This late 1960s photograph shows an early General Dynamics F-111A Aardvark in flight at the NASA Flight Research Center. The wings on this aircraft did not have a supercritical airfoil design.In 1967 the NASA Flight Research Center received the first of two F-111A aircraft (the number six prototype, Serial #63-9771) to evaluate. These early F-111s had problems with their engines and suffered from repeated compressor surges and stalls. After extensive testing, NASA, the Air Force, and General Dynamics arrived at a major inlet redesign to resolve the problems. The second F-111A (#63-9777) arrived at the Center in 1969 and was used for a handling-qualities study.