paper presents a computational analysis regarding the effect of the camber line deformation due to structural errors, on the aerodynamic behavior of a high-pressure steam turbine.

In several cases, inaccuracies in the blade geometry can lead to undesirable flow phenomena strongly affecting its overall performance when put in service. The effect of the camber line deformation on the performance of an experimental axial steam turbine is investigated hereafter. A high fidelity inspection of the actual geometry of both a stator and a rotor blades randomly chosen among the similar blades of the same row has been carried out, using a 3D co-ordinate measurement machine. The cross sections of the blades obtained by the measurement were compared with those produced by the design process to evaluate the change in blade inlet/exit angles. The actual (measured) model has been used as input into a streamline curvature solver to evaluate its overall performance assuming a uniform distribution of the geometrical error across the blades of the same blade row, the loss generation mechanisms within the flow field have been further investigated and analysed using a high fidelity 3D Navier-Stokes solver.

A measurable change of efficiency as well as in the total power delivered by the turbine was found. This suggests that the accumulated error caused during the manufacturing procedure plays a significant role in the overall performance of the machine by making it less efficient by almost 1% due to the intensification of the hub and casing secondary flows, as well as to the thicker boundary layers on the blade surfaces revealed by the numerical prediction of the flow.

This paper explains how flight simulation has made a major contribution to flight safety over the last thirty years to become critical to the operation of civil airlines and military organisations. It not only provides effective training, but for many flight training organisations has reduced the cost of flight training significantly. The paper outlines the increasing role of flight simulation covering flight training and research and development of aircraft and systems. The contribution of the flight simulation industry to the UK economy, in terms of both employment and revenue, is highlighted.

The paper focuses on advances in the underpinning technologies of flight simulation, including mathematical modelling, real-time computation, motion actuation, visual image generation systems and projection systems.

The paper also summarises the broadening roles of flight simulation; from part-task trainers to zero flight-time training in civil aviation; in military aviation, extending to combat domes and mission rehearsal; in defence procurement, where synthetic environments are used widely in evaluation studies prior to major project commitments; in aircraft development, providing powerful design tools to enable system designers to evaluate prototype systems.

As a result of the acceptance of flight simulation in flight training, the use of simulators has been standardised throughout the world, with formal programmes of simulator qualification. These regulations, drawn up with the help of the RAeS Flight Simulation Group, ensure consistency for operators, regulators and manufacturers; the status of these regulations is outlined.

The paper concludes by reviewing the lessons learnt by the flight simulation industry over the last thirty years and summaries the potential areas of growth, which will lead to simulation becoming widespread throughout many industries, in addition to the aerospace industry.

This paper deals with the problem of radar target tracking in cluttered environment from plane position indicator (PPI) radar images collected by low-cost incoherent radar. For this purpose a new five-step technique is proposed, including background subtraction, clutter suppression, measurements extraction, tracking and data fusion; the tracking step uses a particle filtering based data association method. Radar measurements, including target information and clutter interference, are checked whether it belongs to tracking target by data association with Kalman predicted state. If the measurement is generated by target, target state is updated by Kalman filter, and vice versa the predicted state keeps invariant. Moreover, smoothed tracks are given by Kalman smoothing of filtering results. The performance of the tracking algorithm is deeply investigated against Monte Carlo simulations. Finally, the overall multi-frame-based technique is applied to two sets of live PPI radar images, and the results show the effectiveness of the proposed approach.

Aspects of the turbulent wind environment Micro Air Vehicles (MAVs) experience when flying outdoors were replicated in a large wind tunnel. An overview of the facility, instrumentation and initial flight tests is given. Piloting inputs and aircraft accelerations were recorded on fixed and rotary wing MAVs and for some tests, measurements of the approach flow (u,v,w sampled at 1,250Hz at four laterally disposed upstream locations) were made. The piloting aim was to hold straight and level flight in the 12m wide × 4m high × ~50m long test section, while flying in a range of turbulent conditions. The Cooper-Harper rating system showed that a rotary craft was less sensitive to the effects of turbulence compared to the fixed wing craft and that while the fixed wing aircraft was relatively easy to fly in smooth air, it became extremely difficult to fly under high turbulence conditions. The rotary craft, while more difficult to fly per. se., did not become significantly harder to fly in relatively high turbulence levels. However the rotary craft had a higher mass and MOI than the fixed wing craft and further work is planned to understand the effects of these differences.

