In some situations, closed loop control by the pilot can result in the combined pilot-aircraft system becoming marginally stable or even unstable. This can happen whether the pilot is controlling attitude or flight path. In this paper, an investigation into helicopter stability under flight-path constraint below the minimum-power speed is reported. The work provides a theoretical basis for flight path handling qualities criteria particularly for flight on the, so-called, back-side of the power curve. The research uses the theory of weakly coupled systems by partitioning the helicopter longitudinal dynamics to investigate three interacting subsystems – classically the surge mode, the phugoid mode and the heave mode. Under certain conditions, strong control of flight path or vertical speed is shown to drive the aircraft-pilot system unstable and a conflict is shown to exist between feedback gain values to guarantee stability of both the surge and the flight path motions. This conflict constitutes a potential source of adverse rotorcraft-pilot couplings. The problems are exacerbated in cases when the use of collective control is restricted. The phenomenon is explored in both ground based simulation and flight test to provide a verification of the theory.

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.

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.

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.

The unsteady flowfield of a series of mixed-compression hypersonic inlets with different bleeding rates were numerically simulated. Firstly unstart oscillatory flow of hypersonic inlets caused by downstream massflow choking was discussed. Then the effects of boundary layer bleeding on the averaged performance parameter of hypersonic inlets, and on the dominant amplitude and frequency of unstart oscillatory flow of hypersonic inlets were presented. The reasons why the boundary-layer bleeding can suppress unstart oscillatory flow of hypersonic inlets were analysed. In conclusion, the averaged performance parameter of hypersonic inlets during a big buzz is improved greatly, and the dominant frequency of unstart oscillatory flow of hypersonic inlets is reduced in contrast with no bleeding, and all these are benefit to the design and operation of hypersonic inlets.

Within the European project NACRE (New Aircraft Concept REsearch), a team of research centres and universities focuses on the assessment of a test facility in the form of a flying platform. The goal of this Innovative Evaluation Platform (IEP) is to offer engineers a new tool to investigate areas of interest during the early design phases of advanced aeronautical systems.

After an initial phase during which the potential benefits of such a platform have been demonstrated, the go-ahead for the IEP design and manufacturing has been given. In this second phase, a lot of attention has been brought to the system specifications since the platform has to meet the requirements of both an aerial vehicle and a test facility. The subsequent design process followed a stringent course of actions to achieve the design of a competitive test facility. The consortium aims for a final integration and flight trials in fall 2009.