fyp report (repaired)

8/7/2019 FYP report (Repaired)

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Ground Effect Vehicle

SCHOOL OF MECHANICAL & AERONAUTICAL

ENGINEERING

Project No: 10037A


Supervisor: Mr Er Seow Hong

Team members:

Ashwin Ragu (0812874)

Arabathdeen (0811518)

Haresh Chandra (0856029)

Muhammad Ariff (0846147)

Shahul Hameed (0868833)

AY 2010/2011




1

ABSTRACT

This report presents an idea to design and build a Ground Effect Vehicle (GEV) which doesnot only work in ground effect but also as a conventional aircraft. The Ground Effect

characteristic depends mainly on the geometric shape of the wing.

The report was compiled after studies that included designing and building a model wing

shape that provides optimised ground effect. We specifically chose the Clark-Y airfoil for this

wing.

Further modifications were done on the wing structure to ensure that the GEV works both in

ground effect as well as how a conventional aircraft operates. The report covers the test of the

new wing design by bringing together the different aspects of aerodynamics such as anhedral

wing structure, various angles of attack and flaperons.

Such aerodynamic parameters had to be tested, to ensure that optimum ground effect was

generated as well as to create an aircraft that is able to fly out of ground effect.




2

Acknowledgement

The authors of this report would like to express their sincere gratitude to their supervisor, Mr

Er Seow Hong for his guidance throughout the course of the project. We would like to thank

the lab technicians for providing the necessary facilities to carry out our work. We would also

like to thank Mr Roger Chua, Mr Soh Kim Fai, Mr Duncan Sih and Mr Gopal Venkataraman

for their advice. Last but not least, we are grateful to the staff of NTC Engineering Hobbies,

Rotor Hobby Enterprises and Jet Hobby for their invaluable ideas and inputs to improve our

project. We would like to also extend our appreciation to our family for their support,

understanding and encouragement throughout the course of our study in SP and for the

duration of our project.




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Table of Contents

ABSTRACT ..................................................................................................................... 1

Acknowledgement ............................................................................................................ 2

L IST OF SYMBOLS ........................................................................................................ 6

1 INTRODUCTION ..................................................................................................... 8

1.1 Principle of Ground Effect ........................................................................................... 8

1.2 Types of GEVs ............................................................................................................. 9

1.3 Objective.................................................................................................................... 10

1.4 Method....................................................................................................................... 10

2 L iterature Survey ..................................................................................................... 10

2.1 Wings......................................................................................................................... 10

2.1.1 Wing Shape ................................................................................................................. 11

2.1.2 Purpose of Wing............................................................................................................ 13

2.1.3 Aspect Ratio.................................................................................................................. 13

2.1.4 Fineness Ratio ............................................................................................................... 14

2.1.5 Wing Designs................................................................................................................ 16

2.1.6............................................................................................................................................... 17

3 GROUND EFFECT VEHI CLE ............................................................................... 19

3.1 Wing Shape & Structure ............................................................................................ 19 3.1.1 Wing Shape ................................................................................................................... 19

3.1.2 Wing Structure .............................................................................................................. 20

3.2.3 Control Surfaces........................................................................................................... 21

3.2.4 Airfoil Shapes ............................................................................................................... 21

3.2.4.1 NACA 6612 .............................................................................................................. 21

3.2.4.2 Clark-Y ......................................................................................................................... 22

3.3 Our Initial Sketches of GEV ...................................................................................... 22

3.4 GEV Calculation........................................................................................................ 24

4 Working Process ..................................................................................................... 26

4.1 Making of Wings........................................................................................................ 26

4.2 Assembly of Airfoils ................................................................................................... 28

4.3 Skinning of the Wings ................................................................................................ 29

4.4 Fabrication of Flaperons ............................................................................................ 29

4.5 Waterproof Coating ................................................................................................... 30

4.6 Mounting the wings on Fuselage ................................................................................ 31

4.7 Fabrication of End Plates........................................................................................... 33




