Browse Topic: Airships
This historical paper explores the development of vertical lift. Beginning with Leonardo's aerial screw, a profound conceptual leap, which was a helical device intended to compress air beneath it and rise vertically. Though never constructed or flown, it represents the first recorded articulation of rotary lift. The idea of rising directly upward would echo through the dirigible era of the early twentieth century, the helicopter age of the mid-century, and the emerging era of Advanced Air Mobility (AAM). This study traces that intellectual lineage and explores the technological and social forces that shaped the destiny of vertical passenger flight.
Pipeline inspection is a crucial aspect of maintaining the integrity, safety, and reliability of the planet’s energy infrastructure. However, due to cost and scale challenges, infrastructure operators struggle to conduct accurate, large-scale inspections. A French startup, HyLight, offers a solution to precisely detect issues on the infrastructure, such as methane leaks on pipelines and defects on power lines at an industrial scale, without emitting greenhouse gases.
Revealed in 1941, the Dirigible Helicopter or 'Koun's Craft,' was an ambitious but ill-fated fusion of convertiplane and lighter-than-air technology. This S/VTOL (Short/Vertical Take Off and Landing) concept (a veritable puzzle of diverse airplane parts) was powered by a single, tilting propeller engine and was affixed with wing mounted, helium filled enclosures for additional buoyancy. Dismissed historically as being an eccentric folly of its layman inventor, Korean-American Young Ha Koun, the development of the Dirigible Helicopter has never been thoroughly studied. This paper will examine the origins of this unique design, its creator's possible motivations for building such an aircraft, and successor convertiplane concepts that attempt to achieve the same purpose to this day.
This paper presents an accurate analysis of an innovative high altitude platform with an unconventional ellipsoidal shape during the most critical operation. The airship is designed accordingly to the specifications, which have been analyzed in terms of the required CONOPS (Concepts of Operations) which are associated with the proposed High Altitude Pseudo-Satellite (HAPS) technology and special operations and to analyze the operational scenarios. An innovative cruiser feeder system is defined and studied. The CONOPS includes communications relays, support of intelligence, surveillance, target acquisition monitor “mobile targets”, and reconnaissance, including long-range ISTAR missions performed by the feeder, combining satellite vision and HAPS vision for a forest fire, disasters, naval accidents, maritime and ground borders. The paper realizes a multidisciplinary analysis that allows creating the design of the HAPS, referring to both cruiser and feeder in different operative scenarios. It is expected to produce the preliminary basis for a future digital twin based design to generate the best possible configuration by mean of implementing multiphysics simulations. Structured object-oriented design processes involve developing several different system models and configurations. The modular design of the core modules is necessary for both ensuring the adequate performances, the capability of satisfying the operative necessities which have been defined by the CONOPS and fulfilling the requirements.
CIRA is currently designing a HAPS for Earth Observation and Telecommunications named High Altitude Hybrid Airship. The configurations considered, can generate both aerodynamic and aerostatic forces to balance the weight during the different phases of a mission. The design of a hybrid configuration for stratospheric platforms represents a novelty in itself in the aerospace sector while some hybrid platforms have been proposed only for tropospheric applications. In order to carry out the conceptual design, some design tools have been implemented to rapidly obtain a conceptual layout, which can be used to perform CFD, FEM and stability analysis and, at the same time, to compute the relative platform mass breakdown. The proposed conceptual design process is based on two steps. A first coarse exploration algorithm which, starting from some input parameters, determines the best buoyancy ratio and some overall platform parameters (among others: weight, volume and dimensions) using some semi-empirical formulas to define sub-systems masses, aerodynamic coefficients and structures sizing. The second step consists in a finer optimization around the geometry obtained at the previous step, based on a better definition of the layout, which provides, as final output, a 3-D CAD layout of the stratospheric platform and its main structural elements. Layout modification during the design conceptual process represents an innovative aspect, which allows improvements, since the beginning of the design, the results. This layout, finally, represents the input for CFD, flight stability and FEM analysis. In this paper, this innovative conceptual design process defined to obtain some conceptual configurations of a hybrid HAPS, and the implemented design tools will be described. Furthermore, some HAPS layouts and preliminary CFD analysis will be presented.
Ludwig Rudolf Rüb, a passionate inventor, lived in poverty most of his life and is virtually unknown in the rotorcraft community. His inventions covered combustion engines and motorcycles first. Around 1900 he built a paddle-wheel plane under contract by Count Zeppelin, next he designed and built a first version of a coaxial rotor helicopter in Munich, and then he moved to Augsburg for building a large fixed-wing aircraft. None of these were ever finished. At the begin of WW I, with support of the German army, he took up a refined version of his coaxial rotor helicopter concept as a highly agile and maneuverable replacement of the observation balloons used in those times, which also was intended to take an active part in warfare by installing a machine gun or dropping bombs. It included some astonishing advanced features and with the help of his sons the construction was finished; ground testing started in June 1918. The end of the war immediately stopped all works; the contract of Versailles demanded the destruction of that vehicle and thus formed the end of the Rüb aeronautical work. Ludwig Rüb died 1918, after months of illness, without having seen the rotors turning.
