design,analysis and fabrication of wing-in-ground effect vehcile
DESCRIPTION
Project Report on the final year Graduation project 'Design,Analysis and Fabrication of Wing-in-Ground Effect Vehcile' from the Department of Mechanical Engineering,Rajiv Gandhi Institute of Technology(Govt.Engineering College),Kottayam,State of Kerala,India.TRANSCRIPT
DESIGN OPTIMIZATION AND FABRICATION
OF A WING IN GROUND EFFECT CRAFT
(Sponsored by CERD, Govt. of Kerala)
A project report submitted in partial fulfillment of the requirements for the
award of the degree of Bachelor of Technology in Mechanical Engineering of
Mahatma Gandhi University
SUBMITTED BY
ANIL T.
ARAVIND R.
NIKHIL S. PILLAI
RAHUL VINOD
SUDHEESH KUMAR E.
ZAHIR UMMER ZAID
Under the Guidance of
Mr Antony J.K.
DEPARTMENT OF MECHANICAL ENGINEERING
2010-2014
RAJIV GANDHI INSTITUTE OF TECHNOLOGY
(GOVERNMENT ENGINEERING COLLEGE, KOTTAYAM)
DESIGN OPTIMIZATION AND FABRICATION
OF A WING IN GROUND EFFECT CRAFT
(Sponsored by CERD, Govt. of Kerala)
A project report submitted in partial fulfillment of the requirements for the
award of the degree of Bachelor of Technology in Mechanical Engineering of
Mahatma Gandhi University
SUBMITTED BY
ANIL T.
ARAVIND R.
NIKHIL S. PILLAI
RAHUL VINOD
SUDHEESH KUMAR E.
ZAHIR UMMER ZAID
Under the Guidance of
Mr Antony J.K.
DEPARTMENT OF MECHANICAL ENGINEERING
2010-2014
RAJIV GANDHI INSTITUTE OF TECHNOLOGY
(GOVERNMENT ENGINEERING COLLEGE, KOTTAYAM)
DEPARTMENT OF MECHANICAL ENGINEERING
RAJIV GANDHI INSTITUTE OF TECHNOLOGY
GOVERNMENT ENGINEERING COLLEGE
KOTTAYAM– 686 501
Certificate
This is to certify that the report entitled “DESIGN OPTIMIZATION, FABRICATION AND
FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT” is a bonafide record of Graduate Project
presented by ANIL T (Reg. No. 10013661), ARAVIND R (Reg. No. 10013664), NIKHIL S PILLAI (Reg No.
10013689), RAHUL VINOD (Reg. No. 10013692), SUDHEESH KUMAR E (Reg No. 10013707), ZAHIR
UMMER ZAID (Reg No. 10013716) during the year 2013-2014. This report is submitted 1to Mahatma
Gandhi University, Kottayam in partial fulfilment of the requirements for the award of the degree of
Bachelor of Technology in Mechanical Engineering.
ANTONY J.K. CIBY THOMAS
Assistant Professor Professor and HOD
Dept. of Mechanical Engineering Dept. of Mechanical Engineering
RIT, Kottayam RIT, Kottayam
(Project Guide)
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM i DEPT. OF MECHANICAL ENGINEERING,’10–‘14
ACKNOWLEDGEMENT
On the occasion of presenting the project report, we wish to express our deep and
profound feeling of gratitude towards a number of persons who have contributed to the
successful completion of our project.
First of all, we express our deep gratitude to Lord Almighty, the supreme guide, for
bestowing his blessings through each phase of our work.
We would like to thank Antony J.K. (Assistant Professor, Department of Mechanical
Engineering, RIT, Kottayam) for his consistent guidance and inspiration throughout our
project work. We would like to thank Manoj KumarM (Assistant Professor, Department of
Mechanical Engineering, RIT, Kottayam), Mr Graham Taylor (MBA, MCMI,
MIET Hypercraft Associates Ltd, 23 Wyndham Avenue, High Wycombe, Bucks HP13 5ER,
England), Shivprasad (HOD, Ship Technology Dept., CUSAT) and Mr Dileep (Professor,
Ship Technology, CUSAT) for their guidance and support.
We also express our heartfelt gratitude to Ciby Thomas (H.O.D Department of Mechanical
Engineering, RIT Kottayam) and Dr. K. P. Indiradevi (Principal, RIT Kottayam) for
rendering all possible help and support during our project.
Last but not the least we are grateful to the management, all the staff members of RIT
Kottayam for their cooperation and help extended during the course of our project. We would
also like to thank all our friends, family members for their encouragement, inspiration and
moral support without which this work would have never been possible.
Anil T
Aravind R
Nikhil S Pillai
Rahul Vinod
Sudheesh Kumar E
Zahir Ummer Zaid
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM ii DEPT. OF MECHANICAL ENGINEERING,’10–‘14
ABSTRACT
This project mainly encompasses through the design, analysis and fabrication of a
wing-in-ground effect craft. Starting with an introduction to the technology, the project
covers topics such as the design parameters of the hull, main wing, horizontal and vertical
stabilizers and the end plates along with the analysis reports for the same. Covered in more
detail are the fabrication techniques involved in the construction of the same. A brief
feasibility study of the technology considering the Chennai-Port Blair maritime route is
conducted. The project concludes with the challenges and the problems this new technology
might encounter as a new transport replacement in the market.
The WIG craft specified in this report corresponds to the International Maritime
Organization classification type A, and consequently, is designed to operate only within
ground effect. As a result, this type of aircraft is not confined by strict aviation standards, as
well as an increase in safety and usability.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM iii DEPT. OF MECHANICAL ENGINEERING,’10–‘14
CONTENTS
TITLE PAGE NO.
