DESIGN AND FABRICATION OF FIXED WING UAV FOR

AIR AND UNDERWATER ENVIRONMENTS

Project Reference No.: 42S_BE_1559

College : Nitte Meenakshi Institute of Technology, Bengaluru

Branch : Department of Aeronautical Engineering

Guide : Mr. Vinod L.

Students : Mr. Rajath Shetty

Mr. Pavan Kalyan V

Mr. Madhu Pujar

Mr. Peddi Reddy Omkaram Reddy

Keywords :

Unmanned Aerial Vehicle (UAV), Ground Control Station (GCS), Mission Planning

and Control Station (MPCS), Unmanned Aerial System (UAS), Center of gravity (CG),

Center of pressure (CP), Electronic Speed Control (ESC), Mean Aerodynamic Chord (MAC)

and Center of Buoyancy (CB).

Introduction :

Introduction to UAV

Fig.: Unmanned Aerial Vehicle

Unmanned Aerial Vehicle is a system which can be operated without the pilots it can

be remotely piloted or preprogrammed and also autonomous. UAV are used in various

applications for example agriculture, photography, etc. A category of UAV of great interest is

termed as fixed wing UAVs, due to its greater energy efficiency in performing medium and

long range missions and the ability to carry payloads. Most common fixed wing UAVs having

single motor and this is focused on the different application. In particular, this work focuses

on the developing the UAV which operates in both aerial and water conditions. This helps in

merge the benefits of operating in each of these domains. However no previous vehicle has

offered fully functional design capable of operating in both conditions. This type helps in

many applications like aerial mapping , underwater photography, fishery, monitoring water

ecosystem.

Fig UAV system functional structure

1. Air vehicle: The air vehicle is the airborne part of the system which includes the

airframe, propulsion unit, flight controls, and electric power system. The air data

terminal is mounted in the air vehicle, and is the airborne portion of the communications

data link. The air vehicle can be a fixed wing airplane, rotary wing, or a ducted fan.

2. Mission Planning And Control Station(MPCS):It is also called as the GCS, which is

termed as operational control centre of the UAV system where command, and telemetry

data from the air vehicle are proceeded and displayed. In some small UAS, the ground

control can be carried by a remote control and some sort of display, like embedded

microprocessors or hosted on a ruggedized laptop computer.

3. Data Links : The data link is a key subsystem for any UAV. The data links for a UAV

system provides two way communication, either upon demand or on a continuous basis.

The data link may also used to measure the position of the air vehicle by determining

and range from the ground-station antenna. This information is used to assist in

navigation and accurately determining air-vehicle location.

UAV Classification :

When speaking of UAVs, we refer to a category of small or medium sized aerial

vehicles that can fly independently. It is basically said to be as classification based on size

VERY SMALL UAVs

Very small UAVs range from micro sized, which are about the size of a large insect up

to a dimensions of the order of a 30–50 cm (12–20 in.).

SMALL UAVs

Many of these UAVs have the configuration of a fixed wing model airplane and are

hand launched by their operator by throwing them into the air much as we launch a toy glider.

It has dimensions is in the order 50 cm (19.7 in.) to one meter or two.

MEDIUM UAVs

These are too large as it can carry around by one person and still smaller than a light

aircraft. They have typical wingspans of the order of 5 to 10 m (16 to 32 ft) and carry

payloads of from 100 to more than 200.

LARGE UAVs

These UAVs are larger than a typical light manned aircraft. This includes, a particular

group of UAVs that can fly long distances from their bases, and also extended periods to

perform surveillance functions. They also are large enough to carry weapons in significant

quantities.

STABIITY AND CONTROL

A fixed wing UAV is an aerial vehicle which is capable of flight using wings. Fixed

wing UAV are different from rotary wing UAV. In which rotary wings are in the form of a

rotor mounted on a spinning shaft, an ornithopters is in the form of wing flap in similar

manner to a bird. In the fixed wing UAV generation of the lift force can be possible with the

influence of wind and gravity because of their shape and the forward vehicle speed. A larger

distance of the tail, aft of the wing results in greater control and stability.

STABIITY

An air vehicle must be stable if it is to remain in flight. Static stability implies that the

initial tendency of the body to restore the airframe to its original equilibrium position after it

has been disturbed by a wind gust or other force. Dynamic Stability states that overall

tendency of the body to restore the airframe to its original equilibrium position after it has

been disturbed by a wind gust or other force.