4

4.8 Mounting of the Motor............................................................................................... 34

4.9 Wiring........................................................................................................................ 34

5 FL IGHT REPORT .................................................................................................. 35

5.1

First Flight................................................................................................................. 35

5.2 Modifications ............................................................................................................. 36

5.3 Second Flight ............................................................................................................. 37

6 RESULTS AND CONCLUSION ......................................................................... 37

6.1 Results ....................................................................................................................... 37

6.2 Conclusion ................................................................................................................. 37

6.3 Recommendations .................................................................................................... 38




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Table of Figures

figure 1.1…………………………………………………………………………………… .8

figure 1.2…………………………………………………………………………………… .9

figure 2.1…………………………………………………………………………………… .11

figure 2.2…………………………………………………………………………………… .11

figure 2.3…………………………………………………………………………………… .12

figure 2.4…………………………………………………………………………………… .12

figure 2.5…………………………………………………………………………………… .13

figure 2.6…………………………………………………………………………………… .13

figure 2.7…………………………………………………………………………………… .14

figure 2.8…………………………………………………………………………………… .15

figure 2.9…………………………………………………………………………………… .15

figure 2.10…………………………………………………………………………………… .16

figure 2.11…………………………………………………………………………………… .17

figure 2.12…………………………………………………………………………………… .17

figure 2.13…………………………………………………………………………………… .18

figure 2.14…………………………………………………………………………………… .18

figure 2.15…………………………………………………………………………………… .19

figure 3.1…………………………………………………………………………………… ...20

figure 3.2…………………………………………………………………………………… ...20

figure 3.3………………………………………………………………………………………22

figure 3.4. …………………………………………………………………………………… .23

figure 4.1…………………………………………………………………………………… .26

figure 4.2…………………………………………………………………………………… .27

figure 4.3…………………………………………………………………………………… .28

figure 4.4…………………………………………………………………………………… .29

figure 4.5…………………………………………………………………………………… .30

figure 4.6…………………………………………………………………………………… ..30

figure 4.7…………………………………………………………………………………… .32

figure 4.8…………………………………………………………………………………… .32

figure 4.9…………………………………………………………………………………… .33

figure 4.10…………………………………………………………………………………… .34

figure 4.11…………………………………………………………………………………… .34

figure 5.1…………………………………………………………………………………… .35

figure 5.2…………………………………………………………………………………… .36




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LIST OF SYMBOLS

- Density (kg/m3)

V - Speed (m/s)

CD - Coefficient of Drag

CL - Coefficient of Lift

A - Area (m2)

D - Drag

L - Lift

g - Gravitational Acceleration

h - Height

c - Chord Length




7




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1 INTRODUCTION

1.1 Principle of Ground Effect

Ground Effect Vehicles (GEV) or Wing in Ground (WIG) Effect Vehicles take advantage of

a peculiar aerodynamic principle known as ground effect to fly at altitudes on the order of

tens of feet, or a few meters.

A wing generates lift because there is a lower pressure on its upper surface than on its lower

surface. This difference in pressure creates lift, but the penalty is that the higher pressure flow

beneath the wing tries to flow around the wingtip to the lower pressure region above the

wing. This motion creates what is called a wingtip vortex. As the wing moves forward, this

vortex remains, and therefore trails behind the wing. For this reason, the vortex is usually

referred to as a trailing vortex. One trailing vortex is created off each wingtip, and they spin

in opposite directions. These vortices are, in fact, the source of induced drag. The greater the

size and strength of the vortices, the greater the induced drag effect becomes.

FIGURE 1.1

However, when an aircraft flies very close to the surface, the ground partially blocks the

trailing vortices and decreases the amount of downwash generated by the wing. This

reduction in downwash increases the effective angle of attack of the wing so that it creates

more lift and less drag than it would otherwise. This phenomenon is called ground effect.




9

Pilots describe ground effect as a feeling of ‘floating on a cushion of air’, when in reality, no

cushion of air is formed.

