Flight and Power Loss
The pilot reported that the engine began to run roughly and appear to lose power about 10 minutes after takeoff. The power loss was not complete, as the engine subsequently ran roughly again. The pilot applied carburetor heat and switched fuel tanks, but these actions did not significantly affect the engine's operation.
Forced Landing
Faced with a partial loss of engine power, the pilot executed a forced landing in a barley field covered with tall grass. During the landing, the airplane nosed over. The vertical fin and rudder sustained bending damage, and the propeller was also damaged.
Post-Accident Examination
After the airplane was recovered to an airport, an FAA inspector started the engine and operated it at an idle power setting. The reason for the partial loss of engine power was not determined during this examination.