Accident Sequence
The pilot reported that during a max performance takeoff, he set the flaps to 10° and accelerated to 60 mph. He then pulled back and pitched the airplane for Vx (best angle climb), 52 mph, to simulate an obstacle. Subsequently, he pitched for Vy (best rate climb), 72 mph, where he observed a rate of descent. After pitching back to gain altitude, he immediately heard the stall warning horn and felt a lack of responsiveness in the flight controls. The pilot leveled the airplane to touch down on the remaining runway, but the right wing and right horizontal stabilizer impacted the runway.
Damage
The airplane sustained substantial damage to the right wing and right horizontal stabilizer.
Pilot Report
The pilot reported that the cause of the accident was that the published Vx airspeed is below the stall speed. He also stated that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation, but that it was possible that the engine was not performing at optimal performance.
Aircraft Manual Excerpts
The airplane owner's manual checklist titled "Maximum Performance Take-Off" specifies:
1. Wing Flaps – Up. 2. Carburetor Heat – Cold. 3. Brakes – Hold. 4. Throttle – Full "OPEN". 5. Brakes – Release. 6. Elevator Control – Slightly tail low. 7. Climb Speed – 52 MPH (with obstacles head).
The manual also states: "Normal and obstacle clearance take-offs are performed with flaps up. The use of 10° flaps will shorten the ground run approximately 10%, but this advantage is lost in the climb to a 50-foot obstacle. Therefore the use of 10° flap is reserved for minimum ground runs or for take-off from soft or rough fields with no obstacles ahead."
Additionally, the manual indicates stall speeds with 0° angle of bank:
- Flaps Up – 55 mph
- Flaps 20° - 49 mph
- Flaps 40° - 48 mph