The pilot reported that he was performing take-offs and landings when the accident occurred. On one of the landings, when the airplane was on the downwind leg of the traffic pattern, the engine went to idle. The pilot attempted to land the airplane on the runway but struck a fence short of the runway. Examination of the airplane revealed that the outer flexible sheath of the throttle cable had come loose from the crimped metal sleeve which was part of the instrument panel fitting. Movement of the cockpit throttle control would not actuate the throttle arm of the carburetor. Records indicated that the airplane was manufactured in 1946 and the throttle cable appeared to be original. No entry indicating replacement of the cable was found in the airplane's maintenance records.