CONTROL

The maneuverability of an UAV is ensured by some control surfaces, those are able to

locally modify the air flux and to provide the necessary moments to change the body attitude.

Normally they consists of three control surfaces, the ailerons, the elevator and the rudder that

influence the attitude, thus the aircraft motion, jointly with a device able to generate a thrust

force, such as a propeller. A fixed wing vehicle becomes a drone, if it is able to complete a

totally autonomous flight. As such, it is necessary to equip it with a brain, the Flight Control

Unit. The horizontal tail is an important control surface for both stability and the ability to

control the vehicle.

DESIGN PARAMETERS The role requirements, as customer point of view, demands upon the system which

determine the shape, size, performance and costs principally of the air vehicle, but also of the

overall UAV system which operates it. Some of the more important parameters involved,

beginning with the air vehicle, are briefly discussed below.

AIR VEHICLE PAYLOAD

The necessary amount of the payload may also be a significant factor for the

configuration and the layout of the airframe. Payloads can be described has total weight and

application based instruments like weapons, etc.

AIR VEHICLE ENDURANCE

The flight endurance demanded of the air vehicle can range from, about 1 hr for a close- range

surveillance system to more than 24 hr for a long-range surveillance or airborne early warning

system. The volume and mass of the fuel load to be carried will be a function of the required

endurance and the reciprocal of the efficiency of the aircraft’s aerodynamics and its power

plant in an Aircraft, as comparing with UAV it’s about battery capacity.

AIR VEHICLE SPEED RANGE

The required speed range will be a dominant factor in determining the configuration

and battery power of the UAV. However, speed generally comes at a cost in terms of power

consumption and airframe complexity resulting in reduced efficiency of payload and also

range for size, mass and financial cost.

AIR VEHICLE LAUNCH AND RECOVERY

The method for air vehicle launch and recovery are driven by the operational role.

Launch and recovery can be accomplished by a number of techniques ranging from

conventional take-off and landing on prepared sites to vertical descent using rotary wing or

fan systems. Catapults are used by military machine worked by a lever and ropes for hurling

large stones or other missiles using either pyrotechnic (rocket) or a combination of pneumatic

or hydraulic arrangements are also popular methods for launching air vehicles. Some small

UAVs are launched by hand, essentially thrown into the air like a toy glider.

Objectives :

1) To accomplish a conceptual design of a fixed wing UAV, capable of operating in both

Arial and under water environment.

2) To fabricate the conceptual design into a physical model.

3) To analyze and study the transitional properties of the aircraft and its interaction with

air and water.

4) To fabricate a control system comprises of single motor and a propeller combination

for propulsion in both domains, and aerodynamic –hydrodynamic control surfaces.

Methodology :

Initially calculating the weight and the payload carrying ability of UAV and then

estimating the sketch and configuration of UAV for developing the fabrication. According to

the application requirements, UAV will be designed with the help of the CATIA V5 part

modeling. Once modeling will be executed then begins with fabrication. Using such materials

which fulfill the criteria as noted above. There are several components being used to construct

a fixed wing UAV completely such as Propeller, Motor, ESC, Battery, Transmitter, Servos,

and so on. All components are assembled to make Fixed wing UAV. Then the programmed

Sensors will be installed on UAV and finally testing the model.

Figure : Flow chart of the methodology

Design and calculation of different parts of an UAV involves following steps.

According to efficiency and performance of the UAV we approximated the total weight of the

UAV is around 1.2 kgs. The parts of UAV wing, fuselage, and tail are developed by the

following steps.

Design parameters chosen for all the parts of an UAV is done by referring the rating

given in reference[1] by considering with different design parameters, the rating table is

described below.

Ratings Description

1 – 2 Fair

2 – 3 Good

3 – 4 Very good

4 – 5 Excellent

Table: Ratings table

Wing:

Design Parameters chosen for wing by referring reference [1], [5], considering with different

design parameter of wing as per the table 4.1 given below for analyzing the ratings. Highest

average ratings for example 5 in the below table are noted to be as good then lower values

depending up on maximum efficiency and stability. Here we have considered Clark Y airfoil

for the reference which is a flat bottom cambered airfoil which is useful to produce better lift

to drag ratio. Table :Wing design parameters ratings [1]

Design Parameter High wing Mid wing Low wing

Ease of manufacturing 5 3 4

Stability 5 4 3

Ease of hand launch 5 4 3

Ground clearance 5 4 3

Average 5 3.7 3.3

The wing that we considered is a rectangular high wing configuration of following

approximation and dimension with calculation is done.