This study investigates the physical phenomena that affect a high-altitude airship in the presence of lifting gas losses from the hull. General atmospheric thermodynamics and basic physical principles are adopted to describe the behavior of an airship with envelope failures that generate buoyant gas dispersion or depressurisation phenomena. Overpressure that could grant to maintain some controllability during a large part of the descent is assessed by mean of the thermodynamic model of the envelope in the presence of gas losses. Optimisation of the inflation parameters is provided and the conditions for avoiding dangerous crashes on the ground and the potential recovery of a damaged vehicle, people and its payload. In particular, the requirements for a slow depressurisation is computed by the equilibrium with the atmosphere and then how can it be possible to sustain controlled navigation are determined. A key factor for security relates directly to the capability of preserving some airship balloon overpressure for the longest time possible. This condition can extend much the range of control. Complete forfeit conditions will be determined to demonstrate that airship cannot be anymore controllable below 20% of the initial altitude at which the failure has started. In some cases, specific manoeuvres could allow configuring the deflated balloon as a parachute, if coupled with adequate safety systems. This research about safety conditions will also be useful for designing safety systems. A general guideline for safety systems has been defined showing that airship if well created and well governed in emergency conditions will be much safer than any other aerial vehicle.
The flight simulation of airships and hot air balloons usually considers the envelope geometry as a fixed shape, whose volume is eventually reduced by ballonets. However, the dynamic pressure or helium leaks in airships, and the release of air to allow descent in hot air balloons can significantly change the shape of the envelope leading to potential dangerous situations. In fact, in case of semi-rigid and non-rigid airships a reduction in envelope internal pressure can reduce the envelope bending stiffness leading to the loss of the typical axial-symmetric shape. For hot air balloons thing goes even worse since the lost of internal pressure can lead to the collapsing of the balloon shape to a sort of vertically stretched geometry (similar to a torch) which is not able to sustain the attached basket and its payload. These effect should be considered in simulations, however to compute in real time the envelope shape with Finite Element Methods is a complex and demanding task due to the high deformations, complex fabric model, and wrinkling effects. A possible solution to overcome this problem is to apply a Cloth Simulation Technique (CST) to the prediction of the envelope behaviour. This paper describes how such a model can be implemented for airship envelops and hot air balloons shape predictions. Appropriate algorithms have been developed in Matlab® and validation test have been conducted. Results show that this model can provide qualitatively good results, in agreement with the experience and the physics of the problem.
The solution of the both synthesis and implementation problems of high-rapid rates control laws is extremely important for the development of automatic control systems of the aircraft. This is due to the high speed of such vehicles. Along with this, it is imperative that control laws provide that system is asymptotically stable, as the basis for the reliability of their controlled motion. Another important objective of the method of synthesis of control laws for aircraft is compulsory compliance with strict limitations on the values of control inputs at the actuation devices. It is equally important that the control laws provides limitations on the state variables of aircraft, such as velocity, acceleration, etc. Pontryagin's maximum principle is aimed at solving such a time-optimal problem with the limited command variable. However, both the mathematical formalism of this principle, and the mathematical formalism of the methods based on this principle don't provide a solution of the class described tasks. The problem is that, despite the fundamental theoretical validity of these methods, they don't provide robustness synthesized control laws. Robustness is understood here as the insensitivity of the properties of the control system to small variations in the properties of the control object. The reasons for this phenomenon are known. They are as follows: the asymptotic properties absent in positional control, maximum speed law is defined only within a given time interval, the stabilizing feedback is absent. As a result the inadequacy of the dynamic properties of a managed object and calculated data can lead to a complete loss of the control system quality. The essence of the proposed approach consists in influencing the change of the derivatives of the state variables, which form a system of phase coordinates. Each derivative of the state variable is formed by a special non-linear law. These laws impose a number of requirements: the derivative of the phase coordinates is limited, its rate of change is close to optimal for the designated limit, the law of its change is asymptotically stable. In other words, the state-space of the control object form specific invariant manifolds. These manifolds are formed by specially synthesized control law so that their properties are determined by the above requirements. Mathematically varieties are generated by nonlinear functions of the right sides of the system of differential equations of state of the control object. Structures and function parameters form the mathematical model of the control law. The resulting control action (signal input) sequentially generates the processes of change of phase coordinates in such a way that directs the state variables of the system on the given invariant manifolds. Formed diversity determine the dynamics of the controlled system. They in aggregate form its attractor, which meets the following properties: near-optimal performance, bounded of phase coordinates and asymptotic movement. The procedure of successive synthesis of invariant manifolds is given can be implemented for objects that have a mathematical model in the form of the Cauchy problem with the so-called “triangular” structure. For such a model is a characteristic that every i-th state variable of the system, which has the order of “n” and “r” of the control inputs, depends only on the state variables with index not greater than i + 1. In this case, any derivative of the state variable may depend on only one control input, and the n-th derivative is necessarily dependent on one of these inputs. This result is very important for the practical problems of management of working bodies of aircraft. For them, the control speed is a critical factor in the quality of flight and stability and robustness is a critical factor in the reliability of automatic control. Application of the proposed method is illustrated by the example of the construction and study of the automatic control system of the device controlling airship.
