THE PLT HAD ASSEMBLED & FLOWN THE ULTRALIGHT VEHICLE DURING THE PREVIOUS SUMMER. THIS WAS HIS 1ST FLT AFTER REMOVING IT FROM WINTER STORAGE. HE WAS OBSERVED PREFLIGHTING THE VEHICLE BEFORE TAKEOFF. AT ABOUT THE TIME OF THE ACCIDENT, A GROUND WITNESS HEARD THE ULTRALIGHT FLY OVER, BUT NO KNOWN EYE WITNESSES SAW THE VEHICLE CRASH. DURING THE ACCIDENT, IT IMPACTED IN AN OPEN PASTURE IN A STEEP NOSE DOWN, LEFT WING LOW ATTITUDE. THERE WAS LITTLE MOVEMENT AFTER IMPACT & 1 PROPELLER BLADE WAS SHATTERED. APRX 3 GAL OF FUEL WAS REMAINING IN THE FUEL TANK. THE PLT'S TOTAL FLT TIME WAS NOT DETERMINED. ACCORDING TO HIS FATHER, THE PLT CONDUCTED FLTS OVER HIS FARM TO OBSERVE HIS CROPS & CATTLE. THE FLT CONTROLS CONSISTED OF AN ELEVATOR PUSH-PULL ROD & RUDDER CABLES THAT WERE ATTACHED TO A 'JOY STICK.' THE ULTRALIGHT WAS NOT EQUIPPED WITH AILERONS OR SPOILERS FOR ROLL CONTROL.