Dynamic wind tunnel tests using a 5-percent cable-mounted model of the NAL spaceplane have been performed in the NAL low-speed large scale wind tunnel to identify the aerodynamic model including dynamic effects. During the tests performed in March 1991, the lateral-directional motion was excited by aileron and rudder inputs. A flight path reconstruction was applied to the recorded data and a parameter identification study of the reconstructed data was undertaken to extract lateral-directional stability and control derivatives using the least square method. The estimated derivatives were compared with the results of static wind tunnel tests and theoretically estimated dynamic derivatives. They were also evaluated by comparing mathematically simulated time histories calculated using them with the wind tunnel test data. As a result, all major derivatives were estimated well and effectiveness of the dynamic test was shown.