While operational airships globally number in the low dozens, interest in buoyant or semi-buoyant platforms continues to arouse imaginations of commercial and military planners and developers alike. The airship-as-advertisement business model is the only model that has proven sustainable on any scale since the crash of the initially successful LZ-128 Hindenburg effectively ended regular passenger and cargo transport by airship, and the 1962 termination of the US Naval airship program terminated regular large-scale surveillance from airships. Efforts in the US and Japan during the 2000's to have a self-sustaining sight-seeing business model using the modern semi-rigid Zeppelin NT both failed. In theory, the buoyant nature of airships provides compelling endurance and cost-per-ton-mile capability which fills a niche arguably not currently occupied by other modes of transportation. The potential endurance capability motivated the US Military to fund two nearly-simultaneous airship surveillance programs in 2010. Having similar missions, the primary differentiator between the two programs had to do with choice of basic hull form. The Army's Long endurance Multi-Intelligence vehicle was to be a lifting-body semi-buoyant “hybrid” vehicle. The Air Force's Blue Devil Block 2 was to be a conventional ellipsoidal airship. The author's pre-contract-award 2010 paper compared the loitering performance of the two platforms using a basic mission simulation, giving the nod to the conventional ship. This study revisits the basic assumptions of the simulation in view of new publicly available aerodynamic information, and revises the results, finding the hybrid to be the superior option.
The aim of this paper is to develop a new concept of unconventional airship based on morphing a lenticular shape while preserving the volumetric dimension. Lenticular shape is known to have relatively poor aerodynamic characteristics. It is also well known to have poor static and dynamic stability after the certain critical speed. The new shape presented in this paper is obtained by extending one and reducing the other direction of the original lenticular shape. The volume is kept constant through the morphing process. To improve the airship performance, four steps of morphing, starting from the lenticular shape, were obtained and compared in terms of aerodynamic characteristics, including drag, lift and pitching moment, and stability characteristics for two different operational scenarios. The comparison of the stability was carried out based on necessary deflection angle of the part of tail surface. The comparison results indicated that new shape concept possesses much better aerodynamic and stability characteristics and could be used for detailed optimisation studies.
The maturity reached in the development of Unmanned Air Vehicles (UAVs) systems is making them more and more attractive for a vast number of civil missions. Clearly, the introduction of UAVs in the civil airspace requiring practical and effective regulation is one of the most critical issues being currently discussed. As several civil air authorities report in their regulations “Sense and Avoid” or “Detect and Avoid” capabilities are critical to the successful integration of UAV into the civil airspace. One possible approach to achieve this capability, specifically for operations beyond the Line-of-Sight, would be to equip air vehicles with a vision-based system using cameras to monitor the surrounding air space and to classify other air vehicles flying in close proximity. This paper presents an image-based application for the supervised classification of air vehicles. First, several vehicle images, taken from different points of view, are transformed using a descriptor of salient features as to build the five-class database used to train the classification algorithm. Then, the latter compares the descriptor of a vehicle image taken from a random point of view to records in the database. With a positive match, the vehicle will be assigned to one of the following classes: a) civil transport aircrafts, b) military aircrafts, c) general aviation aircrafts, d) helicopters, and e) airships/hot air balloons. The paper provides a possible layout for the algorithm implementation and presents the outcome of several tests performed to evaluate its efficiency and possible exploitation. Indications useful to further studies are presented to help future researches.
This paper presents a structural analysis of an engine chassis for a disc-shaped airship demonstrator. The objective was to verify such design solutions for application in the European Union's MAAT (Multibody Advanced Airship for Transport) project. In many airship designs, the engines are attached to the airship frame, located inside the balloon, in order to allow for thrust vector control. These airships have aerodynamic control surfaces to improve maneuverability. For the demonstrator, three engines are considered, with a non-rigid internal structure for their attachment. The engines are located on a horizontal plane (the symmetry plane of the balloon), with two lateral engines and one in front of the balloon. The chassis installation allows the engines to be attached either directly to the exterior envelope by using Kevlar connections, or to the central structural pipe. This chassis design has a simple construction, compared to typical structures addressed in the literature. The structures have a kinematic device based on a servomotor, which provides the torque to tilt the engine. The critical condition is defined with the vertical wind that varies the load factor. A finite element analysis is performed, considering the full structural model with different tilt angles. The Von Mises criterion is applied for the ductile and the Mohr-Coulomb criterion for the brittle materials. The obtained results show that the stresses are within the safety limits. It is concluded that the presented structure can be applied to build the envisaged MAAT demonstrator.
