WITNESSES REPORTED THAT THE ACFT APPEARED TO BE TOO HIGH, TOO FAST, AND IN A CRAB AS IT APPROACHED THE RWY. OVER THE RWY THE GLIDER WAS OBSERVED TO ROLL INTO A RIGHT TURN AS THE NOSE CAME UP. SHORTLY THEREAFTER THE RIGHT WING STRUCK 3 PARKED ACFT AND COLLIDED WITH THE TERRAIN. DURING AN INTERVIEW ON THE EVENING OF THE ACCIDENT THE PILOT STATED THAT DUE TO A HIGH FAST APCH HE ATTEMPTED A RIGHT 270 DEGREE TURN IN ORDER TO LAND TO THE NORTH, JUST PRIOR TO THE ACCIDENT. IN A WRITTEN STATEMENT SUBMITTED ON 6-25-84 THE PILOT REFERS TO CONTROL INPUTS FROM THE PASSENGER IN THE FRONT SEAT CAUSING THE ABNORMAL APPROACH AND AN UNCOMMANDED NOSE HIGH ATTITUDE JUST BEFORE COLLISION WITH THE PARKED GLIDER. THE PILOTS LOGS REFLECT 3 HRS IN THIS MAKE AND MODEL GLIDER. HE STATED THAT HE HAD FLOWN SIMILIAR GLIDERS IN THE LATE 1960'S AND HAD ABOUT 3.5 TOTAL HRS IN THE ACFT. HE FURTHER REPORTED TO INVESTIGATORS THAT HE WAS USED TO FLYING ANOTHER GLIDER IN WHICH 90 DEGREE FLAPS ALLOWED STEEPER APPROACHES AND MORE RAPID DESCENTS.