McDONNELL DOUGLAS (MDC) has joined the forward and centre/aft fuselage sections of the first F-18E/F fighter, using a laser-alignment technique pioneered on the MDC C-17 transport. Computer-controlled alignment reduces assembly time and results in a "near-perfect" splice, MDC says.
The F-18E/F is the first US fighter to be assembled using the system, produced by Seattle, Washington-based Nicholson Manufacturing. Compared with conventional splice methods yielding an alignment accuracy of within 10mm, the laser-guided system is accurate to within 0.25mm, according to MDC.
On the F-18C/D, the MDC-produced forward fuselage and Northrop Grumman supplied centre/aft fuselage are positioned on movable dollies, then manually aligned. On the F-18E/F, the centre/aft fuselage is loaded into a fixed holding tool and the forward fuselage into a movable tool.
The laser-alignment system uses measurements from 43 inspection points on the sections to determine the perfect splice. The computer-controlled system then brings the forward fuselage to within 25mm on the centre/aft section. An operator guided by horizontal and vertical light-planes generated by lasers, then aligns the sections exactly.
The sections are scribed and separated for trimming. The system then moves the forward fuselage back to the centre/aft section for the manual installation of some 1,500 fasteners to complete the splice. MDC says that the alignment accuracy achieved results in a smooth mould-line for improved aerodynamic performance.
The first of ten development aircraft, a single-seat F-18E, is due to be flown for the first time in December. The E/F is a structural upgrade of the F-18 and is about 25%% larger than the C/D.
Source: Flight International
