Air Force picked fighter by flying rivals, not paper

Through the 1960s the Air Force selected fighter designs largely on paper: engineering studies, contractor reputation, and projected performance figures a manufacturer supplied about its own design, with prototypes built only after a winner was already picked and full production money committed.

A group of officers and analysts known as the Fighter Mafia, led by Colonel John Boyd's energy-maneuverability theory, pushed the Air Force to fund two competing prototypes outright and fly them against each other before choosing either one, over resistance from a service that preferred locking in a design early.

General Dynamics and Northrop each built two flying prototypes, the YF-16 and YF-17, and flew them through real evaluation sorties in 1974 — 330 sorties and 417 flight hours for the YF-16, 268 sorties for the YF-17 — with pilots directly comparing dogfight performance neither company's paper specs could fake.

Forced both rivals to build flying prototypes and compete in real evaluation sorties, so pilots compared actual dogfight performance instead of paper claims.

Real flight tests expose weaknesses that paper specs can hide.

Pilots comparing actual dogfight performance see which design truly wins.

Prototype cost is small next to the risk of locking in the wrong airframe for decades.

For mission-critical buys, fund two real competing prototypes and test them operationally before committing production money.

The Air Force picked the YF-16 in 1975 on flight performance; it reached 4,600-plus built worldwide, and the YF-17 became the Navy's F/A-18. The prototype fly-off became the Pentagon's model for future high-stakes procurement decisions and is credited with producing one of the most successful and widely exported fighter designs in history, at a fraction of what a paper-only competition between two entrenched contractors would have risked getting wrong.