THE PILOT AND PASSENGER WERE PARTICIPATING IN A FLOUR BOMBING AND POWER OFF SPOT LANDING CONTEST. AFTER COMPLETING THE FLOUR BOMBING EVENT THE PILOT ENTERED A LEFT DOWNWIND TO LAND ON A NORTH RUNWAY. THE SURFACE WINDS WERE FROM THE WEST AT 10 MPH, GUSTING TO 20 MPH WITH ASSOCIATED DOWNDRAFTS OFF OF THE RIDGE WEST OF THE AIRPORT. THE AIRPLANE OVERSHOT THE FINAL APPROACH COURSE WHILE AT A LOW ALTITUDE AND SLOW AIRSPEED. THE PILOT APPLIED POWER, BUT CONTINUED TO INCREASE THE BANK. THE WING STALLED AND THE AIRPLANE CRASHED.