1. INTRODUCTION 1
2. INITIAL DESIGN 4
3. HULL DESIGN 6
4. WING DESIGN 12
5. HORIZONTAL STABILIZER 26
6. VERTICAL STABILIZER 29
7. END PLATE 30
8. FABRICATION 31
9. ENGINE AND RELATED COMPONENTS 35
10. ELECTRIC AND ELECTRONIC UNIT 39
11. SCOPE OF WIG CRAFT 40
12. COST REPORT 45
13. ADVANTAGES AND OPPORTUNITIES 47
14. CHALLENGES AND LIMITATIONS 48
15. CONCLUSION 50
16. REFERENCE 52
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM iv DEPT. OF MECHANICAL ENGINEERING,’10–‘14
LIST OF FIGURES
FIGURE NO. DESCRIPTION PAGE NO.
FIGURE 1 EFFECT OF CL VALUE OF AIRCRAFT 2
FIGURE 2 VORTEX STRENGTH 3
FIGURE 3 PLAN PROVIDED BY GRAHAM TAYLOR 4
FIGURE 4 CATIA MODEL OF THE PLAN 5
FIGURE 5 PLAN OF HULL 7
FIGURE 6 HULL STRUCTURE 9
FIGURE 7 DROP TEST ON HULL 10
FIGURE 8 HULL MODAL ANALYSIS 11
FIGURE 9 AIRFOILS OPERATING IN STRONG GE AT LOW AOA 13
FIGURE 10 CL VS AOA 15
FIGURE 11 CD VS AOA 16
FIGURE 12 VELOCITY CONTOUR AT 130
AOA 16
FIGURE 13 AERODYNAMIC EFFICIENCY VS AOA 17
FIGURE 14 OPTIMUM AIRFOIL CONFIGURATIONS 19
FIGURE 15 STRUCTURE 20
FIGURE 16 EQUIVALENT ELASTIC STRAIN 21
FIGURE 17 EQUIVALENT ELASTIC STRESS 22
FIGURE 18 TOTAL DEFORMATION OF WING 23
FIGURE 19 MODAL ANALYSIS 24
FIGURE 20 WIG DESIGN 27
FIGURE 21 COUNTOUR OF STATIC PRESSURE OVER NACA0006 27
FIGURE 22 PRESSURE COEFFICIENT OVER NACA 0006 27
FIGURE 23 COUNTOUR OF STATIC PRESSURE OVER NACA16006 28
FIGURE 24 PRESSURE COEFFICIENT OVER NACA 16006 28
FIGURE 25 FINAL WIG DESIGN 31
FIGURE 26 FINAL DESIGN 38
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 1 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 1
INTRODUCTION
Ground Effect is a phenomenon when a lift generating device, like a wing, moves
very close to the ground surface which increases the lift-to-drag ratio. Pilots of huge airplane
often experience the plane „bounces‟ off the runway in the presence of ground effect just
before touch down. This phenomenon that resulted in the aerodynamic efficiency of the
vehicles was first exploited by the Russians whom designed and build the first WIG craft
during the cold war.
1.1 Theory of Ground Effect Aerodynamics
When a wing approaches the ground, an increase in lift as well as a reduction in drag
is observed which results in an overall increase in the lift-to-drag ratio. The cause of the
increase in lift is normally referred to as chord dominated ground effect (CDGE) or the ram
effect. Meanwhile, the span dominated ground effect (SDGE) is responsible for the reduction
in drag. The combination of both CDGE and SDGE will lead to an increase in the L/D ratio
hence efficiency increases.
1.2 Chord Dominated Ground Effect (CDGE)
In the study of CDGE, one of the main parameters which one considers is the height-
to chord (h/c) ratio, h. The term height here refers to the clearance between the ground
surface and the airfoil or the wing. The increased in lift is mainly because the increased static
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 2 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
pressure creates an air cushion when the height decreases. This result in a ramming effect
whereby the static pressure on the bottom surface of the wing is increased, leading to higher
lift. Fig shows the difference between an airfoil without ground effect and with ground effect.
Theoretically, as the height approaches 0, the air will become stagnant hence resulting in the
highest possible static pressure with a unity value of coefficient of pressure.
Fig 1: Effect on the value of CL when an airfoil is in ground effect and outside ground
effect. LEFT: With ground effect CL=0.71. RIGHT: Without ground effect CL=0.558
1.3 Span Dominated Ground Effect (SDGE)
On the other hand, the study of SDGE consists of another parameter known as the
height to- span (h/b) ratio. The total drag force is the sum of two contributions” profile drag
and induced drag. The profile drag is due to the skin friction and flow separation. Secondly,
the induced drag occurs in finite wings when there is a „leakage‟ at the wing tip which creates
the vortices that decreases the efficiency of the wing. In SDGE, the induced drag actually
decreases as the strength of the vortex is now bounded by the ground. As the strength of the
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 3 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
vortex decreases, the wing now seems to have a higher effective aspect ratio as compared to
its geometric aspect ratio resulting in a reduction in induced drag.
Fig 2: Vortex strength of aircraft in flight 1) In ground effect 2) Without ground effect
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 4 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 2
INITIAL DESIGN
It was very difficult to start the design of a craft right from the start. In the search for a
basic design structure, after many days of rigorous search, we came across a website called
the www.grahamktaylor.com.
We contacted Mr Graham K. Taylor (MBA, MCMI, MIET Hypercraft Associates
Ltd, 23 Wyndham Avenue, High Wycombe, Bucks HP13 5ER, England) who was
overwhelmed by the project and offered to send the basic plan packs which usually came
with a small fee, free of cost.
Fig 3: Plan provided by Mr Graham Taylor
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 5 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 4: CATIA model of the plan
The basic design came by airmail in the first week of January in an A1 sheet with a
full scale drawing and was the initial design for the project.
On close research, we found that though the hull structure was structurally strong it
couldn‟t minimize hydrodynamic resistance to a great extent.
Moreover the wing was flat which means it wasn‟t an aerodynamically viable one and
had to be replaced.
So it was decided to drop the canard configurations, elevators, replace the balsa wood
with proper substitutes, increase the aspect ratio to 2 from 1 and replace the electric motor
propulsion with engines.
