Relationship between throttle position and nozzle in an aircraft with a variable pop-open nozzle.
A nozzle on a jet engine with a variable geometry outlet. This type of nozzle often is found on engines with afterburning. The nozzle generally is fully open (the largest dimension) at idle and progressively closes to the fully closed position at full throttle. The nozzle then opens as the engine afterburner is selected. The nozzle position is a function of many variables, but it is linked normally to the throttle position.