Airship designers research application versions of systems with several ballonets for adjustment of airship roll and/or pitch as a whole. This requires effective automatic status management of each separate ballonet. But multi-ballonet system control issue encounters the absence of industrially measurable variables of each separate ballonet status. Thus status control issue of the system becomes uncertain. The fact requires the issue studying and shaping new scientific and technical solutions. This publication represents research results implying that fairly simple implementation and effective result can be achieved by application of fuzzy control concept. Its application is built on generating the representative quantity of fuzzy production rules. They are based on present set evaluation of known parameters and measured variables. This results in fuzzy but meaningful image of ballonet system status and airship as a whole. Thus achieving fairly good control over multi-ballonet system. This article represents development results of fuzzy automatic control system version of two-ballonet system containing determined positional control systems of pressure difference between body gas environment and atmosphere. The resulted hybrid control system maintains necessary pressure in airship body and provides airship trim control efficiency at low traveling speed. Modes like that appear during take-off and landing. The development is based upon airship model with ballonet control system which adequacy has been checked by previous researches. This model was used to research and experimentally correct conditions and influence results of developed production rules on ballonet system status and airship as a whole. Control law fuzzy derivation procedure is demonstrated and explained. Described is simulation modeling diagram of fuzzy control hybrid system of two-ballonet system in Simulink environment and its computer testing results. Illustrated is airship positioning fuzzy control maintaining boost pressure in body to provide its specified rigidity.
Airship dimensions define the application of the computer modeling methods under their development and investigation. Herein, the need to simulate the flight environment state - the atmospheric conditions of their traffic route - arises. The atmospheric parameters have both regular and random components, which is due to the nonstationarity of the atmospheric phenomena. Hence, it is essential to define the actual ranges, and the representative values of the atmospheric effects. Weather data are used for the analysis and the airflow performance computation in the operational area. Through their statistical processing, we need to obtain the most informative characteristics of the weather conditions in whole, and of their trends. The investigation has shown that the weather data gathering system is nonperfect. The sampling frequency is irregular and not high, test values in the specific parameters are obtained asynchronously. At this, altitude is the most critical parameter under measuring, and all the observable parameters are to be referenced to the altitude in the problem on the flight environment parameter simulation. Consequently, the problem on the statistical processing of the weather data array acquires importance and specificity. Efficient algorithms of the Integrated Global Radiosonde Archive application are considered in the paper. It is shown how the most informative estimates of the route time and calendar conditions affecting the flight aerodynamics can be obtained on the base of the data statistical processing. The research and calculation algorithm is based on the fact that all the controlled parameters are to be referenced to the altitude. Thus, the problem on the data statistical processing acquires clear directionality from the preprocessing and efficient data structuring up to the objective estimation of their processing results.
The paper describes methods for control of docking of two moving stratospheric airships. One of them (cruiser) implements cruising flight at the defined altitude with defined velocity. The other one (feeder) fulfills the mission of chasing the cruiser with following docking operations. Mathematical model of exact airships are used in the work. Instances of structural and algorithmic implementation are based on position-trajectory controller. Simulation of docking control was accomplished with proposed methods.
This paper introduces a new equipment, which allows autonomous landing and docking of a VTOL aircraft and any mobile system. It has been studied and developed inside the MAAT (Multibody Advanced Airship for Transport) EU FP7 project to control autonomous docking of manned cruiser and feeder airships in movement. After a detailed analysis it has been verified that It could be considered a technological spin off the MAAT project. It defines a new instrumental system for governing relative positioning between a movable target and VTOL air vehicles, such as helicopters, airships and multi-copters. This solution is expected to become a short time to market equipment for helicopters (both manned and unmanned) ensuring autonomous landing ability even in case of low visibility. Infrared emitters allow controlling both position and yaws angle. It is in advanced testing phase after a preliminary successful testing using a quadcopter. Tests has produced autonomous landing on a small platform mounted on an unmanned vehicle. In some experiments also landing on a target in movement has performed. The proposed solution is an alternative to more sophisticated vision based controls. It ensures high affordability, high simplicity and low costs. In addition, this concept can equip any fixed and mobile platform and open the novel scenario for autonomous scout vehicles equipped by UAVs.
