This paper considers capabilities and benefits of aircraft-sized radio/radar frequency anechoic chambers for Test and Evaluation (T&E) of Electronic Warfare (EW), radar and other electromagnetics aspects of air and ground platforms. There are few such chambers worldwide. Initially developed to reduce costs, timescales and risks associated with open-air range flight testing of EW systems, their utility has expanded to most areas of platforms’ electromagnetics’ T&E. A key feature is the ability to conduct T&E of nationally sensitive equipment and systems, fully installed on platforms, in absolute privacy. Chambers’ capabilities and uses are described, with emphasis on key infrastructure and instrumentation. Non-EW uses are identified and selected topics elaborated. Operation and maintenance are discussed, based on experiential knowledge from international use and the authors’ 30 years’ involvement with BAE Systems’ EW Test Facility. A view is provided of trends and challenges whose resolution could further increase chamber utility. National affordability challenges also suggest utility expansion to support continuing moves, from expensive and difficult to repeat flight test and operational evaluation trials, towards an affordability-driven optimal balance between modelling and simulation, and real-world testing of platforms.

This article aims to present a novel control strategy for quadrotor helicopter. It is composed of three main parts constituting the system modelling, the integral back-stepping control, and fuzzy logic compensator. In the first part, a non-linear model is presented taking in consideration some non-linearities and variables that are usually neglected. In the second part, a controller based on the integral back-stepping algorithm has been developed for the system in order to make the system follows a desired path. However, due to complexity of paths and to the presence of unknown disturbances, a fuzzy logic compensator is added in parallel to the integral back-stepping controller to improve trajectory tracking in some critical conditions (high wind speed, mass variation, etc.). Simulation results have been presented to show the effectiveness of the proposed approach.

One key task in computational aeroelasticity is to calculate frequency response functions of aerodynamic coefficients due to structural excitation or external disturbance. Computational fluid dynamics methods are applied for this task at edge-of-envelope flow conditions. Assuming a dynamically linear response around a non-linear steady state, two computationally efficient approaches in time and frequency domain are discussed. A non-periodic, time-domain function can be used, on the one hand, to excite a broad frequency range simultaneously giving the frequency response function in a single non-linear, time-marching simulation. The frequency-domain approach, on the other hand, solves a large but sparse linear system of equations, resulting from the linearisation about the non-linear steady state for each frequency of interest successively. Results are presented for a NACA 0010 aerofoil and a generic civil aircraft configuration in very challenging transonic flow conditions with strong shock-wave/boundary-layer interaction in the pre-buffet regime. Computational cost savings of up to 1 order of magnitude are observed in the time domain for the all-frequencies-at-once approach compared with single-frequency simulations, while an additional order of magnitude is obtained for the frequency-domain method. The paper demonstrates the readiness of computational aeroelasticity tools at edge-of-envelope flow conditions.

A composite guidance law is proposed for intercepting moving target while strictly satisfying the constraints on multiple No-Fly Zones (NFZs) distributed arbitrarily. The research has two major steps. In the first step, by considering only one NFZ, a guidance law is developed with three parts: Orientation Adjustment Scheme (OAS), Boundary-Constraint Handling Scheme (BCHS), and Proportional Navigation (PN). OAS determines the major flight direction by predicting the collision point of the missile and target. BCHS controls the missile to approach and then fly along the boundary of the NFZ smoothly so as to bypass the NFZ through a short path. PN is used to intercept the target in the endgame phase. In the second step, we use the multi-step decision process to set up a series of appropriate waypoints in order to avoid multiple NFZs. The superior performance of the proposed guidance law has been demonstrated by trajectory simulations.

As part of the ongoing development of small unmanned air systems by the University of Southampton, an all laser sintered aircraft has been test flown from the Royal Navy's ice patrol ship HMS Protector to assist with navigating through the Antarctic. These flights were carried out with pre-planned autopilot control with oversight from Andrew Lock, acting as the pilot embarked on HMS Protector. This is the first time the Royal Navy has used unmanned aerial vehicles in this part of the world. In this paper, we set out the trial reports and lessons learnt from this series of test flights.

Higher-Order Spectra (HOS) are used to characterise the nonlinear aeroelastic behaviour of a plunging and pitching 2-degree-of-freedom aerofoil system by diagnosing structural and/or aerodynamic nonlinearities via the nonlinear spectral content of the computed displacement signals. The nonlinear aeroelastic predictions are obtained from high-fidelity viscous fluid-structure interaction simulations. The power spectral, bi-spectral and tri-spectral densities are used to provide insight into the functional form of both freeplay and inviscid/viscous aerodynamic nonlinearities with the system displaying both low- and high-amplitude Limit Cycle Oscillation (LCO). It is shown that in the absence of aerodynamic nonlinearity (low-amplitude LCO) the system is characterised by cubic phase coupling only. Furthermore, when the amplitude of the oscillations becomes large, aerodynamic nonlinearities become prevalent and are characterised by quadratic phase coupling. Physical insights into the nonlinearities are provided in the form of phase-plane diagrams, pressure coefficient distributions and Mach number flowfield contours.

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.