DURING TAKEOFF, THE RIGHT SIDE OF THE CANOPY SEPARATED FROM THE AIRCRAFT AS IT WAS CLIMBING THROUGH ABOUT 150 TO 200 FT AGL. THE PILOT NOTIFIED THE TOWER OF THE SITUATION AND CLEARANCE WAS OBTAINED TO LAND ON ANY RUNWAY. ACCORDING TO THE PILOT, HE TURNED CROSSWIND TOO SOON AND BEGAN A DOWNWIND TOO CLOSE-IN WHILE AVOIDING GLIDER OPERATIONS. SUBSEQUENTLY, HE BEGAN A TIGHT 180 DEGREE TURN FROM A LOW DOWNWIND TO FINAL APPROACH. THE PILOT REPORTED THAT DURING THE TURN, THE AIRCRAFT "BEGAN TO FALL OUT OF THE SKY." HE ADDED FULL POWER AND STATED THAT PARTIAL CONTROL WAS ACHIEVED OVER A TAXIWAY. HE ELECTED TO CHOP THE POWER AND LAND. THE AIRCRAFT LANDED HARD IN A 3 POINT ATTITUDE AND WAS DAMAGED. THE PILOT BELIEVED THAT THE FRONT CANOPY PIN WAS ENGAGED BEFORE TAKE- OFF (IT WAS VISUALLY CHECKED). HOWEVER, HE NOTED THAT THE REAR PIN WAS LOCATED OUTSIDE. HE RECOMMENDED A MORE PRUDENT CHECK OF THE CANOPY ATTACHMENT (FRONT AND REAR PINS). HE HAD INSTALLED A NEW WEATHER SEAL AT THE REAR HATCH.