Abstract: A method of and apparatus for operating a propeller, the propeller moving through a fluid, the method including: measuring a value of a property of the fluid (e.g. a parameter related to the density of the fluid); measuring a value of a parameter, the parameter related to one or more forces applied to the propeller (e.g. a torque applied to the propeller) or derived at least in part from the action of the propeller (e.g. a thrust produced by the action of the propeller, a drag produced by the action of the propeller, or a velocity produced by the action of the propeller); and controlling the propeller depending on a function of the measured value of the property of the fluid and the measured value of parameter. The propeller may be a propeller on an aircraft.

Abstract: Disclosed is an air vehicle mounted or mountable transmitting and/or receiving equipment including a transmitting and/or receiving turret allowing at least a forward field of view, the device being mounted or mountable on a fuselage such that it extends away from the fuselage to which it is mounted; and a fairing mounted to the fuselage adjacent the device at a rearward side of the device for reducing aerodynamic drag, the fairing being retractable by, for example, an electrically driven mechanism, to afford the device a rearward (arrow R), or more effective rearward, field of view for transmitting and/or receiving.

Abstract: A method of and apparatus for operating a propeller, the propeller moving through a fluid, the method including: measuring a value of a property of the fluid (e.g. a parameter related to the density of the fluid); measuring a value of a parameter, the parameter related to one or more forces applied to the propeller (e.g. a torque applied to the propeller) or derived at least in part from the action of the propeller (e.g. a thrust produced by the action of the propeller, a drag produced by the action of the propeller, or a velocity produced by the action of the propeller); and controlling the propeller depending on a function of the measured value of the property of the fluid and the measured value of parameter. The propeller may be a propeller on an aircraft.

Abstract: Disclosed is an air vehicle mounted or mountable transmitting and/or receiving equipment including a transmitting and/or receiving turret allowing at least a forward field of view, the device being mounted or mountable on a fuselage such that it extends away from the fuselage to which it is mounted; and a fairing mounted to the fuselage adjacent the device at a rearward side of the device for reducing aerodynamic drag, the fairing being retractable by, for example, an electrically driven mechanism, to afford the device a rearward (arrow R), or more effective rearward, field of view for transmitting and/or receiving.