WITNESSES RPTED A NORMAL TAKEOFF. RADAR INDICATED THE ACFT TURNED RIGHT AS CLEARED AND BEGAN CRUISE AT 1900 FT, HDG NW AT 235 KTS. 65 SECS AFTER CALLING CLEAR OF THE CONTROL ZONE THE ACFT'S RADAR TRACK ENDED. THE ACFT WAS FRAGMENTED BY THEIMPACT WITH ALL FLT CONTROL SURFACES AND ACFT EXTREMITIES FOUND AT THE IMPACT SITE. PITCH TRIM WAS FOUND IN THE NORMAL CRUISE SETTING WITH GEAR, FLAPS, AND SPOILERS IN THE RETRACTED POSITION. EXAM OF THE ENGS INDICATED OPERATION AT IMPACT.ACFT STRUCK THE TERRAIN IN APPROX 80 DEG NOSE DOWN, WNGS LEVEL ATTITUDE & HEADING OPPOSITE TO THE PREVIOUS DIRECTION OF FLT. IN FLIGHT SIMULATOR TESTS, WITH THE ACFT INITIALLY IN LEVEL FLT AT 1900 FEET AND THEN ROLLED INVERTED AND THE PITCHCONTROL MOVED AFT, THE ACFT ATTITUDE WAS SIMILAR TO THE ATTITUDE AT IMPACT. THERE WERE TWO UNAUTH PAX ON BOARD, ONE WAS THE COPILOT'S WIFE. THE IMPACT POINT WAS IN A VERY SMALL REGION OF UNCONTROLLED AIRSPACE VERY NEAR THE COPILOT'S AND RELATIVE'S HOMES. THE COPILOT WAS NEW TO JET OPERATIONS. THE ACFT DEPARTED WITH SEVERAL DISCREPANCIES UNCLEARED.