FEASIBILITY REPORT ON SOLAR PLANE

OBJECTIVE

• The amount of energy the sun sends towards our planet is 35000 times more than we currently produce and consume.• This energy can be easily harnessed for practical purposes.• The objective of our report is to contribute to the cause of renewable energies to

demonstrate the importance of clean technologies for sustainable development.• Solar impulse wants to mobilize this enthusiasm in favour of technologies that

will allow decrease demand.• Our endeavour try to deal with the current state of art of empower the aviation

industry with solar power and the shortcomings and the future aspects.• The aim is to study the possibility of solar powered aircrafts in the atmosphere

more efficiently.

INTRODUCTION

• A solar aircraft is the one which collects energy from the sun by the means of photovoltaic solar cells.• The energy may be used to drive the electric motor to power the aircraft.• Our basic principle is use solar power by means of aircraft and this thing can be

done by solar panels which covers the whole surface of wing.• During the night, the only energy available comes from the battery.• Our project is based on the solar power utilisation.

HISTORY OF SOLAR POWERED VEHICLES

• The first Silicon photovoltaic cells capable of converting enough of the sun’s energy into power to run electrical equipment.• UNMANNED SOLAR POWERED FLIGHT

• Sunrise I• Solaris• Solar Excel• Centurion

• MANNED SOLAR FLIGHT• Solar Riser• Solar Challenger• Helinet• Solar Impuse And Solar Impuse 2

BASIC PRINCIPLE OF OPERATION

• Solar power conversion into electric energy by means of aircraft.• It can be done by solar panels which covers the definite surface area of wings.• A convertor ensures that the solar panels are working at their maximum power

point.• The electric energy is used to charge battery which drives electric motor.• Propeller is mounted on motor shaft produces thrust continuously.

AERODYNAMICS OF WINGS

• The design and analysis of wings of aircraft is principle application of science of aerodynamics.• Once a plane leaves the ground, it is acted upon by four aerodynamic forces.

• Thrust• Drag• Weight• Lift

• The lift maintains the airplane airborne compensating the weight.• The drag that is compensated by the thrust of the propeller.

BERNOULLI’S PRINCIPLE

• P+½ρv2 +gρh=kWhere, P=Pressure (Pa) ρ=Density (kg/m3) v=Velocity (m/s) g=Acceleration (m/s2) h=Distance from reference, measured in opposite direction of the gravitational force (m) k=constant (kg/m2)• If density, height and acceleration are fixed the pressure will be inversely

proportional to velocity. • It means area under high velocity will have lower pressure and vice versa.

CONCEPT OF LIFT

• The basic concept of lift is simple and is based on the Bernoulli’s equation. • The air flow meeting the leading edge of the object is forced to split over and

under the object. • Due to the pressure gradient and the viscosity of the fluid, the flow over the

object is accelerated down along the upper surface of the object.• The two sections of the fluid each leave the trailing edge of the object with a

downward component of momentum, producing lift.

AIRFOIL

• An airfoil is any surface producing more lift than drag when passing through the air at a suitable angle. • Airfoils are most often associated with production of lift. Airfoils are also used for

stability (fin), control (elevator), and thrust or propulsion (propeller or rotor). • The main and tail rotor blades are airfoils, and air is forced to pass around the

blades by mechanically powered rotation.• Airfoils are carefully structured a specific set of flight characteristics.

AIRFOIL TERMINOLOGY

• Blade Span• Chord Line• Chord• Mean Camber Line • Leading Edge• Flight Path Velocity• Relative Wind And Resultant Relative Wind• Angle Of Attack• Angle Of Incidence• Center Of Pressure

AIRFOIL TYPES

• Symmetrical Airfoil -The symmetrical airfoil is distinguished by having identical upper and lower surfaces. The mean camber line and chord line are the same on a symmetrical airfoil, and it produces no lift at zero AOA.• Nonsymmetrical Airfoil (Cambered) -The nonsymmetrical airfoil has different upper and lower surfaces, with a greater curvature of the airfoil above the chord line than below. The mean camber line and chord line are different. The nonsymmetrical airfoil design can produce useful lift at zero AOA.

