Online BOOK of Abstracts

Invited Talk/Keynote Session

Shri. Vivek Mairothia, Scientist 'F', ADRDE, DRDO, Agra

In Place of Dr. (Ms.) Tessy Thomas, Distinguished Scientist & Director General - Aeronautical Systems (AS)

Shri. Vivek Mairothia is Scientist ’F’ at Aerial Delivery Research and Development Establishment (ADRDE) DRDO Agra. He is the Project Director for Design & Development of various Aerostat and Airship platforms. He received the B.Tech and M.Tech. degree in Electronics & Communication Engineering from IET Lucknow in 1991 and IIT Roorkee in 1994 respectively.

He is the recipient of DRDO Agni award for self reliance and eight lab level awards for performance excellence for development of Aerostat avionic system and payload integration.

Panel Discussion I : "Relevance of LTA systems for the Future of Indian Aviation"

Lighter-than-Air systems have regained an immense interest globally due to their high fuel economy and eco-friendly operations. Considering the ever expanding need for implementing novel green technologies for a sustainable aviation future in India, this session will bring together well-versed LTA systems experts from academic, industry and policy making organizations. The session will deliberate on the scope and key challenges on the adoption of LTA systems in India.

Cleaner, Greener & Lighter Future in Indian Aviation


Dr. (Ms) Harpreet A De Singh

Executive Director, Air India Limited

Chairperson, Aeronautical Society of India, Mumbai Branch, and

Chairperson, IWPA

LTA Systems for Defence Applications

Padma Shri Dr. Prahalad Rama Rao

Padma Shri Awardee, 2015

Former Director, DRDL, DRDO

Design of Stratospheric Airships

Dr. Mohammad Irfan Alam

Assistant Professor, Department of Aerospace Engineering

VIT Bhopal University

Envelope Materials for LTA Systems

Prof. Anirban Guha

Professor, Department of Mechanical Engineering

IIT Bombay

Certification Requirements for LTA systems

Mr. Jitendra Singh

Visiting Faculty RVCE,

Former Scientist DRDO & NAL

LTA Systems for Cargo Transportation in India

Mr. Shailesh Dhuri

Founder, Director, and CEO

Empyreal Galaxy

Invited Talk/Keynote Session

Ms. Swati Mehta, Director and COO, Empyreal Galaxy

Swati Mehta is the Co-founder and COO at Empyreal Galaxy. Her vision is to build a technology-led enterprise, which uses innovation towards the betterment of society and the world at large. She brings with her rich experience in Talent Management, strategy & Innovation with various organizations across different verticals. Her specialty has been building innovation-centric culture of high performers and at Empyreal Galaxy, she aims to build a world beating team who work together to achieve a new reality for the society.

Technical Session 1 (Aerodynamics)

Session Chair: Dr. Manish Tripathi

Paper ID 016

Airship Turn Performance Estimated from Efficient Potential Flow Panel Method

A first-order potential flow panel method is used in the present work to calculate aerodynamic yaw torques and other parameters involved in the turning performance of a stratospheric lighter-than-air airship. A specific mesh is generated to model the airship geometry in order to solve the Laplace potential flow equation by a sum of source and doubled distributions on the boundary, using a mix of Neumann and Dirichlet boundary conditions. As a result, it is possible to simulate the effect of the rudder and elevons within their angular range at different flight conditions. Air flow rotation is included in the boundary conditions to simulate airship yaw rate. Thus, the result of the model includes not only yaw momentum but also its derivative with respect to yaw rate and the lateral force. They are contrasted with a series of tests carried out in a wind tunnel for a stratospheric airship model and with the literature. Despite of the simplicity of the potential method (5 s execution for a 6000-cell mesh) compared to a more complex CFD simulations, the conclusions demonstrate that the correlation between numerical and experimental data is high enough to provide valuable performance insights during the design process, showing a considerable reduction of the necessary computational resources. A 30-m ECOSAT model with proper fins can turn with a steady radius of 50 to 60 m.