Fuselage

Design Parameters chosen for fuselage is done by referring reference [1], [5],

considering with of fuselage as per the table 4.2 given below for analyzing the ratings. Highest

average ratings in the below table are noted to be as good then lower values. Based on

different design parameter of fuselage which is having relatively lower weight and price we

have considered foam and balsa wood as material.

Table : Fuselage design parameter ratings [1]

Design Parameter Plastic tube and aluminium cylinder Balsa wood Foam

Ease of manufacturing 5 3 4

Strength of structure 5 2 3

Price 5 2 5

Weigh of structure 4 5 4

Average 4.8 3 4

Here mainly we have selected the design of fuselage with cylindrical type configuration [12].

It is 75% of the wing length [1] and the attachment of propeller is used at the front. In tractor

configuration the position of propeller axis is parallel to fuselage symmetric axis.

Tail: Design Parameters chosen for tail by referring reference [1], [5], considering with different

design parameter of tail as per the table 4.3 given below for analyzing the ratings of tail.

Highest average ratings for example 4.8 in the below table are noted to be as good then lower

values. Table: Tail design parameter ratings [1]

Design Parameter Conventional T-Tail V-Tail

Ease of manufacturing 5 4 4

Weight of structure 5 3 5

Aerodynamic performance 4 5 3

Average 4.8 3.8 4.2

The tail we have considered is conventional type which has less weight of structure

and more aerodynamic performance. It include horizontal and vertical stabilizer used for

stabilization during flight operation.

Conceptual design:

Conceptual design marks the first phase in an aircraft’s design. The basic knowledge of

configuration arrangement, size, weight, and performance are evaluated during a conceptual

design phase. Conceptual design is a highly iterative process. Every time we analyze and size

the latest design, it must be redrawn to give a new weight, wing size, and other changes.

Before going into conceptual design, let us take a look at some of the important parameters

that define the designing process.

Wing loading :

In optimal design, wing loading is the all up weight of an airplane divided by its wing area

(W/S). The quicker an aircraft flies, the more lift can be created by every unit of wing area, so

a smaller wing can convey a similar mass in level flight. An aircraft with a low wing loading

has a bigger wing area in respect to its mass when contrasted with an aircraft with a high wing

loading. Thus, quicker aircraft, for the most part, have higher wing loadings than slower

aircraft. This expanded wing stacking likewise builds takeoff and landing separations. A

higher wing loading additionally diminishes mobility. Wing loading is a lousy method to

contrast models and one another and with full-scale planes since wing loading differs with the

measure of the plane. Wing Cube Loading (WCL) gives relative esteem which can be utilized

as a pointer, or a standard guideline, for gathering radio controlled, smaller than expected,

aircraft by comparative flight attributes and "fly ability". WCL is given by

WCL=𝑤

𝑠∗ 𝑠 =

𝑤

𝑠3

2

Typical WCL values , in oz/sq ft, for different aircraft configuration are

Aircraft WCL VALUES

Slow flyers and thermal gliders under 4

Trainers, park flyers, 3D 5 to 7

General sport and scale aerobatics 7 to 10

Sports and scaled model 10 to 13

Ward birds and racers 13 and over

Effect on Stall:

Stalls depend just on the Angle of Attack (AOA), not velocity. Never the less, the

more slowly a plane goes, the higher the AOA it needs to create lift equivalent to the plane's

weight. As the speed diminishes further, sooner or later this angle will be equivalent to the

critical AOA. This speed is known as the "stall speed". An airplane flying at its stall speed

can't climb, and an aircraft flying below its stall speed can't quit descending. Any endeavor to

do as such by expanding AOA, without first expanding velocity, will result in a stall. The stall

speed of an aircraft in straight, level flight is somewhat dictated by its wing loading.

