During the Vietnam War, American fighter jets struggled to win close air combat with Soviet MiGs. The solution came from the Lightweight Fighter Mafia, a group of engineers and defense analysts who advocated for a fighter prioritizing speed and maneuverability. The result was the YF-16, a prototype that intentionally had an unstable design to make it more maneuverable. This was achieved by making the aircraft smaller, removing one of its engines, and removing its aerodynamic stability.
The YF-16’s first accidental flight resulted from a high-speed taxi test that turned into a pilot-induced oscillation, which the pilot resolved by powering up and taking off. This first flight led to the development of the infamous F-16 fighter jet, which became one of the most successful combat aircraft in history. The YF-16’s unstable design was intentional and necessary for the aircraft’s increased maneuverability, distinguishing it from stable passenger airliners.