Paper ID 036

Numerical Investigation of Laminar to Turbulent Boundary Layer Transition over Airship Envelopes

The shape of a conventional airship’s envelope is usually an axisymmetric body of revolution. Previous numerical and experimental studies have indicated that at zero angle of attack, the flow over such shapes is either fully turbulent or transits from laminar to turbulent at nearly half of the envelope’s length. In most numerical investigations of such bodies, k- ɛ or k-ω-SST turbulence models are used. In recent studies, a four-equation k-ω SST-LM transition turbulence model has been proposed and shown to predict transition on a flat plate quite well. In this study, the transition of the laminar boundary layer to the turbulent boundary layer over the bodies of revolution of airship envelopes is investigated using the k – ω SST – LM transition turbulence model. The results obtained in the numerical analysis are validated with the data available in the literature. It is seen that the two-equation k-ω SST Turbulence Model is not able to capture the laminar to turbulent transition, whereas the four-equation k-ω SST-LM transition turbulence model can capture it quite well.

Paper ID 040

Virtual Presentation

Effect of Reynolds Number on the Aerodynamic Characteristics of Leading-Edge Protuberanced Airship Fin

Arunvinthan S, Hari Babu C, Manoj V and Nadaraja Pillai S

In this paper, we present the computational investigation on the aerodynamic characteristics of the Leading-edge protuberanced (LEP) fins subjected to Reynolds number in the range of 102 to 106 for wide range of angles of attack between 0o to 45o. The aerodynamic force coefficients like coefficient of lift (CL), coefficient of drag (CD) and surface pressure distribution with respect to chord-wise position (x/C) for the modified leading-edge protuberanced models at different Re is analyzed in detail. Assessment of aerodynamic characteristics of modified leading-edge protuberanced fins under different Reynolds number is one of the immediate issues which needs to be addressed to bring such novel design in to airships and different kinds of LTA platform.

Invited Talk/Keynote Session

Mr. Goparaj Gopalakrishnan, Airworthiness Specialist, FLYING WHALES

Mr. Goparaj Gopalakrishnan is an Airworthiness Specialist working with FLYING WHALES since 2018, specialised in Airframe and Electromechanical Systems. He is also representing the team currently evaluating the Indian market for the LCA60T. Prior to joining FLYING WHALES, he completed his master’s in aviation safety from the prestigious ISAE-SUPAERO institute.

He has also worked for six years in Infosys Limited as an Engineering Analyst, where his contributions were noted in aircraft programs such as the Airbus A350-900, Mitsubishi Regional Jet (MRJ) 90 and Boeing 787.

Technical Session 2 (Design and Optimization)

Session Chair: Dr. Mohd. Irfan Alam

Paper ID 008

CPACS LTA - Using Common Data Structures for Visualization and Optimization of Airship Designs

Complex engineering projects require compartments from different engineering fields to work in close contact and exchange data from their workflows and specialized software tools regularly. Common data models are an immanent feature of systems engineering applications that can be used to reduce the number of interconnections between software modules. Using common open source data structures in airship design helps engineers evaluating and visualizing early designs using several methods. In the presented paper, we used the Extensible Markup Language (XML) data structure Common Parametric Aircraft Configuration Schema (CPACS) and associated high-level software libraries by German Aerospace Center (DLR) for a design optimization. The design optimization maximizes payload of a 15 t airship by its hull shape. Handbook methods for estimating weights and drag as well as a brute force algorithm are used in the design optimization. The result shows an explicit optimum of the design. With the experiences made, we developed an updated version of CPACS, allowing the definition of an additional vehicle category named 'dirigible'.

Paper ID 009

Airship Sling-Load Operations: a Model Flight-Test Approach

The transportation of heavy loads is the ultimate yet to be achieved mission for airships. Several other cargo is being transported by airships successfully. Objective of this research is focused on how load exchange with near equilibrium airships can be performed. Proposed solutions aiming at similar targets have not demonstrated successfully yet or did not meet certification requirements. We introduce a viable approach and describe the procedure, that resembles helicopter sling load operations, step-by-step. Demonstrating its viability is achieved by building a suitable airship model and performing model flight tests. The research identifies weaknesses and critical points in load exchange procedures. Setting up the flight test environment, controller and suitable airship configuration is the first step performed. Operational challenges during the flight missions result in learnings and observations of importance for performing such flight tests. Observations regarding maneuverability of the model help in improving the propulsion and controller configuration of heavy load airships.

