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International Journal of Computer Aided Engineering and Technology

Modelling, Sizing and , Simulating an Omni Wing using

MATLAB, XFLR5 and eCalc Programs

Dr. Sudhir Chaturvedi*

Assistant Professor
Department of Aerospace Engineering
University of Petroleum and Energy Studies (UPES),
Dehradun, 248007, India
Email: sudhir.chaturvedi@ddn.upes.ac.in
*Corresponding Author

Dhananjay Notnani
Department of Aerospace Engineering
University of Petroleum and Energy Studies (UPES),
Dehradun, 248007, India
Email: 500063806@stu.upes.ac.in

Prithvi Adhikary
Department of Aerospace Engineering
University of Petroleum and Energy Studies (UPES),
Dehradun, 248007, India
Email: 500060986@stu.upes.ac.in

Servesh Chaturvedi
Department of Aerospace Engineering
University of Petroleum and Energy Studies (UPES),
Dehradun, 248007, India
Email: 500061622@stu.upes.ac.in

Abstract: An omni-wing aircraft is a complete single body wing planform

without a fuselage or a longitudinal compartment to house freight or
passengers or equipment. It lacks an empennage section, hence forth no
stabilizers to control yaw. It also lacks the form drag which acts as an
advantage towards the aerodynamics of the aircraft by providing high lift
to drag ratio. In this paper, we present a nonorthodox approach to the
classical design of an Omni-wing aircraft. Our objective will be primarily
directed onto modelling and simulating an Omni-wing with a decent
range and high endurance capabilities. We selected this design of omni-
wing aircraft since we wanted to build a UAV which is able to mediate the
operational capabilities of the fixed-wing drone as well as the
conventional aircraft. The advantage we hope to exploit is the fast pace
and agility of an omni-wing aircraft in the realm of surveillance. In order
to achieve surveillance capabilities, we plan to install miniature cameras
and infrared sensors to capture images of the terrain as well as potential
targets on ground and relay them in real time through electromagnetic
wave connectivity with the aircraft at a later stage.

Keywords: form drag, longitudinal, omni-wing, real-time, stability, UAV

Abbreviation: CL, Coefficient of Lift; C Lo,w, Coefficient of Lift at 0° Angle of

Attack; CLα,w, Coefficient of Lift at α° Angle of Attack; C M, Coefficient of
Moment; CM0,w, Coefficient of Moment at 0° Angle of Attack; C Mac,w, Coefficient
of Moment about Aerodynamic Chord; CMα,w, Coefficient of Lift at α° Angle of
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Sudhir Chaturvedi
Attack; CD, Coefficient of Drag; α, Angle of Attack; b, Wingspan; c, Chord
length; XN, Position of Neutral Point; Xcg, Position of Centre of Gravity; Xac,
Position of Aerodynamic Centre; Xc/4, Position of Quarter Chord; lr, Root Chord;
lµ,c̅, MAC, Mean Aerodynamic Chord; λ, Taper Ratio; Φ, Sweep Angle; CG,
Centre of Gravity; UAV, Unmanned Aerial Vehicle; DC, Direct Current; LiPo,
Lithium Polymer

1. INTRODUCTION
Aerodynamic engineers have always been
fascinated with an efficient design with superior
dynamics. In an aircraft, the wing is the most
important primary lift producing member. Hence, it
has always been wondered if a clean wing design,
will be able to match or uplift the performance of a
conventional aircraft. It has always been a point of
concern of how to reduce the drag encountered
due to non-lift producing members such as the
empennage and fuselage and if these extra
sections could be omitted while still making the
aircraft suitable for stable flight.

