The airplane was substantially damaged at 1956 Central time in a forced landing following a loss of engine power during initial takeoff. The Commercial pilot and the pilot-rated passenger were seriously injured. Visual conditions prevailed. The pilot and pilot-rated passenger had been performing maintenance on the engine and elected to take a short flight to verify its operation. On the initial climb, the engine lost power. The pilot elected to return to the airport, and while attempting to make the airport, the pilot lost control of the airplane. The airplane impacted in a nose-low attitude into a cotton field approximately 300 feet west of the runways extended centerline. There was no fire.