The basic things we incorporated from the basic design into our final design were:
Propulsive unit positioning
Basic dimensions
End plate shapes
Augmented lift production by tilting the engines
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 6 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 3
HULL DESIGN
One of the important design aspects in the project was that of hull. Since the craft is in
close proximity to water during flight and takes off and lands in water bodies, it was really
important to have a good solid hull design that would keep the craft afloat when in water. The
transitory phases of operation from rest through boating, planing or hovering through hump
speed and accelerating through take-off into ground effect flight all require minimum
hydrodynamic resistance so as to minimise installed power.
For a proper hull design, it was necessary to take the aid of experts in the field and
help was sought from the department of Ship Technology of Cochin University of Science
and Technology.
The head of the department Mr. Sivaprasad and Mr Dileep Kumar (Professor, Ship
Technology) gladly extended their support.
The design of the hull commenced with the computations to find the maximum
loading capacity of the craft. It was fixed to be around 8 kgs as per the instruction of the
professors, Hull Model No. TMB-4667 (Hard-chine boat, Lp/bpx=4.09) was selected (as the
hull shape was simpler and would easily suit to the demands of overcoming hump speed
faster) from the “Small craft Data sheets” by “Society of Naval Architects and Marine
Engineers, New York”.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 7 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 5: Plan of hull
The hull design is a planing hull, with a low drag profile compared to others
researched. A planing hull operates by pushing water downwards and sideways as the hull
moves over the water surface, thus, creating a hydrodynamic lift force.
From the reference hull given, (whose length is around 8 feet), the block coefficient
was found to be around 0.587 from the body plan and the outboard profile.
Cb= / Lw Bw T
Where = Volume of Displacement at rest
Then the model of size 8 feet had to be dimensionally brought down to something that would
be around 1m for the model.
New Station Spacing = Model Station Spacing x L2/L1
Where L2= new length
L1= model length
The weight carrying capacity for a craft of 1m length and corresponding dimensions
were computed and was found to be around 5 kg which was way short of the required weight.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 8 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
W=CbLwlBwlT
Where
W = Total weight of the body it can sustain
Cb = Block coefficient
Lwl = Length at waterline
Bwl = Breadth at waterline
T = Draft
= Density of water
In order to accommodate a weight of around 8 kg, the length was now proportionally
increased.
L23=L1
3*required weight/ obtained weight for a length of 1 m
Where L2 = new length
L1 = Initial computation length (1 m)
After certain iteration of the same sort, the following dimensions were fixed for the hull.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 9 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
HULL Parameters
Craft : Tentative Parent for Planning Series
Type of Section Shape : Convex (Forward), Straight (Aft)
Maximum Length : ` 1.19 m
Maximum Breadth : 0.29 m
Breadth at Waterline : 0.24 m
Draft : 0.05 m
Projected Planning Bottom Area : 0.2816 m2
Weight Carrying Capacity : 8.4 kg
Fig 6: Hull structure
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 10 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 7: Drop test of hull. (From top) 1) Equivalent Strain 2) Equivalent Stress 3) Total
Deformation
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 11 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 8: Hull modal analysis
The fundamental mode of is 77.585 Hz, the hull would be safe until the exciting
frequency matches with this point or matches with the frequency of higher modes of
vibration. If the exciting frequency matches with this point resonance would take place,
leading to high amplitude of oscillations and damaging of the hull.
From the analysis it was confirmed that the hull has enough strength to endure the forces
generated during a sudden impact with the water surface.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 12 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 4
WING DESIGN
The objective of the wing design is to provide sufficient lift to the aerodynamic body,
also the wing should have a streamlined shape to reduce the drag force and the configuration
should be such that it provides maximum aerodynamic efficiency.
The wing design started with choosing the wing profile. For an aircraft flying in the
ground effect region the shape of lower side of the airfoil is very important. In many cases
designers opt for a flat lower side because a convex lower side may in certain situations lead
to suction at the lower side, either hydrodynamic or aerodynamic. A concave bottomed wing
section leads to very poor longitudinal stability. Based on the data collected, DHMTU airfoil
was found to provide maximum efficiency in the ground effect region as it is having a flat
lower portion and an S shaped camber line which is favourable for stability. To verify this
CFD analysis of the DHMTU profile was done and this was compared with the CFD analysis
of other NACA profiles which were commonly used. DHMTU 8-40-2-10-3-60-20-15 was
chosen as it has an appropriate nose radius which would lag the flow separation in strong
ground effect region. It was also found out that this airfoil has maximum aerodynamic
efficiency at 6 degree of angle of attack.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 13 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 9: Airfoils operating in strong ground effect region at low AOA. LEFT: suction
effect is very high on a NACA 0015 profile, CL=-1.2. RIGHT: suction effect is very small
on a DHMTU, CL=-0.1.
Characteristics of DHMTU airfoil
It was found that the drag of the DHMTU decreases with decreasing altitude.
The DHMTU possesses superior L/D at low angles of attack when in ground effect.
Lift of a section increases as the proximity to the ground decreases.
The airfoil geometry was obtained from UIUC Applied Aerodynamics Group‟s website.
DAT files of various airfoils shape are available for free in their website, as DAT file is not
compatible for CATIA the designers used PROFSCAN software to generate a DXF file
which is compatible in CATIA. The CFD analysis was performed in ANSYS software.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 14 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
4.1. CFD analysis for different airfoils at 6 degree angle of attack in ground effect
region (h/c=20%) at 30m/s
Comparison of DHMTU airfoil with other airfoils [5] used for ground effect vehicles
shows that, DHMTU has the maximum lift coefficient in the ground effect region and hence
it provides maximum lift to the vehicle.
AIRFOIL CL
DHMTU 0.778
GLENN MARTIN 2 0.734
CLARK Y 0.736
NACA 2412 0.73
NACA 16006 0.715
TABLE 1: CL values of different airfoils at 6 degree angle of attack in ground effect
region (h/c=20%) at 30m/s.
