Pilot's Account
The pilot reported using the pre-takeoff checklist and setting the elevator trim to "almost neutral" with one notch of flaps selected. During the takeoff roll, the pilot sensed that the airplane seemed inclined to lift off earlier than usual and had to maintain forward pressure on the controls to keep the nose down. When rotation was finally initiated, the aircraft "jumped up quicker than normal" and the pilot continued to hold the nose down. After the airplane began to accelerate and climb, the landing gear was raised. Shortly thereafter, a wind gust was felt, causing the aircraft to drift left. The pilot corrected back to the runway heading, but the airplane then started to descend. Reducing power, the pilot executed a landing with the gear retracted on the grass airstrip. The lower fuselage sustained substantial damage. The pilot stated that no pre-existing mechanical anomalies were present that would have prevented normal operation. The reported wind was from 20 degrees to the right of the runway at 14 knots, gusting to 22 knots.
Manufacturer's Observations
A representative of the airplane manufacturer noted that landing gear retraction typically takes between 3 and 6 seconds. During this process, the movement of the inboard landing gear doors creates additional parasitic drag. The representative also mentioned that in previous similar occurrences, pilots have taken off at lower airspeeds than normal and then retracted the landing gear, which resulted in the aircraft settling back toward the surface instead of climbing.