Configurations analysis for high‐altitude/long‐endurance airships

Abstract

PurposeIn recent years, high‐altitude/long‐endurance airship platforms have generated great interest as a means to provide communications and surveillance capabilities. The purpose of this paper is to develop a model for airship conceptual design and help provide insight into the viability of high‐altitude/long‐endurance airships.Design/methodology/approachA configuration analysis model with the consideration of pressure difference, temperature difference, and helium purity, etc. was developed. The influences of the airship payload, size and area required of solar cell with environment and operation parameters, such as operation latitude, pressure difference, temperature difference, helium purity, seasons, latitude, and wind speed, etc. were analyzed.FindingsThe results show that the area of solar cell required for stratospheric airship is very large under the condition of low altitude, high latitude, wind, and in winter, etc. which might make the design of high‐altitude/long‐endurance airship an elusive goal. They also show that the solar cell efficiency is the key technology in the control of solar cell area required for airships, and the technology advances in regenerative fuel cells and propeller efficiency have significant effects among on the airship payload, size, and solar cell area required for airship.Originality/valueThe paper analyses the energy balance of the high‐altitude/long‐endurance airship.

Heuristic Algorithms Applied to Multidisciplinary Design Optimization of Unconventional Airship Configuration

“…According to [3], the ballonets should compensate the increase in volume from zero altitude to the ceiling or, in other words, should contain the difference of gas volume at the ceiling with respect to the gas at zero altitude. By this way, the volume of the ballonets at zero altitude can be found by…”

“…The energy produced by photovoltaic panels is roughly proportional to the product of the surface area and the angle between the solar rays and the normal to the surface of the panels; therefore, airship shapes with more flat top surfaces can be useful to increase the energy produced to be fed in efficient way to electric motors producing the thrust needed to propel airship forward and to increase its controllability. In case of night operations [2,3], part of the solar energy obtained by the solar films during the day can be stored in batteries and used at night. Also regenerative fuel cells (RFCs) can be used instead of batteries by hydrolyzing water during the day, obtaining hydrogen and oxygen, and can be recombined to obtain water and energy in a zero-emission cycle during the night.…”

“…In particular, the model of Yu and Lu [3] is used as a reference in this work for weight assessment, for its simplicity and needed accuracy during conceptual design phases. The unconventional airship shape configuration selected in this study is derived from the sum of two ellipsoids, and it needs to be defined in terms of geometry, system and subsystems features, propulsion, and weights.…”

“…Several studies have been carried out about design methods for high-altitude platforms [2][3][4][5], and their findings can be used for airship modeling with systemic approach. In particular, the model of Yu and Lu [3] is used as a reference in this work for weight assessment, for its simplicity and needed accuracy during conceptual design phases.…”

“…These parameters are strongly dependent on each other and they must be considered together to obtain an optimum and balanced design. = coefficient of moment for given angle of attack around center of buoyancy C 1 , C 2 , C 3 = coefficients representing error in constraints satisfaction EnSt Batt = energy stored in lithium-polymer batteries, W · h EnSt RFC = energy stored in regenerative fuel cells, W · h ENtoM Batt = ratio of energy stored to mass of lithiumpolymer batteries, W · h∕kg ENtoM RFC = ratio of energy stored to mass of regenerative fuel cell, W · h∕kg F = fitness function FLMtoTSRF = ratio of solar films to top envelope surface g = acceleration of gravity, m∕s 2 HT arm = distance between center of buoyancy and horizontal tail center of pressure, m IRR mean = mean solar irradiation in the day, W∕m 2 L HT = single tail horizontal surface span, m M AerCB = aerodynamic moment around center of buoyancy, N · m M CABtoPAY = ratio of cabin mass to payload M S = stabilizing moment, N · m m t = airship total mass, kg mA ball = ratio of ballonets mass to area, kg∕m 2 mA E = ratio of envelope mass to area, kg∕m 2 mA Pv = ratio of solar film mass to area, kg∕m 2 mA tail = ratio of tail surfaces mass to area, kg∕m 2 MD = disturbance moment, N · m m BALL = mass of ballonets, kg m BATT = mass of the batteries, kg m CAB = mass of the cabin, kg m E = mass of the envelope, kg m HT = mass of the horizontal tail, kg m PAY = mass of the payload, kg m PS = mass of the propulsion system, kg m RFC = mass of the regenerative fuel cells, kg m VT = mass of the vertical tail, kg N Ball = number of ballonets P A = available propulsive power, W P Eng = total power of engines installed, W P PV = power from solar panels, W POWtoM = ratio of power of motor to mass, W∕kg p = empirical value in Thomsen formula p 0 = air pressure at zero altitude, n∕m 2 p air H = air pressure at altitude H, N∕m 2 p ceil = air pressure at ceiling, N∕m 2 RFCtoBATT = ratio between energy stored in regenerative fuel cell and total stored energy [ …”