Paper ID 026

Virtual Presentation

A Multidisciplinary Design Optimisation (MDO) Algorithm for the Automatic Sizing of an Unmanned Lighter-Than-Air Platform

This study aims to present a Multidisciplinary Design Optimisation (MDO) algorithm for the automatic sizing and design of an Unmanned Lighter-Than-Air (LTA) platform, given its mission requirements. The mission in question consists of a territorial mapping, made possible through the implementation of several remote sensing onboard systems. Once assigned the parameters of the mission as inputs, the algorithm, through a process of iterations, returns the optimal sizing of the airship, shows the distribution of all the systems’ masses, and chooses the preferable energy system between the two considered (fuel cells or batteries). Moreover, a sensitivity analysis on the main variables allows to examine how the variation of each of the parameters of the mission affects the distribution of the masses in the airship, and therefore how the optimal design and sizing change. Finally, further studies on the energy systems are presented, to verify the convenience of one option above the other one as a function of the distance from the mission location and the survey area.

Paper ID 027

Virtual Presentation

The Concepts of Telescopic and Self-Deployable Tensegrity-Based Helium-Filled Aerostats

In this contribution we propose two novel concepts of an adaptive ultra-light high-altitude aerostats. Both proposed concepts enable changes of aerostat volume and shape during the flight, which results in the possibility of vertical motion control. The first proposed construction is telescopic aerostat with multi-segmented construction and controllable segments’ couplings. In turn, the second construction is based on a self-deployable tensegrity structure equipped with prestressed and tensioned elements of controllable lengths. Basic advantages and features of the proposed design are shown using dedicated numerical examples.

Paper ID 037

Virtual Presentation

Designing Helium-Filled Aerostats Applying Scaling Procedure, Mini-Models CANDY and Fly-Tests on SKYLAB

Helium filled aerostats can be lifted by the traditional hot-air balloon (SKYLAB), in the compact form, and then, after reaching some starting level , helium can be pumped into the aerostat (using storage tank with a compressed gas), starting its autonomous mission. Optimal design process of aerostats dedicated to perform determined mission (between the altitudes and ) will be discussed with preliminary experimental verification process, based on scaling procedure of aerostat mini-model, so-called CANDY, and fly-tests on SKYLAB will be proposed.

Invited Talk/Keynote Session

Dr. Barry E. Prentice, Professor, Supply Chain Management,

University of Manitoba

Dr. Barry E. Prentice is a Professor of Supply Chain Management, at the University of Manitoba. In 2002, Dr. Prentice organized the first Airships to the Arctic conference. This began the public interest in Canada of using cargo airships for Northern transportation. In 2005, he founded ISO Polar as a not-for-profit institute to coordinate airship research, cold-weather testing and to hold further Airships to the Arctic Conferences. In 2011, Dr. Prentice established Buoyant Aircraft Systems International (BASI), to undertake airship and drone research.

Economics of Cargo Airships and Potential Applications

The economics of freight transportation are complicated because the demand is derived, and the product is a service, rather than a good. As a service, the output of transportation is extremely perishable. Excess capacity cannot be stockpiled and sold at a later date. In addition, the creation of transportation services always involves a spatial dimension. The same inputs applied to transport between two separated locations has different values depending on direction. And no two locations or transport routes are the same. Needless to say, the provision of transport is fought with a number of economic trade-offs.

Within the derived demand for transport are several sub-markets. The character of the freight can demand larger capacity, higher speed, more gentle handling, greater reliability, or some combination of these attributes. One vehicle cannot serve all demands, and this is as true for cargo airships as it is for any other form of transport. Transportation has to size itself to the demand, first to accommodate the market, but equally, to obtain the necessary utilization to sustain a profitable operation.

