Search

Hybrid airships, combining aerodynamic lift and buoyant lift, are efficient near-space aircraft for scientific exploration, observation, and surveillance. Compared to conventional airplanes and airships, hybrid airships offer unique advantages, including stationary hovering and rapid deployment. Due to the different task requirements and strong coupling between flight and environment, trajectory-optimization methods for traditional aircraft are difficult to apply to hybrid airships directly. We propose a trajectory-optimization model based on the variational method to calculate the optimal time and energy paths under weak, uniform, and latitudinal linear wind fields. Our model shows that the influencing factors for the optimization path can be categorized into three types: airship design parameters, wind field parameters, and departure parameters. The result indicates that the optimal time paths are generally straight lines, and the optimal energy paths are piecewise curves with a 24-h cycle under typical hybrid airship design parameters. This work has provided new insight into the trajectory optimization and parameter design of future hybrid airships. [ABSTRACT FROM AUTHOR]

With the growing demand of low-cost transportation service, Hybrid airship plays a significant role for providing this service as a cargo nowadays. This paper deals with the controller design for winged hybrid airship with suspended payload for maintaining stability and controllability of the system. Controller design is required for the system to achieve desired tracking performance and collision avoidance for closed loop analysis. Internal Model Control (IMC) compensator is also designed to make few subsystems represented as velocity transfer function stable. The system is a small sized winged hybrid airship with attached suspended payload and having controlling maneuvers like elevator. The system taken is discussed as an approach of single body longitudinal dynamics. A Proportional-Integral-Derivative (PID) controller has been designed for pitch control of hybrid airship including collision avoidance in the pitch up and pith down path. A Hardware-In-the-Loop (HIL) solution also provided for the designed PID controller on UNO kit. Open loop and closed loop stability analysis is done for the longitudinal dynamics of winged small sized hybrid airship. Internal model compensator is required to make overall system as a stable system. A Simulink model for longitudinal dynamics of the hybrid airship with controllers and compensators is developed and result is analyzed and verified with open literature. Overshoot of u is the problem, although it settles to zero trim values within 30 sec. Except that all other parameters of longitudinal dynamics settle to equilibrium points within few seconds. Altair Embed software is used for HIL development. [ABSTRACT FROM AUTHOR]

Hybrid airships, combining aerodynamic lift and buoyant lift, are efficient near-space aircraft for scientific exploration, observation, and surveillance. Compared to conventional airplanes and airships, hybrid airships offer unique advantages, including stationary hovering and rapid deployment. Due to the different task requirements and strong coupling between flight and environment, trajectory-optimization methods for traditional aircraft are difficult to apply to hybrid airships directly. We propose a trajectory-optimization model based on the variational method to calculate the optimal time and energy paths under weak, uniform, and latitudinal linear wind fields. Our model shows that the influencing factors for the optimization path can be categorized into three types: airship design parameters, wind field parameters, and departure parameters. The result indicates that the optimal time paths are generally straight lines, and the optimal energy paths are piecewise curves with a 24-h cycle under typical hybrid airship design parameters. This work has provided new insight into the trajectory optimization and parameter design of future hybrid airships.

The excessive depletion of fossil fuels and increasing environmental concerns have led to the need to explore alternative sources of power for aircraft. This has spurred various stakeholders in the aerospace industry to explore hybrid electric propulsion technology and fully electric vehicles. Airships are aerial platforms based on lighter-than-air systems technology. They have several unique features compared to other vehicles, chiefly their being more environmentally friendly due to low fuel consumption. Among airships, lifting-body dynastats are the most suitable configuration for implementing different levels of hybridization in propulsion systems owing to their large surface-to-volume ratio. The present study deals with the relevance of a hybrid propulsion (conventional engine + electric motor) system and its comparison to conventional ones. An objective function based on envelope volume is formulated to achieve an optimal configuration of a tri-lobed dynastat to carry 10 tons of payload over a 500 km range for specified operating conditions powered by conventional fuel and batteries. The design space is explored assuming a predicted future battery technology level with specific energies ranging from 250 to 750 Wh/kg. Three case studies based on the source of power are investigated: fuel alone, fuel + batteries, and fuel + batteries + solar array. It is seen that the airship can be fully electric with zero carbon emissions but at the expense of a longer length (+18%) and higher envelope volume (+63%) compared to the baseline model. [ABSTRACT FROM AUTHOR]