At level flight, lift (L) equals the weight (W), i.e.,

L=W→1

2𝜌𝑉𝑠𝑡𝑎𝑙𝑙

2 𝑆𝐶𝐿𝑚𝑎𝑥 = 𝑊

Thus , 𝑉𝑠𝑡𝑎𝑙𝑙 = 𝐾 ∗ 𝑊 𝑆 where, K 2 𝜌𝐶𝐿𝑚𝑎𝑥

Aspect ratio

In early days, when most wings were of rectangular shape, the aspect ratio was simply

defined as the ratio of span to the chord of the wing (AR=b/c). In case of a tapered wing, the

aspect ratio is given as the square of span divided by the wing area (AR=b2/S). Hence, a wing

of 60" span, 10" chord can be said to have an aspect ratio of 6 (or 6:1). The longer is the

aspect ratio, the better will be the glide slope. This doesn't necessarily convey that the aircraft

will stall at a lower speed, only that it glides much farther in losing the similar degree of

altitude, as when compared to a lower aspect ratio wing. Aspect Ratio has always been an

important factor in designs, for several reasons, but, it's even more important in gliders than in

powered craft. Another effect of aspect ratio on the aircraft performance is how it affects the

plane's roll rate. The higher the aspect ratio is, the slower the roll rate will be. Depending on

the mission profile that the aircraft is intended to fulfill, a designer chooses a suitable aspect

ratio.

Fig 3.1.1 Typical values of aspect ratio for different airplane configurations are as follows:

Aspect ratio Application

>3 Funflys, with very fast rol rates

3-4

Combat planes, and some sport planes

4-5 Sport planes

5-6 Trainers

>6 Gliders

Taper Ratio

Wing taper ratio (λ) can be defined as the tip chord divided by the root chord (λ=

Ctip/Croot). The distribution of lift along the span is dictated by the taper ratio, as according

to Prandtl wing theory, minimum induced drag (or drag due to lift) exists when the lift

distribution has an elliptical fashion across the wings. Rectangular wings (λ=1) are easiest to

design and manufacture but since they have the same chord throughout the span, there is

excess chord towards the tip when compared to the elliptical wing. This results in the wing

being “loaded up”, or generating more lift towards the tip than at the root, which ultimately

increases the induced drag.

If the wing is tapered, the tip chord gets shorter, reducing the undesired drag due to lift

obtained in the rectangular wing. When taper ratio equals 0.45, the wing almost entirely

removes the excess induced drag on the unswept wing and it’s lift’s distribution matches very

closely to the elliptical ideal lift distribution. Typically, low sweep wings have a taper ratio of

around 0.4 - 0.5 while high sweep wings have a taper ratio of 0.2 - 0.3.

Wing geometry and mean aerodynamic chord

Prior to designing wing geometry, wing loading, aspect ratio, and taper ratio must be

known. Then,

a) 𝑆= 𝑊𝑊/𝑆

b) 𝑏=√𝐴𝑆

c) 𝐶𝑟𝑜𝑜𝑡= 2𝑆𝑏(1+𝜆)

d) 𝐶𝑡𝑖𝑝= 𝜆𝐶𝑟𝑜𝑜𝑡

For an aerofoil in subsonic flow, aerodynamic center (the point at which rate of change of

pitching moment is zero) is usually located at the quarter-chord (at 40% chord for

supersonic). This is fairly simple for the rectangular wing, but for the tapered wing, where the

chord varies as we move along the span, quarter-chord is defined for the complete tapered

wing and is dependent on the “Mean Aerodynamic Chord” or MAC. MAC is the chord of

an alternative rectangular wing under similar conditions. In other words, the tapered wing can

now be replaced by a rectangular wing of chord length equal to MAC in order to obtain same

aerodynamics as that of the tapered wing.

e) 𝑀𝐴𝐶=23𝐶𝑟𝑜𝑜𝑡(1+𝜆+𝜆2)(1+𝜆)

f) The distance of MAC from centreline = 𝑏6[(1+2𝜆)(1+𝜆)]

Once the wing dimensions are calculated, other components can be designed using the given

typical values for fuselage and tail-planes:

i. Fuselage length: 60-75% of the wingspan

ii. Aileron Area: 12.5 -25% of the wing area.

iii. Vert stab area: 9-10% of the wing area

iv. Hor. stab area: 18-20% of the wing area.

v. Elevator area: 25-50% of the horizontal stab area

vi. Rudder area: 25-50% of the vertical stab area.

vii. Fuselage height: 10% to 15% of fuselage length

viii. Length from propeller to the wing LE: 20% fuselage length.

ix. Length from wing TE to horizontal surface LE: 40% fuselage length.

