ACCORDING TO THE PLT, HE TOOK OFF ON RWY 18 & WAS CLIMBING THRU ABOUT 250 FT AGL WHEN THE ENG LOST POWER & HE MADE A FORCED LANDING. HOWEVER, A CO-OWNER, WHO WAS ON BOARD, STATED THAT THE PLT HAD RETARDED THE THROTTLE, THEN THE ACFT STOPPED STOPPED CLIMBING, ACTING AS IF THE ENG HAD LOST POWER. HE STATED THAT THE ACFT SEEMED TO SHUDDER & SUDDENLY DROP TOWARD THE GROUND. HE BELIEVED THE PLT ATTEMPTED TO RECOVER THE SPEED, BUT WAS UNSUCCESFUL. SUBSEQUENTLY, THE ACFT IMPACTED THE GROUND IN A LEVEL, BELLY DOWN ATTITUTDE. LATER, WHEN ASKED WHY THE PLT HAD RETARDED THE THROTTLE AFTER TAKEOFF, HE REPLIED THAT THE ENG WAS EXCEEDING 2575 RPM. THE ACFT WAS EQUIPPED WITH A VARIABLE PITCH PROP WHICH IS CONTROLLED BY THE PLT. THE CO-OWNER STATED THAT PROCEDURE TO CONTROL THE ENG RPM WAS FOR THE PLT TO CHANGE THE PROP PITCH ANGLE. THE PLT HAD NO PREVIOUS FLT TIME IN THIS MAKE & MODEL.