Incident
The aircraft was being ferried to a nearby airport for winter storage. Immediately after takeoff, the engine began running rough and RPM was lost. The pilot turned the aircraft and landed in a plowed field. During the landing roll, the aircraft nosed over.
Pilot Actions
The pilot suspected that moisture caused a magneto problem, such as cross-firing, misfiring, or carbon tracks. He alternated between the right, left, and both magnetos in an effort to regain power, but was unsuccessful.
Background
The magnetos had been checked and found good before takeoff. The aircraft had been parked outside without being flown for five days prior to the flight, and heavy rain fell during that period. The pilot drained the sumps before departure and noted no water in the fuel.