Investigation into the Time Varying Mass Effect on Airship Dynamics Response

Abstract

This paper addresses the significance of airship time varying inertia properties due to fuel consumption on the airship dynamic behavior. First, a new set of nonlinear, 6–DOF airship equations of motion which include the effect of time-varying mass and inertia properties associated with fuel consumption, as well we wind effect, are developed. Since the Center of Mass (CM) of the airship is time–varying during flight, the equations are written in a reference frame whose origin is at the airship Center of Volume (CV). The dynamic effects due to fuel consumption are modeled by considering the mass change to be confined to a finite number of lumped masses, which would normally represent the fuel tanks on the airship. Once the fuel consumption begins, by using the design parameters such as the shape, size and location of the individual fuel tanks and the rate of fuel being consumed from each of them, the mass and location of the individual lumped masses are calculated and fed into the equations of motion as exogenous inputs. The simulation results obtained both with and without the time varying mass terms in the equations of motion, with and without the effect of a prevailing wind, are compared to determine the significance of the fuel consumption to the airship dynamic response.