4.2. CFD analysis of DHMTU airfoil at different angle of attacks at 30m/s
Table 3 provides indication that as the AOA increases the value of CL increases up to
a certain point and later it decreases. The maximum value of CL is at 130 AOA and its value
is 0.9. It can be seen that the maximum value of aerodynamic efficiency is at 60 AOA and its
value is 13. The aerodynamic efficiency is high at low values of AOA.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 15 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
AOA L/D
3 0.25 0.023 10.86
4 0.49 0.04 12.25
5 0.51 0.04 12.75
6 0.52 0.04 13
7 0.72 0.07 10.28
8 0.77 0.09 8.55
9 0.88 0.109 8.07
12 0.89 0.17 5.2
13 0.9 0.175 5.1
14 0.86 0.2 4.3
TABLE 2: Table of aerodynamic efficiency of DHMTU airfoil at different angle of attacks.
Fig 10: Cd vs A.O.A
It can thus be inferred that increase in the angle of attack increases the coefficient of drag as
well.
0
0.05
0.1
0.15
0.2
0.25
3 4 5 6 7 8 9 12 13 14
Cd
Angle of Attack
Cd vs A.O.A
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 16 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 11: Cl vs A.O.A
From the above graph, it can be inferred that Cl increases with an increase in the angle of
attack till 13o after which stalling occurs and the value of Cl starts decreasing.
Fig 12: Velocity Contour at 130
AOA
0
0.2
0.4
0.6
0.8
1
3 4 5 6 7 8 9 12 13 14
Cl
ANGLE OF ATTACK
Cl vs A.O.A
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 17 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Fig 13: Aerodynamic efficiency VS AOA
From the above analysis it is clear that the maximum value of aerodynamic efficiency
is at 6 degree angle of attack. Therefore 6 degree angle of attack was chosen.
After fixing the wing profile and the angle of attack, the next thing that was calculated
was the surface area of the wing. Before that the shape of the wing was taken as rectangular
for the ease of fabrication.
L= ⁄
Lift force is equal to the weight of the WIG aircraft which is equal to 10*9.81=98.1N
The value of at sea level is 1.225kg/
V is the true air velocity which is 30m/s
is the coefficient of lift which depends on the airfoil shape and its angle of attack.
Considering the wing tip vortices effect was taken as 0.5.
S is the area of the wing surface which was calculated to be 0.363 sq meters.
0
2
4
6
8
10
12
14
3 4 5 6 7 8 9 12 13 14
L/D
RA
TIO
ANGLE OF ATTACK
L/D RATIO vs AOA
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 18 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
For a WIG aircraft the effective span increases due to incomplete vortices formation
as discussed earlier. So considering the geometric constraints, the aspect ratio was fixed as 2.
The small aspect ratio of the WIG aircraft provides maximization of efficiency of power
augmented take-off.
Aspect ratio=
=
So Chord=0.429m and Span=0.853m
4.3. CFD analysis for DHMTU airfoils at various heights above the sea level in ground
effect region at 6 degree angle of attack at 30m/s
It can be inferred from Table 4 that as the proximity to the ground increases the value of CL
and hence lift force increases.
h/c %
20 0.778
30 0.76
40 0.594
50 0.584
60 0.568
100 0.5
TABLE 5: Variation of with height in ground effect region
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
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4.4 CFD analysis for DHMTU airfoil at various velocities.
It is indicated from the table that as the value of free stream velocity increase the
value of lift increases and that of drag reduces as the result the value of aerodynamic
efficiency increases.
VELOCITY(m/s) CL CD CL/CD
30 0.7617 0.0753 10.11
40 0.765 0.0745 10.26
50 0.767 0.0741 10.35
60 0.7685 0.0739 10.39
70 0.769 0.0736 10.47
80 0.7715 0.0734 10.51
90 0.7734 0.0735 10.52
100 0.7735 0.0733 10.55
120 0.776 0.0732 10.60
140 0.777 0.0728 10.67
TABLE 4: Variation of CL/CD with velocity in ground effect region
Fig 14: OPTIMUM AIRFOIL CONFIGURATION: CFD analysis of DHMTU airfoil at
60 AOA, V=30m/s, h/c=20%
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
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4.5 WING STRUCTURE DESIGN
The objective of structure design was to provide sufficient strength to the wing so that
it doesn‟t buckle and flutter due to the forces acting on it. Three wing structures were chosen
and designed; model analysis and structural analysis were performed on all the three wings
and the optimum wing was chosen.
WING 1 WING 2 WING 3
WEIGHT 0.632 kg 0.613 kg 0.604 kg
NUMBER OF
SPARS
NPS 1/8 SCH 5 SDS NPS 1/8 SCH 5 SDS NPS 1/8 SCH 5 SDS
NUMBER OF RIBS 3 of 0.02 inch 2 of 0.02 inch 2 of 0.02 inch
TABLE 5: Different wing configuration.
1) 2)
3)
Fig 15: Structure 1) WING 1, 2) WING 2, 3) WING 3
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 21 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
1) 2)
3)
Fig 16: Equivalent Elastic Strain 1) WING 1, 2) WING 2, 3) WING 3
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 22 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
1) 2)
3)
Fig 17: Equivalent stress 1) WING 1, 2) WING 2, 3) WING 3
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 23 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
1) 2)
3)
Fig 18: Total deformation 1) WING 1, 2) WING 2, 3) WING 3
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 24 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
1) 2)
3)
Fig 19: Modal analysis 1) WING 1, 2) WING 2, 3) WING 3
It was determined from the above analysis that for efficient and strong designs the
spacing or ribs should lie around 50% of chord length as in design wing 1.
As weight of all three wings were approximately the same, wing 1 was easy to
fabricate and didn‟t flutter much even if its resonance frequency matches with the exciting
frequency. So wing 1 was chosen as the optimum wing.
Frequency of fundamental mode for wing 1 = 51.363 Hz
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In an aircraft the exciting frequency is due to vortex shredding, which occurs in a
oscillating flows that takes place when a fluid such as air or water flows past a surface at
certain velocities, depending on size and shape of the body. In this flow, vortices are created
at the back of the body and detach periodically from either side of the body. The fluid flow
past the object creates alternating low pressure vortices on the downstream side of the object.
