The man behind the project was Maynard Hill, a retired metallurgist from Maryland. By the time he attempted the Atlantic, Hill had already set twenty-five world records in model aviation and had been inducted into the Model Aviation Hall of Fame in 1977. The Atlantic was his white whale. The team built twenty-eight airframes in the attempt - successive prototypes, each refining the design. They selected the five best for actual transatlantic flight attempts. Four failed. The 25th airframe, the fifth selected, was the one that made it. It was designated TAM-5 - Transatlantic Model 5 - and given the more affectionate nickname The Spirit of Butts' Farm, in honor of the farm in Maryland where the team did most of its flight testing. When word reached Hill that the autopilot had handed his aircraft to a successful landing in Ireland, he said: 'I just grabbed my wife, hugged her and cried like a baby.'

The aircraft was tiny by manned-aircraft standards - 72 inches long, 74-inch wingspan, weighing just under 11 pounds at takeoff with fuel. The engine was an O.S. Engines FS-61 four-stroke modified almost beyond recognition: smaller valves to reduce fuel consumption, a custom carburetor mounted remotely, triple fuel filtration down to 1 micron to prevent debris choking the lines mid-Atlantic, a pressurized fuel tank using crankcase pressure, and a custom power take-off to run the avionics. The 14-inch wooden propeller had its trailing edge sanded to razor sharpness for efficiency. The autopilot - similar to that used by the Insitu Aerosonde 'Laima' that crossed the Atlantic in 1998 - flew the airplane for more than 99 percent of the journey, holding heading and altitude while the Argos satellite system reported position to the team in Maryland. Cruising speed was 42 mph in still air; with tailwinds, the ground speed averaged 48 mph. The launch time of 22:15 UTC on 9 August was chosen carefully - good Atlantic weather and an arrival in daylight.

The flight covered 1,881.6 statute miles in a straight line - exceeding both the FAI world record for distance and for duration in its category. The use of an autopilot and satellite telemetry was new enough that the FAI created new record categories to accommodate what Hill's team had done. The aircraft used 99.2 percent of its fuel. When it touched down on Mannin Beach, just south of Clifden on the Connemara coast, it had 1.5 fluid ounces of alcohol-based fuel sloshing in the tank - enough for another forty-four minutes in the air. Any small change in wind, any small additional inefficiency, and the aircraft would have come down in the Atlantic. Mannin Beach is wide and flat and gentle. The Spirit of Butts' Farm settled onto the sand having done something nobody had ever done before, watched over by an autopilot a few hundred dollars in components could now replicate, but at the time genuinely at the frontier of what unmanned aviation could accomplish. Maynard Hill died in 2011 at the age of 85. The aircraft is preserved in the Smithsonian's National Air and Space Museum collection.