LIFT AND DRAG

• The circulation of the airflow creates a different pressure distribution on the upper and lower side.• The section that once integrated can be represented as two forces, the lift and

the drag.

INCLINATION EFFECT ON LIFT

ANGLE OF ATTACK

• It is the angle between the wing chord and the relative wind. We have used software to create airfoil. • By putting proper angles of attack related values of other parameters like

coefficient off lift, coefficient of drag, Reynolds number etc. can be generated.

SOLAR CELLS

• A solar cell or photovoltaic cell is a device that converts solar energy into electricity by the photovoltaic effect. • It is very widely used in space application because it allows a clean and long-

duration source of energy requiring almost no maintenance. • Solar cells are composed of various semiconducting materials, constituting one or

more layers.

SOLAR IRRADIANCE

• Solar Irradiance is a measure of the irradiance (power per unit area on the Earth's surface) produced by the Sun in the form of electromagnetic radiation.

CURRENT AND VOLTAGE OF SOLAR CELL

• When the cell pads are not connected, no current produced and the voltage equals VOC, the open circuit voltage. • When it is short circuited, the voltage is zero but the current equals ISC. • In between these two points where in both cases the power retrieved is zero,

there is working point, called the maximum power point. • The current of a solar cell is proportional to its area and varies almost linearly

with the light intensity

POWER STORAGE

• When the energy production is not constant and continuous, a good energy storage method is necessary. • Different ways to store energy:

• Chemical (hydrogen, biofuels)• Electrochemical (batteries, fuel cells)• Electrical (capacitor, super capacitor, superconducting magnetic energy

storage or SMES)• Mechanical (compressed air, flywheel)• Thermal

• In the case of a solar airplane, the gravimetric energy density also called specific energy. • The peak power are the most crucial parameters that determine the choice of the

energy storage method. • In present case, the electrochemical batteries and the fuel cells are the two best

candidates.

ELECTROCHEMICAL BATTERIES

• Electrochemical batteries are energy storage devices, which are able to convert chemically stored energy into electrical energy during discharging. • They are composed of a cathode and an anode, made of two dissimilar metals

that are in contact with an electrolyte. • When all elements are in contact with each other, a flow of electron is produced.

FUEL CELLS

• A fuel cell is a system where the chemical energy of reactants, often a gaseous fuel and the oxygen. • The fuel cell consists of two electrodes, known as the anode and cathode that are

separated by an electrolyte.• A fuel cell on a solar airplane to store the energy during the day and reuse it

during the night.

MAXIMUM POWERPOINT TRACKER

• A solar cell has a working point on its current to voltage curve where the power retrieved is maximal.• The constantly changing irradiance conditions, and thus get the highest amount

of energy, a so called Maximum Power Point Tracker (MPPT) is required. • An MPPT is basically DC/DC converter with variable and adjustable gain between

the input and the output voltage.• The input being the solar panels and the output the battery. • It contains electronics that monitor both the current and the voltage on each

side.

PROPELLER

• The propeller is a device consisting of a set of two or more twisted, airfoil shaped blades • The blades are mounted around a shaft and spun to provide propulsion of a vehicle

through a fluid. • It accelerates incoming air particles creating a reaction force called thrust.

BLADE ELEMENT THEORY

• In this theory the blade is assumed to be composed of numerous, infinitesimal strips with width ’dr’ that are connected from tip to tip.

• The lift and drag are estimated at the strip using the 2-Dairfoil characteristics of the section.

• Also, the local flow characteristics are accounted for in terms of climb speed, inflow velocity, and angular velocity.

• The section lift and drag may be calculated and integrated over the blade span.