An aircraft operating in ground effect is much more efficient than at high altitudes. This is

because the aircraft is experiencing a loss of induced drag (up to 70%) and does not require

as much fuel. Thus, ground effect vehicles exploit the ground effect phenomenon to enhance

their performance.

FIGURE 1.2

This unique class of aircraft has been studied since the 1960’s by engineers attempting to

design highly efficient aircraft.

1.2 Types of GEVs

There are various types of GEVs that have been around since the 1960’s. The International

Maritime Organization has classified GEV’s according to three classes:

1. Type A - cannot operate out of ground effect.

2. Type B - can jump to clear obstacles, but only for very short periods of time as the

wings are not designed for conventional flight.

3. Type C – are certified as aircraft, with the ability to operate safely and efficiently out

of ground effect.




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1.3 Objective

The aim of this report is to document the process of designing and manufacturing a Ground

Effect Vehicle (GEV) that is capable of operating in and out of ground effect efficiently. TheGEV will be classified as a Type C ground effect craft.

1.4 Method

We will design a set of wings using the appropriate airfoil and we will supplement the wings

with endplates and floats. The fuselage of the plane will be bought instead of fabricated as wehave decided to focus on the aerodynamic aspects instead of the hydrodynamic aspect of this

project, and the fuselage does not provide significant aerodynamic importance.

2 Literature Survey

This literature survey consists of the review of the designs of the wings, their shapes and their

aerodynamic characteristic. It also includes reviews of different airfoil shapes that have

different characteristics. For our investigation, we had to look for the airfoil that would be

ideal for ground effect.

2.1 Wings

The wings are the main lift generating surface on aircraft. Wings are also used to generate

aerodynamic lifting force to support the aircraft in flight by deflecting the airflow downwards

while the aircraft moves forward. Wings also balance the aircraft about the roll axis.




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2.1.1 Wing Shape

There are several wing designs the common ones are swept, straight, elliptical, tapered and

delta wings. The shape and the design of the wing play a major role the lift and

manoeuvrability as well as the handling and stability of the aircraft. These parameters are

affected with the different designs and shapes of the aircraft’s wings.

2.1.1.1 Straight Wing

There are different designs of straight wings such as rectangular (Fig 2.1), tapered (Fig 2.2)

and elliptical (Fig 2.3).In general aviation, usually slow speed and small aircrafts tend to use

the straight wing concept. Although this wing design is not suited for high speed flight, the

wing is able to create high lift with lower speed. However, as the wing is in a relative position

to the wind there is significant drag created.

FIGURE 2.1

FIGURE 2.2




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FIGURE 2.3

2.1.1.2 Swept Back Wing

Swept back wings are the common set of wing designs used nowadays. It is done so because

of its advantages such as adaptability in fast speeds which is how majority of the planes are

flown. Moreover, it has manoeuvrability at high speeds. Furthermore, the main reason for

using swept back wings is because of the low drag factor in comparison to the straight wings.

There are several types of swept back wing designs such as slightly, moderately and highly

swept back wings . The extent of

sweep of the wing is dependent on the purpose it is built for. The larger the angle of sweep,

the higher the maneuverability and the speed the aircraft can fly at, having lesser drag and at

the same time, having lesser stability.

The commercial transport (passenger) aircraft has moderately swept back wings (Fig. 2.5) to

ensure stability as well as maneuverability at high speeds as well as low drag, while

supersonic aircraft tend to have highly swept back wings (Fig 2.6) or delta shaped wings,

which are very unstable at low speeds. They take off and descend for landing at a high rate of

speed

FIGURE 2.4




13

FIGURE 2.5

FIGURE 2.6

2.1.2 Purpose of Wing

The main purpose of the wing is to generate optimum lift for the aircraft. Although lift is the

main contributing factor of the wing, there are other factors that contribute to flight such as

the control of the wing and the stability that also plays a major role in flight. The factors that

contribute to the stability and manoeuvrability are slenderness (Aspect Ratio) and thickness

(Fineness Ratio) of the wing. There are control surfaces on the wing as well such as the

ailerons, flaps, flaperons and slats which will be explained later in the report.

