The AV-8B Harrier remains one of the most instantly recognizable jets in the world, one of the few that can take off vertically, hover, and land without a runway—a capability known as V/STOL. Of course, crafting a fixed-wing aircraft that could perform in such a manner required very intentional design elements, an engineering scheme that combined thrust-vectoring, reaction controls, and lightweight design, leading to an end product that helped redefine what an aircraft could do.

The heart of the Harrier’s V/STOL performance is the Rolls-Royce Pegasus turbofan engine, which drives four rotating exhaust nozzles. Two “cold” nozzles in the front expel bypass air while two “hot” nozzles in the rear expel combustion gases. All four nozzles rotate in sync with one another, from 0 degrees (horizontal) to........

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