Northrop Grumman has begun building the centre fuselage for the first international F-35 joint strike fighter meant for the UK.

The fighter, an F-35B short take-off, vertical landing (STOVL) variant designated BK-1, underwent the first stage of the assembly process with the loading of an all-composite air inlet duct into a special tooling structure called a jig.

The stage will be followed by 18 major steps for assembling the centre fuselage ,which consists of attaching metal frames around the duct.

The frames serve to brace and position the duct properly within the centre fuselage.

Northrop, a part of the F-35 industry team, is designing and developing the centre fuselages for all three variants of F-35 aircraft, apart from radar and other key avionics, mission systems and mission-planning software.