2.1.3 Aspect Ratio

Aspect Ratio refers to the slenderness of the wing. High aspect ratio would mean that the

wing is slender and long causing it to be very stable. However, too long of a wing can also

cause the aircraft to be less manoeuvrable. Low aspect ratio refers to a short and thick wing

which leads to poor stability but better manoeuvrability. Commercial aircrafts tend to have




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Aspect Ratio = Span2/Wing Area

wings of high aspect ratio which makes them very stable but they do not only focus on high

aspect ratio but also on the manoeuvrability.

The equation below shows how the aspect ratio is derived

AR is derived by square of the wing span divided by the wing area. The diagrams below

show the different types of aspect ratio and how they affect the stability and manoeuvrability

of the aircraft.

FIGURE 2.7

2.1.4 Fineness Ratio

Fineness ratio refers to the measurement of the thickness of the airfoil (cross-section of the

wing). The higher the fineness ratio means that the longer the chord length but a thin airfoil

shape. A lower fineness ratio refers to a shorter chord length but a thicker airfoil. Therefore,

the higher the fineness ratio the lesser the drag caused by the wing as it has a thin airfoil.

Therefore with higher fineness ratio the aircraft is able to fly at a faster speed since there is

lesser drag.




15

Fineness ratio = Chord length/Thickness

However, the lower fineness ratio results in significant amount of drag or resistance to

airflow over the wing. Because of the significant amount of drag caused by the thick airfoil,

the aircraft is unable to operate at fast speed.

The equation below shows how the fineness ratio is being achieved.

Fineness ratio is calculated by dividing the chord length by the thickness of the airfoil used.

The diagram below shows how the thickness of the airfoil affects the resistance of the airflow

and thus causing significant amount of drag.

FIGURE 2.8

FIGURE 2.9




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2.1.5 Wing Designs

There are 2 different types of wing designs - dihedral and anhedral wing.

2.1.5.1 Dihedral

Dihedral wing refers to the aircraft’s wing having an upward angle from the horizontal parts

of the aircraft such as the wing root (dihedral angle) to create a dihedral effect. Dihedral

effect refers to the roll moment produced per degree of sideslip. Dihedral wings are crucial

factor in the stability of the aircraft as they tend to be more stable during roll operation. The

figure below shows the dihedral design.

FIGURE 2.10

2.1.5.2 Anhedral

Anhedral wing refers to the aircraft’s wing having a downward angle from the horizontal tail

plane of the aircraft. Usually fighter jets that does not need to be stable which cause the

aircraft to be less manoeuvrable, tend to have anhedral angle to be able to compromise the

stability for manoeuvrability. The figure below shows the anhedral wing design used in

aircrafts.




17

FIGURE 2.11

2.1.6 Control Surfaces – Wing

Apart from creating lift the wing also consists of various control surfaces such as slats, flaps.

These control surfaces help to control the aircraft in flight such as to do a roll, or to increasethe wing camber by using the slats as well as the flaps. Further explanations of the control

surfaces are given below.

2.1.6.1 Slats

Slats are usually located on the leading edge of the wing. Slats are used during takeoff

operation so as to increase the wing chord length. An increase in wing chord length means

more lift will be generated with a shorter distance. Although operation of the slat in high

speeds caused significant amount of drag, it is usually used during slow speed to reduce the

drag caused or no drag when cruising. The operation of the slats is demonstrated in the figure

below.

FIGURE 2.12




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2.1.6.2 Flaps

The flaps are used in the trailing edge of the wing. Flaps are operated during takeoff as well

as during landing. During takeoff the flaps are operated at around 15 deg so as to increase thewing area. Therefore, creating more lift for short distance. Flaps are deployed during landing

so as to cut the continuous airflow and decrease lift.

