The potential of Flapping Wing Micro Air Vehicles (MAVs) for sensing and information gathering relevant for environmental and disaster monitoring and security surveillance leads to the identification and modelling the salient features and functional significance of the various components in the flying reasonably sized Biosystems. The dynamics, kinematics and aerodynamics of their wing systems and the production of mechanical power output for lift and thrust will be synthesized following a simplified and generic, but meticulous, model for a flapping wing ornithopter. Basic unsteady aerodynamic approach incorporating viscous effect and leading-edge suction is utilized. The first part of the study is focused on a Bi-Wing ornithopter. Later, parametric study is carried out to obtain the lift and thrust physical characteristics in a complete cycle for evaluating the plausibility of the aerodynamic model and for the synthesis of an ornithopter model with simplified mechanism. Further analysis is carried out by differentiating the pitching and flapping motion phase-lag and studying its respective contribution to the flight forces. A similar procedure is then applied to flapping quad-wing ornithopter model. Results are discussed in comparison with various selected simple models in the literature, with a view to develop a practical ornithopter model.