REPORTEDLY, A FATHER & HIS 14 YR OLD SON HAD BEEN RECEIVING GROUND & TAXI INSTRUCTION, AND HAD RECEIVED 'CROW-HOP' PRACTICE IN THE PREVIOUS FEW WEEKS. ON 6/27/83, THE VEHICLE BECAME AIRBORNE WITH THE SON ON BOARD. HE FLEW IT IN A PATTERN AROUND THE OPEN FIELD THAT WAS BEING USED BY ULTRALIGHT PLTS. WITNESSES REPORTED THAT THE PLT ATTEMPTED TO LAND BY APPROACHING OVER TREES FROM SOUTH TO NORTH, BUT OVERSHOT THE 500 FT LANDING AREA. DURING A GO-AROUND, HE STRUCK GROUND VEHICLES IN A PARKING LOT AT THE NORTH END OF THE FIELD, BUT CONTINUED TO FLY. ON THE 2ND APPROACH, THE ULTRALIGHT CAME OVER TREES AT THE SOUTH END & EXECUTED A SERIES OF STAIR-STEP MANEUVERS ON THE APPROACH. AT APRX 60 FT AGL, THE VEHICLE NOSED OVER & STRUCK THE GROUND IN A STEEP DESCENT. NO PREIMPACT/MECHANICAL FAILURES WERE FOUND. THE INVESTIGATION DID NOT DETERMINE WHETHER OR NOT THE FLT WAS INTENTIONAL.