Two hundred years ago the first manned balloon launch was attempted. On 21st November 1783 the hot air balloon, Montgolfiere, carried two men, the adventurer Pilatre von Roxier and the Marquis D’Arlandes, nine kilometres during their twenty minute flight.

The history of flight continued with many ambitious and inventive men. Among them were Graf Zeppelin, famous for airships, Otto Lilienthal for motorless flight, and the Wright brothers for the first powered flight. Since then the development went further until today large scale aircraft have become commonplace. Tomorrow, space flight could be just as common. Who dares say no to the technology that has brought us today’s living comforts?

The following contribution deals with an actual problem in present day hot air balloon construction.

Following Parts 1 and 2 of this experimental study the effects of rows of spherical roughness elements upon transition of the boundary layer are now described. Data presented includes that for the start of the end of transition, the effect of spacing of the roughness elements, the effective origin of the turbulent boundary layer and its development and the spanwise variations across the turbulent boundary layer.

A rig for measurement of forces and moments due to continuous rate of roll has been commissioned at RAE Bedford. Tests have been made on a High Incidence Research Model (HIRM) in two wind tunnels at M = 0·2, 0·4 and 0·7. At present models can be tested up to 40° angle of attack at rotational speeds up to 350 rpm.

Tests on HIRM included an investigation of configuration and Reynolds number effects. Results are compared with similar data from tests with another rolling rig and from small amplitude oscillatory tests.

Attention is focused on the installation aerodynamic aspects, rather than ejector design itself, of ejector augmentors installed in combat aircraft as part of the lift and propulsion system.

It is indicated that in the case of the combat aircraft required to perform vertical land but not VTO, the installed thrust is such that only a small level of augmentation is required. The reason for installing an ejector is that it is capable of providing this augmentation together with a benign ground footprint. The design problems are seen to be those of relatively large volume and ensuring satisfactory aerodynamic performance in all relevant flight regimes.

The installation aerodynamic problems focus on the inlet and exhaust. Performance is very sensitive to intake pressure recovery with the critical area being at the start of the landing transition. In the second case, the problem is that of providing a degree of thrust vectoring for the large low pressure exhaust to provide adequate transition performance in the face of considerable intake momentum drag.