The object will tend to move towards the lower pressure zone. If this frequency matches with
the resonant frequency, large amplitude vibrations takes place leading to damaging of the
parts.
St = fL/V
St is the Strouhal number = 0.198(1-1/Re)
Re is the Reynolds number = =8.89*
is the = 1.798* Ns/
L is the chord length = 0.429m
V is the flow velocity = 30m/s
f=vortex shedding frequency which was calculated to be, = 14Hz
As the value of exciting frequency is very much far away from the fundamental frequency of
the wing so the wing would not go into resonance and hence it would be safe and no
fluttering would occur.
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Chapter 5
HORIZONTAL STABILIZER
The main objective of designing the horizontal stabilizer is to trim the aircraft.
The centre of pressure of the main wing is at 0.33h/c as it is in the ground effect
region and that of the horizontal stabilizer is taken at the quarter chord point as it is outside
the ground effect region.
The centre of gravity of the WIG aircraft is 0.15m in front of the centre of pressure of the
main wing.
Main wing
Chord length = 0.429m
Span = 0.853m
Aspect ratio = 2
Horizontal stabilizer
Chord length = 0.255m
Span = 0.355m
Aspect ratio = 1.7
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Fig 20: WIG Design
The centre of pressure of the horizontal stabilizer is at a distance 5*(distance of centre
of pressure of front wing from the centre of gravity). The lift force acting on the horizontal
stabilizer is 20N.
For horizontal stabilizer, for ease of fabrication symmetric airfoil profile is chosen. To
choose an optimum profile CFD analysis was done on some airfoils.
NACA0006
Fig 21: Contours of static pressure Fig 22: Pressure coefficient over a NACA0006
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RIT, KOTTAYAM 28 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
NACA16006
Fig 23: Contours of static pressure Fig 24: Pressure coefficient over a NACA16006
From the above analysis it is clear that in NACA16006 flow separation is delayed due
to delay in the adverse pressure gradient, hence NACA 16006 would have lower drag
compared to NACA 0006. Angle of attack was fixed as -6 degree, as aerodynamic efficiency
is maximum at this angle. for NACA 16006 at 6 degree angle of attack was found to be
0.5, considering the end effects for calculation it was taken as 0.4.
From L= ⁄
True air velocity was found to be 30m/s. The surface area was calculated to be 0.0907 sq.
meter.
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Chapter 6
VERTICAL STABILIZER
The main objective to design a vertical stabilizer is to provide direction stability. For
the ease of fabrication the same airfoil was chosen i.e. NACA16006.The vertical stabilizer
was designed to have approximately half the area as that of the horizontal stabilizer. Height
of the vertical stabilizer was fixed as 0.192m. This value was taken considering the diameter
of propeller being mounted upon the horizontal stabilizer. The vertical stabilizer was made bit
curved from the front side to increase the supporting area for the engine mountings to be kept
over the horizontal stabilizer. The mean chord of the wig is 0.2725m.
6.1 Rudder and Elevator
The main objective of designing a rudder is to allow the pilot to control the yaw
motion of an aircraft. The rudder should have sufficient area to help the pilot to control the
yaw motion.
The elevator is designed to control the pitch of the WIG craft.
The rudder and elevator hinge line is positioned at 73% of vertical and horizontal stabilizer
chord respectively.
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RIT, KOTTAYAM 30 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 7
ENDPLATES
The main purpose of endplates in WIG aircraft is to increase the ram effect. The ram
effect is due to the growth of the pressure difference below and above the vehicle, the
endplates become an effective means to hinder the leakage of the air from under the wing.
Characteristics of endplates
Use of endplates leads to noticeable augmentation of the effective aspect ratio.
The smaller the aspect ratio the more efficient are endplates.
The highest increase of the lift coefficient due to the endplate occurred when the
centre of the endplate coincided with the centre of the wing.
The endplate should be so designed that its bottom surface should be just touching the
water level.
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Chapter 8
FABRICATION
Fig 25: Final wing design
8.1 Hull
The parameters of the hull have been as given in the previous section on hull design.
Fabrication of a hull is an intricate process and hence needs to be done in good
precision limits. As a result, it was initially proposed to fabricate the hull using fibre glass. As
a part of moving on, help was sought from Praga industries, Aroor who initially consented
and assured the fabrication with the same.
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On further analysis, the project team and the industry decided to drop the idea of
complete fabrication in fibre glass due to the high cost incurred and the difficulty in making a
pattern and finally a die for a single piece of experiment which seemed impractical.
It was later decided to fabricate using plywood, as suggested by the MD of the
industry, who also promised to give us a coating of fibre glass to the model if the need arises.
But the complex shape of the hull and the related 3D curves made it a difficult task
for us to pursue the fabrication with plywood.
Finally, it was decided to continue with wood and the probable materials were
shortlisted. Keeping in mind the requirements of light weight, low cost, easy availability and
easy machinability the wood were shortlisted to mahogany.
Advantages of Mahogany wood
It is straight grained and free of voids and pockets
It has excellent workability and durability
It resist wood rot
Attractive appearance
Can be glued easily and can be finished and polished
The item was purchased with the help of a local carpenter who has would assist in the
machining of the wood into the required shape. Two lumps of wood of 5 inch by 5 inch by 5
feet were purchased.
As per the plan, the entire hull design had to be divided into 14 different planes
incorporating side and top view with cross sectional view in each plane for fabrication. These
different views should collectively give the entire structure of the hull.