Tail Volume coefficient

The force due to tail lift is proportional to the tail area. Therefore, the effectiveness of

the tail is proportional to the tail area times the tail moment arm. Since we are multiplying the

area by length, the product has units of volume, which gives the "tail volume

coefficient" method for initial sizing of tail surfaces.

To calculate the tail size, the moment arm must be estimated. The moment arm (L) is

commonly approximated as the distance from the tail quarter-chord (i.e., 25% of the mean

chord length measured back from the leading edge of the mean chord) to the wing quarter-

chord.

At initial stages of design, the tail arm can be defined as a percent of the fuselage

length. For a remote-controlled aircraft with propeller engine mounted at the front, the tail

arm is around 60% of the total fuselage length.

Tail Volume Coefficients are given as

𝐶𝑉𝑇 =𝑆𝑉𝑇 ∗ 𝐿𝑉𝑇𝐵𝑊 ∗ 𝑆𝑊

𝐶𝑉𝑇 typically lies between 0.02-0.05 where,

0.02 is the least effective and 0.05 is most effective.

And,

𝐶𝐻𝑇 =𝑆𝐻𝑇 ∗ 𝐿𝐻𝑇𝑀𝐴𝐶𝑊 ∗ 𝑆𝑊

Where, 0.35 is the least effective and 0.8 is most effective

2) Design Calculations

In designing the wing there is a symmetric approach in order to determine various

parameters step by step. To start the calculation the minimum data is required is the Gross

Weight of the aircraft and Wing Span.

So, weight of the aircraft is 1200gms, wing span is 1200mm (47.2 inches) and aspect ratio is

5.5.

Table: Aspect ratios for various aircrafts

SL

NO.

AIRCRAFT TYPE ASPECT RATIO

1 Hang glider 4-8

2 Glider(sail plane) 20-40

3 Home built 4-7

4 General aviation 5-9

5 Jet trainer 4-8

6 Low subsonic transport 6-9

7 High subsonic transport 8-12

8 Supersonic fighter 2-4

9 Tactical missile 0.3-1

10 Hypersonic aircraft 1-3

1) Airfoil selection:

Airfoil is basically the cross section of the wing. For the following model CLARK Y airfoil

configuration is selected. The wingspan of the aircraft is around 1200mm (47.244inches).By

using the value of wing span (b) and the aspect ratio (AR) the wing chord length is calculated.

Aspect ratio (AR) =5.5

Wing span (b) =1200mm

Therefore the wing chord is given by,

Chord(C) =wing span /aspect ratio

=1200/5.5

=218.1818mm=21.8181cm

Later the wing chord value is used to plot the airfoil geometry by using the airfoil tool.

Fig: Airfoil geometry

By considering the weight and the aspect ratio for the UAV the following calculations were

made. This includes the following,

a) Wing Sizing Wingspan area (SW) = 2618.18 sq cm

Wing span (bW) = 120 cm

Root chord (Croot) = 21.818 cm

chord (Ctip) = 21.818 cm

Sweep Angle = 0 deg

Mean Aerodynamic Chord (MAC) = 21.818 cm

Distance of MAC from centreline (y) = 56.165 cm

b) Fuselage Sizing % of wing span = 70%

Fuselage length = 86.3092cm

Length from prop to the wing LE = 17.9832 cm

Length from wing TE to horizontal surface LE = 32.83 cm

c) Horizontal Tail Sizing % of wing area = 25%

HT span area (SHT) = 163.2254 sq. cm

HT span (bHT) = 43.18 cm

HT root chord (Croot) = 15.24 cm

HT tip chord (Ctip) = 8cm

HT sweep Angle = 17.71 deg

CHT = 0.426

d) Vertical Tail Sizing % of wing area = 12.5%

VT Span area (SVT) = 261.2898 sq. cm

VT Span (bVT) = 25.4 cm

VT Root chord (Croot) = 15.3 cm

VT Tip chord (Ctip) = 8.4 cm

VT Sweep Angle = 21 deg

CVT = 0.041

e) Control Surfaces Sizing

i. Aileron

% of wing area = 13%

Area = 287.74136 sq. cm

Breadth = 4.318 cm

Length = 33.3248cm

ii. Elevator

% of HT area = 40%

Area = 163.22548 sq. cm

Breadth = 8cm

Length = 22.36 cm

iii. Rudder

% of VT area = 35%

Area = 65.16116sq. cm

Breadth = 7.5 cm

Length = 25.4 cm

CATIA Modelling

During the initial phase of the design, the model is designed using the designing softwares.In

this particular case we used the CATIA V5R20 software to make the model. Each component

which is present in the UAV is modeled separately and they are modeled to the exact same

dimension according to the design calculation prospective. Later the each individual part is

assembled to make the final assembly of the UAV.

