According to the pilot/owner/builder of the airplane, he conducted taxi tests, and then a final engine run-up and flight control check prior to takeoff on the airplane's second flight. After rotation, the airplane reached approximately 3 feet above the runway when the nose dropped, and application of full up elevator had no effect. The airplane struck the runway nose first, which resulted in substantial damage to the firewall. This was the identical outcome as the first flight several months prior. An FAA inspector estimated that the builder had added about 63 pounds with his modifications to the original airplane plans. The pilot performed the weight and balance on the airplane using bathroom scales and stated that there were no mechanical deficiencies that would have precluded normal operation of the airplane. His NTSB Form 6120.1 Operator/Owner Safety Recommendation was: "Re-weigh aircraft with calibrated scales to determine weight and balance. Fix apparent nose heavy aircraft with appropriate movement of the battery or additional weight in the tail section."