Saturn’s moon Titan is of high interest for in situ study due to its many intriguing features. This moon has a dense atmosphere; rough, icy terrain; and low surface winds that make it the ideal place to send a controlled aerial robotic platform, such as a conceptual Aerobot Airship. An important feature of a self-propelled, lighter-than-air aerial vehicle is that it must be autonomously controlled to navigate and avoid obstacles because of a 2.6-hour communication delay between the Earth and Titan. Developing a dynamic model that can be tuned will enable robust and reliable control of the Aerobot Airship.
Typical lighter-than-air vehicles utilizing a superpressure design such as balloons, aerostats, or blimps, have one or more fittings attached to the gas containment skin that can serve as load attachment points or inflation/vent ports. These fittings are often sealed to the skin with a silicone gasket and a room temperature vulcanizing (RTV) adhesive. This type of seal works very well over the temperature range encountered in the Earth’s atmosphere (–60 to +40 °C). However, balloons designed to operate at Titan or Mars would encounter temperatures much colder than those found on Earth, making this type of seal inadequate.
This paper presents a mathematical model of the vertical forces acting on an airship during vertical motion. The main effort is the definition of an airship model, which move only vertically by ballast, and buoyancy effects, with a much reduced energy consumption for take-off and landing operations. It has been considered a disc-shaped airship, which can operate using the open balloon airship architecture defined to operate safely with hydrogen. This architecture does not require internal ballonets, because of the connected increased fire dangers that they create even if vented. Several models of airship based on vertical forces have been presented in literature. They often consider only the US or International Standard Atmosphere models and they neglect effects of weather conditions. The latter are connected with the location and with the season. These environmental and climatic factors have a large influence on behaviors of the airship system, because it is well known that the internal buoyant gas changes pressure and density condition because of external temperature. This paper defines the lifting behavior in terms of speed and acceleration. It evaluates the load factor as a function of the buoyancy and the ballast on board as a function of climatic conditions. A very simple methodology has been also presented on daily basis, authors neglect the effect of overheating of the gas due to solar radiation on the surface of the balloon, which can support the predefinition of climatic effects. The proposed methodology corrects the International Standard Atmosphere model by considering climatic data such as temperature, density and pressure of the air dependent on seasonal factors and location on annual basis.
The European project MAAT (Multi-body Advanced Airship for Transport) is producing the design of a transportation system for transport of people and goods, based on the cruiser feeder concept. This project defined novel airship concepts capable of handling safer than in the past hydrogen as a buoyant gas. In particular, it has explored novel variable shape airship concepts, which presents also intrinsic energetic advantages. It has recently conduced to the definition of an innovative design method based on the constructal principle, which applies to large transport vehicles and allows performing an effective energetic optimization and an effective optimization for the specific mission. While the traditional constructal method performs an optimization with a down-to-top approach, it produces an optimization process in two stages: the first one defines the optimal characteristics of the system understood as a unitary system to achieve the desired performances; the second analyzes the subsystems, examining those most disadvantaged, in order to optimize its performance for the desired goal. It has been deeply tested on a traditional shaped airship allowing verifying that a changing volume airship has globally better energetic performances than a fixed volume one. This paper performs a preliminary analysis of the method for the design of a cruiser/feeder multibody airship such as the one, which is going to be designed inside the MAAT project. The model presented defines the guidelines for the optimization of the system considering the magnitudes involved in flight physics to achieve the goal of energetic self-sufficiency.
The flow around the nacelles of high altitude airships is very important in order to assess the inlet conditions and losses associated to their propulsion systems. The aerodynamics prediction of low Re number flows is a problem usually associated to the lack of accuracy of most of the turbulence models in everyday use. Herein we present a laminar kinetic energy transitional model that is then applied on the analysis of the flow around an example of the MAAT airship nacelle. The model is also validated using several well known test cases from the literature. Results indicate the effects of accurate transition prediction in the redesign of the nacelle for improvement in efficiency.
This paper is devoted to a method of creating of the automated ballonet system for pressure control inside an airship envelope. Along with the study of the effects of the positional control system parameters, the authors develop novel control scheme. It is based on a new hybrid controller, which combines positional approach to forming the output control signal with a contour of continuous correction of input signal, which defines the pressure drop on the surface of the envelope as a function of the flight altitude. This approach allows reducing the effect of self-oscillations of airship envelope internal pressure on the flight altitude. In order to prove the new approach the mathematical model is being obtained. The results of the derivation and simulations of the control system operation are presented in this paper.
