It is common for aerospace companies to use modified commercial aircraft as specialized testbed aircraft to test new technologies before integrating them onto new aircraft. Not only do Boeing and Airbus maintain fleets of commercial aircraft used to develop next-generation commercial aircraft, but aerospace defense companies also maintain commercial aircraft to develop next-generation fighter jets. One of the most notable modified testbed aircraft today is the modified Boeing 757-200 'Excalibur' used to help develop the Global Combat Air Programme (GCAP)/Tempest sixth-generation fighter jet. Somewhat confusingly, the names Excalibur and Catfish have been applied to multiple separate testbed aircraft, as it...