This paper gives an overview of the work carried out in a GARTEUR (Group for Aeronautical Research and Technology in Europe) program, under the chairmanship of the author, to develop and validate analytical and numerical methods to characterise real impact damage in composite structures, particularly those designed to sustain load in a postbuckled state, and to study the durability of bonded repairs. GARTEUR is an inter-governmental agreement between the seven European countries with the largest direct employment in the Aerospace industry, to mobilise scientific and technical knowledge between the member countries. A number of Action Groups have been launched, since GARTEUR’s inception in the early 1970s, to address specific technical issues of interest to the participating members. The research presented in this paper was performed under Action Group 28 with partners from ONERA, EADS-CCR (France), DLR, AIRBUS-Deutschland, EADS-M (Germany), CIRA (Italy), INTA (Spain), SICOMP, Saab, (Sweden), NLR (The Netherlands), QinetiQ, BAE Systems, Imperial College London and the University of Sheffield (United Kingdom). The Action Group tasks were divided into four Work Elements (WEs): WE1-Prediction and characterisation of impact damage, WE2-Postbuckling with delamination, WE3-Repair and WE4-Fatigue. This paper outlines the main developments and achievements within each Work Element.

This paper deals with the design methodology of multi-variable flight control systems through a H∞ loop-shaping technique. A new procedure for the design of non-diagonal pre-and post-compensators is described. In particular, important improvements over existing methods are introduced to both make the selection of weights easier and to contain the order of the resulting controller. The new procedure can be easily managed through suitable Matlab commands and functions, thus simplifying the whole algorithm implementation and providing an effective control system design with a minimum effort. Two typical design problems are addressed: a pitch pointing control system and a lateral controller for coordinated turns. In both cases, a good decoupling between existing channels is obtained by means of a non-diagonal pre-compensator which shapes the plant transfer function, and provides the desired response settling time. The design approach is particularly effective even for nominal plants with strong cross-coupling between channels. The design procedure is illustrated with the aid of a Matlab/Simulink model of a single seat fighter aircraft. We show that a trade-off between the conflicting requirements of fast response and moderate use of control surfaces can be easily managed by varying the constant terms of the diagonal post-compensator.

The pace at which new technologies are assimilated into society is driven by trends in the regulatory, budgetary, and societal environments in addition to the pace of technology development itself. This study merges trends in these areas to develop an integrated forecast of the levels to which unmanned aviation can be expected to emerge in the military, air cargo, business, general aviation, and airline aviation segments over the coming 40 years. One out of every 80 aircraft on an instrument flight rules (IFR) flight plan over the US are anticipated in this forecast to be unmanned by 2025 and two out of nine (18 of every 80) by 2050. Portions of this study were originally researched in 2005 in support of the Federal Aviation Administration’s (FAA’s) Joint Planning and Development Office (JPDO) for planning the Next Generation (NextGen) air traffic system and later presented at the 23rd Bristol UAV Systems Conference.

Quantitative and qualitative results of a series of experiments conducted on a rotor in ground effect at low forward speeds are presented. The velocity over a wide area of the ground effect wake was measured using particle image velocimetry, and the evolution of the flow is described as the forward speed increases. The formation of a dust cloud leading to so-called helicopter brown-out was simulated through a series of flow visualisation experiments. The technique involved sprinkling a fine dust on the ground below and ahead of the rotor. Larger dust clouds were observed at lower forward speed, and the dust cloud penetrated into the areas of the flow including those where vorticity levels were of low magnitude and occasional velocity fluctuations from the mean were large.

This work looks to harness atmospheric energy through thermal soaring to optimise the flight persistence of Micro Air Vehicles (MAVs) and Unmanned Air Vehicles (UAVs). There are two key challenges when considering thermal soaring, the first being the locating of thermals and the second being the extraction of the maximum potential energy from the thermals. Thermal location is by no means an exact science with experienced glider pilots needing to consider many factors to improve the probability of encountering a thermal. As thermals are caused by the uneven heating of the Earth’s surface it is, however, possible to predict likely thermal locations. With the application of a suitable guidance algorithm which considers these ‘hot spots’ it is possible to increase the likelihood of encountering a thermal. Once a thermal is found it is important to attempt to extract the maximum energy from the thermal. To do this the vehicle needs to move quickly to the centre of the thermal. There are many potential techniques for thermal centring, some of which appear to be entirely contradictory to each other, the crucial factor determining the success of such a technique has been found to be the response time of the onboard sensors. This paper considers the many aspects of thermal soaring such as locating thermals, thermal detection and thermal centring. Five different thermal models are presented which are used to demonstrate the thermal centring techniques. Finally a commercial glider simulation package is used to demonstrate the control architecture and simulate a fully autonomous flight.