The economics of cargo airships are largely theoretical at this stage. To date, no airship has ever been designed for cargo and flown in commercial usage. Experimental cargo airships at the scaled prototype level have been flown, but most cargo airships are still at the design and research stage. The best that can be done is an extrapolation of the large, rigid passenger airships of the 1930s, and the experience with the operations of non-rigid (inflatable) blimps. Nevertheless, economic theory can provide a guide to the potential success of the new generation of airships being developed for the 21st century.

Dr. Csaba Singer, CEO, CTO and Co-Founder

Hybrid - Airplane Technologies GmbH

Dr. Csaba Singer is since 2016 founder, CEO and CTO of the deeptech aerospace StartUp Hybrid-Airplane Technologies GmbH based in Germany. He has completed his Diploma in Aeronautical Engineering form the University of Stuttgart, Master of Engineering in Engineering and Computer Science from the University of Exeter with distinction and Ph.D worked out at the German Aerospace Center (DLR) and the University of Stuttgart in 2012. Csaba is specialized in aerospace computer-aidedided engineering, ultra-lightweight construction, computer science (CAE) and renewable energies and has experience in project and personnel management, prototyping and programming. For the development of an emission-free sustainable aircraft, Dr. Singer was motivated by the first solar airship "LOTTE", the solar glider "ICARÈ", the high-altitude platform "HELIOS" as well as his professors from the beginning of his studies. Other motivating factors are the energy turnaround, the quest for sustainability and environmental protection. In the meanwhile, he has multiple issued international patents and accomplished as a pioneer the market introduction of LTA-UAVs into various international markets.

Mr. James Eagen, CEO

Plimp Airships LLC

James Egan is a lawyer from Seattle Washington State who as a child experimented with helium balloons and gliders in his backyard in Bellevue. James has always been convinced a further form of aircraft could be designed with slow descent from helium lift plus wings for directional control. In 2013 James hired a renowned aircraft designer – a prior guest of this conference as an expert in hybrid airships – to design a fast forward and slow descent speed aircraft with rotational wings for vertical take-off.

Combining the words plane and blimp, James trademarked it as “Plimp” and secured international patents on the concept. We are proud to host and display this futuristic and realistic scalable design which claims to have the highest potential speeds and agility while still descending slowly even unpowered for any hybrid airship.

Technical Session 3 (Materials and Structures)

Session Chair: Dr. Anirban Guha

Paper ID 015

Optimization of TPU/TiO2 Films using UV Additives for improved Weather Stability of LTA Hull Materials

Titanium dioxide has sustained a vital role over the past few years as the most widely used material among various commercial inorganic UV absorbers due to its chemical stability, low cost, and good UV protection. TiO2 and numerous organic UV absorbers have been explored to be incorporated in TPU (Thermo-Plastic Polyurethane) based films for coated and laminated textiles useful for aerostats and airships as LTA (Lighter than Air) hull material. TPU films based on TiO2 were prepared using commercially available UV additives (Hindered Amine Light Stabilizer, benzotriazole-based UV absorber, and Antioxidant) at various concentrations. Prepared films were optimized to achieve the best possible combination of all UV enhancing materials and assessed for artificial weathering tests. UV-VIS spectrum and infrared spectrum were obtained. Characterization of material and another testing such as Tensile testing, Yellowness index, UPF, and gas barrier properties of prepared TPU/TiO2 films were determined after every 100 hours. TPU/TiO2 films that incorporate UV absorbers and other additives accomplished the requirement for improved resistance against UV and photooxidation.

Paper ID 017

Evaluation of High-Performance Fabric Based Laminated Hull Material for High Altitude Airship

The aim of the present study was to develop a continuous laminated material system that could be very lightweight, having very high strength, extremely low helium permeability. In this paper, a multilayered laminated structure has been designed, prepared, characterized, and developed using high-performance fabric including para-aramid (Kevlar) fabric as a strength layer due to high strength-to-weight ratio and excellent mechanical properties in order to achieve a lower aerial density material with the help of PU based adhesive and different polymeric films including PVF film as a weather resistance layer and BOPET film as a gas barrier layer. The artificial weathering of all the prepared specimens was carried out in a from 100 h to 400 h machine in order to decide the approximate durability of the laminated samples. The prepared unexposed and exposed laminates were subjected to various mechanical and physicochemical characterizations such as tensile testing, cut slit tearing testing, t-peel testing, helium gas permeability testing, and UV protection factor testing. It has been investigated that the helium gas permeability of Kevlar-based laminate (K5 laminate) was 0.04 L/m2/day which is extremely low and there was no significant change in tensile properties from fabric to laminate, even after 400 h of UV exposure. The tearing strength of laminates was significantly enhanced than that of fabric due to the greater flexibility of PU adhesive. Therefore, using this type of multilayered laminated fabric would be the potential, effective and new alternative for the envelope of high-altitude airship applications.