Fig: fuselage Fig: wing rib

Fig: main wing assembly Fig :Horizontal control surface

Fig : Vertical stabilizer

Fig : Final assembly of the UAV

The three views of the UAV along with the measurement is given below

Front view

Top view

Side view

Material procurement:

Some materials that have been used in this project are as follows:

a) Depron sheet

b)Balsa wood

c) Aluminium rod C-section

d) Propeller

e) Motor

f) Electronic Speed Controller

g) Servos

h) Battery

i) RC Transmitter Receiver

j) coro sheets

a) Depron sheets

Depron is an extruded polystyrene closed cell foam. It was initially developed for floor

insulation purpose but later on, it was widely used in modelling of aircraft and rc plane

because of its properties like weight and rigidity.

In this project 5mm Depron sheets were was primarily used to make the control surfaces of

the UAV especially the ailerons. The main purpose is to reduce the weight of the model.

Some of the desirable properties of the Depron are as follows,

i. Light weight

ii. High strengths

iii.Low cost

Fig Depron sheets

b) Balsa wood:

Balsa wood is the common material which is used in hobby world. The main thing

about the balsa wood is that, it has got the best strength to weight to ratio. Not only it has got

the properties like the high strength and low density but it can be shaped , sanded ,glued and

painted according to the requirement.

In this project 5mm balsa sheets where used to make the wing ribs. The balsa sheet is cut in

the shape of the wing rib and they are glued in to the wing spar. The main purpose of using

this is to provide the shape to the wing and to add the strength in the wing.

The properties of the balsa wood were as follows,

i. High impact strength

ii. High strength

iii. Flexible

iv. Light weight

Fig Balsa wood

c) Aluminium „c‟ section rod:

Aluminium is one of the most commonly preferred and used the material for adding structural

strength to aircrafts including RC aircrafts. The C- section although is inefficient compared to

other beams is very useful where single faces are required for easy fixtures

The wing structure contains a single aluminium cross-section extending from the wing root to

tip through the plywood cross sections. The overall length of the rod is 1.2 m and the it has

dimension of 10 cm in each face.

The desirable properties why the aluminium was the preferred material to be used as the

stingers are,

i. High Strength to Weight Ratio- It is understood that aluminium provides very

high strength to its low weight in nature. This allowed maintaining the overall

actual weight of the aircraft to its calculated weight when compared to other

materials like steel.

ii. High Corrosive Resistance-Aluminium is resistance to corrosion this allowed

the RC aircraft to have a longer safe life and retain its structural strength over a

longer time.

iii. Ductility- Due to the ductile nature of the aluminum the shape of the rod could

be changed and drilled into the airfoil easily without any cracks within the

material.

Fig Aluminium rod

d) Propellers:

Propeller is the main thrust producing component of an aircraft. Propeller has different sizes

depending upon their pitching capacity of blade diameter. For example blade dia of 10 inches

has the pitch of 4.5 inches. Twin bladed propeller of scales 10 X 4.5, 8 X 6.5 are preferable

for the model RC planes. The propeller, the rotating fan-like structure, gets the rotary motion

from the motor which propels or pushes the plane forward or backward.

Propellor used in this project is of 10X4.5 which is made of plastic and contains 2 blades

which propel the aircraft forward. The main characteristics of using a propeller are:

i. Efficiency- In general it is seen that twin-bladed propeller have higher

efficiency thus require less power from the motor to produce thrust

ii. High Thrust- Propeller is the main thrust producing component of an aircraft.

The chosen propeller in the design phase should be able to provide enough

thrust to sustain flight and low drag at the same time.

Fig propeller blade

e) Motors:

The motor in RC aircraft has one main purpose, to power the propeller to produce the thrust.

The motor has various types and configurations and are chosen according to the requirements

and the applications of the aircraft under consideration.

For this project, the motor chosen was a brushless motor of 1000kv powered by a battery of

3000 mAh, this gives an average flight time of 10 minutes. Of course, there is no restriction to

choose this specific type of motor and battery only, choosing higher power motor and battery

would result in greater thrust and thus greater endurance in terms of battery power. The main

characteristics of the motor are:

i. Brushless motor- These motors have greater efficiency and have a lesser chance of

failure.

ii. High Torque- For the configuration of propeller used, it is understood that this motor

provided produces enough torque to rotate the propeller and produce the required

thrust.