This paper investigates the ancient idea of augmenting the thrust produced by a rotating fan by producing a thermal gradient by heating the outflow. Some of the pioneers of aeronautics have originally conceived this idea: the indirect jet (Bleriot Coanda Monoplane, 1910) and the “thermojet” (Caproni-Ciampini CC2, 1942). They were abandoned because of the better performances by traditional jets such as the ones developed in Germany and USA during 2nd World War. Antony Colozza (NASA), one of the modern fathers of high altitude airships, has recently proposed it again to be used on fuel cells powered airplanes and airships. Most fuel cells have a large thermal dispersion at high temperature (about 40%), but it could be possible to use it for heating the propulsive stream of high-speed air produced into ducted fan propulsive units. The actual state of the research is only introductory and aims to verify the feasibility of this energy recovery, which could in future enhance the energy efficiency of electrical airplanes powered by ducted fan units especially for high altitude operations. The preliminary research activities presented are conducted assuming a reduced scale system in order to have the possibility of future costless experimental activity for validation. The CFD evaluations have been performed by two different codes: the well tested Ansys Fluent and a lightweight academic code EasyCFD.
Added masses computation is a crucial aspect to be considered when the density of a body moving in a fluid is comparable to the density of the fluid displaced: added mass can be defined as the inertia added to a system because an accelerating or decelerating body displaces some volume of neighboring fluid as it moves through it. The motion of vehicles like airships and ships can be addressed only by keeping into account the effect of added masses, while in case of aircrafts and helicopters this contribution is usually neglected. Lighter Than Air flight simulation, unmanned airships flight control system, airships flight dynamics are typical applications in which added masses are fundamental to achieve an effective and realistic modeling. A panel based method using the mesh of an airship external shape is developed to account for the added massed. While the mathematical background of the methodology is described in literature, what is missing is a proper description suitable for unconventional manned/unmanned airship. Two applications of the methods have been carried out to check the precision of the methods, and results have been also compared to a case study whose added masses are described in literature. A sensitivity study on the effect on the added masses of the number of elements in which the envelope is discretized is performed. Finally, for an unconventional unmanned airship model, the computations of the terms of the added masses matrix are shown.
It is possible to define a novel optimization method, which aims to overcome the traditional Multidisciplinary Design Optimization. It aims to improve Constructal design method to optimize complex systems such as vehicles. The proposed method is based on the constructal principle and it is articulated in different stages: 1 preliminary top-down design process to ensure that the full system has one of the best configurations for the specified goals (contour conditions for constructal optimization could be stated ensuring an effective optimization at full-system level). 2 constructal optimization of the elemental components of the system to maximize the system performances; 3 eventually a competitive comparison between different configurations choosing the better one. The definition of an optimized flying vehicle (an airship) has been produced an example of this improved design method with the objective of minimizing the energy consumption during flight. Following this method, this paper aims defining the guidelines for an effective energetic optimization of an airship. The produced results allow defining a novel airship concept, which optimizes the airship shape to reach three fundamental energetic goals: energy consumption minimization, photovoltaic energy production maximization, definition of the conditions for energetically self-sufficient flight. This paper also demonstrates that the resulting architecture can fit perfectly novel operating conditions such as effective point to point logistic without any airport infrastructure having a potential breakthrough impact on the aerial logistic models and allowing an effective and better integration with any other terrestrial, maritime and aerial transport mode.
Scaled models are often used to check the aerodynamic performance of full scale aircraft and airship concepts, which have gone through a conceptual and preliminary design process. Results from these tests can be quite useful to improve the design of unconventional airships whose aerodynamics might be quite different from classical configurations. Once the airship geometry has been defined, testing is required to acquire aerodynamic data necessary to implement the mathematical model of the airship needed by the flight control system to develop full autonomous capabilities. Rapid prototyping has the great potential of playing a beneficial role in unconventional autonomous airship design similarly to the success obtained in the design process of conventional aircrafts. By reducing model cost, build time, difficulty of construction, and maintaining acceptable surface quality and finish, designers have greater ability to analyze several configurations of airships and to change the geometry in order to increase stability, reduce drag, or fulfill mission requirements. This work presents aspects of unmanned airship design which are supported by the use of RP techniques: a test model of a multi-body, cruiser-feeder unconventional airship system has been developed using hot wire cutting and SST printing technology which helped to construct necessary parts for complex body shapes. Taking into account actual model shape and material properties, model verification checks were performed on the final products through FEM and CFD analysis to ensure structural strength and integrity during test procedures and to virtually simulate wind tunnel tests; experimental data from the wind tunnel campaigns are then used in the development of an unmanned airship flight simulator, which is of critical importance in multi-body concepts when cruiser/feeder configurations need to perform docking and rendezvous maneuvers. Results which assess the quality of the test models by comparison of wind tunnel results to CFD simulations are also presented; a final discussion of advantages obtained applying RP technique to the airship design cycle concludes the paper.
