A turbulent boundary layer, subjected to a freestream velocity which changes sinusoidally with time around a spatially uniform mean value has been studied experimentally. The experiments were conducted in a specially designed unsteady-flow water tunnel. A two-component laser Doppler anemometer was used to measure the instantaneous velocities, and hence the turbulent stresses, in the periodic boundary layer. A surface-mounted heat-flux gauge was used to measure the unsteady wall shear stress. The experiments were conducted at relatively high amplitudes of oscillation (≈ 40% of the mean) and over a wide range of reduced frequencies (1.7-28). While the present data on the oscillatory flow properties generally confirm previously known trends the information on the turbulent shear stress and skin friction obtained in the present studies is more complete than previously available. The experimental data, all of which has been archived on magnetic tape, form a comprehensive base for the development and verification of predictive models for unsteady turbulent boundary layers.

A comparison is presented of three methods for the generation of numerical, modal approximating functions for use in modal Lagrangian analysis of rotating flexible blades. The methods considered are those based on the use of uniform beam/bar eigenfunctions, smooth bending moment or torque modes, and modes generated by recourse to one stage of the Stodola method. For blades which are highly non-uniform in their specific stiffness and inertial properties, and where the objective is to use a small number of approximating functions, consistent with accurate determination of eigen-solutions in the fundamental spectrum, it is demonstrated (as is well known) that direct use of uniform system eigenfunctions is unsatisfactory. On the other hand, it is demonstrated that the use of smooth bending moment modes, even in cases where the variations in sectional inertia properties are very large, can produce excellent results. The use of ‘Stodola modes', however, is shown to offer the all-important advantage of enhanced convergence rate in all cases considered.

Aircraft longitudinal ride-bumpiness during flight at high speed and low altitude is described in terms of the response to discrete gust patterns. Results are expressed statistically in a form that incorporates data from recent turbulence measurements. Effects of basic airframe parameters and of active controls are illustrated and data from a computer-simulation study are used to confirm the validity of the prediction method.

The results of an experimental programme conducted in the University of Southampton's induced flow supersonic wind tunnel are presented. The pitch static force coefficient and centre of pressure data relate to a series of bodies with a blunt cone nose forebody with afterbodies comprising circular, square and triangular cross section. The blunt cone nose forebody has a forward located, body axis, aerodynamic spike system.

The data presented reveals the well known benefits of aerospikes with blunt nosed axisymmetric vehicles. This is then used as a base to explore the coupled flowfield effects on force coefficients due to spike deployment on bodies of non-axisymmetric cross section. The results identify how the body-only benefits of triangular cross sections are not degraded by the spike presence, with the main aero-spike benefit of drag reduction preserved throughout the angle of attack range investigated.