Design of a rotorcraft is a very challenging task due to its inherent complex aerodynamics and structural coupling. It is inevitable that the response characteristics and handling qualities should be analyzed in the earlier stage of design itself. Most of the handling qualities such as quickness parameters, agility parameters, bandwidth and phase delay are defined based on the control response characteristics. The flight dynamic model is needed to analyse the response characterstics of rotorcraft. The aim of the present study is to develop relatively simple flight dynamic model. It should have the ability to analyze trim, stability and response characteristics of a rotorcraft under various maneuvering conditions. This study further addresses the influence of numerical aspects of perturbation step size in linearized model and integration time step on nonlinear model response. A new updated Drees model is proposed in this study and the applicability of this approach in rotorcraft flight dynamics is studied. The effects of inflow models on the linearized model response and nonlinear model response are anlysed. © 2015 by the Asian-Australian Rotorcraft Forum. All rights reserved.