Abstract: Known variable nozzle actuating mechanisms are of complicated construction. This is acceptable where the devices are used on engines which power manually controlled aircraft. The invention although usable on engines used as described above, is particularly useful on engines which power pilotless vehicles i.e. missiles by virtue of its simplicity and therefore reliability. The variable nozzle has flaps which are held in a first throat constricting position by a knuckle mechanism. Opening of the throat is achieved by moving ram rods to the left as viewed in the drawings, to straighten the knuckle mechanism about an intermediate pivot. Gas loads on the inner surfaces of the flaps push the flaps outwards. At all operating positions of the flaps except this fully open position, gas loads are transferred via the knuckle mechanisms onto the fixed cowl. Secondary flaps may be included.

Abstract: A propeller module for an aero gas turbine engine comprises two contra-rotating propellers driven by a reduction gearbox positioned axially between the propellers.Pitch change mechanisms operated by a pitch change power unit are provided to change the pitch of the propeller blades. The pitch change power unit is positioned in the hub of the second multi-bladed propeller and is remote from the first multi-bladed propeller. The first and second pitch change mechanisms are mounted on the reduction gearbox. The first pitch change mechanism comprises first pitch change gears which are rotatably mounted on a carrier of the reduction gearbox by spindles which extend axially through planet gears of the gearbox. The second pitch change mechanism comprises second pitch change gears rotatably mounted on the carrier.

Abstract: A bypass gas turbine aeroengine has an exhaust mixer of the lobed type. The trailing edges of the confronting sides of each lobe are cut back to form notches or scallops in the sides of the lobe. To reduce aerodynamic losses and engine length and weight, the final turbine stage within the engine core is without outlet guide vanes so that the turbine exhaust gas stream issuing from the turbine has a substantial swirl component of velocity. Correction back to an axial direction of mean flow at the downstream end of the exhaust mixer nozzle is achieved by making the area of the scallop in one of the confronting sides of each lobe greater than the area of the scallop in the other side, the arrangement being such that sufficient of the turbine exhaust stream effuses from the larger scallops in directions contrary to the swirl component of velocity to produce the desired correction.