On October 1, 2016, at 1300 central daylight time, an experimental light sport, amateur-built Drake Kitfox Speedster, N157D, collided with the terrain following a loss of control after takeoff from the Jennings Airport (3R7), Jennings, Louisiana. The pilot received serious injuries. The airplane was substantially damaged. The airplane was registered to and operated by the private pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The intended destination was Slaughter Airpark (SL77), Slaughter, Louisiana.The pilot reported that he was the last airplane in a flight of four to takeoff. He stated he verified his altitude and airspeed, and retracted the flaps during the takeoff. He stated he checked the airspeed, lowered the nose of the airplane, and resumed the climb. The pilot reported the airplane rolled to the right, which he corrected, then the airplane "abruptly" rolled to the left. He was unable to correct the roll and the airplane descended to impact with the terrain. The pilot reported that there were no mechanical failures/malfunctions of the airplane. A witness reported the airplane was airborne in a wings level, "very high" nose up attitude when he first saw it. He stated that after a few seconds the left wing dropped and the nose lowered. Shortly after that, the right wing dropped and the airplane nosed down even more until it impacted the terrain. A video posted on YouTube by furley85 showed the airplane climbing out in a steep, nose-high attitude after takeoff. The airplane was a couple hundred feet above the grass airstrip when the left wing dropped and the nose lowered. The airplane rolled back through wings level then the right wing dropped and the airplane impacted the terrain. The airplane received substantial damage to the wings and fuselage.