Narrative:

As part of the preflight; I sumped both fuel tanks and the gascolator finding no indication of water or foreign debris. I checked the quantity of fuel and found that I had eighteen gallons (nine in each tank). I intended to fly to a nearby airport about ten minutes away.after completing the preflight check; I started the engine. It started normally and ran well. I taxied to the run-up area for runway 23 and performed the pre-departure check including the engine run-up. Everything was normal.I then announced my departure and taxied onto the grass runway using a 'soft-field' method (10 degrees of flaps; full throttle; and the yoke all the way aft). During the previous evening there had been a very small amount of rain so I anticipated an initial slower than normal ground roll. I kept the aircraft in the middle of the runway to minimize the drag on the wheels from any wet grass. Since the middle is used more often; it is usually a little rougher than the edges. The initial acceleration was normal and as I slowly increased speed I begin to feel the bumps in the runway. As I lifted off the ground I noticed that the 'bumps' I had felt earlier were continuing. At that point I was about 30-40 feet in the air and my airspeed was about 55-60 mph. I was about three quarters (3/4) down the 2;500 feet runway. I knew that the plane would not continue flying as the engine was not producing enough power to increase my airspeed or altitude. Another indication of lack of airspeed was the stall horn was sounding. I decided to land straight ahead since I did not have enough altitude to turn the aircraft back to the runway.I came to rest in a plowed field about 500 feet from the end of the runway. (The field is part of the airport property.) the uneven ground damaged two of the three wheel pants. There was not a prop strike and the ELT was not activated.when the aircraft came to rest; the engine was still running so I shut it down and exited. I was not injured. About a year ago I installed shoulder harnesses in the plane. I believe my harness prevented me from being thrown into the yoke which would probably have caused injury.in recalling the event; I realize that I mistakenly attributed the vibration in the takeoff roll to the runway surface being rough instead of considering that some or all of the vibration was due to a poorly performing engine.

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Original NASA ASRS Text

Title: C-172 pilot reported that because of engine vibration and insufficient power he was unable to accelerate after takeoff from a grass strip; so at about 30 feet he landed on unprepared airport property damaging two of three wheel pants.

Narrative: As part of the preflight; I sumped both fuel tanks and the gascolator finding no indication of water or foreign debris. I checked the quantity of fuel and found that I had eighteen gallons (nine in each tank). I intended to fly to a nearby airport about ten minutes away.After completing the preflight check; I started the engine. It started normally and ran well. I taxied to the run-up area for Runway 23 and performed the pre-departure check including the engine run-up. Everything was normal.I then announced my departure and taxied onto the grass runway using a 'soft-field' method (10 degrees of flaps; full throttle; and the yoke all the way aft). During the previous evening there had been a very small amount of rain so I anticipated an initial slower than normal ground roll. I kept the aircraft in the middle of the runway to minimize the drag on the wheels from any wet grass. Since the middle is used more often; it is usually a little rougher than the edges. The initial acceleration was normal and as I slowly increased speed I begin to feel the bumps in the runway. As I lifted off the ground I noticed that the 'bumps' I had felt earlier were continuing. At that point I was about 30-40 feet in the air and my airspeed was about 55-60 MPH. I was about three quarters (3/4) down the 2;500 feet runway. I knew that the plane would not continue flying as the engine was not producing enough power to increase my airspeed or altitude. Another indication of lack of airspeed was the stall horn was sounding. I decided to land straight ahead since I did not have enough altitude to turn the aircraft back to the runway.I came to rest in a plowed field about 500 feet from the end of the runway. (The field is part of the airport property.) The uneven ground damaged two of the three wheel pants. There was not a prop strike and the ELT was not activated.When the aircraft came to rest; the engine was still running so I shut it down and exited. I was not injured. About a year ago I installed shoulder harnesses in the plane. I believe my harness prevented me from being thrown into the yoke which would probably have caused injury.In recalling the event; I realize that I mistakenly attributed the vibration in the takeoff roll to the runway surface being rough instead of considering that some or all of the vibration was due to a poorly performing engine.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.