Reportedly, the pilot took off from a yard, and when the ultralight vehicle had climbed to about 200 ft AGL, the engine lost RPM momentarily, then regained power. A witness reported that when the RPM decreased, the ultralight nosed over and went upside down. During the sequence, the wings folded and the vehicle fell to the ground. No mechanical irregularities of either the engine or airframe were found. An associate, who was flying in another ultralight, stated that the normal procedure for a loss of power would be to lower the nose to gain airspeed. He stated that in a weight shift control vehicle, such as this was, the response would be immediate. He further reported that should the engine regain power, while the pilot's weight was shifted forward, the thrust would push the nose further forward (down). He also stated that the pilot may not have completely removed frost from the canard, and if the canard loses lift, the nose would drop.