Paper ID 020

Functionalization of Polyurethane based adhesives with UV additives for LTA Applications

The high interlaminar strength in the multilayered structure is one of the crucial parameters of lighter than air (LTA) envelope material. In this work, different Polyurethane (PU) based adhesives were functionalized and their synergistic effect of adhesion with fabric has been studied. Three types of PU based adhesives were used which were based on two-component systems that was further functionalized with carbon black and UV-additives and the peel strength was determined. PU based adhesives were applied on a substrate and laminates were prepared and the gram per square meter (gsm) of the adhesives was optimized. The Tensile strength, UV resistance property of the functionalized adhesives were improved and the UPF of the adhesives film was measured. Thermal properties and stability of the functionalized adhesives films were analyzed through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The crosslinking and the interaction between the carbon black and PU based thermoset adhesives was analyzed through Fourier transform infrared spectroscopy (FTIR). Also, the prepared adhesive films were exposed to artificial weathering for 200 hr. Functionalized PU adhesives films shows excellent weather resistance behavior as compared to neat adhesive films due to better UV resistance property of carbon black.

Paper ID 021

Degradation Study of Aromatic and Aliphatic TPU Films in Artificial Weathering: Impact on the gas barrier and Mechanical Properties

Neeraj Mandlekar, Rishabh Tiwari, Sampath Parasuram and Mangala Joshi

This study investigates the influence of the artificially accelerated weathering test on the degradation behaviour of thermoplastic polyurethane (TPU) films. Accelerated artificial weathering test parameters were specially designed to simulate outdoor natural exposure parameters with higher UV radiation exposure. Artificial weathering tests were carried out in a laboratory weatherometer and changes in mechanical properties, chemical structure and morphology were studied. In this study, two types of polyether based aromatic and aliphatic TPU films were exposed for 500 h. The result shows that exposure to UV radiation affects the key properties like breaking strength, helium gas barrier and surface properties of TPU films. The mechanical strength reduces as the irradiance time is increased. The SEM and AFM analysis reveal that the film surface that was exposed to irradiance become rough and cracks on the surface were observed. The FTIR analyses of the exposed film prove that chemical structure changes due to the formation of the polyurea group. It was found that aromatic TPU gets crosslinked after 300 h exposure, however, in aliphatic TPU long molecular chains break into shorter chains, the number of chain scission increases with increasing exposure time.

Sponsored Poster Presentation

Mr. Nicolas Caeymaex , Project Leader


Technical Session 4 (Stability and Control)

Paper ID 053

Estimation of Stability Derivatives due to Translational Motion of Various LTA Vehicles using CFD

In this paper, the aerodynamic model parameters (stability derivatives) of the aerostat is investigated based on a CFD based approach. The stability derivatives due to the translational motion of the aerostat are considered for the analysis in this paper. The extraction of the stability derivatives involves the simulation of the oscillations of the aerostat along the vertical direction (heave motion) and axial direction (surge motion). A forced sinusoidal oscillation is used for the simulation of the aerostat, and one stable period of oscillation is taken for the derivatives extraction. Four different aerostats are considered for the current study with four different angles of attack. Zhiyuan aerostat, HAA aerostat, NPL aerostat and GNVR aerostat are the aerostats considered for this study. The stability derivative results obtained for the four aerostats are analysed and compared with respect to their geometrical features. The dynamic stability derivatives of the Zhiyuan aerostat suggests its superiority among the four aerostats considered.