This paper describes a shape exploration and multidisciplinary optimization method of unconventional semirigid nearing space airships. The approach includes several improved mutually interacting disciplines, viz., aerodynamics, structure, propulsion, pressure control, energy, avionics, and electric cable. To describe the nonstreamlined envelope shape of the semirigid nearing space airships, a parameterization methodology involving 12 variables is proposed. And an aerodynamics surrogate model is established using the results of computational fluid dynamics simulations. To obtain the configurations of airship, detailed improved subsystem models are proposed. And a combinatorial optimization strategy is established to search for the optimal solutions. The approach can directly obtain the optimal general configurations such as envelope shape and size, as well as parameters of subsystems such as the required number of valve and air blowers. Optimization results show that the payload capacity increases 16.8% for the airship with same volume. Besides, effects of payload capacity of mass and power are investigated. Finally, sensitivity analysis on the subsystem parameters shows that the volume of semirigid airship is most sensitive to five parameters, viz., areal density of outer envelope, areal density of inner envelope, energy density of lithium battery, propulsion efficiency, and density of carbon fiber material, in turn. [ABSTRACT FROM AUTHOR]

The excessive depletion of fossil fuels and increasing environmental concerns have led to the need to explore alternative sources of power for aircraft. This has spurred various stakeholders in the aerospace industry to explore hybrid electric propulsion technology and fully electric vehicles. Airships are aerial platforms based on lighter-than-air systems technology. They have several unique features compared to other vehicles, chiefly their being more environmentally friendly due to low fuel consumption. Among airships, lifting-body dynastats are the most suitable configuration for implementing different levels of hybridization in propulsion systems owing to their large surface-to-volume ratio. The present study deals with the relevance of a hybrid propulsion (conventional engine + electric motor) system and its comparison to conventional ones. An objective function based on envelope volume is formulated to achieve an optimal configuration of a tri-lobed dynastat to carry 10 tons of payload over a 500 km range for specified operating conditions powered by conventional fuel and batteries. The design space is explored assuming a predicted future battery technology level with specific energies ranging from 250 to 750 Wh/kg. Three case studies based on the source of power are investigated: fuel alone, fuel + batteries, and fuel + batteries + solar array. It is seen that the airship can be fully electric with zero carbon emissions but at the expense of a longer length (+18%) and higher envelope volume (+63%) compared to the baseline model.

In recent years, hybrid airships have been identified as promising alternatives for high altitude, long endurance missions. In this study, a design methodology to study the feasibility of a winged hybrid airship powered by solar energy is presented. The proposed methodology involves five disciplines of the airship, viz., geometry, aerodynamics, environment, energy and structures that have been coupled in order to develop an optimum design which incorporates the maximum advantages of the modules. A total of fourteen design variables have been finalized, which are required to carry out the sizing of the envelope, wing, and solar panel layout. The Particle Swarm Optimization (PSO) algorithm is implemented to carry out optimization of a user-defined fitness function for given user-defined operating conditions. The optimization study is subjected to general constraints of weight balance and energy balance. Optimal solutions have been obtained for two different configurations. These are—conventional airship and winged hybrid airship. The solutions have been obtained for four different days of the year, in order to analyse any potential benefits and pitfalls of the two configurations for the varying conditions over the course of one year. The results obtained are generally found to be in excellent agreement with the imposed constraints. The winged hybrid airship configuration was found to have offered no significant benefits in comparison to the conventional configuration. The analysis of the key parameters and data values readily supports this conclusion.

Highlights • A multidisciplinary model of solar-powered hybrid airship is carried out. • A mission-based flight strategy of the hybrid airship is presented. • Multi-objective optimization is conducted to obtain the optimal design set. Abstract This paper presented a multidisciplinary optimization methodology of a high altitude solar-powered hybrid airship. A multidisciplinary model of the hybrid airship is proposed including the geometry, aerodynamics, structures, propulsions and energy consisting of the photovoltaic array and energy stored system (ESS). To achieve a continuous flight and reduce the total mass and energy cost, a multi-phase strategy including the climb, daytime cruise, glide and nighttime cruise is proposed. The mission-based optimization is achieved through an enhanced collaborative optimization and the result shows a large decrease in the total mass compared with a baseline design. Since the flight altitude has a great influence on the hybrid airship with the multi-phase strategy, a multi-objective optimization achieved by NSGA-II (Non-dominated Sort Genetic Algorithm-II), is carried out to discuss the design tradeoffs in different altitudes. The result also indicates that the multi-objective optimization provides a solution set so that the optimal design of the hybrid airship in different flight altitudes could be obtained. [ABSTRACT FROM AUTHOR]

