The aim of this paper is analyse the practicality or otherwise of solar-powered propulsion (after launch using conventional chemical rocketry) for a space vehicle’s late pre-orbital trajectory phase, for orbital transfer and for post-orbital flight. We introduce a ‘concept’ vehicle that in principle permits the use of solar-powered propulsion in each of these stages. Some of the technical challenges that such a vehicle might face are analysed, including the problem of how to keep a large ultra-low mass optical concentrator arrangement sufficiently accurately positioned in different parts of such a trajectory.

In this second Aeronautical Journal paper providing a technical appraisal of the Wright brothers’ achievements, the authors use modelling and simulation and associated flight dynamics analysis to present the development of the first practical aeroplane. The aircraft in question, the Wright Flyer III, was deemed fit for service by the Wrights in October 1905, and had evolved significantly from the first powered aircraft of 17 December 1903. The appraisal tries to shed light on many of the flight handling problems that the Wright brothers faced during this, their third phase of aeronautical endeavour, in 1904 and 1905. They retained their unstable configuration born in the 1901 and 1902 gliders, gradually refining the performance and handling until they considered the aircraft was ready for market. Their process of refinement has been reconstructed in simulation within the Liverpool Wright project, highlighting the many important developments during a period when Wilbur and Orville’s own documentation was limited. Apart from their engineering excellence, the Wright brothers are to be acknowledged for their perseverance and resolve in overcoming setbacks, for their ability to innovate and to recover and learn from their mistakes. In many ways the Wright brothers represent a model for the modern aeronautical engineer, and it is hoped that their legacy will be better preserved through the documentation of this project.

It is argued that acoustic resonance phenomena in open cavities such as weapons bays cannot be adequately predicted through numerical solution of Reynolds averaged Navier-Stokes (RANS) equations. The requirement to resolve the growth of the shear layer instability from the lip of the cavity inevitably implies that turbulence further downstream is resolved while also being modelled thus making RANS over dissipative. Large eddy simulation (LES) models only unresolved scales and a hybrid method combining RANS near walls with LES in the cavity appears a practical alternative to pure RANS. This paper compares computations of the M219 cavity configuration made with unsteady RANS and with the hybrid method known as detached eddy simulation (DES). It is shown that whilst unsteady RANS and DES give very similar predictions for the 1st and 3rd modes of the acoustic resonance the 2nd mode (which is dominant near the centre of the cavity) is absent in the RANS results but well predicted by DES. The 2nd mode is thought to arise from an interaction with vortical structures in the shear layer which are suppressed in the highly dissipative RANS method. The 4th mode, which is much weaker than the other three modes, is over-predicted by DES and under-predicted by a smaller amount in RANS.

After identifying the ecological and economic drivers for use of laminar flow technology, we outline the mechanisms of laminarturbulent boundary layer transition and review the status of natural laminar flow (NLF) and hybrid laminar flow control (HLFC). New ways to reduce the complexity of HLFC systems are presented, and the remaining steps to achieve technology readiness are discussed.