There are various types of flaps that are used in the aircrafts. They are split flaps, hinged flaps

and fowler flaps. The different types of flaps are shown below.

FIGURE 2.13

FIGURE 2.14




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FIGURE 2.15

3 GROUND EFFECT VEHICLE

Our motive of the project was to design a ground effect vehicle but also to create a wing

structure that is not only fixed for ground effect but also used to fly the aircraft out of ground

effect like any other conventional plane.

3.1 Wing Shape & Structure

The conventional ground effect vehicles have fixed wing shape and structure. They tend to

have a fixed wing that only caters for ground effect cause the aircraft only to operate in

ground effect. We have decided to create a wing shape and structure that can be changed so

as to operate in ground effect as well out of ground effect.

3.1.1 Wing Shape

Therefore, the shape of the wing we chose was straight wing. The reason for choosing the

straight wing of rectangular shape rather than other types such as swept back or delta was

because of the design we wanted to construct. Moreover, we discovered that straight wing

was able to give better lift with slower speed. As basic motive was to design a ground effect




20

wing, we had to keep that key factor in mind. The straight wing was not suitable for high

speed flight as ours does not require flying at a fast speed.

3.1.2 Wing Structure

We decided to use anhedral wing structure because we discovered that conventional ground

effect vehicles tend to use anhedral wing structures but however their wing structure was

fixed with a bend at the trailing edge of the wing to create optimum ground effect. Instead of

creating a fixed ground effect wing, we decided to use a conventional aircraft’s anhedral

wing but to generate ground effect we decided to incorporate control surface on the wingsthat will help not only generate ground effect but also to be used as normal aircraft’s

controls.

The diagram below explains how ground effect occurs

FIGURE 3.1

The picture of a conventional ground effect vehicle’s unique wing shape & structure

FIGURE 3.2




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3.2.3 Control Surfaces

Since we decided to use anhedral wing structure for the ground effect vehicle, we decided to

use flaperons for our wing control surfaces instead of separate ailerons and flaps. This is

because flaperons (flaps + ailerons) are relatively simple to fabricate and would fulfil the

need for creating a seal between the wings and the surface. When we use the anhedral wing

structure with flaperons at maximum deflection, we are able to trap air under the wings

causing ground effect to occur.

3.2.4 Airfoil Shapes

We used the foilsim software generated by NASA to conduct research on certain airfoil

models so as to show their lift capabilities, lift to drag ratio and other necessary airfoil

characteristics. The software also allowed us to focus on airfoil shapes that were meant only

for ground effect purposes. After doing much research on the different types of ground effect

airfoils, we narrowed the options to 2 best airfoils that have good lift to drag ratio

characteristics; catering well for ground effect. The airfoil shapes are NACA 6612 and Clark-

Y.

3.2.4.1 NACA 6612

NACA 6612 airfoil design (fig.3.3) was such that also it was meets our requirements of the

characteristics we wanted. The airfoil tends to be too complex in shape and design.

Moreover, the airfoil base was curved and having a curve base means more precision was

needed in scaling out the airfoil profile in CAD; it also meant that we had to cut the airfoil

shapes precisely using machines. This was going to be made tough to achieve as even slight

changes in the size or shape in the airfoil will lead to changes in the characteristics of the

wing.




22

FIGURE 3.3

3.2.4.2 Clark-Y

The Clark-Y airfoil design was also such that it met our requirements of characteristics of the

wing we wanted. However, this airfoil was much simpler in design but giving the almost

equivalent characteristics. This airfoil’s bottom was flat, this allows us to build accurate ribs

and easily align them without a problem of misalignment. Moreover, the Clark-Y airfoil has

a better low speed flight characteristic which was relevant to our model that we were

creating.

3.3 Our Initial Sketches of GEV

PLAN

Flaperons




23

FRONT

Figure 3.4

Flat & Straight Wing design

Anhedral wing structure

End Plate Design (Float)

Flaperons fully extended




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3.4 GEV Calculation

After doing the basic sketches and design, we decided to calculate for the wing. The wing

calculations are as follows.