Corrugated structures offer a potential solution for morphing wing skin applications due to their anisotropic behaviour that allows chordwise camber and length changes. Aerofoils with corrugated skins in the aft 1/3 of the chordwise section have been studied experimentally and computationally using various corrugation shapes and forms (sinusoidal, trapezoidal and triangular) at different Reynolds numbers. The study showed that the aerodynamic performance is highly dependent on corrugation amplitude, wavelength, gradient (combination of amplitude and wavelength) and Reynolds number. Evidence is given highlighting that penalties for having a non-smooth surface in the aft 1/3 of the chordwise section of an aerofoil can be eliminated for the lift curve slope and minimised for the zero lift drag coefficient.

A real-time model of a wake vortex has been developed for an engineering flight simulator, which enables studies to be undertaken into the effects of wake vortex encounters with civil transport aircraft. A brief summary of the methods used to create a vortex model and integrate it with a real-time flight simulator is presented. Tools have been developed to determine the structural loads on an aircraft during a simulated wake vortex encounter and to visualise the airframe loads. Four wake vortex encounters were flown with different pilot recovery strategies and automatic flight controls. It is clear from analysis of these results that it is difficult for a pilot to appreciate the margin of tail loading during an encounter and a prototype training display is outlined to enable pilots to fully understand the effects of rudder inputs in recovery from these events.

This paper investigates a novel method for the control of aircraft. The concept consists of articulated split wing-tips, independently actuated and mounted on a baseline flying wing. The general philosophy behind the concept was that adequate control of a flying wing about its three axes could be obtained through local modifications of the dihedral angle at the wing-tips, thus providing an alternative to conventional control effectors such as elevons and drag rudders. Preliminary computations with a vortex lattice model and subsequent wind tunnel tests and Navier-Stokes computations demonstrate the viability of the concept for co-ordinated turns, with individual and/or combined wing-tip deflections producing multi-axis, coupled control moments. The multi-axis nature of the generated moments tends to over-actuate the flight control system, leading to some redundancy, which could be exploited to optimise secondary objective functions such as drag or bending moment.

This paper is devoted to modelling and control algorithms for a slung load transportation system composed of one or multiple helicopters, where the load is coupled by the means of flexible ropes (see Fig. 1). The coupled helicopter system overcomes the payload limitation of a single small size helicopter, while keeping most of its advantages: small costs of operation, low maintenance costs and increased safeness. Therefore, the system can be utilised whenever the use of full size helicopters is impossible, too expensive or prohibited by law. We focus on the deployment and repairing of distributed sensor networks, using a transportation system based on multiple small size helicopters. A possible real world application is the deployment of fire fighting equipment, where space limitation of the fire trucks prohibits the application of bigger UAVs and using full size helicopters is too dangerous. The problem of load transportation using one or two full size helicopters (twin lift helicopter system), connected to the load by means of flexible ropes, has been discussed in the aerospace research community at least since 1960. We have shown in our previous work that there is a fundamental difference in the mathematical description between small and full size helicopters. Therefore, also the control design for the case of small size helicopters needs to be different. To our knowledge, the control of a slung load transportation system composed of multiple small size helicopters has not been studied until now. In this paper, the complete mechanical setup of the slung load transportation system based on one or more small size helicopters is presented. This includes a short description of the used UAVs, the additionally required sensors, and how the load is mounted. A model of one/multiple helicopters transporting a load is introduced. This model is used in a simplified form for the controller design and in full form for simulation. The controller for one and two helicopters, which is based on a state feedback controller, as well as the controller for three and more helicopters, which is based on a non linear controller, are explained in detail. Both controllers utilise an underlying non-linear orientation controller. We propose a feedback loop, based on forces measured in the ropes, to compensate for the influence of the rope. The controllers were tested in simulation and in real flight experiments. The world wide first flight experiment with three coupled helicopters was successfully conducted at the end of 2007.

This paper presents an analytical-numerical methodology for the geometrically nonlinear analysis of laminated composite plates under dynamic loading. The methodology employs Galerkin technique, in which suitable polynomials are chosen as trial functions. In the solution process, Newmark’s scheme for time integration, and modified Newton-Raphson method for the solution of resulting nonlinear equations are used. In the formulation, first order shear deformation theory based on Mindlin’s hypothesis and von Kármán type geometric nonlinearity are considered. The results are compared to that of finite strips, and Chebyshev series published elsewhere. The method is found to determine closely both the displacements and the stresses. A finite element analysis has also been carried out for the validation of the results. The present method can be efficiently and easily applied for the nonlinear transient analysis of laminated composite plates with various boundary conditions.