This paper investigates the control of the phase difference in between three different motions of bat flight: pitching, apping, and lead-lag. For active control, a robotic bat test bed capable of simulating different wing motions is used to test the control of these wing motions and the phase differences using central pattern generators (CPG's). Previous work with the robotic bat is expanded upon by modifying the robotic bat test bed to allow for three dimensional motions of the entire bat, instead of only the wings. This is done by mounting the robotic bat onto a 3D pendulum. Experiments analyzing the steady state behavior of the bat's flight with varying phase differences showed a change of pitch while elevation and forward velocity remains constant. This shows promising results regarding the relation between phase differences of wing motions and longitudinal stability.