This lecture recognises the background and distinguished work of Frederick William Lanchester, and notes that my background has a few similarities with his. These include a shared interest in wings, lift and vortices. My career at the NASA Langley Research Center spans the time-frame from America’s Super Sonic Transport through 2009. An early emphasis involved wind-tunnel testing of research aircraft models and the development of computer codes for subsonic aerodynamics of wing planforms. These attached-flow codes were applied to various configurations, including those with variable-sweep, dihedral, and more than one planform in both the analysis- and design-modes. These codes were used to provide a connection between leading-edge-forces and the associated additional lift on delta-wings with shed-vortex systems through the leading-edge suction analogy of Edward C. Polhamus. Subsequently, I extended the suction analogy to configurations with side-edges to predict the vortical-flow aerodynamics on complex configurations, including wing-strake combinations. These analysis codes could also be used in a design-by-analysis mode for configurations with leading-edge shed vortices. Later, I was involved in vortical-flow flight research with the F-106B and the F-16XL aircraft at cruise and maneuver conditions. Associated CFD predictions, generated by me and other members of the RTO/AVT-113 task group, have increased our understanding of the flight flow-physics measured on the F-16XL aircraft.

In this paper, flow control effectiveness of a passive device in relation to open cavity flowfield is investigated computationally and compared with experimental work. Specifically the modification in the cavity flowfield due to the presence of a spoiler is studied in details to explain the physics behind the flow control effects. A combination of 2D and 3D flow visualisation tools are used to understand the flow behaviour inside the cavity and the quantitative analysis of the unsteady pressure fluctuations is also performed to assess the unsteady effects. Flow simulations with a turbulence model based on a hybrid RANS/LES (commonly known as Detached-Eddy Simulation (DES)) are used in this study. The time-mean flow visualisation clearly showed the presence of three dimensional effects inside the empty cavity whereas the 3D effects were found to diminish in the presence of a spoiler. In the unsteady flow analysis, near-field acoustic spectra were computed for empty cavity as well as cavity-with-spoiler cases. Study of unsteady pressure spectra for the cavity-with-spoiler case was found to record the complete suppression of the dominant tones in the presence of the spoiler. The analysis has indicated that the main reason behind this suppression is due to the inability of faintly energised vortical structures (faintly energised as a result of the extraction of turbulent kinetic energy by the spoiler) to maintain the unsteady flapping of the separated shear layer.

In this paper a geometric sizing method for a small electric powered flying wing is proposed. The geometric sizing method aims to reduce the effects of variations in the power plant characteristics on endurance. This results in a single-objective design optimisation problem where the sensitivity to power plant characteristics of the endurance equation is minimised, constrained to Reynolds number, wing load, wing taper ratio, aircraft size and wing sweep angle. As a result, geometric characteristics of the flying wing such as span, tip chord and root chord are obtained. Flying wing aerodynamic characteristics are obtained by means of an inviscid fluid flow analysis program of the type low-order panel methods, known as CMARC. The optimisation problem involves a non convex function so that it is necessary to rely on heuristic programming methods. In particular an Evolutionary Algorithm based on differential evolution is considered.

Recent work by Tsitas and Kingston(1) has demonstrated that an 8kg 6U CubeSat can be designed to perform Earth observation missions equivalent to those of 50-150kg microsatellites. Their design is reviewed and its commercial potential is compared to the 156kg RapidEye spacecraft. Three other commercial applications of this design are described. These are: a standard spacecraft for space scientists and astronomers; the spacecraft component of an N nation 5 spectral band disaster monitoring constellation and a night imaging satellite. Nanosatellites should now be considered for commercial missions previously thought to require microsatellites.

Detached-eddy simulations for the 1303 UCAV geometry are undertaken aiming to investigate the flow physics of the interaction of a store with the flow inside a UCAV weapons bay. Advanced multi-block topologies had to be used to properly represent the planform of the UCAV and all the details of the weapon bay, including doors and hinges, while sliding meshes were needed to insert the store into the UCAV configuration. Results with an empty bay were encouraging for such complex configurations. Flow visualisation revealed the added turbulent content due to the door leading edges and hinges. The addition of a store in between the doors had little effect close to the front wall of the bay. However averaged flow-fields showed that the proximity of the shear layer to the apex of the store deflected it downwards into the bay and restricted its growth.