Abstract: This invention relates to a craft designed to move through or on a surface of a fluid. It is believed to be principally of use in relation to airborne craft and missiles but the theory behind the invention is equally applicable for example to submarines.

Abstract: Devices for generating streamwise vorticity in a boundary includes various forms of vortex generators. One form of a split-ramp vortex generator includes a first ramp element and a second ramp element with front ends and back ends, ramp surfaces extending between the front ends and the back ends, and vertical surfaces extending between the front ends and the back ends adjacent the ramp surfaces. A flow channel is between the first ramp element and the second ramp element. The back ends of the ramp elements have a height greater than a height of the front ends, and the front ends of the ramp elements have a width greater than a width of the back ends.

Abstract: This invention relates to a craft designed to move through or on a surface of a fluid. It is believed to be principally of use in relation to airborne craft and missiles but the theory behind the invention is equally applicable for example to submarines.

Abstract: Devices for generating streamwise vorticity in a boundary includes various forms of vortex generators. One form of a split-ramp vortex generator includes a first ramp element and a second ramp element with front ends and back ends, ramp surfaces extending between the front ends and the back ends, and vertical surfaces extending between the front ends and the back ends adjacent the ramp surfaces. A flow channel is between the first ramp element and the second ramp element. The back ends of the ramp elements have a height greater than a height of the front ends, and the front ends of the ramp elements have a width greater than a width of the back ends.

Abstract: In aeronautical devices where a fluid such as air flows over a surface (1) to create lift or thrust, improved performance can be obtained by energising a so-called 5 “boundary layer” (10) of the fluid flow close to the surface. This is known to help prevent separation of the fluid flow stream from the surface thereby maximising the lift or thrust achieved. The invention provides a facility (7A) for controlling the mechanisms (7) used for energising the boundary layer so as to selectively increase or decrease the effect 10 in different areas. When this is done for example on different sides of an air vehicle, it provides an effective mechanism for steering the vehicle.

Abstract: An elongate probe suitable for measuring one or more properties of a stream of fluid, the probe having an external planar sensing surface, which in use is exposed to the stream of fluid, at a longitudinal end thereof and comprising a plurality of sensors at the planar external sensing surface.