Linear elastic buckling strength assessments are presented for a range of thin plate arrays with optimal strength to weight ratio configurations subject to a range of arbitrary in-plane stress states. The outcomes of the assessment are presented as design curves demonstrating relative buckling strength increases with respect to the classical square plate datum of equal mass.

A stiffness matrix method is adopted for the initial buckling strength predictions. The method is based on exact flat plate theory and assumes that the plate is continuous over supports, whereby deformations in one cell of the plate array influence the deformations in adjacent cells. The supporting webs of each cell are approximated in this study by simple rigid supports that enforce nodal lines or lines of zero out-of-plane displacement in the buckled panel, i.e. the bending and torsional stiffness provided by the supporting webs of the real structure are ignored. Selected results are validated by FEM prediction.

The use of solar sail propulsion is investigated for both Mercury orbiter (MO) and Mercury sample return missions (MeSR). It will be demonstrated that solar sail propulsion can significantly reduce launch mass and enhance payload mass fractions for MO missions, while MeSR missions are enabled, again with a relatively low launch mass. Previous investigations of MeSR type missions using solar electric propulsion have identified a requirement for an Ariane V launcher to deliver a lander and sample return vehicle. The analysis presented in this paper demonstrates that, in principle, a MeSR mission can be enabled using a single Soyuz-Fregat launch vehicle, leading to significant reductions in launch mass and mission costs. Similarly, it will be demonstrated that the full payload of the ESA Bepi Colombo orbiter mission can be delivered to Mercury using a Soyuz-Fregat launch vehicle, rather than Ariane V, again leading to a reduction in mission costs.

A computational study has been performed to investigate the effectiveness of film cooling in hypersonic laminar flows. Both the primary and the coolant flow are air. First, three different primary flow conditions are used for validation. A uniform boundary condition at the slot exit is found to give unrealistic predictions of the heat transfer rate, whilst a boundary condition involving extended coolant inlet gives improvement. Then five coolant injection rates and three slot heights are examined. It is confirmed that increasing the coolant injection rate can increase the film cooling effectiveness for laminar cases. But slot height does not play an important role under the flow conditions in this study. The computational results are compared with the experimental results and good agreement is achieved.

This paper presents an examination of dynamic stall onset on both a rectangular wing and a nominally two-dimensional aerofoil with the same cross-section. The intention is to determine the extent to which the onset of dynamic stall is changed in the three-dimensional case. To do this, three different criteria are applied to measured pressure data to identify both the onset of the stalling process and the formation of the dynamic stall vortex. It is shown that examination of the vorticity flux in the vicinity of the leading edge provides a means of determining vortex formation in the absence of strong three-dimensional effects. It is also shown that this technique is not applicable on outboard sections of the rectangular wing where the phasing of dynamic stall onset with respect to the leading edge response is altered by the three-dimensionality of the flow. It is concluded that the application of two-dimensional stall onset criteria is inappropriate under such conditions.

This paper presents a simple and efficient way of calculating stall flutter using the ONERA aerodynamic model. At first, the model is presented along with a solution technique based on the harmonic balance method. The parameters of the model are estimated using data either from experiments or CFD calculations and optimised using the Levenberg-Marquardt algorithm. The aerodynamic model is then coupled with a structural one using the Rayleigh-Ritz formulation and a solution technique is devised based on the Newton- Raphson method. Finally the model is used to ‘fit’ aerodynamic loads of oscillating aerofoils generated using CFD. The aeroelastic analysis of a helicopter blade is finally undertaken using material properties found in the literature. The model appears to be robust and efficient and able to fit the unsteady aerodynamics of various cases. The proposed aeroelastic analysis was also found to be efficient and capable of providing adequate results for preliminary analysis of stall flutter.

This paper describes the development of an approach to handling qualities investigation that can be applied at an early stage in t he design of the vehicle. It makes use of inverse simulation techniques, together with a pilot model to provide an integrated description of the man-machine control system. In order to incorporate pilot effects into data generated by inverse simulation, the output from an inverse simulation run is applied as input to a closed-loop system model that includes the vehicle dynamics and a simple parametric model of the pilot. Parameters of the pilot model are determined by optimisation and the pilot effect is added to the system output. Validation of the approach is achieved through a case study involving a predefined mission task involving a lateral manoeuvre. Equalisation characteristics estimated for each pilot are compared with those found by inverse simulation for the same manoeuvre. This approach may be applied using a simple real-time simulation on a desk-top computer and could be of value in identifying any potential deficiencies in a helicopter flight control system at an early stage in its development

The purpose of this paper is to present a new approach in the concept and implementation of autonomy for autonomous spacecraft. The one true ‘artificial agent’ approach to autonomy requires the spacecraft to interact in a direct manner with the environment through the use of sensors and actuators. Rather than using complex world models, the spacecraft is allowed to exploit the dynamics of its environment for cues as to appropriate actions to take to achieve its mission goals. The particular artificial agent implementation used here has been inspired by studies of biological systems. The so-called ‘cue-deficit’ action selection algorithm considers the spacecraft to be a non-linear dynamical system with a number of observable states. Using optimal control theory a set of rules is derived which determine which of a finite repertoire of behaviours the spacecraft will perform. A simple model of a single imaging spacecraft in low polar Earth orbit is used to demonstrate the algorithm.