Comprehensive Characterization of Airship Response to Wind and Time Varying Mass

Abstract

This paper addresses the significance of airship time varying inertia properties due to fuel consumption, as well as the effect of external wind, on the dynamic response of an AS500 airship. A previously developed 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 as wind effect, have been implemented with an alternate aerodynamic model that has been validated by flight test. The simulation results obtained are both with and without the time varying mass terms in the equations of motion, in both steady cruise and prevailing wind conditions, and involving the exercise of all control mechanisms on board to include those exciting the airship both longitudinally and laterally.

Guidance, Navigation and Control of Unmanned Airships under Time-Varying Wind for Extended Surveillance

“…The unmanned airship selected for this work is the AS500 airship [17][18][19][20]. The AS500 has a main hull engulfing the lifting gas, as can be seen in Figure 1a.…”

“…Numerical values for some of the airship physical parameters are given in Table 1. The equations of motion presented here are based on the methodology presented in [19][20][21]. The derivation is omitted here for brevity; however, a detailed one can be found in [22].…”

“…The aerodynamic model implemented here is based on published data [20]. The aerodynamic forces acting on the airship during flight are expressed as:…”

“…The aerodynamic force and moment coefficients for the airship are represented based on three different cases that correspond to the deflections of the tail fin aerodynamic surfaces ∆ 1 and ∆ 2 [20] and are summarized below. +1.855 sin(α + 0.085δ eq ) cos(β) sin 2 (α + 0.085δ eq ) cos 2 (β) + sin 2 (β) where α and β are the angle of attack and side-slip angle.…”

Lighter than Air Robots

“…The pressure difference between the surrounding atmosphere and the inner gas (Helium) should be kept as constant as possible at each altitude level. The mass of all internal components can be derived by accounting all elements of the airship as a consolidation of point and distributed masses [215,217]. As the atmospheric pressure changes with the altitude, it should be compensated by the internal pressure.…”