Fig Brushless motor

f) Electronic speed controller:

The main function of ESC is to control the speed and direction of the brushless motor. It acts

as an interface between the battery and the brushless motor by simultaneously switching on

and off the power to the motor. The DC power source of the battery is converted into AC

signals by the ESC to power the motor. Out of the three wires from the ESC to the motor, 2

wires transmit AC signals and the third one controls the direction of the motor rotation.

For this project, ESC of 40A is sufficient to power the motor.

Fig ESC

g) Servos:

Servos are used in an aircraft to actuate the control surfaces like ailerons, rudder, elevators

and other applications depending on the requirement. Selection of servo motor depends on the

specification like torque, speed, weight, and dimension.

The servos we used in this project is Tower Pro SG90 9g Micro servo motor. There are four

servo motors in this aircraft, one for the rudder, one for elevator and the other two for

ailerons. Both the servos for ailerons are connected to a Y-connector before connecting it to

the receiver so that their movement can be maintained.

Fig servo

h) Battery:

The battery is the powerhouse of the aircraft. Li-Po or Lithium Polymer battery is widely used

in RC airplanes because of its high power to weight ratio and recharge ability. The battery

power greatly determines the overall flight time and in turn the performance of flight. Thus it

is very important to select the battery based on the following characteristics:

i. Voltage/ cell count

ii. Capacity

iii. Discharge rating

iv. Charge rate

In this project, we have used a Li-Po battery of power 2200mAh. The weight of the battery is

crucial in the design phase since it is the heaviest component of the aircraft and can greatly

affect the CG and in turn the stability of aircraft.

The main functions of the battery in his project are:

i. To power the motor to produce thrust through ESC

ii. To power the servos for the movement of the control surface

Fig Battery

j) RC Transmitter and receiver:

For the manual flight control RC(Radio Controlled) transmitter and receiver are used to

control the aircraft where the transmitter sends the signals to the receiver using radio waves.

The receiver then sends those signals to the servos. Hence the servo mechanism actuate the

control surfaces.

The two levers in the transmitter are the key control of the control surfaces like ailerons,

elevator, rudder, etc which in turn affects the orientation of the aircraft.

Fig RC Transmitter and Receiver

h) Coro sheets :

Coro sheets are also caked as the fluted poly propylene sheets is light weight, resilient material

largely used in packaging and advertising. These sheets contain parallel holo flutes which

make materials light and strong. The material usually does not break on impact. These

characteristics are suitable for building the rc planes. In this project we used 4 mm Coro

sheets which is used to make the wing of the model. Along with that they are also used in

horizontal and vertical control surface.

Fig coro sheets

FABRICATION AND ASSEMBLY

The following steps were involved in fabricating the UAV,

1. Initially the wing airfoil is printed and which is glued in to the balsa sheets. Later they

are cut accordingly. For our respective wing 9 of similar wing ribs were cut.

2. Later the cut pieces were glued on to the aluminium c channel frame and they are

placed with equal space between them

Fig Fabricated wing rib

3. Then, an Aluminium C section rod was passed through 25% of chord of the airfoils to

get the wing skeleton. It was done to add strength to the wing, while keeping the

weight as light as possible

Fig wing skeleton assembly

4. Once the main wing assembly is complete, then Coro sheet is wrapped around the

main wing to cover the outer surface of the wing.

Fig Assembled wing

5. While covering the entire wing with the Coro sheets, hot glue gun is used to glue the

Coro sheet in to the main wing assembly.

6. The wing ribs are consists of holes to provide the flooding of the wing when it is

submerged in case of water.

7. On the upper surface of the wing spoilers are also cut. This is because to rapidly drain

the water out of the wing when it comes out of the water.

8. The fuselage of the UAV is made from the cylindrical cardboard tubes. The entire

tubular structure is covered with the cello tape to make it waterproof.

Fig Fuselage assembly

9. For tail and fuselage sections, no plywood were used. Coro sheet was simply cut and

folded to get the required size. A room was created in the fuselage, beneath the wing

surface, to allocate batteries and all other electronics.

