If a sodden rice paddy feels soft and forgiving underfoot, it is not a merciful place to set down an airplane at 200 mph. And that’s only one of Mike Selby’s reasons to look nervous as he watches his A-10 Warthog—a 10-foot-wide, 65-pound, hand-built model—begin its maiden takeoff roll down a rough asphalt runway near Bangkok, Thailand. Selby, who spent over $12,000 and the better part of a year fabricating and building this radio-controlled jet, stands runwayside with his thumbs hooked into the belt loops of his jeans, trying to look relaxed as he draws on a Cuban cigar. But he can’t stop tapping his foot. Next to him, pilot Ray Johns, a U.S. Air Force general and test pilot who has flown everything from Air Force One to the U2 surveillance plane, chews a wad of gum with anxious rapid-fire chomps and leans back against the weight of the control console hanging from his neck.

It’s been nearly a year since Johns last flew one of Selby’s finished models, at the Top Gun competition in Lakeland, Florida, and the memory haunts them both. Top Gun, held each April, is the de facto world championship of radio-controlled scale-model aeronautics, an invitation-only event that hosts some 130 entries, jets and prop-planes alike, from around the world. Selby had spent the two years before the event building and tweaking his Embraer Tucano 312 (a Brazilian turboprop fighter trainer), and the plane had a grip on first place going into its final competition flight. But suddenly, as it went into a tight turn, the plane stopped responding to Johns’s control inputs. “We saw it jink to one side, and then it just keeled over and dove into the forest,” Selby says. “We had to rent a helicopter to recover the pieces.”...