The increasing application of hybrid airships which have been recently proposed as high altitude platforms, makes it necessary for research into the thermal performance of such airships that possess a photovoltaic module array(PVMA). In this study, a simplified thermal model of a high-altitude hybrid airship with a PVMA, was proposed that included direct solar, infrared, reflected, and scattered radiation and convective heat transfer. Based on computational fluid dynamics(CFD), a simulation methodology, using a user defined function(UDF) program, was introduced to investigate the PVMA's thermal effects on the hybrid airship. A ground experiment was also performed to validate this numerical method's effectiveness. Further simulations and discussion of temperature and velocity distributions of the hybrid airship's internal helium were conducted. The results showed that the PVMA atop the hull had large effects on the hybrid airship's thermal performance. The temperature distribution of the envelope varied greatly during the day and night because of the PVMA's influence as well as the internal helium flow. In addition, forced convection had little influence on the PVMA's output performance, which was analyzed in detail. [ABSTRACT FROM AUTHOR]

An increasing focus on hybrid airships and the developments in renewable energies has allowed a methodology for conceptual design and analysis to be described. After a model presented and its aerodynamic characteristics obtained through a computational fluid dynamics method, two types of hybrid airships, solar powered at high altitudes and hydrogen powered for cargo, are demonstrated using a wing loading as their independent variable. Then the constraints determining the design point are presented. Parametric estimates of two types for component mass are then illustrated on distribution diagrams. And the sensitivity of wing loading and its effects on hybrid airships are discussed. [ABSTRACT FROM AUTHOR]

The aerodynamic lift and drag performance is one of the important considerations for hybrid airship configuration design. In conjunction with this, simulation study of aerodynamic characteristics can certainly benefit the process of deriving the best possible configuration for hybrid airship design. The aim of this study is to investigate the trend of aerodynamic lift and drag performance for an airship design in different velocities, altitudes and design fineness ratio using the Star CCM+ analysis tool. The airship model applied in this case study is an approximate model of the Atlant-100 airship. It is found that the airship model with low design fineness ratio typically generates much better aerodynamic lifting force in comparison to those with high design fineness ratio. On the other hand, while the range of estimated drag coefficient values is found to be rather insignificantly different, the presence of effects from the design fineness ratio is still evident. Generally, high design fineness ratio for the airship model seems to produce much lower drag force. [ABSTRACT FROM AUTHOR]

This paper aims to develop a high-altitude solar-powered hybrid airship, which combines aerodynamic lift and buoyancy with buoyancy force and cruises continuously. A multi-lobed configuration is employed and the solar irradiance and photovoltaic array model are proposed. After introducing all the parts mass of the hybrid airship and design procedure, an optimal problem with the constraint of energy and the equilibrium between buoyancy and weight are proposed. Through a hybrid optimization search method, the solution is obtained and the sensitivities of geographical location and seasons are discussed. The results show a comprehensive influence of the constraint both in latitude and wind field environment. [ABSTRACT FROM AUTHOR]

In this research, an experimental investigation was carried out at the International Islamic University Malaysia - Low Speed Wind Tunnel facility on a generic model of a hybrid lifting hull. Based on the historical trends of non-rigid airships, the fineness ratio of the said hull has been selected equal to 4. Free stream velocity was kept at 20 m*s and, along with the estimation of aerodynamic parameters, longitudinal and lateral stability characteristics were determined over a range of angles of attack from −8° to +12° and angles of sideslip from −10° to +10°. Zero lift coefficient was obtained at −4.2°, and the corresponding value was found to be greater than that at zero angle of attack. The comparison of the experimental results with the existing analytical relationships of wing has revealed that such an airfoil shaped hull cannot be considered as a wing due to 37% less analytical value of lift coefficient than that obtained by CFD simulations of the said hull. Existing equation of form factor of hull for conventional airships was also revisited, and a correction factor equal to 1.16 in the fundamental drag equation of aircraft’s fuselage was also proposed for fineness ratio equal to 4. Trends of the experimental data and comparison of the same with the theoretical calculations and computational results posed some interesting findings. The longitudinal and directional stabilities of a hybrid lifting hull were found to be statically unstable.

In this research, an experimental investigation was carried out at the International Islamic University Malaysia - Low Speed Wind Tunnel facility on a generic model of a hybrid lifting hull. Based on the historical trends of non-rigid airships, the fineness ratio of the said hull has been selected equal to 4. Free stream velocity was kept at 20 m·s-1 and, along with the estimation of aerodynamic parameters, longitudinal and lateral stability characteristics were determined over a range of angles of attack from -8° to +12° and angles of sideslip from -10° to +10°. Zero lift coefficient was obtained at -4.2°, and the corresponding value was found to be greater than that at zero angle of attack. The comparison of the experimental results with the existing analytical relationships of wing has revealed that such an airfoil shaped hull cannot be considered as a wing due to 37% less analytical value of lift coefficient than that obtained by CFD simulations of the said hull. Existing equation of form factor of hull for conventional airships was also revisited, and a correction factor equal to 1.16 in the fundamental drag equation of aircraft's fuselage was also proposed for fineness ratio equal to 4. Trends of the experimental data and comparison of the same with the theoretical calculations and computational results posed some interesting findings. The longitudinal and directional stabilities of a hybrid lifting hull were found to be statically unstable. [ABSTRACT FROM AUTHOR]

