The problem was simple: fuel runs out. The solution, on 27 June 1923, was fifty feet of rubber hose and a lot of nerve. Over Rockwell Field on San Diego’s North Island, two Army Air Service de Havilland DH-4Bs—one flown by 1st Lt. Virgil Hine and 1st Lt. Frank Seifert, the other by Capt. Lowell H. Smith and 1st Lt. John P. Richter—linked up at 500 feet. Seifert dangled the hose; Richter grabbed it. Seventy-five gallons and one hour later, aviation had its first successful air-to-air refueling. Two months after that, Smith and Richter stayed aloft for 37 hours and 25 minutes, setting sixteen world records and proving a 275-mile airplane could be stretched to 1,280. It was a stunt until it wasn’t.