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8.2: Wing
SL
NO
MATERIAL SPECIFICATIONS QUANTITY
1 Aluminium sheet 0.508 mm*500mm 2 m
2 Aluminium sheet 0.508 mm*500mm 0.4 m
3 Aluminium pipe Outer
radius:5.144mm
Inner radius:4.255mm
3 m
4 Wood-Mahogany
Table 6: Material requirement
Advantages of Aluminium over other materials:
Low Density of 2.7g/m^3
Relative high strength properties
Good thermal and electric property
High corrosion resistance
Technological effectiveness
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It is decided to fabricate the wing using Aluminium sheet of thickness 0.508 mm. The
joining is done by riveting. The strengthening structure will also be constructed in
aluminium. The ribs will be made by cutting airfoil shape in aluminium sheet of 0.508 mm
thickness. The holes are drilled for connecting spars. There will be two spars connecting the
ribs. The spars are made up of aluminium pipes of outer radius 5.144 mm and inner radius
4.255 mm. The free space between the ribs and spars are filled with thermo coal. The wing is
attached to the hull by screwing the spars at the platform at the centre of hull. The end plates
are made up of wood (Mahogany) and screwed to the outer rib.
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Chapter 9
ENGINES AND RELATED COMPONENTS
The power-plant for the craft was selected on the basis of the thrust produced by it when
coupled to the propeller of specified pitch and diameter. The nitro-fuel model IC engines
were preferred over the electric motors for the following reasons:
comparatively higher power-output (available power ratings of the electric motors
were insufficient )
operating cost (market survey confirmed that even though the motor cost was lower,
the battery was expensive)
weight ( mechanical leverage over the heavy batteries )
To select the IC engine and a suited propeller, it was required to fix the thrust essential
for the craft. As the estimated dead weight of the craft was about 8 kg, it was decided to have
a thrust of 8kg to overcome the different types of drag that the craft experiences which
includes hydrodynamic drag, the planning mode-GEZ transition drag and the aerodynamic
drag, thus assuring a completely effective propulsive unit. The combined thrust of the three
IC engines should overcome all of the above cited drag, so each engine-propeller
combination should at least possess a thrust of 2.66 Kg. For deciding on the IC engine it was
required to decide on the manufacturer based on the criteria of cost, weight and simplicity of
the design and operation. Many RC flying-clubs were contacted for getting acquainted with
the various engine manufacturers and it was decided to contact the Super-Tigre company,
based in Illinois, US. The different categories of engines were again compared and the 2-
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
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stroke engines were selected for their superior power-to-weight ratio and operational
simplicity over the 4-stroke engines. There were a total of 10 engines available from the
company for aero-applications. Three engines, namely GS 40, GS 45 and GS 75,were
selected for comparison and performance study based on its application. The possible power-
plant configurations were as cited below:
Two GS 40 engines as bow-thrusters and one GS 75 engine as the main propulsive
unit.
Two GS 45 engines as bow-thrusters and one GS 45 engine as the main propulsive
unit.
The power-plant configuration was selected by the determining the static thrust parameter for
various engine-propeller combinations. The static thrust (the thrust produced at zero air-
speed) was initially decided to be determined using the following equation:
However as the multitude of the inputs required were not available and the calculation
which related the thrust with the power output of the engines rendered additional complexity
to the procedure, it was decided to devise an alternative method. Different soft wares were
available for calculating the thrust from a particular engine-propeller combination; a well-
regarded software, the Static Thrust Calculator was used to determine the thrust for all the
engine-propeller combinations specified by the manufacturer.
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The STC software required the following inputs:
Propeller diameter and pitch
Propeller type (Manufacturer-dependent)
No. of blades
Operating RPM
Air temperature and density
The calculation yielded the thrust produced from the combination and the horse-power
required producing that much of thrust, so for each engine-propeller combination it was
required to counter-check whether the calculated „required horsepower‟ was within the rated
horsepower of the engine.
This required-horsepower parameter helped in confining the propeller selection criterion
to a small range of propellers for each engine. For example, the GS 75 engine produced 3.22
kg of thrust @ 2.2 hp when a 10X8 propeller was used and produced 3.5 kg thrust @ 2.4 HP
when a 11X8 propeller was used.
By calculating and comparing the thrust and required horsepower parameter the second
power-plant configuration was confirmed given our geometric constraints and thrust
parameters and expenditure. The GS 45 engine was rated 1.5 HP @ 16000 rpm and the
propeller was a 10X6 APC W standard, the engine-propeller combination yielded 3.33kg
thrust @ 1.48 HP with an estimated flying speed of 90kph.
The RFQ was placed for the engines and accessories and the company acquainted an
affordable package, consolidating the total cost at INR 15,800/- .
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Fig 26: Final design
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Chapter 10
ELECTRICAL AND ELECTRONIC UNITS
This aircraft is a scale down model and the control is carried out through a radio
control unit. There are total five servomotors in this system for controlling the throttle
openings of three engines, rudder and to actuate the front engine platform tilting mechanism.
The five channel radio control unit of 300 meter range (Including transmitter, receiver) for
controlling these servomotors is purchased as a readymade unit and the servomotors with
control unit of required specifications are also purchased. A 6V rechargeable DC battery is
used to power these motors, control system and receiver. The servomotors are linked with
rudder and carburettor through simple linkages and the servomotor controlling the engine
angle is connected to engine platform through a reduction gear mechanism. The system is
tuned according to convenience of the operator.
The specifications of electrical and electronic units:
Throttler servo: Hitec HS311, 3.5 kg.cm,0.11 sec/60 deg @ 6V
Rudder servo: Hitec HS485B, 6.41 kg.cm,0.18/60 deg @ 6V
Tilter servo: Hitec HS5565MH Digital Programmable Servomotor(metal
gear),11kg.cm,o.11s/60 deg @ 6V
Hitec Optic 5 channel transmitter and receiver
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RIT, KOTTAYAM 40 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 11
SCOPE OF WIG CRAFT
12.1 Civil applications
According to a preliminary analysis, there exist encouraging prospects for developing
commercial ekranoplans to carry passengers and/or cargo, to be used for tourism and leisure
as well as for special purposes, such as search-and-rescue operations.
