Nearly blind in the velvet blackness of night in the thin air over Rock Springs, Wyoming, the pilot can only aim at the glowing exhaust overhead. At 85 miles an hour, he feathers the airplane's throttle and pulls to within a few dozen feet of the plane directly above him. Out of the blackness, a hose appears. Skimming inches below its flailing nozzle, Nick Mamer eases his biplane closer, so his copilot can capture the hose and fill his tank with...