Abstract: A variable air inlet includes an air intake duct with upper ramps, an air inlet bottom spaced below the ramp and a movable air scoop lip pivotally secured to the end of the air inlet bottom closer to the opening into the air intake duct. The air scoop lip is pivotally displaceable through two angular operating ranges, a wider one in the subsonic/transonic range and a narrower one in the upper supersonic range. Various control members including computers are used to control the position of the lower air scoop lip. The movement in the subsonic/transonic range is effected in response to the flight machnumber and the aircarft angle of attack based on a given control law. The control in the supersonic range is established in response to a variable demand pressure ratio between the static pressure above the upper ramps and the free stream total pressure, with the variable demand pressure ratio being a function of the actual air scoop lip position.

Abstract: The thrust nozzle opening angle of two cycle gas turbine jet engines is controlled in a system which comprises a low pressure compressor driven by a low pressure turbine. A first compressor is arranged radially inward for a first flow cycle or circuit and a second compressor is arranged radially outward for a second flow cycle or circuit. A high pressure compressor is driven by a high pressure turbine. A combustion chamber is situated upstream of the high pressure turbine. An afterburner is supplied with the turbine gases from the first, hot flow cycle and with compressed air from the second, relatively cool flow cycle or circuit. The system may have multiple shafts. The control is effected with reference to the instantaneous pressure relationship (.pi.NVZ) between the static pressure (p.sub.sD) downstream of the radially outer compressor (1a) of the second flow cycle (k2) and the static pressure (p.sub.sE) of the air flowing into the propulsion system. This ratio constitutes a variable rated control value (.