The present paper sheds some light on simplified mechanical models in order to discuss the dynamic stability of slender flight bodies subjected to aerodynamic loads. Firstly, we discuss the nature of a suitable simplified mechanical model to demonstrate body divergence and flutter. A method leading to a rational mechanical model is presented. It is shown that a simplified model composed of three bars connected together by two elastic rotational hinges, having four degrees-of-freedom, is preferable to discuss both body divergence and flutter. Secondly, after having a duly simplified mechanical model, effects of mass distribution, stiffness distribution and location of a stabilizer fin are discussed. A perspective of body divergence and flutter of slender flight bodies is demonstrated on the basis of the proposed simplified mechanical model.