In this paper we consider one of the problems in the development of control system for the feeder for MAAT transportation system. This problem is connected with estimation of inboard energy requirements. Traditionally such estimation is made on the basis of static relations. They allow assessing the power required to move a solid body with a constant air speed. However a contribution from aerodynamic forces and moments can vary depending on a regime of motion (value of linear and angular accelerations, angle of attack, etc). Because of that fact, this work investigates the estimation of the total required inboard energy and contribution of aerodynamic forces and moments to it in specified feeder motion regimes. The method of assessment is based on the feeder model, which is built on the equations of the rigid body. This paper contains general structure of feeder mathematical model, which includes equations of statics, dynamics and control mechanisms. The example of the exact feeder shape gives the application of this models with the details in terms of aerodynamic characteristics, inertial mass parameters and locations of control mechanisms. Feeder model is complemented by the external environment model, including the wind flow model. Development of the latter models is investigated in the talk “Probabilistic Approaches to Estimation of Flight Environment for Feeder of Multibody Transport Airship System”, presented on this conference. Three main feeder motion regimes were chosen for the estimation of the required power. These three regimes are hovering in one point, motion along a straight line and motion along a specified circle. Steady motion is considered along with transient regimes, when the feeder is moving to the specified trajectories. The results allow assessing the required power for steady and transient regimes for each considered trajectory, different values of air speed, different locations of centre of gravity and different angles of attack. Additionally, study of Kalman controllability and Lyapunov stability was made for the special feeder motion regimes. The conclusions about the optimal feeder shape are given based on this work.
Functional and energetic issues of control of feeder-airship of MAAT system are considered in the paper. MAAT (Multibody Advanced Airship for Transport) [1,2] is an environmentally friendly system for transportation of passengers and cargos. It consists of cruiser and a few feeders. Cruiser flies in stratosphere at almost fixed altitude. Feeder acts like an elevator, it delivers passengers and cargos from airport to cruiser and in opposite direction. Paper shows, that wide altitude range feeder flies through, strong and dynamic wind loads at various tropospheric and stratospheric altitudes, makes definition of control strategies and energy requirements for control a nontrivial task. That is why this work pays much attention to assessment and mathematical description of feeder flight environment, existing and potential wind profiles, essentially influencing at feeder flight trajectory. Energy efficiency increase is considered in the paper.
This paper presents a model of energetic consumption and photovoltaic production for a large airship which acts as feeder connecting the ground with a large cruiser. The analysis of energy needs and productivity allows defining both an ideal sizing and operative mission profiles. The specialised mission of this airship is to ascent and descent. It includes also the connection with the airport buildings on the ground and with the cruiser at high altitude. Photovoltaic production has evaluated in terms of hydrogen and electric propulsion. They have estimated both and a calculation methodology has proposed. The evaluation has supported by CFD evaluations on aerodynamic behaviour of the system at various altitudes.
This paper explores a novel structural design concept for a demonstrator of a high altitude photovoltaic feeder airship. The presented structural design concept aims to minimize the use of strategic materials in the structure of the airship, but also to maximize the ease of construction of the structure. The proposed design concept and method an effective analysis of historic airship structures considering their efficiency vs. weight and desired performances. By this analysis a novel structural design has been defined to reach the ambitious goal of a lighter and cheaper structure concept which can ensure comparable performances with traditional rigid airships. A discoid shaped airship with a central column has been taken into account. Structural calculations and constructive design has been presented in depth.
This paper presents the new Hydrogen Fire-safe Airship system that overcomes the limitations present in previous airships designs of that kind, when considering their functioning at advanced operative position. Hydrogen is considered to be more effective than helium because of its low-cost production by hydrolysis, which process is nicely driven only by the photovoltaic energy. This paper presents a novel architectural concept of the buoyant balloon designed to increase the fire related safety, when applying hydrogen as the buoyant gas. The proposed buoyant volume is designed as a multi-balloon structure with a naturally ventilated shape, to ensure that hydrogen cannot reach the dangerous concentration level in the central airship balloon. This concept is expected to be the start of a novel hydrogen airship type, to be much safer than preceding ones. It permits to reduce the traditional economic costs, when compared with helium inflated airships, due to the helium scarcity in the world gas resources and its related production costs. This paper presents the volumetric analysis necessary for a preliminary design activity of this novel control system of the ballonets in this airship concept and to define the design of the airship's architecture.
