ATL84FU003

The plt took off in conditions of turbulence & gusty winds. Witnesses reported the ultralight vehicle pitched & rolled erratically after lift-off. The plt then made a right climbing turn to a downwind heading & proceeded over a tall tree line toward a field where he ultimately crashed. One witness heard a 'pop', then looked & saw the acft descending with the wings folded. Others said the wings flexed upward 1st, then the acft flipped over & the wings reversed & folded around the airframe. An exam revealed upward deformation of the carard, but it had no significant evidence of ground impact. The wings had evidence of both upward & downward bending. The kingpost was bent rearward & its top cap was found 175 ft from the main wreckage. No airspeed indicator was installed. The manufacturer reported that an airspeed indicator was required to judge the speed with the engine running, that the max speed (vne) was easily exceeded & that the flight controls became extremely sensitive at higher airspeeds.