It might seem a huge step from 1969-vintage Harrier to 21st-century Lightning II, but one very historic aircraft links them. The unmistakable Vectored-Thrust Aircraft Advanced Flight Control, or VAAC, testbed — the world’s oldest two-seat Harrier — was instrumental in resolving divisive arguments on the choice of flight and propulsion control for the F-35B

When UK-based technology and evaluation group QinetiQ retired the VAAC Harrier in November 2008, it brought to a close the distinguished and varied career of an aircraft that had been dedicated to pushing the boundaries for almost four decades.