Dimensions: 0.56 x 0.22 m

Weight: 1300g

Wing loading: 22.04 oz/sq. ft

b (span) = 2s

b = 2×0.56

= 1.12

c (chord length)= 0.22m

Tmax = 0.02m

Fineness Ratio= c/Tmax

= 0.22/0.02

= 11

Thickness Ratio = 1/Fineness ratio

= 1/11

= 9%




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Aspect ratio = b/c

= 1.12/0.22

= 5.1

S (wing area) = /4

=

W (Lift) = 1300×9.81

= 12.753kN

Wing Loading =

=

= 65.87 kN/




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4 Working Process

4.1 Making of Wings

After purchasing the wood from the hobby shop, we started working manufacturing the

wings. We selected the airfoil Clark Y airfoil, printed out the airfoil design in A4 paper, and

then traced the airfoil on balsa wood. Our initial design consisted of 7 ribs on each side of the

wing. Since we had 14 similar airfoils to make, we cut the balsa wood into 14 rectangular

smaller pieces. As a safety precaution, we made 18 ribs, in case some of them were damaged.

Upon cutting out pieces, we used masking tape to hold all the rectangular pieces together.

We traced the airfoil shape on the top (First) facing surface. Pencil was used to darken the

lines of airfoil shape. The main purpose of attaching all 18 pieces before tracing and

machining was because we wanted the airfoils shape to be accurate and precise in the

dimensions. After this, we used the scroll saw to cut out the airfoil shape. After attaining the

airfoil shape without detailing of the slots and holes, the airfoil was sanded with a sanding

machine to attain a smooth surface throughout the corners.

FIGURE 4.1




27

Our first airfoil consisted of two holes at the front and back, a large hole in the middle and

two slots at the top and bottom of the airfoil. A carbon rod was inserted into the back hole.

This helps to hold all the airfoils in place while cutting and also to form the skeleton of the

wing. The large hole in the middle was for saving weight on the aircraft wing. The slots on

top and bottom are meant for the installation of the spars.

A diameter of 8mm drill bit was used to cut both holes in the front and back. As for the

middle hole and slots, a scroll saw was used to cut the specific design. During machining of

the holes and slots, all the 18 pieces were still attached together by masking tape. After

completing cutting the holes and slots, a miniature file was used to smoothen the slots on the

top, bottom and middle surface. A round file was also used to deburr the holes that were cut

and also to give it a more rounded finish.

At this stage, all the machining on the airfoil was done. We used the sanding machine again

to sand the airfoil to give it a very smooth surface finish. This is to ensure that air flowing

over the airfoil has a smooth flow which will contribute significantly to the aerodynamics of

the wings.

FIGURE 4.2




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4.2 Assembly of Airfoils

Based on our design and calculation on the wing length, we calculated to have 7 airfoils in

each wing with an interval of 50mm between each airfoil. Carbon rods were cut according to

the specific wing length. The 7 individual airfoils were slit in the carbon rods through the

holes in front and back. Airfoils were adjusted within the carbon rods to ensure the spacing

between the airfoils were even.

Spars were also cut according to the wing length. The spars were inserted on the slots on the

top and bottom of airfoils. Adequate amount of glue (epoxy resin) was used to seal the spars

onto the slots. This created the main skeleton of the wing. Initially, we were going to mount

two servos in the fuselage, but this would have required a complex pushrod system. Instead,

we glued in one servo to the rib next to the root rib (F ig.4.3) and connected it to the flaperon

with a simple straight pushrod. The disadvantage of this method is that the servos are more at

risk of getting wet while the plane is operating on water but we managed to minimize the area

of which the servos were exposed to the elements.

FIGURE 4.3




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4.3 Skinning of the Wings

After creating the frame of the wing, we needed to attach a skin on all surfaces of the wing.

