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Solar-Wind Powered HALE Autonomous System with Pressurized

Structure

Manikandan M1

and Balbir Singh2

Manipal Institute of Technology, Manipal, Karnataka, 576104

Bajrang Maheswari3

Manipal Institute of Technology, Manipal, Karnataka, 576104

Pioneering the future aerial systems and motivated by long-endurance mission requirements for

defense, communication etc., this paper focuses on the aerodynamic design, airfoil selection,

performance and component selection required for long endurance solar and wind powered

unmanned aerial vehicle with the aid of buoyancy force. The amount of fuel carried by

unmanned aerial vehicle will severely limit the aircrafts endurance so the only source of energyavailable to very long endurance platforms is solar and wind energy and the fact that the gases

that are lighter than air can also help for the better performance of the UAV can also be taken

under consideration.

The design process was an interdisciplinary approach, and included a selection of high lift

aerofoil, aerodynamic optimization of wing, stability analysis, weight balance, structural

reliability, cost and performance optimization. Based on studies of several previous preliminary

designs for solar-wind-powered UAVs, the minimum power requirement for maneuvers is

considered. However, an integrated design process must consider the environment, mission and

payload of an aircraft together, in order to specify geometry and assess performance. The design

includes the consideration for the solar panels that are to be fitted on the upper wing surfaces

which will convert the solar energy into the propulsive force for the UAV, the turbines which

will use the wind power for supporting the propulsive force and the pressurized structures filled

with Helium gas or any other gas which is lighter than air. These pressurized structures will helpin increasing the performance of the UAV.

The solar energy is the one of the most abundant and freely available source of energy and

because of all these reasons modern UAVs are more and more based on the use of solar power.In this design, what we are going to do is that we will be providing solar cells on top of the wing

surface facing the sun which will absorb the solar power and will convert it into electric power

and this electric power produced will be used in running the propellers and charging the high

density batteries provided on the UAV for backup and also for running other systems as per the

use of the UAV i.e. the UAV may be for civil use or for military use.The power output of solar

cells depends primarily on the absolute value and spectral distribution of irradiance in the plane

of the cell and the resulting operational temperature. The total amount of energy produced by the

solar cells is a function of the geographical position (latitude, longitude, and altitude), time of the

year, atmospheric absorption and efficiency of the cells. The Linke turbidity factor is used to

characterize the clearness of the sky, the lower this factor, the clearer the sky, the larger the beam

1Assistant Professor, Aeronautical & Automobile Engineering Department, Manipal, Member

2Assistant Professor, Aeronautical & Automobile Engineering Department, Manipal, Member

3Student, Aeronautical & Automobile Engineering Department, Manipal, non-member

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irradiation and the lower the relative fraction of the diffuse irradiation. The most important thing

is that the use of solar power is pollution free and has no effects on the environment.

The wind energy is another renewable source of energy that is freely available everywhere in

abundance. The use of wind power in the UAVs is the wave of the future. The design is

considered in such a way that we will be able to put a highly efficient wind turbine in the UAV.Considering the flying height of the UAV, the addition of a highly efficient wind turbine will

give a boost to the performance of the UAV. The wind energy could also be used as a substitute

for solar energy during night. Just like the solar energy, the wind energy is also a pollution free

source of energy and has no side effects on the environment.

The endurance of a solar-wind powered aircraft is determined by the Power Ratio, a non-

dimensional number that can be computed before flight and that represents the ratio of power

collected by the solar cells and wind turbines to power spent overcoming drag. The Power Ratio

of an aircraft depends explicitly on environmental factors, such as atmospheric density, and

geometric factors, such as wing span.

Humans have always wanted to achieve more. Thin-film flexible solar cells, high energy density

batteries, miniaturized MEMS and CMOS sensors and highly efficient wind turbines have

become vital for the endurance of UAVs within the past decade. Here also we can add some

more features to the UAV which will help in enhancing the vehicles performance. This addedfeature is the force of Buoyancy. In this project, we have designed UAV in such a way that a

considerable percentage of its weight is supported by or constructed from inflatable structures

containing helium gas or any other gas lighter than air. This lighter than air gas, is filled in a

pressurized hollow structure provided in the vehicle. The pressurized body structures will reduce

the amount of energy required to keep the UAV in flight mode thus allowing the use of smaller

and quieter motors. An airframe near neutral buoyancy will allow much slower flight speeds and

increased maneuverability while expending little power. In order to realize maximum benefits of

the pressure structures, the material for the pressured structure is also considered.

There is a critical need to improve the performance and utility of unmanned aerial vehicles

(UAVs). Several areas of UAV performance need to be improved for the next generation of

UAVs to be used successfully in expanding future roles. The present generation UAVs lacks

precision, slow-speed maneuverability required for urban navigation and targeting and they are

not capable of stealth mode also due to which they are easily sighted. There are many other

possibilities for the better design of unmanned aerial vehicles. This paper in itself is an attempt to

push the boundaries in the design of UAVs and here an attempt is made for the better

performance of both civil and military unmanned aerial vehicles.