The aircraft accelerated over the runway after a 10 second hover. After acceleration, the aircraft went into a nose high, steep, right climbing turn. The angle of bank was described as 45 to 90 degrees. The pitch varied from 15 degrees up to 30 degrees down just prior to impact. Maximum altitude was estimated to be 75 to 200 feet above ground level. The nose dropped through after 90 degrees of turn. The descending right turn continued until ground contact. Witnesses reported that a recovery was apparently started just prior to impact. This type of maneuver was previously used in demonstrations during upgrade training, but not in winds that existed on the day of the accident. According to an MBB report, the maneuver (as described) was considered dangerous. No malfunctions of the aircraft were found. Both pilots had very little experience in the BO-105. The aircraft that they had previously flown had a delayed control response when compared to the instantaneous response of the MBB hinge rotor system.