A flying wing or Omni-Wing, as the name Figure 1: The adverse yaw

suggests, is a complete single body wing planform
without a definite fuselage and houses payload
and equipment inside the main wing structure. It Technically, the flying wing is more efficient than
lacks an empennage section, hence forth no their rotary counterparts as they have much
stabilizers to control yaw. The center of gravity is simpler structure, ease of maintaining and high lift
designed to be further than the center of pressure to drag ratio. They also have an edge over drones
during flight and a reflex camber is provided in the in range, stability and recovery. Normally, their
airfoil which makes the flying wing possible. The stall behavior is good and tendency to spin is low.
reflex, though giving longitudinal stability, causes They can also maintain a constant attitude of a
loss of some of the Newtonian lift and hence flying bank angle while circling[ CITATION Ahm18 \l
wings aren’t as efficient as their non reflexed 1033 ]. However, there are disadvantages too.
counterparts[ CITATION Bas \l 1033 ]. Flying The permissible CG limits are lower and they often
Wings also encounter adverse yaw i.e. yaw (side have inferior flight performance. Crosswinds make
slip) in the opposite direction of roll. It occurs them difficult to operate. They are also bulky for
every time the ailerons are used. This happens transportation.
due to more lift and drag on the outboard aileron
deflected downwards than the inboard one A tailsitter is also essentially a flying wing capable
deflected upwards in the direction of roll. of taking off and landing vertically on its tail with
the nose and thrust direction pointing upwards.
For fast forward flight, the vehicle tilts to a near-
horizontal attitude resulting in a more efficient lift
production with conventional wings. Compared to
other powered lift aircraft types, the major
advantage of a tailsitter is its mechanical
simplicity; no mechanism for changing the
direction of the propulsive system has to be
added, saving weight and reducing susceptibility
to malfunctions. As a result of the availability of
cheap, lightweight electronic components and the
numerous potential applications of such small
3 Modelling, Sizing and Simulation and Omni Wing aircraft by MATLAB, XFLR5 and e Calc Programs

hybrid vehicles, many researchers and companies propellers

have recently started research programs exploring
the capabilities of these flying machines. Payload To be decided
[ CITATION Rob15 \l 1033 ] Range 500 meters
2. MATERIALS AND METHOD Endurance 20 inutes
We commence by defining a mission specification
and then reviewing the literature done in this field
and understand the parameters influencing the 2.2. Related Work
design and stability. We would then do a
preliminary analysis in MATLAB and XFLR5. A Various researches involving flying wing have
design in Solidworks or Catia will follow and been conducted to understand and optimize the
simultaneous simulation in FEA software to flying characteristics and its stability. Bird Flight
understand the theoretical behavior of the design. characteristics such as dynamic soaring of
Then, the design will be fabricated and tested in a albatrosses, Hummingbird’s ability to hover and fly
wind-tunnel. After a successful flight, integration backwards and formation flights have been
with sensors and payload will be done to meet its studied and tried to be quantified using
objective. mathematical models.

Various surveillance categories with subsystems

and performance parameters have been studied in
Mission Literature Preliminary “UAV Requirements and Design
Specification Review Design Consideration”[ CITATION Erd \l 1033 ] which
provides an insight to the applications of such type
of aircrafts.

Aerodynamic Detailed Stability [ CITATION Ahm18 \l 1033 ] have presented

Analysis Design Analysis an untraditional method of building a flying wing
from scratch. They have taken help of other
researches to specify the geometry and then have
Flight analyzed the aerodynamic performance using 2D
Simulation
and Manufacturing Flight Test and 3D analysis by various techniques.
Performance
Analysis NASA’s research on Prandtl-D wing[ CITATION
Alb16 \l 1033 ] confirms that a bell-shaped
span-loading will be able to achieve a proverse
Payload yaw, which can act as a thrust rather than drag at
addition
the wingtips and presents the tail as unnecessary
thereby seeking to modification in airplane design.
Figure 2: Design Methodology
A propulsion sizing guide named “Electric
Propulsion System Sizing for Small Solar-powered
2.1. Mission Specification
Electric Unmanned Aerial Vehicle“ [ CITATION
The aircraft to be build should neither be very Par16 \l 1033 ], explores tip static speed as key
small as it would cause sensitivity, stability issues parameter for propulsion sizing instead of power
and avionics placement problem, nor too large as to weight ratio. It also concludes that efficiency of
it would be hard to manufacture and is to be used electric motor decreases with larger diameter and
for surveillance. Therefore, the specifications can pitch even though thrust and power to weight ratio
be summarized as: is high.

Table 1: Mission Specifications In “A Global Strategy for Tailsitter Hover

Control”[ CITATION Rob15 \l 1033 ], a self-
Parameter Choice stabilizing mechanism using Machine Learning
and AI has been presented and validated by an
Propulsion System Electric Motor with
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Sudhir Chaturvedi
experiment in ETH Zurich Flying Machine Arena.
The results indicate a good performance in
external aerodynamic disturbances such as gust
given the initial velocity is under a certain limit.
The ability of the vehicle to stabilize from any
initial attitude marks the onset of a new era of an
all-weather highly versatile, efficient, geofenced
and failsafe recoverable UAVs.

