Abstract—Helicopter offers the capability of hover, slow forward movement, vertical take-off and landing (VTOL) while a conventional airplane has the performance of fast forward movement, long range and superior endurance. The aim is to simulate and analyze the dynamic motion of tilt T-tri rotor UAV‟s configuration that combines the advantages of both rotary wing and fixed wing vehicle. The dynamic response of vehicle using force and moment equation in vertical flight, horizontal flight and also the most important of all, transitional mode transition from vertical to horizontal flight has been analyzed in 3 degrees of freedom. The response of the UAV during transition from vertical flight into horizontal flight in the longitudinal plane has been explained using MATLAB programs. Transition period response under constant thrust and constant altitude condition of the dynamics is analyzed separately. Extensive simulation results are obtained to validate the effective time of transition. Keywords—Tri rotor, Tilt T-tri rotor UAV, Transitional mode, UAV, VTOL. I. INTRODUCTION HE development of the Tilt Rotor Micro Air Vehicle in the market has shown a great improvement in terms of its capability to do vertical take-off and landing and to cruise around in air within a certain area. It is relatively small and light, which means that it can do more missions, particularly in missions that involves tight confined spaces, in urban areas etc. On top of that, this enables the air vehicle not to use runway for its take-off and landing as discussed in [1]. In this paper, focus will be on vertical flight, cruising and also the transition from vertical flight to horizontal flight. Transition is the intermediate moment factor from hover to cruise. This special step is the most crucial because a UAV that is design with both hover and cruise can never cruise from hover if the transition fails. So to ensure that the UAV are able to hover and then cruise, the transition moment must be looked into carefully as it involves a totally different picture and involves much consideration such as velocity, thrust, gimbal angle and pitching requirements. K.Senthil Kumar, is with Department of Aerospace Engineering, Avionics Division, Madras Institute of Technology, Anna University Chennai, Tamil Nadu, India (e-mail: ksk_mit@annauniv.edu). Mohammad Rasheed, is with Department of Aerospace Engineering, Avionics Division, Madras Institute of Technology, Anna University Chennai, Tamil Nadu, India. T.Anand, is with Department of Aerospace Engineering, Avionics Division, Madras Institute of Technology, Anna University Chennai, Tamil Nadu, India (phone: 0-99940236549 ; e-mail: t.anandaero@gmail.com). All these happen differently at different gimbal angle. The gimbal angle here is the angle at which the motor makes with the UAV (airframe‟s) in the horizontal direction. To visualize the simulate moment of hover, transition and cruise, A mathematical model is required. With the mathematical model and the necessary parameters only then it can be translated into coding by using software called MATLAB. With that, plots and graphs for the various moments and gimbal angles can be generated and analyzed. The main difference between the rotor air vehicle and fixed wing air vehicle is the source of lift. For fixed wing, the source of lift comes from the fixed airfoil surface while the rotorcraft derives its lift from the rotating motion of its rotor as mention in [3]. II. TRI ROTOR UAV The control policy of the UAV will be that, during the hover mode to transition mode, there will be various motions effects on the platform. From the generic model, it is known that there will be two rotors at the wing tip and another rotor at the aft of the platform. Hence, during the hover and transition mode, there will be a vertical lift cause by the three rotors propelling at the same rate and power. During this time, a pitching motion will occur when there is a change in the angular velocity of the rotor at the aft of the platform. An increase in power will cause the platform to be in nose down position, while decrease in power will cause the platform to be in a nose up position, clearly mentioned in [2]. Also, roll motion is achieved by the front two motor speed control. Meaning that, when the left rotor angular velocity decreases, the UAV will bank in to the left and when the right rotor angular velocity decreases, the UAV will then bank into the right. The rotor at the aft of the m o t o r will act as a stabilizer ensuring that during cruise flight, it stabilizes the whole air vehicle while other motions are taking place. Yaw is the complicated motion because it involves the coordination of all rotors and also the gimbal angle of either rotor at the wing tip. The two rotors at the wing are rotating in the opposite direction of each other, and this yaw forces created by each rotor on the wing, will cancel out each other and the third rotor will be located at the tail platform which creates unbalanced torque [5]. With this understanding, we will use equations to equate the motions that was mentioned before and turn it into a mathematical model which will be in a program call MATLAB, and henceforth, allowing us to see and analyze Design and Development of Unmanned Tilt T-Tri Rotor Aerial Vehicle K. Senthil Kumar, Mohammad Rasheed, and T.Anand T Int'l Journal of Advances in Mechanical & Automobile Engg. (IJAMAE) Vol. 1, Issue 1(2014) ISSN 2349-1485 EISSN 2349-1493101 http://dx.doi.org/10.15242/IJAMAE.E0314598 113