The skin provides the aerodynamic shape of the whole wing, without the skin, the wing

would not display aerodynamic properties. Skinning was done on the wing using a single thin

sheet of balsa wood, approximately 1.5mm in thickness. Epoxy glue was used to secure the

skin on the wing. Gaps and slack will change the shape and aerodynamics properties of the

airfoil; therefore we had to be precise.

4.4 Fabrication of Flaperons

After skinning both wings, the next section was the fabrication of the flaperons. Flaperons are

one of the most important components attached to the wing. Since ground effect works on the

principle of trapping air, the flaperons deflect downwards during flight to trap air. The

flaperons were constructed using a piece of prefabricated balsa wood.

Upon cutting the flaperons, we created slots in the flaperons and in the back of the 18 airfoils.

This is to facilitate the installation of hinges. The hinges are used to connect the flaperons to

the wings. The slots which are created within the airfoils and flaperons are cut with equal

depths. This is to make sure that flaperons are attached with the airfoil evenly. Glue was also

FIGURE 4.4




30

used in securing the hinges with the wings and flaperons. Attaching the flaperons on the main

wings completed the mechanical aspects of the wings.

FIGURE 4.5

4.5 Waterproof Coating

FIGURE 4.6




31

Now that the both wings were completed, we needed to waterproof them. We purchased an

iron-on plastic film called Ultracote that would provide waterproofing and make the wings

look glossy and attractive.

The Ultracote came in a big sheet; we had to cut the sheet accordingly to the specific length

of the wing span. The skin was cut as a whole piece to cover the wing. This is because using

of 2 sheets would cause a bulge when overlapping. This bulge would create irregularities

with the airflow and disturb the aerodynamics of the wings. We completed the ironing on

both wings and both the flaperons.

4.6 Mounting the wings on Fuselage

After the skinning, the next big task our group had to face was the mounting of the wings on

the fuselage. Since we were using an existing plane, we couldn’t fix the wings easily on the

fuselage. To overcome this problem, we had to make a new design for the fuselage (middle

part) for the wings to be mounted. We used blue foam to make a base to sit on the fuselage.

The foam was cut using a wire cutter; the foam was also sanded to accomplish a better finish.

The foam was cut in a square shape and the inner surface was also cut for allocation of the

wiring and transmitter. We also cut two slots in the foam base for the servo wires to run

through.

After solving the problem of manufacturing a suitable base for the wings to be mounted on

fuselage, we had to have the wings to be mounted in a specific angle. We sanded two balsa

wood pieces down to a wedge shape and glued them onto the foam base. We experimented

with various anhedral angles until we settled on 4 degrees.




32

FIGURE 4.7

FIGURE 4.8

The wings were mounted by screwing on the spars onto the wedges. We had to use two

screws on the spars to secure the wings tightly. After securing the mounting of the wings on

the fuselage, the mountings of the elevators and rudder was much of ease.




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4.7 Fabrication of End Plates

FIGURE 4.9

Last but not least we still had to manufacture the end plates. The end plates are used to trap

air underneath the wings in conjunction with the flaperons. Additionally, we installed floats

on them which help the GEV to float in water. Sanding Sealer was sprayed onto the end

plates in layers to provide water proofing on the plates. Water proofing on the end plates are

important because the end plates are constantly in contact with water if the aircraft were to

maneuver in water. The floats were made out of blue foam after we tested their properties in

water.




34

4.8 Mounting of the Motor

FIGURE 4.10

Since we were working on an existing plane, there was already a pre-installed engine mount.

However, the engine mount was too small so we decided to remove it and fabricate our own.

We glued four rectangular sections to the foam and then mounted the motor to the makeshift

frame. After consulting with staff of Rotor Hobby, we were advised to offset the motor

downwards and to the right to counteract propeller torque and to direct thrust upwards.

