On August 1, 1995, at 1500 central daylight time, a Bellanca 7ECA, N5068K, was substantially damaged by a collision with a hangar at Naperville, Illinois. The private pilot told investigators that he had experienced loss of directional control during takeoff from runway 36 (2575' x 40', dry bituminous) at the Naper Aero Club Airport. Visual meteorological conditions prevailed at the time of the accident. The personal, 14 CFR Part 91, local area flight was not operating on a flight plan. The pilot and passenger reported no injuries. The pilot, operating the controls from the front cockpit, reported that during takeoff roll the airplane veered to the left. He applied right rudder but it did not correct the aircraft heading. He aborted the takeoff but was unable to stop the aircraft before impacting the hangar. The pilot held a valid tailwheel endorsement dated November 9, 1993, and had acquired 15 hours total flying time in tailwheel equipped aircraft but had no tailwheel flying time within the last 90 days. The pilot told investigators that he thought he was the second pilot. The second pilot, who occupied the rear cockpit during the flight, held a Private Pilot's license and reported 100 hours flying time in tailwheel equipped aircraft. She reported that during preflight inspection of the aircraft the pilot seemed very knowledgeable about the plane and in response to her inquiry told her he had fifteen hours experience in tailwheel equipped aircraft. She noted "no problems at all in taxiing the plane" or the engine pre-takeoff run-up. During the taxi she and the pilot discussed which runway to use for departure and the pilot announced his intention to use runway 36 even though she told him that runway 18 was the preferred runway when the wind is calm. She acquiesced to his decision. She reported that as soon as takeoff power was applied the pilot lost directional control, veering left, then right, then left off the runway and into the hangar. She too told investigators that she thought she was the second pilot.