Changes in flight stability characteristics at the advanced stage of aircraft design are complex and require thorough investigations. This paper examines the impact of wing strake modification on high-performance aircraft using computational fluid dynamics (CFD). The dynamic behaviour is calculated using the forced oscillation technique, while the effect of geometric variation on longitudinal stability characteristics is extensively studied. Steady-state experimental data is utilised to validate the computational setup. Static aerodynamic coefficients, dynamic stability derivatives and the positions of aerodynamic and pressure centres are employed to quantify the changes. Furthermore, the alterations in stability characteristics are correlated with flow physics. The results indicate a reduction in longitudinal static and dynamic stability at various flight conditions due to the proposed modification. This deliberate reduction was necessary to accommodate the installation of a fly-by-wire system. The discussed design changes have been effectively implemented on an in-service aircraft.

This paper investigates the potential of a lever-type pitch trimmer to cause an overstress in light and microlight aeroplanes. It concludes that this potential exists and could potentially cause a catastrophic structural failure – with the evidence from one reported fatal accident suggesting that this may have already happened. However, it is shown that this need not be the case, with restricted nose-up control authority, high manoeuvre stability and the use of a trim wheel (as opposed to a lever) with a restrictive rate of control input shown as three methods, most likely in combination, by which this potential can be removed. Suggestions are made for airworthiness standard wording which might be used to ensure adequate safety of future aircraft designs.

A representative sample of 328 children with hemiplegia was assessed by behavioural screening questionnaires completed by parents and teachers; just under half were also individually assessed. Four years later, 90% of the sample were followed up by questionnaire. There was substantial continuity across time for most measures of psychopathology. Depending on the measures used, around 70% of children who were psychiatric “cases” initially were still cases 4 years later. In addition, around 30% of children who were not psychiatric cases initially had become cases 4 years later. In the preschool years, externalising symptoms were predictive of later conduct and hyperactivity problems, whereas emotional symptoms were not predictive of later problems. In the school years, hyperactivity was particularly predictive of continuing psychiatric problems. Neurological, cognitive, demographic, and family factors did not add much predictive power once allowance had been made for the severity and type of the initial psychiatric problems. Since the psychiatric complications of childhood hemiplegia are persistent as well as common, they warrant increased clinical and research attention. All children with hemiplegia deserve careful monitoring for psychiatric problems, with a view to early intervention or the deployment of preventative approaches.