3. Preliminary Design

Airfoil Selection
Figure 4: CD vs α
Requirements for an optimum airfoil for tailless
aircrafts are as follows:

 Cm0 i.e. the pitching moment should be very

near to zero
 There should be high degree of positive
difference between CL/CD at αstall and CL/CD at
cruise angle of attack.
 Low CD at cruise and critical angle of attack.

The analysis of various parameters for optimum

airfoils is done in XFLR5 and the graphs are
plotted. For the selection, MH-aerofoils
website[ CITATION Bas \l 1033 ] was referred
where the MH 40 and MH 60 series were
suggested for good performance.

Figure 5: CM0 vs α

Inspecting the performance of the airfoils, it was

concluded that MH-46 airfoil would be the most
suitable as it has a very small nose-down moment
compared to other airfoils and has a high stalling
angle.

Figure 6: MH46 11.39% smooth aerofoil

Figure 3: CL vs α

Wing planform geometry design

Using the Reynold’s number (Re=150,000) we

obtain a value for the Mean Aerodynamic Chord of
the wing to be 0.15 m by using the formula:

ρvc
ℜ=
μ
5 Modelling, Sizing and Simulation and Omni Wing aircraft by MATLAB, XFLR5 and e Calc Programs

Using this obtained data, we first plot a Heatmap

(required to have a graphical representation of the
range of data) in MATLAB with Root Chord Length
Sq. (square matrix), Mean Aerodynamic Chord
(single line matrix), and Taper Ratio (single line
matrix) as the parameters, relating them with the
following formula[ CITATION Bas \l 1033 ] :-

2 1+ λ+ λ2
I μ= l
3 1+ λ r

Figure 8: Regression Plot

We want the taper ratio to be higher than 0.375,

since the model being fabricated is relatively
small. So, a small taper ratio will result in even
Root Chord Length 0.175 m smaller root chord, thus increase difficulty in
manufacturing. We now co-relate the range of
Span 1.051 m Root Chord Length Sq., obtained from the earlier
Heatmap, to find a range on this Linear
Neutral Point 0.115 m Progression plot. From this range (red shaded
area), we find the mean of all the points. We
Taper Ratio 0.6938 obtain a specific value from this mean, which we
again use to find the Root Chord Length Sq. and
MAC Length 0.15 m the Taper Ratio of the wing. So, by co-referencing
both the Linear Regression Plot, and the
Heatmap, we obtain the following results:

Table 2: Regression Result

Figure 7: Heatmap
From the above Heatmap, we select a range of
Root Chord Length Sq. using our obtained value
of Mean Aerodynamic Chord as highlighted. Then
we plot a Linear Progression Plot (required to
estimate the initial design as well as sizing Winglet Geometry Design
parameters) in MATLAB between Calculated
Neutral Point (single line matrix), Span of the wing Table 3: Winglet Characteristics
(single line matrix), and Root Chord Length Sq.
(square matrix) as the parameters relating them Character Value
with the following formula[ CITATION Bas \l
1033 ]: Cant angle 0̊

lr 2 b λwl 0.42
x n= + tan ϕ0.25 ,if taper ratio>0.375
4 3π
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Sudhir Chaturvedi

bwl
0.133
bbw

C wlr
0.33
Cbwt

bwl
is the ratio of winglet span to basic wing semi-
bbw
span.

