Abstract: A gas turbine engine comprises a casing defining a duct for a thrust producing gas, the casing is divided into an upstream and a downstream portion movable between a normal position form a continuous duct and a thrust reversal position in which the two portions are separated by a gap. A plurality of thrust reversal doors are pivotally connected at or towards one end thereof to the downstream portion and a number of struts and pivotally connected at or towards one end thereof to the upstream portion, the thrust reversal doors and the struts in the normal position and as the upstream and downstream portions move towards the thrust reversal position, extending downstream to leave the duct unobstructed thereby.

Abstract: A gas turbine engine comprises a duct for the passage of a thrust producing gas, the duct having an upstream portion and a downstream portion spaced apart in a direction parallel to the axis of the duct, the downstream portion being movable relatively to the upstream portion between a closer spaced position and a further spaced position. A plurality of thrust reversal doors are pivotally connected to an upstream end of the downstream portion and extend therefrom towards the upstream portion, and a linkage assembly has a one end fixed relatively to the upstream portion and acts on each thrust reversal door.

Abstract: A flight vehicle comprises a vehicle body with a duct having a longitudinal axis extending through the body, and a fan for inducing a flow of ambient air through the duct from an inlet end to an outlet end to provide a thrust acting along the axis of the duct. A system of control is provided for varying the attitude of the vehicle without re-directing or substantially re-directing the thrust whereby the vehicle is capable of controlled flight from a take-off mode in which the axis of the duct is vertical or substantially vertical, to a forward flight mode in which the axis of the duct is inclined to the vertical. A pair of wings are provided on the outer surface of the body, the wings being on opposite sides of the body and having no or substantially no dihedral.

Abstract: The invention provides an angular position reference device for measuring changes in the attitude of a moving body and comprising a closed chamber filled with a liquid and rotatable about an axis by drive means, and position sensing means such as a vane assembly mounted within the chamber for rotation with the liquid independently of the chamber about an axis co-axial with the chamber axis and which, with the liquid, defines a reference position fixed in space in a plane normal to said axis, and which co-operate with the chamber to define a datum position of the chamber relatively to the reference position, in use, rotation of the chamber about said axis tending to cause relative rotation between the chamber and the liquid from said datum position which is sensed by the position sensing means which produces an output proportional to said rotation, said output so controlling the drive means to rotate the chamber to return the chamber to the datum position and, in use, providing a measure of a change in the pos

Abstract: The position of a body is determined using a beam of electro-magnetic waves directed along a sight line generally towards the body. The cross-section of the beam is changed and a sensor mounted on the body senses these changes in cross-section and from the time periods in which electro-magnetic waves are received by the sensor two signals are produced in sequence, a first signal representative of a first co-ordinate position of the body within the cross-section of the beam and a second signal representative of a second co-ordinate position of the body within the cross-section of the beam.