The effects of base bleed on the flow about a two-dimensional model with a blunt trailing edge were examined at Reynolds numbers, based on model base height, between 1·3×104 and 4·1×104. The ratio of boundary layer thickness at the trailing edge to half the model base height was approximately 0·4. Measurements were made of base pressure, vortex shedding frequency and the distance to vortex formation. With a sufficiently large bleed quantity the regular vortex street pattern disappeared and the base drag of the section was reduced to about a third of its value without bleed. The base pressure was found to vary linearly with the inverse of the vortex formation distance. Results of a previous splitter plate investigation were found to agree closely with those of the present experiments.

A simple potential theory for flow through cascades of low solidity is developed. The analysis is an extension of Glauert’s theory for single aerofoils. The variation of outlet angle and lift coefficient with space/chord ratio and stagger angle is predicted. The simple analysis is shown, by comparison with other methods of computation, to be valid for cascades of space/chord ratio in excess of 1·5 and staggers over 50 degrees.

An experimental investigation of natural transition and turbulent boundary layers on a cold flat plate in hypersonic flow was carried out in the Imperial College Gun Tunnel. Studies were also made of the effects of both two- and three-dimensional roughness elements including vortex generators.

Results indicate that the Reynolds number based on the end of transition consists of two separate parts. These are the Reynolds numbers based respectively on the position of the apparent origin of the transition region behaviour, Ri, and on the length of the transition region measured from this origin. Ri is shown to be independent of unit Reynolds number for a sharp leading-edge model, and by correlations of other published data to vary little with Mach number. This origin is perhaps the most relevant point when comparisons are made between experiment and classical stability theory. The variation of the heat transfer rate during the transition region is compared with findings at low speed and shown to be similar to that expected from the turbulent spot concept of Emmons. The measured variation of the length of the transition region (x) from this origin gives an explanation for the unit Reynolds number effect on transition, and the rapid increase of transition Reynolds number with Mach number in hypersonic flow. The effect of bluntness on these factors is discussed.

The virtual origin of the turbulent boundary layer is shown to lie close to the measured beginning of transition. At these high Mach number and low wall temperature conditions experimental values of heat transfer and values of skin friction coefficient derived from the estimated momentum thickness growth in the turbulent region are found to be appreciably higher than predictions by present theories.

Roughness trips were found to bring the whole transition region forward. Only small differences in the measured boundary layer thickness, shape and heat transfer rates in the turbulent region (referenced to the estimated virtual origin in each case) were found after natural and forced transition. The transition point locations on a flat plate with either spherical roughness elements or vortex generators were found to agree with values predicted by the method of Potter and Whitfield as modified by Luxton to account for the effects of heat transfer.

A recent calculation method proposed by Curle has been applied to the flow U=U0ξe-ξ for which a computer solution exists. An earlier approximate method due to Head, presented here in a simplified form, has been applied to the same problem. All three solutions are found to be in close agreement. A further problem, already examined by Curle, is treated by Head’s method. Again the results are in good agreement with each other and with an exact solution obtained subsequently.

An exact analysis is made of reinforced sheets having three fibre directions using netting analysis. Load envelopes of shear combined with both uniaxial and biaxial tension are assumed and optimum fibre arrangements are determined on the assumption that limits exist on the compressive and tensile forces which may be developed in a fibre. Such optimum fibre arrangements are compared with the best-arranged isotropic reinforced sheets and with hypothetical solid sheets having the same properties as the fibres. Elastic constants are derived for the optimum systems. The total allowable load envelopes of the optimum arrangements are found and are related to the prescribed load envelopes.

At the Aerodynamische Versuchsanstalt Gottingen (AVA), base pressure measurements were made on five elliptic cones. The ratios of the axes of the ellipses were: 1:12, 1:3, 1:1, 3:1, and 12:1. All the cones had the same volume and the same length. The investigations were carried out for Mach numbers M∞=1·50, 1·73, and 1·98 at angles of incidence between about —2 degrees and about 8 degrees. Reynolds numbers, based on a mean length, lm, varied from 2·5×106 to 3·0×106; the boundary layer approaching the base was turbulent. The base pressure coefficients are given as a function of geometry. Some of the results were compared with the base-flow theory of Korst and reasonable agreement was found.