The existence of a platform at the stratosphere is expected to be the role to gain a foothold in space. When the platform is employed airship in, it is transported by advection due to its light-weight body. Thereupon, a mooring of platform is reasonable in order to incarnate fixed-point platform. Conception of a captive platform system is similar to the Rockoon one which rendered remarkable services for the space observation of the early days. Therefore, the application of captive platform system to the launch site is highly expected in order to realize the space transportation system with a large quantity and high frequency. In this study, the motion of a captive platform system constructed from an airship and a tether is analyzed in order to ensure that the motion of a captive platform system is practically incarnated. Moreover, the sensitivity of aerodynamic performance of the airship is observed. Consequently, the practically incarnated motion of a captive platform system has been identified under the condition of the storm environment. Furthermore, the reduction of the advection distance driven away by the storm has been quantitatively indicated under the different condition of aerodynamic performance of the airship. [ABSTRACT FROM AUTHOR]

It is scientifically important science value and engineering promising to develop the buoyancy-lift integrated hybrid airship for high attitude platform. Through the numerical method, a new tandem wings hybrid airship with both higher utility value and economy efficiency was obtained and its total performance and technical parameters were analyzed in detail. In order to further improve the lift-drag characteristics, we implemented the optimization design for aerodynamic configuration of tandem wings hybrid airship via the response surface method. The results indicate that the tandem wings hybrid airship has considerable volume efficiency and higher aerodynamic characteristics. After optimization, the lift-drag ratio of this hybrid airship was increased by 6.08%. In a given gross lift condition, tandem wings hybrid airship may provide more payload and specific productivity. Furthermore, the size of tandem airship is smaller so the demand for skin flexible materials can be reduced. Results of this study could serve as a new approach to designing buoyancy-lifting integrated hybrid airship. [ABSTRACT FROM AUTHOR]

In recent years, hybrid airships have been identified as promising alternatives for high altitude, long endurance missions. In this study, a design methodology to study the feasibility of a winged hybrid airship powered by solar energy is presented. The proposed methodology involves five disciplines of the airship, viz., geometry, aerodynamics, environment, energy and structures that have been coupled in order to develop an optimum design which incorporates the maximum advantages of the modules. A total of fourteen design variables have been finalized, which are required to carry out the sizing of the envelope, wing, and solar panel layout. The Particle Swarm Optimization (PSO) algorithm is implemented to carry out optimization of a user-defined fitness function for given user-defined operating conditions. The optimization study is subjected to general constraints of weight balance and energy balance. Optimal solutions have been obtained for two different configurations. These are—conventional airship and winged hybrid airship. The solutions have been obtained for four different days of the year, in order to analyse any potential benefits and pitfalls of the two configurations for the varying conditions over the course of one year. The results obtained are generally found to be in excellent agreement with the imposed constraints. The winged hybrid airship configuration was found to have offered no significant benefits in comparison to the conventional configuration. The analysis of the key parameters and data values readily supports this conclusion. [ABSTRACT FROM AUTHOR]

• Proposed multidisciplinary design optimization approach for hybrid airship. • Developed Kriging-based surrogate model to evaluate envelope drag coefficient. • Particle Swarm Optimization technique hybridized with Pattern Search method. • Sensitivity analysis of energy storage devices. In the recent years, there has been a lot of interest in developing hybrid airships as aerial platforms for various applications because of their several advantageous features. This paper presents a multi-disciplinary design optimization based methodology for an airship with a tri-lobed envelope. The proposed methodology involves five disciplines, viz., Geometry, Environment, Energy, Aerodynamics and Structures. To reduce computational complexity involved in evaluating the aerodynamic characteristics of the tri-lobed envelope, a Kriging-based surrogate model was developed to estimate the envelope drag coefficient and coupled to the optimization framework to achieve the optimal solutions for different operating conditions. The surrogate model predicts the drag coefficient of the tri-lobed envelope with less than ± 3% error with respect to the results obtained through CFD. Since the problem follows a multi-disciplinary design approach, a composite objective function is formulated based on volume of the envelope, area of the solar array, and total mass of the airship, which isminimized using Particle Swarm Optimization (PSO) Algorithm. This study reveals that for meeting the same mission requirements, a tri-lobed airship powered by regenerative fuel cells requires half the volume and 33.5% lower solar array area, and has ~ 46% lower mass compared to the one powered by rechargeable batteries. [ABSTRACT FROM AUTHOR]