THE PILOT STATED THAT JUST AFTER TAKEOFF, HE ENCOUNTERED A STRONG GUST OF WIND THAT CAUSED HIM TO LOSE CONTROL OF THE AIRPLANE. HE SAID THE LEFT WING SUDDENLY WENT DOWN TO ALMOST 90 DEGREES AND HIT THE GROUND. THE AIRPLANE THEN CARTWHEELED AND CAME TO A STOP. THE PILOT, PASSENGER, AND THREE GROUND WITNESSES SAID THE WINDS HAD BEEN VARIABLE AND GUSTY. THE PILOT WAITED ON THE RUNWAY FOR SEVERAL MINUTES FOR MORE FAVORABLE WINDS BEFORE STARTING THE TAKEOFF.