Paper ID 002

Effect of Geometrical Parameters of a Tethered Aerostat on Longitudinal Stability Boundaries

Dynamic instabilities often impair the operations of a tethered aerostat (such as supporting antennas and/or aerial platform), especially during the strong wind conditions. Effect of various geometrical parameters on longitudinal stability boundaries of an aerostat tethered in a steady wind is presented in this paper. The mathematical modeling used for stability analysis of the tethered aerostat includes buoyancy forces, apparent mass terms and static forces resulting from the tether cable. The effect of variation of geometrical parameters on longitudinal stability boundaries of the tethered aerostat has been presented graphically. The presented analysis and a judicious/ feasible choice of various geometrical parameters of the tethered aerostat can be utilized to design a new aerostat that can remain stable for wide range of wind speeds.

Paper ID 018

Adaptive Control Design for Stratospheric Airship with Actuator Faults

This paper presents the design of adaptive fault-tolerant control for a stratospheric airship model with actuator faults. First, linear airship dynamics is derived from the nonlinear airship model. Derivation of post-fault airship model including various actuator faults and external disturbances followed by controller stability analysis of adaptive fault-tolerant control is presented. Simulation results are presented for actuator efficiency loss and actuator bias fault, and compared with reference state trajectories. Results show efficacy of the proposed adaptive controller in following the reference trajectory with desired transient characteristics in the presence of actuator faults.

Paper ID 019

Look Ahead Steering Based Path Following Control for an Airship

This paper describes design and development of an integrated Guidance, Navigation, and Control (GNC) algorithm for smooth navigation of an airship following a series of planar waypoints for surveillance applications. The guidance algorithm employed in this study is a look ahead based steering guidance law which provides the required guidance command to the controller for executing the target mission. The command signal generated by guidance law is based on the airship current location relative to the next target waypoint. Two different control architectures are used in the GNC algorithm in order to execute the guidance command and carry out the path following mission. A Proportional-Integral–Derivative (PID) law based outer loop kinematic controller is designed to control airship attitude/orientation and a Linear Quadratic Regulator (LQR) based inner loop optimal controller is designed to control the airship’s speed and angular rates. Performance and robustness of developed GNC scheme are evaluated in MATLAB® based simulation environment for two different flight scenario. Results show that an optimal path following trajectory is obtained with minimum deviation from the given target waypoints.

Paper ID 047

Autonomous Tilt Rotor Stabilized Plimp Hybrid Airship Unmanned Aerial Vehicle

Stabilizing the remotely operated hybrid VTOL tilt rotor unmanned aerial vehicle that has an envelope of gas particularly installed to provide hydrostatic buoyancy force to generate lift, with a payload bay equipped with sensors and electronic components attached to the envelope and having a pair of wings extended on both the sides of the bay to generate lift through motion as well act as a stabilizing surface, and the thrusters pivoted at wing tip would be tilted with powerful servo motors to provide vertical takeoff and landing capabilities. This manuscript deals with stabilizing the undamped forces and moments using automatic control system. Mathematical modeling of equations would be framed based on the obtained kinematics of flight that would be converted to autopilot codes in MATLAB. The MATLAB results further determines the stability of the designed tilt rotor Plimp Unmanned Aerial Vehicle.

Paper ID 052

Virtual Presentation

Numerical Approach to Maneuver Design and Feasibility Evaluation for the Autonomy of Airship

Maneuver design is a vital prerequisite for autonomy in aerospace guidance and control. It ensures system safety by analyzing the feasibility of the proposed maneuvers. This paper demonstrates a holistic approach to maneuver design by emphasizing its feasibility with consideration on the complete dynam-ics of the system and its constraints. Computational bifurcation analysis is em-ployed to generate a sequence of trim solutions based on specified state and con-trol constraints that define a stipulated maneuver. Implementing this approach on a stratospheric airship model helps attempt a few of its challenging and interest-ing facets like autonomous hovering, ascending, and descending by gauging its performance and formulating realistic maneuvers pertaining to the imposed lim-itations on the lateral excursion, control and state constraints. The effectiveness of the proposed maneuvers is then evaluated using numerical simulations with computed control schedules in an open-loop.