12.1.1 Search-and-rescue operations
An analysis of existing means of rescue on water shows that surface ships are unable
to come to the place of disaster quickly enough, while airplanes cannot perform effective
rescue operations because the airplanes cannot land close to a sinking ship. Even most
modern seaplanes have both lower payload and seaworthiness as compared to the
ekranoplans. The GE search-and-rescue vehicle „„Spasatel‟‟ is under construction at
„„Volga‟‟ plant in Nizhniy Novgorod.
12.1.2 Global Sea Rescue System
There is a worldwide concern to develop effective rescue measures on the high seas.
Experience shows that it is very difficult if not impossible to provide timely aid at wreckages
and ecological disasters at sea. Use of seaplanes is often limited because of unfavorable
meteorological conditions, whereas use of helicopters is restricted to coastal areas. Until now,
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the main means of rescue (salvage) on water has been ships finding themselves accidentally
near the disaster area and hardly suitable for this purpose.
12.1.3 Other civil applications
Transportation of non-standard commercial payloads of large sizes and weights,
Search-and-rescue operations of large scale,
Transportation of perishable goods in quantity throughout the world,
High-speed luxury transportation,
Rapid response to international market fluctuations.
12.2 Naval application
Analysis of known projects and future naval applications have confirmed that the
above listed properties of ekranoplans together with their high surprise factor due to speed,
low radar visibility, sea keeping capability, payload fraction comparable to similar size ships,
dash speed feature and capacity to loiter afloat in the open ocean make them perfect multi-
mission weapons platforms which can be deployed forward and operate from tenders.
Naval ekranoplans can be used as strike warfare weapons against land and seaborne
targets, launch platforms for tactical and strategic cruise missiles, aircraft carriers and
amphibious assault transport vehicles. Easy alighting at moderate sea states makes it possible
to utilize ekranoplans as antisubmarine warfare planes capable of effectively deploying
hydrophones or towed arrays. They can also be used in a wide variety of reconnaissance and
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transport roles. WIG effect vehicles could adapt themselves to an operational concept of
anchorages all over the world to maintain a forward posture.
12.2.1 Anti-surface warfare
Sustained sea-level operations of ekranoplans would reduce the horizon-limited
detection ranges of defending airborne early warning systems, significantly reducing warning
time. If the defender has no airborne early warning assets, mast height ship radars would not
see the ekranoplan until it almost reached its target.
From operational and tactical viewpoints, the ekranoplan has incontestable advantages
versus any other missile-carrying platform, in particular
Ekranoplan speeds exceed by an order of magnitude those of conventional surface
ships. Unlike aircraft, the ekranoplan is not tied to airports or aircraft carriers and can
be depressively based in any coastal area,
Unlike aircraft, the ekranoplan is less visible, flies in immediate proximity to the
water surface, and has large combat payloads. Due to its additional capability to
conduct flight operations far from the underlying surface, the ekranoplan can perform
self-targeting for larger ranges.
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12.2.2. Anti-submarine warfare
The ekranoplan would be an effective platform for anti-submarine warfare (ASW),
being capable to detect, localize and destroy submarines at long ranges from their base. Its
significant payload capability would allow it to carry numerous sonobuoys, torpedoes and
mines. The ekranoplan could operate in a sprint-drift mode, alighting only to dip its sonar.
12.2.3. Amphibious warfare
The speed, payload and low-altitude cruising capabilities of the WIG would enable
devastating surprise assaults. The major difficulty with PAR-WIG amphibious operations is
the actual landing of men and equipment. Since reduced structural weight is a key factor
enabling efficient WIG flight, the vehicle cannot be reinforced to allow beaching without
deterioration of its cruise performance.
12.2.4. Sea lift
Ekranoplans are expected to be quite effective in providing a sealift function.
However, as shown by some estimates, in order to reliably brave high sea states, a trans-
oceanic WIG would need to be very large, at least 900 gross weight tons. Even so it is
estimated that one such WIG could deliver more cargo farther than three 300-ton C-5 aircraft-
and do this while using 60% less fuel.
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12.2.5. Nuclear warfare
The performance characteristics of the WIG would make it suitable as a launch
platform for tactical and strategic cruise missiles. Its sea skimming cruise capability would
allow it to exploit gaps in low-altitude radar coverage. Furthermore, its sea loiter feature
would give it a flexibility not found in conventional strategic bombers. In fact, in a crisis, the
WIGs could deploy to mid-ocean and alight on the surface to maximize their survivability.
12.2.6. Reconnaissance and Patrol
Maybe, the weakest mission application for large WIGs would be in reconnaissance
or patrol. The limiting horizon resulting from low-altitude operation would greatly reduce
radar or signal intercept range, and therefore area coverage, to the point where it might not
represent a cost-effective use of the platform. Even in the strike warfare posture against ships,
WIGs would require targeting information from other platforms.
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RIT, KOTTAYAM 45 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
Chapter 12
COST REPORT
The expenses incurred as of date (for purchase, excluding transport and other petty charges)
NO PRODUCT DESCRIPTION QUANTITY EXPENSES(RS)
SuperTigre GS-45 Dual BB ABC w/Muffler 3 16000
1 Servomotors 6 6800
2 Carpentry and tool charges 5000
3 Wood- Mahogany 5 cubic feet 4900
4 Starter Motor (Tower Power Deluxe 12V starter
motor)
1 2400
5 Model engine fuel( 15 % nitro fuel) 4 litres 2400
6 Araldite gum 750 gm 1200
7 Tower Power Glow Plug 3 1100
8 Master Air screw Fibre glass propeller 9.5 X 6 inch 3 890
9 Engine Mount 3 800
10 Propeller spinner cone (2-inch Blazer spinner) 3 780
11 Fuel Filter 3 700
12 Aluminium sheet 0.5 mm gauge – 0.45 kg
0.3 mm gauge – 0.45 kg
630
13 Square fuel tank 3 610
14 Fuel tubing 3 520
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17 Aluminium pipe 19 mm dia, 4 m length
15 mm dia, 8 m length
350
18 Paint 2.5 litres 300
19 M seal 500 gm 100
20 Bolts and screw 0.9 kg 90
TOTAL : 45570
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Chapter 13
ADVANTAGES AND OPPORTUNITIES
As the craft will not be operated at high altitudes, the fuselage (or cabin) of the craft
need not be constructed for pressurization, as for commercial aircraft.