10. Next, all the basic electronics required for manual flight were placed at their

appropriate locations, i.e., servos for control surfaces, control horns, battery, motor,

ESC and receiver.

11. For the water applications, all electronics on board the UAV must be waterproofed.

The waterproofing is usually done by the usage of 5 min epoxy.

12. The epoxy( resin and hardener) are mixed in equal proportion and applied on to the

electronics on board the UAV.This is act as a seal, that prevents the entry of water in

to the electronics.

13. The servos and esc are connected to receiver channel as follows

Throttle control: channel 3

Rudder control: channel 4

Aileron control: channel 2

Elevator control: channel 1

14. The aircraft was then tested for manual flight in air and water. CG adjustments were

done by shifting the places of battery and other electronics inside the fuselage to make

the aircraft stable in flight.

15. Where as in case of water, CB is adjusted to make sure that the uav is 0.9 times the

CB.

16. Many test flights were performed to get the required performance from the UAV.

Fig Complete Assembled UAV

Fig Surface locomotion in water

Air flight

8. RESULT and CONCLUSION

RANGE, ENDURANCE AND STATIC THRUST

Range and endurance plays a major role in the performance of fixed wing UAV, here

according to the flight test data it covers around 1km for about 20minutes. Range depends up

on the transmitter coverage length and endurance is based on the battery capacity.

1. Endurance

Endurance of Unmanned Aerial Vehicle can be described at the total time taken during flight.

For an electric fixed-wing aircraft this is directly related to the capacity of the battery and the

amount of current the motor produces to keep the aircraft in the air. There are many other

aircraft parameters that determine the endurance for any aircraft, however for simplicity the

endurance calculation will be estimated as shown in the equation below..

Flight time=𝒃𝒂𝒕𝒕𝒆𝒓𝒚 𝒎𝑨𝒉∗𝟔𝟎

𝒎𝒐𝒕𝒐𝒓 𝒅𝒓𝒂𝒘 𝒊𝒏 𝒎𝒊𝒍𝒍𝒊𝒂𝒎𝒑𝒔

Where, motor draw= 29 Amps at full throttle

Battery mAh=3000 mAh

So the flight time= 10.34±1-2 minutes

2. Range

The amount of distance a UAV can cover and also how far away you can control the UAV.

Using mathematical equation to easily determine the range of a drone range calculation for

both fixed-wing and quad rotor can be estimated using the equation below

Range(miles)=𝑘𝑉∗𝑉∗60∗𝑝𝑖𝑡𝑐 ℎ

12∗5260*Endurance(Hrs)

The kV value is the number of revolutions per minute the motor will turn when 1V is applied

to the motor = 1000

The pitch value is the pitch (in inches) of the propeller on the UAV = 4.5inch

The endurance value is the amount of time in hours the aircraft can stay in the air.

Voltage = 11.1V

Range = 1.75 miles

Speed = Range / Endurance = 10.5mph = 3.13m/s

3. Static Thrust

F=1.8594e-11*RPM2*𝐷4.5

𝑃∗ (

𝑃

𝐷+ 0.2)

Where RPM =Typically 9000rpm

D=Diameter of the propeller in inches=10 inch

P=Pitch in inches=4.5 inch

So the static thrust =14.6N=1.48kgs

CONCLUSION

This project presented the design,testing,and characterization of a proof of concept of fixed

wing cross domain UAV which is capable of operating under both aerial and water

conditions.The vehicle manages buoyancy passively by using the floodable compartment in

both fuselage and wing section which allows vehicle weight for the flight.

For water application all the electronics onboard the UAV are water proofed such that the

UAV was able to operate in water condition without causing any damage to the electronic

components. During the vehicle testing and characterization process the vehicle has under

gone different mission cycles which includes surface loitering and flight operations.This

project demonstrates that the same type of propulsion system that can be used in air and

water.

The prototype is successfully tested in aerial and water conditions but in water it was unable

to submerge due to buoyancy but vehicle was able to loiter successfully on surface of water.

9. Scope for Future

We Designed and fabricated a Fixed wing UAV for operating in both Air and Water

conditions our model was successfully able to fly and move on surface of the water but unable

to submerge for future work they can try for submerging it.We used balsa wood for wing ribs

and spars it can be replaced with any other material which is of high strength and less

weight.The endurance time can also be increased by using different motor and battery.

The thrust produced by our model is around 1.3kg it can be increased by using the different

motor and different dimensions of the aircraft.