THE PILOT HAD COMPLETED REFUELING AT HIS FATHER'S FARM AND TOOK OFF TO THE WEST FROM A DIRT FIELD. AT ABOUT 25 FT AGL, THE AIRCRAFT ENTERED A RIGHT TURN AND REMAINED IN A BANK UNTIL IT STRUCK THE GROUND WITH THE RIGHT WINGTIP. THE AIRPLANE WAS DESTROYED AS IT CARTWHEELED TO REST. THE PILOT SUSTAINED SERIOUS INJURY AND HAD NO RECALL OF THE FINAL MANEUVERS.