1. BLADE ELEMENT SUBDIVISION• A propeller blade can be subdivided as shown into a discrete number of sections.• For each section the flow can be analyzed independently.• If the assumption is made that for each there are only axial and angular velocity

components.• The induced flow input from other sections is negligible.

2. INFLOW FACTORS

• The induced flow components can be defined as factors increasing or decreasing the major flow components.

3. AXIAL AND ANGULAR CONSERVATION OF MOMENTUM• The governing principle of conservation of flow momentum can be applied for both

axial and circumferencial directions.• For the axial direction, the change in flow momentum along a stream-tube starting

upstream, passing through the propeller.• Then moving off into the slipstream, must equal the thrust produced by this

element of the blade.

4. PROPELLER THRUST AND TORQUE COEFFICIENTS AND EFFICIENCY • So designing an efficient propeller comes to the same challenges as for an

airplane wing.• Find the best airfoil, chord and incidence angle that minimize the resistance

torque and maximize the thrust for a given axial speed. • This optimum varies along the blade, from the hub to the tip, due to the

increasing radius and thus airspeed, explaining the twisting shape of propellers. • Good propeller designed for a specific flight domain should have an efficiency of

at least 80 %, 85 % being an excellent value that is difficult to surpass.

SCALING DOWN: - SOLAR MICRO AERIAL VEHICLE

• The miniaturization of processors, sensors, communication chips, the development of efficient robotic platforms is not only possible at the UAV size, but also at the MAV size.

SCALING DOWN:- ADVANTAGES AND DRAWBACKS

• Airframe• Low Reynolds Number Airfoil And Propeller• Actuators• Solar Cells• Maximum Power Point Tracker• Energy Storage• Control

METHODOLOGY ADAPTATION:-DAY FLIGHT ONLY

• The methodology can be slightly modified to design an airplane that flies only during the day. • For this purpose, we can set Tnight = 0 and give Tday any value higher than zero. • A quick look at the influence of this modification shows that no battery will be

considered and that the area of solar cells will be lower, • As logically no battery needs to be charged during the flight.• We consider a mean irradiance, the value of Imax has to be multiplied by α/2

because it was divided by the same value to obtain the mean irradiance on an entire day.

SCALING UP: - MANNED SOLAR AIRPLANE

• The feasibility at a much reduced size, we will now go in the other direction and consider the case of a manned solar airplane at low altitude.

• A body mass of 80 kg is assumed to which we add 40 kg of additional equipment’s, i.e. a seat, a parachute, food, beverages, etc., yielding a total payload of 120 kg.

• We will also consider 20 kg for the avionics system, including navigation instruments and communication means that require an electrical power of 100W.

SCALING UP: - ADVANTAGES AND DRAWBACKS

• Aerodynamics and Efficiencies• Solar Cells and MPPT• Airframe Structure

CONCLUSION • This thesis presented a new methodology for the conceptual design of solar

airplanes. • It has the advantage to be very versatile and usable for a large range of

dimension, from UAVs with less than one meter wingspan to manned airplanes.• The models are used for efficiency or weight prediction and constitute a key part

of such design method. • The design methodology consists of a simple routine that takes 5 parameters

linked to the mission and 25 to the technologies used as inputs. • It allows the designer to output the layout of a solar airplane rapidly, with size,

weight and power information.

POTENTIAL APPLICATIONS AND THE FUTURE OF SOLAR AVIATION

• Airports and hangars with solar panels and use this energy to hydrolyze water into hydrogen and oxygen.• The hydrogen would then be stored and used on the airplane in a fuel cell.• To summarize, what makes solar airplane not so ideal is that they have to embed

the whole factory that converts the few energy coming from the sun in real-time, which is, as we saw, a heavy and not so efficient undertaking. • Thus, the better idea is to let this heavy factory none the ground, concentrate the

energy, and then only use it on a fast airplane with reasonable dimensions and thus a correct maneuverability.• One part of the wing could still be covered by solar panels, but to cover only a

small percentage of the electrical power consumption.