Flight Performance Analysis of Hybrid Airship

Abstract

Hybrid airship denotes one kind of aircraft that combines the use of aerodynamic and buoyant lift. It is supposed to achieve the best combination of the high speed characteristics of the airplane and the heavy lifting capacity of the airship. In this work, an improved flight performance analysis method for hybrid airship is proposed, aiming to provide a set of new formulas that are more suitable for hybrid airship. The new formulas for analyzing the steady and accelerated performances of hybrid airship are derived out in a systematic way. The main advantage of the new formulas is that the relationship between the flight performances of hybrid airship and airplane is indicated in a clearer and simpler expression. Base on the derivation, it is concluded that the ratio of aerodynamic lift to the total lift, the effective power-to-weight ratio, the effective wing loading are three key parameters that affects the performances of hybrid airship. An example of designing a winged hybrid airship is presented to demonstrate and evaluate the developed method. Nomenclature C H = airship pressure height (The airship pressure height [1] is defined as the height at which the ballonets are fully deflated and is therefore the maximum height to which the airship can climb without overpressuring the envelope or venting gas) a ρ = gas density of air ( a,c ρ is the gas density of air at airship pressure height) h ρ = gas density of lifting gas ( h,c ρ is the gas density of lifting gas at airship pressure height) ship V = airship volume ' ship V = volume of the helium ballonet inside the airship ship