A dark mass of clouds hung low over North Charleston as Marine Col. Charles "Tre" Del Pizzo began his descent. It was a Sunday afternoon, late September 2023. Del Pizzo's hands were on the control stick and throttle of an F-35B Lightning II, the U.S. military’s most advanced stealth fighter, a $136 million supercomputer with wings. The F-35B can hover like a helicopter, and Del Pizzo planned to use that technology to land. Del Pizzo had just finished a training sortie over the Atlantic with a second F-35B pilot, practicing tactics at upwards of 500 mph at seven times the...