Prior to the takeoff, the pilot performed a run-up of the engine and all systems were normal. During the takeoff, the pilot rotated the airplane at 67 knots and retracted the landing gear. Shortly thereafter, the airplane began to descend toward the runway. The pilot attempted to apply aft elevator control; however, the airplane continued to settle toward the runway. The pilot "kept trying to fly higher..." and the propeller struck the runway surface. After the runway contact, the pilot continued to keep the airplane airborne. When he realized the airplane would not climb, he moved the airplane over toward a grass area. The airplane impacted terrain, rotated to the right, and came to rest upright in a ravine adjacent to the runway. A pilot-rated witness reported he thought the airplane stalled during the takeoff. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operations.