The F-35 is in widespread service in considerable numbers with many more to come in due course. However, before the F-35, there was the X-35 – the Lockheed Martin contender in the JSF competitive fly off. Up against the Boeing X-32, two X-35s were built. One of them was initially used to demonstrate the proposed Air Force configuration before it was modified with the vertical lift system proposed for what became the F-35B in USMC service.

With the competition complete, the demonstrators were superfluous and the X-35B airframe made its way to the National Air and Space Museum. Here it sits on display. What is the most interesting part – at least to me – is that they have taken the propulsion system out of the jet and put it on display separately. You can see the main engine as well as the lift fan module, the shaft coupling the two, the nizzle that both have to direct the flow and the roll posts that are used to provide both additional lift and roll control in the hover.

It is a cool demonstration of the basic configuration that is now operational in the F-35B. it has certainly been developed since this design, but the basic principles remain the same. Unlike the Harrier that had the engine in the centre of gravity of the aircraft (not a very convenient location) and redirected all thrust through four nozzles, this configuration has a mighty engine at the rear which can be vectored down when required through a three bearing nozzle that is both simple and ingenious but then a shaft drive from the same engine to a fan module that sits behind the cockpit drawing air from above and directing it down with some ability to vector it too. This forward fan balances against the rear main nozzle. It provides a significantly higher amount of vertical thrust than the Harrier ever managed and allows a larger and more capable aircraft to land vertically at the end of missions. Quite a smart piece of design.