UPON RETURNING TO THE CARSON AIRPORT, N3545 (NIEUPORT) APPROACHED FROM THE SOUTH AND EXECUTED A 45 DEGREE ENTRY TO THE DOWNWIND LEG FOR RUNWAY 27. WHILE ESTABLISHED ON FINAL AND APPROXIMATELY 100 FEET FROM THE THRESHOLD TO RUNWAY 27, AND AT AN ELEVATION OF APPROXIMATELY 200 FEET AGL, N3545 COLLIDED WITH N6389 (PITTS S- 1C). IMPACT MARKS INDICATED THAT N6389 STRUCK THE UPPER LEFT WING OF N3545 WITH ITS WHEELS. THE LOWER RIGHT WING OF N6389 THEN DISINTEGRATED AS IT PASSED THROUGH THE PROPELLER ARC OF N3545. NEITHER PILOT REPORTED SEEING THE OTHER AIRCRAFT AND BOTH AIRCRAFT CRASHED SHORT OF THE RUNWAY. NEITHER AIRCRAFT WAS EQUIPPED WITH ANY POSITION, ANTICOLLISION OR STROBE LIGHTS AND N3545 WAS NOT EQUIPPED WITH ANY COMMUNICATION EQUIPMENT AND WAS UNABLE TO RECEIVE THE RADIO CALLS CITING N6389'S POSITION ON BASE AND FINAL. ALTHOUGH BOTH AIRCRAFT WERE BIPLANE (EQUIPPED WITH UPPER AND LOWER WINGS) IT COULD NOT BE DETERMINED WHETHER THIS DESIGN HAD ANY BEARING IN OBSTRUCTING EITHER PILOT'S VIEW OF THE OTHER AIRCRAFT.