The WIG can be operated across shallows and does not need marked channels by
water depth or pre-designated navigation routes. Tidal conditions are also no problem
if a slipway and hard standing terminal apron is used.
Low visibility for radar and other electronic devices.
High payload capability compared to conventional vessels.
drag is very low once the craft has taken off from the water surface into ground effect,
enabling much higher cruise
Speed higher than other marine vehicles, and also a smaller speed loss during
operation over waves.
High fuel efficiency, low environmental emissions and low weight.
The specific fuel consumption SFC is improved for WIG compared with other high-
speed marine craft due to the ability to cruise at a much lower proportion of total
installed power.
The economic efficiency of WIG can compete with an airplane. At short range, the
lower fuel requirement for WIG can be translated into higher payload.
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Chapter 14
CHALLENGES AND LIMITATIONS
Aerodynamic stability and control within very fine limits due to its proximity to the
water surface.
The challenge of designing a configuration of main hull, lifting wing(s) and
stabilizing surfaces to give minimum drag in all the modes from floating, possibly
hovering, through planing, to flying in ground effect.
To fly at a steady clearance height.
Varied operating conditions from low-speed waterborne operation, transitions to
planing and take-off, followed by ground effect operating mode and out-of-ground
effect mode for some special craft.
Speeds of up to 400 knots at low operating altitude, wave impact, take-off and landing
loads as well as bird strike all have to be taken into consideration in the design
process. Take-off and
Landing operations in rough water at speeds from 50 kph up to 150 kph involve
hydrodynamic forces much larger than experienced by all except the fastest marine
craft.
Obtaining reliable data during testing phase of the craft.
Due to the low-level flight, turbulence levels are high, particularly when flying over
rough water.
Rotating the complete propulsion unit imposes significant structural design challenges
especially with multiple units installed side-by-side. The dynamic loads due to gust or
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water impact induced by the large mass of the propulsion units cantilevered outboard
can be difficult to handle, especially when they are mounted on rotating mechanism.
There are no WIG commercial service routes operated so far, even though the WIG
has been successfully operated and tested for more than 30 years.
Will require area outside normal navigation channels suitable for a water runway of
1,000–2,000 m in length and 500 m in width for take-off.
The collision risk for WIG is higher than that of conventional high-speed craft
because of its very high speed and operation essentially at ground level, so the
navigation equipment installed such as radar has to be responsive, precise, light and
reliable.
Setting up operations with a WIG service will require considerable vision on the part
of the operator and careful training of personnel.
For successful and safe commercial operations, the route of an established service
should be designated as a WIG route and documented on charts so that ships would be
warned of the presence of these high-speed craft.
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Chapter 15
CONCLUSION
The most optimum wing configuration for the ground effect vehicle was obtained.
The research conducted so far shows that DHMTU airfoil is having superior lift performance
when compared to other airfoils. This might be due to the flat lower portion of the airfoil and
a S shaped camber line which provides stability in the ground effect region. It has also been
observed that as the proximity to ground increases that value of CL increases and hence lift
force increases, this is due to the increase in ram effect ie the amount of air trapped beneath
the airfoil increases hence increasing the difference between the amount of air below and
above the airfoil also there is reduction in drag of the airfoil due to span dominated ground
effect. The drawback of DHMTU is that out of ground effect it doesn‟t offer high lift as it
does in ground effect region contrary to this the value of CL for NACA 2412 out of ground
effect is 0.8 and in ground effect it was found out to be 0.72, same was the behaviour of other
airfoils. It was also observed that for small value of AOA at very high ground effect region
(h/c<=0.1) airfoil having convex bottom surface, there is occurrence of suction effect at the
bottom portion of the airfoil; it was also observed that the suction was not so high for
DHMTU airfoils. It was also observed that the DHMTU offers superior aerodynamic
efficiency at low AOA and has the maximum aerodynamic efficiency at 60 AOA. It was also
observed that the value of aerodynamic efficiency increases as the velocity of airflow
increases.
WIG is a transport technology that can deliver different craft with operating speeds
anywhere from 80 kmph up to 600 kmph and one where craft size can also be significantly
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larger than aircraft. It has been rightly over 4 decades since the advent of the largest WIG
ever build- Caspian Sea Monster, the largest aircraft at the time.
But this hasn‟t now spawned into a great industry already. But the new century had
brought in hopes for the technology with Boeing too entering into the arena with its Pelican
project. A large-scale WIG development would be very capital intensive and so require major
government funding if it were to succeed, just as the Russian Ekranoplan development in the
1970s and 1980s. That program died when the government funding was unable to be
continued.
One requirement WIGs have taken some time to respond to is wave height capability.
While cruising, wave height is not so much of a problem, but if you can only take off and
land in rather small waves, it becomes quite difficult to plan long journeys where the seas
will exceed the landing criteria. Creating a very large model will cause a series of problems
such as air compression under the main wing in strong GEZ, aero-elasticity of the structure,
structural vibration, etc.
In order to get the WIG into commercial operation, a good deal of equipment,
facilities and regulations will need to be designed and agreed as standards, such as special
ground equipment, allocated air navigation zones close to terminals, agreed methods for
collision avoidance with marine craft and new safety codes for operation. Since the WIG is a
mixture of aviation, shipbuilding and air cushion industry technology, including both
aerodynamics and hydrodynamics, some novel problems will continue to be encountered as
craft designs evolve. In spite of all these, we fervently hope that this technology would one
day pioneer a new dawn into the maritime transport industry and this concept would one day
ply in the waters and would be a viable transport replacement for fast and large freight and
human transport.
DESIGN OPTIMIZATION, FABRICATION AND FEASIBILITY STUDY OF A WING IN GROUND EFFECT CRAFT
RIT, KOTTAYAM 52 DEPT. OF MECHANICAL ENGINEERING,’10–‘14
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