Nautilus S.p.A. and the Polytechnic of Turin, in cooperation with Blue Engineering, have developed a very versatile product, the ELETTRA Twin Flyers [6] (ETF), which consists in a very innovative remotely-piloted airship equipped with high precision sensors and communication devices. This multipurpose platform is particularly suitable for border and maritime surveillance missions and for telecommunication, both in military and civil area. To assess the actual maneuver capabilities of the airship [14], a prototype of reduced size and complexity has been assembled [16]. Before the flight tests a further assessment on the flight simulator is needed, because the first version of the software is tuned on the full scale prototype. Steady state performance and static stability of the demonstrator have been evaluated with CFD analysis. The dynamic stability have been evaluated using CFD as well, because the classical methods to calculate dynamic derivatives, using USAF Datcom or wind tunnel tests, are not accurate enough, for unconventional shaped aircrafts in particular. Moreover, these methods refer to body pitch and plunge motion: it follows that derivatives are affected to a great extent by the frequency [17] and these derivatives are not suitable for aircraft model. To overcome all of these shortcomings, an innovative approach, based on looping and heaving motion has been used to calculate the dynamic derivative in order to update the flight simulator and thus to train the pilot with a realistic mathematical model.
The MAAT project (Multibody Advanced Airship for Transport) aims to investigate aerial transportation possibility by airship based cruiser-feeder system. MAAT is composed by two modules: The cruiser, named PTAH, (acronym of Photovoltaic Transport Aerial High altitude system); the feeder, named ATEN (Aerial Transport Elevator Network feeder), is a VTOL system (Vertical Take Off and Landing) which ensure the connection between the cruiser and the ground. They can lift up and down by the control of buoyancy force and displace horizontally to join to cruiser. The project aims to: 1 identify and design the most functional cruiser/feeder airship architecture based on a discoid innovative airship able to remain airborne for long periods and to travel great distances; 2 design the best type of propulsion both for cruiser and feeder so they can contribute together to the propulsion of an innovative modular airship; 3 minimize the environmental air transport impacts by annulling the fossil fuels energy consumption by designing both cruiser and feeder are energetically autonomous by photovoltaic energy and innovative electric propulsion. 4 study the different possible ways of approaching and joining between ATEN and PTAH, and consequently, the release of ATEN from PTAH. 5 design the best procedure of docking operations thus identified in order to obtain the minimum disruption to passengers and the maximum safety for themselves and for goods 6 study the different architectures of PTAH and Athens, in such a way that : a the lift up capacity guaranteed by the buoyancy force, may be accompanied by the power of the engines; b effective and safe procedures for docking; c ATEN can land and take off from Airport Hubs named AHA located in major populated centres d PTAH satisfies the better possible aerodynamic performances possible for the dimensions and the operative mission. To study the transfer operations between ATEN and PTAH of goods and people and vice versa, to: minimize distress conditions for passengers, maximize performances especially for goods; enhance safety of these operations to maximum possible level. The objectives described are congruent with each other and to achieve this study of the system and components must be highly structured…
MAAT project is a large airship project presented to the last European 7 Framework Program Transport including Aeronautics 2011 deadline. MAAT project is an airship based cruiser-feeder transport system. This paper analyzes the criticalities of the project and the way to upfront these problems which have different natures and possible solutions. Most important criticalities are analyzed both on a methodological point of view and on a direct point of view. Enhanced design methodologies are analyzed in depth to analyze problems, upgrade the project design status continuously and to examine different design options and solutions. An innovative design method has been defined to avoid that problems can produce show stoppers and minimize time delays during project definition.
This paper deals with the ground testing of the technological demonstrator of the innovative remotely controlled ETF airship1. The testing activities are intended to validate the flight control system of the ETF, which is based on the thrust vectoring technology and represents one of the major innovations of the ETF design, together with the airship architecture. A research team of the Aeronautical and Space Department of the Polytechnic of Turin, in collaboration with Nautilus, a small Italian private company, has been working since a few years on the ETF (Elettra Twin Flyers). This airship is remotely-piloted, with high maneuverability capabilities and good operative features also in adverse atmospheric conditions2. The Nautilus new concept airship features architecture and appropriate command system, which should enable the vehicle to maneuver in forward, backward and sideward flight and hovering with any heading, both in normal and severe wind conditions. To achieve these capabilities the ETF demonstrator3 has been conceived with a highly non conventional architecture based on a double hull with a central plane housing structure, propellers, on board electric system and payload (Figure 1). As primary command system, the aerodynamic control surfaces are replaced by six propellers, which are moved by electrical motors and allow the airship to be controlled and maneuvered in the whole flight envelope. In this paper the results of the preliminary testing runs are analyzed and the power requirement is compared with the performance of the Fuel Cell system, purposely developed for the ETF Demonstrator4.
In this paper a control system design for robotic airship is developed. The nonlinear multilinked mathematic model of airship is considered. The results of aerodynamic analysis, parametric and structure disturbances estimation, nonlinear control algorithms are presented. Airship motion simulator is developed and successfully applied. Airship is implemented on experimental robotic mini-airship.
An affordable technology designed to facilitate extensive global atmospheric aerosol measurements has been developed. This lightweight instrument is compatible with newly developed platforms such as tethered balloons, blimps, kites, and even disposable instruments such as dropsondes.
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