THE CHRISTIAN EAGLE BIPLANE WAS RETURNING FROM A LOCAL INTRUCTIONAL FLIGHT AND ENTERED THE PATTERN ON A NORMAL 45 DEGREE ENTRY, ANNOUNCING POSITION AND INTENTIONS ON THE UNICOM FREQUENCY. THE CESSNA 150 WAS DEPARTING THE AIRPORT ON A LOCAL INSTRUCTIONAL FLIGHT AND HAD JUST COMPLETED AN ENGINE RUNUP AND TAXIED ONTO THE RUNWAY. THE BIPLANE PILOT SAID HE WAS IN A 3 POINT LANDING ATTITUDE, WHICH PRECLUDED FORWARD VISIBILITY. THE CESSNA 150 PILOT SAID HE LOOKED BOTH ON FINAL AND BASE LEGS PRIOR TO INITIATING THE TAKEOFF. JUST AFTER THE CESSNA 150 MOVED ONTO THE RUNWAY AND ADDED POWER THE FOR THE TAKEOFF, THE CHRISTIAN EAGLE COLLIDED WITH THE CESSNA'S RIGHT WING AT ABOUT THE MID SPAN POINT. THE COMMUNICATIONS RADIO HAD BEEN REMOVED FROM THE CESSNA 150 FOR MAINTENANCE REPAIR. THE CLOSEST OFFICIAL WEATHER REPORTING STATION, 8 MILES EAST, LISTED A VISIBILITY OF 2 MILES IN HAZE AND SMOKE, HOWEVER, BOTH PILOTS AND OTHER WITNESSES SAID THE VISIBILITY AT THE AIRPORT WAS '3 MILES.'