N78DK

The pilot/owner of the experimental weight-shift airplane said he confirmed that the winds were calm prior to takeoff for a flight around the traffic pattern. He said the airplane encountered updrafts and downdrafts on the downwind and base legs of the traffic pattern, and he could not control the altitude of the airplane with either control or power inputs. While on final approach, about 400 feet above ground level, the pilot "saw the airplane nose going down at a 45-degree angle and then the hit." The wind speed reported at the airport at the time of the accident was 3 knots. The pilot reported that there were no mechanical deficiencies with his airplane that would have precluded normal operation.