THE ACFT WAS FLOWN EARLIER IN THE DAY FOR A SALES DEMONSTRATION. ON THE RETURN FLT, WHEN THE LANDING GEAR WERE LOWERED, THE PLT THOUGHT HE HEARD A NOISE EMITTING FROM THE GEAR, ALTHOUGH COCKPIT INDICATIONS WERE NORMAL. THE ACFT LANDED AT JOHNNYCAKE ARPT & WAS REFUELED FOR A FLT TO BRADLEY FIELD WHERE IT IS HANGARED. THE PLT STATED HE INTENDED TO MAKE THE 22 MI FLT WITH THE GEAR DOWN AS A PRECAUTION. HE ALSO STATED HIS INTENTION TO FLY BELOW THE OVERCAST BECAUSE OF DELAYS OF UP TO 45 MIN IN OBTAINING IFR CLEARANCES. MOMENTS AFTER TAKEOFF THE ACFT COLLIDED WITH TREES EAST OF THE ARPT. ABOUT 1 MI EAST OF THE ARPT IS A NORTH-SOUTH RIDGE. ANOTHER PLT, WHO DEPARTED 15-20 MINS EARLIER, REPORTED ENTERING THE OVERCAST BETWEEN 400 & 700 FT AGL. GROUND WITNESSES 1 MI SE OF THE ARPT WHO HEARD THE CRASH DESCRIBED THE WX AS HEAVY FOG & MIST. ONE WITNESS ESTIMATED THE CEILING AS 100 FT AGL.