This paper deals with the synthesis of optimal trajectories for aerobatic air races. A typical example of an air race event is the Red Bull Air Race World Series, where high-performance aerobatic aircraft fly a prescribed slalom course consisting of specially designed inflatable pylons, known as ‘air gates’, in the fastest possible time. The trajectory that we seek to optimise is based on such a course. The air race problem is formulated as a minimum-time optimal control problem and solved in open-loop form using a direct numerical multi-phase trajectory optimisation approach based on collocation and non-linear programming. The multiphase feature of the employed collocation algorithm is used to enable a Receding-Horizon optimisation approach, in which only a limited number of manoeuvres in sequence is considered. It is shown that the Receding-Horizon control approach provides a near-optimal solution at a significantly reduced computational cost relative to trajectory optimisation over the entire course. To avoid the path inclination singularity in the equations of motion based on Euler angles, a point-mass model formulation is used that is based on quaternions. Numerical results are presented for an Extra 300S, a purpose-designed aerobatic aircraft.

This experimental investigation concentrates on the aerodynamic behaviour of a generic fan-in-wing configuration. The effects of the fan(s) on the flow circulation in a short take-off and landing or a transition flight condition without ground effect are evaluated. A wind-tunnel model has been constructed and tested to quantify the aerodynamic effects. Force measurements, surface pressure measurements, stereo-particle image velocimetry and wool tufts flow visualisation are performed. Different fan-in-wing configurations with the fans rotating in the wing plane, one fan either at the rear or front part of the wing and two fans are compared to the closed wing without fans set as reference. A fan placed near the trailing edge improves significantly the lift coefficient due to a jet flap effect on the wing lower side combined with enhanced suction on the wing upper side. The jet exiting the nozzle rolls up in a counter rotating pair of vortices affecting significantly the wing behaviour.

This experimental investigation constitutes also a useful database for further CFD comparison.

The aim of this paper is to consider the role of air power in the future, within the wider security environment and across the full spectrum of conflict. The key is to make some reasonable assumptions about the future strategic environment for the next ten to fifteen years, extrapolating from our experience since the end of the cold war and our existing knowledge of potential state threats and substate threats and challenges. One of our failings since the end of the cold war has been to focus on the operational level of war at the expense of thinking hard about national strategy. The formulation of national strategy is supposed to be directed by government, but if that government fails to provide strategic direction, as it has done over recent years, the result is short-termist perspectives, and a ‘hand to mouth’ approach to crisis management. This has been reinforced further by financial constraint and the electoral cycle. Ideally, a strategic perspective helps us not only to set our current age in a much wider context, thus preventing or making us less inclined to ‘knee-jerk’ reactions to single events, but it also assists in the making of correct judgements about the nature of a conflict or scenario, thus enabling us to apply the appropriate type of tool (air power or otherwise). History is littered with instances of the inappropriate use of military force, and air power is no exception, and we cannot afford nugatory manpower and material expenditure. The challenge is, therefore, enormous: to meet current commitments, while preparing for future possibilities.

The Asia-Pacific GNSS Test Bed is a regional collaborative programme that brings together aviation practitioners in the field of satellite navigation within the Asia-Pacific to study the performance of global navigation satellite systems (GNSS) and to develop a regional plan that will lead to a successful implementation of GNSS in the region. The program is a work program under the Asia-Pacific Economic Cooperation GNSS Implementation Team (APEC GIT), a working group under the APEC. The Test Bed has been in operation since August 2006. The system architecture reflects hybrid architecture between a satellite-based augmentation system (SBAS) and a ground-based augmentation system (GBAS). Test reference stations (TRSs), consisted of a dual-frequency GPS receiver, a communication interface, and a data archival hardware, have been installed in the participating economies. GPS data collected at the TRSs will be transmitted to the test master station (TMS) in Bangkok, Thailand. SBAS messages will be generated and the messages will be broadcasted through a test VHF station (TVS). A test user platform (TUP) will receive GPS signal and the SBAS messages broadcast from TVS and then calculate and archive the TUP’s positions.

This paper discusses performance analysis and flight test results conducted in Thailand in September 2007. During flight trials, noting that the Test Bed broadcasts SBAS messages through a VHF data link (VDL) similar to that of GBAS, the impacts of VHF broadcast, such as transmitting power, terrain effects, and impacts of different aircraft attitudes and positions are analysed. Preliminary analysis result indicates that, while the GBAS VDL coverage is very good through out the 30nm airport terminal area, during approach, and even during taxi, considerations should be given to levels of transmitting power to eliminate possible intermittent loss of VHF messages received by the aircraft receiver. This intermittent loss of VHF messages results in very strong fluctuation of horizontal protection levels (HPL) and vertical protection levels (VPL) calculated by the TUP. To yield with possible problem, windowing techniques are proposed and analysed.

A methodology is described that determines the statistical confidence bounds on the results from flight flutter tests: modal parameter estimates, flutter margin values and flutter speed estimates, without the need for Monte-Carlo simulation. The approach is based on least squares statistics and eigenvalue perturbation theory applied to the various stages of the analysis process, starting with frequency and damping estimation through to the flutter margin calculations. The technique is demonstrated upon a number of data sets from aeroelastic simulations of flight flutter tests.

Experimental studies have been conducted on a NASA 17-percent thick supercritical aerofoil with a Coanda trailing edge at subsonic speeds in both the boundary-layer control and circulation control regimes. Detailed boundary-layer surveys were performed along the mid span on the suction surface and around the Coanda trailing edge. The wake located at 43% chord-length behind the aerofoil was measured with a single-component hotwire anemometer, and the profile drag coefficients were calculated from the integration of wake momentum deficit. Lift forces and pitching moments were recorded from –20deg to +20deg incidence using a 3-component force balance. In the circulation control regime, the boundary-layer results indicated that separation bubbles are not present at high incidences compared to the boundary-layer control regime, and that minimised the potential for flow separation delay around the Coanda trailing edge. The spectral analysis of the wake showed a significant reduction of wake fluctuations at high incidences and improvement of the stability at the edge of the wake. The study of aerodynamic forces suggested the need to increase the blowing momentum coefficient if the circulation control is used near the stalling angle-of-attack.