Device for controlling the passing of a gas jet in a jet nozzle of a flying vehicle, and flying vehicle comprising such devices

The device (7) has a controllable movable sealing unit (13) including a linear actuator (14) with a piston (23) dividing a cylinder (10) into a pressurized chamber (24) supplied directly with a part of gas jet and a variable chamber (25) with a spring (27). The sealing unit has a proportional exhaust modulation fluidic element (16) connected to the pressurized chamber by an exhaust port (35) and arranged to create controllable leak which permits regulation of pressure in the pressurized chamber and displacement of a sealing cap (15) by the spring in the variable chamber.