4.9 Wiring

FIGURE 4.11




35

Since all the mechanical aspects of the aircraft were done, we had to focus on the electrical

wiring of the aircraft. Initially we had problems on the wiring as we were not well versed in

electrical systems. But with help from other friends, we were able to connect the wiring

within the aircraft. The wiring consists of connecting the servos to the flaperons and

connecting the transmitter to the wiring. After programming the control surfaces (flaperons,

rudder & elevator) using the remote controller, we were able to proceed with the flight

testing.

5 FLIGHT REPORT

5.1 First Flight

We decided to do a float test at the Kallang River to observe the plane floating properly and

to check for leaks. However, we did not conduct a flight test in water as the risk of losing the

plane was too high. Instead, we conducted the flight test on a field. We managed to get the

GEV airborne after taking off from the pavement but unfortunately, it crashed into a tree

shortly after.

FIGURE 5.1




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During the flight, we realized that the plane needed a considerable distance to take off. We

also noticed that the foam floats were unnecessary in the water as the plane was light enough

to float under its own weight. We also realized that the wing mounting was not secure

enough. After reviewing the calculations and the video of the flight test, we made a number

of conclusions:

the wing area was too small

the angle of attack was too big

the wing should be stronger

the anhedral angle was too big

the wing mounting should be more secure

the floats were causing unnecessary friction

We intended to resolve these issues by building a second set of improved wings.

5.2 Modifications

We immediately started to make improvements to the design of the second set, namely,

increasing the chord length and the wingspan. The fabrication period for the new wings was

much faster than before as we experienced all the issues previously and knew how to avoid

them. An extra carbon rod was added to each wing to increase rigidity and new flexible skin

sheeting was used. Also, we designed servo hatches for our wing after researching on them

from the internet. These servo hatches (Fig.5.2) would enable us to remove the servos

anytime we wanted instead of permanently encasing them like the previous design.

FIGURE 5.2




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We also made minor modifications to the pushrods and control arm positions to make the

movements more responsive. Finally, we did away with the foam floats completely and made

the endplates larger but less thick to keep the weight down. Securing the wings to the

fuselage was relatively easy as we reduced the anhedral angle to 2 degrees and mounted the

wing at an angle of attack of 1 degree. This made the wings visibly flatter and contributed to

the improved aerodynamics of the new wings.

5.3 Second Flight

After performing a second float test and adjusting the center of gravity backward, we flew the

new and improved GEV in the sports stadium. Now, it needed much less distance to take off

and was less sluggish as before. We observed the GEV flying in ground effect although it is

not immediately apparent in the video Instead; we observed it with our own eyes. We also

noted that the GEV tends to veer off-course during takeoff because of the nature of the

undercarriage; the endplates provide no directional stability. This can be countered by the

addition of wheels to the GEV.

6 RESULTS AND CONCLUSION

6.1 Results

The results were favorable, although we intended for a longer flight in ground effect. We also

encountered problems trying to prove that the GEV flew in ground effect. A wind tunnel test

would be ideal for this. The design of the GEV might have some minor flaws but all in all,

the project was still a moderate success.

6.2 Conclusion

With the results obtained and observations made, it is concluded that for the project was

moderately successful. We managed to get the GEV airborne for a very short period and we

managed to prove that endplates and flaperons, when added to a conventional wing, would

enable it to operate well in ground effect. However, we feel like we can improve on the

project if we had more time. Perhaps, a future group can improve on the wing and/or the hull

design and also construct the fuselage themselves, time permitting. As a group, we have




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learned the importance of time management and group dynamics. Even though two group

members were from a non-aeronautical engineering background, everyone still learned

something about aeronautical engineering while doing this project.

6.3 Recommendations

We believe that our project can be improved further if more time is dedicated to it. For

example, the addition of wheels to the GEV will enable it to be steered on the ground. By

fabricating the fuselage ourselves, we could have made a better designed GEV as we don’t

need to rely on the given measurements. Also, a future group can design and build a

hydrodynamic fuselage instead of using an existing model.




APPENDIX

fyp report (repaired)

Documents