C wlr Figure 9: XFLR model of flying wing

is the ratio of winglet tip chord to basic wing
Cbwt
tip chord

λwl is the taper ratio of winglet. 3.2. Aerodynamic and Stability Analysis:

The bwl / bbw and Cwlr / Cbwt ratio was set by XFLR5 software is being used for detailed flow
concluding multiple iterations on calculations of analysis of our design. The main objective of this
data points, in effect to analyse the progression of analysis is to achieve a proper variation of the Cp
the effect the ratio had on the stability of the plane, with change in the AOA. The variation of Cp should
primarily on how much it differed the slope of the be decreasing as we move from the LE to the TE
Cm vs AOA curve. Hence 0.133 and 0.33
respectively were chosen. Cant angle is chosen for the top surface of the wing, which is a general
zero degrees for ease of manufacturing. The airfoil observation in wing design. Increasing the AOA
for the winglet is chosen to be same as of the will result in even more increase in Cp over a
wing. particular section of the wing. The following
figures are some of the values obtained for Cp vs
AOA:
3.1. Computer aided design

The flying wing is drawn using XFLR5 so that

design can be improved, flow visualization and a
manufacturing database can be created. This
CAD model is used to predict the center of gravity
of the wing which lies 108 mm from the nose of
fuselage. For a statically stable airplane, the static
margin needs to be positive, which means that for
flying wings

the center of gravity needs to be in front of the

mean aerodynamic center.[ CITATION
Ser01 \l 1033 ] The static margin of 12.5% is Figure 10: Cp at 1̊ angle of attack
taken into account for calculation of CG.
7 Modelling, Sizing and Simulation and Omni Wing aircraft by MATLAB, XFLR5 and e Calc Programs

Figure 14: Flow visualisation around the Omni

Figure 11: Cp at 2̊ angle of attack wing

The Threftz Plot of our aircraft is obtained from

XFLR5 which provides the exact variation of
induced AOA with the span of the wing. Threftz
plot depicts the lifting line or the pressure curve
along the span of the wing.

Figure 12: Cp at 3̊ angle of attack

Figure 15: Threftz Plot

For most flying wings, longitudinal stability is

achieved through aerodynamic means (reflex
airfoil) and/or geometric twist (changing of local
Figure 13: Cp at 4̊ angle of attack incidence angle with change in
span[ CITATION Kar94 \l 1033 ]. A stability
analysis was performed to establish eigen values
and damping times along with frequencies to
determine the aircraft’s longitudinal and lateral
stability. The longitudinal mode 1 resembles
phugoidal motion and the lateral mode 1
resembles spiral motion and lateral mode 2 is roll
damping. The longitudinal mode 3 resembles as
short period disturbance and the lateral mode 3
resembles dutch roll stability. The frequency of
oscillation in both longitudinal and lateral mode 1
analysis prove that the model designed is stable
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Sudhir Chaturvedi
for pitching and rolling motion. There is instability
in the model for longitudinal mode 3 which
represents short period motion, and this is
observation is a general observation for a flying
wing aircraft since it lacks an empennage section.
Although adding winglets to the design does help
in reducing the amplitude of short period
perturbations.

Figure 19: Longitudinal Mode 1 rolling parameter

(q-pitch rate)

Figure 16: Lateral Mode 1 shifting perturbation

velocity (v-lateral speed)

Figure 20: Longitudinal Mode 1 rolling parameter

(theta- pitch angle)

Figure 17: Lateral Mode 2 rolling parameter (p-roll

rate)

Figure 18: Lateral Mode 2 rolling parameter (phi- Figure 21: Longitudinal Mode 1 perturbation
rolling angle) velocity (u-axial speed)
9 Modelling, Sizing and Simulation and Omni Wing aircraft by MATLAB, XFLR5 and e Calc Programs

Table 4: UAV power to weight ratio guide

Accordingly, we got the average current drawn by

the motor fixing the 3-S LiPo Battery pack as it is
the most readily available and used in RC aircrafts
of this weight category.
Figure 22: Longitudinal Mode 1 perturbation Keeping the current, power, thrust and speed into
velocity (w- vertical speed) account we have concluded the propulsion system
for our flying and the components of the same are
stated below:

Table 5: Propulsion Sizing

Component Specifications

KV 1400 KV

Electric Weight 65 g
Brushless
Motor Power 180 W

Thrust 661 g

Constant
Figure 23: Cm vs AOA Electronic 20 A
Current
Speed
Controller
Weight 25 g
From the above Cm vs AOA plot, we find out that
the aircraft’s cruising angle is 3.9 ° . Capacity 1600 mAh
Battery
Weight 114 g

3.3. Propulsion Sizing Diameter 7.0 in

Propeller
Pitch 4.0 in
From the practical learning and testing experience
on propulsion sizing of RC planes, brushless DC
Torque 1.8 kgf.cm
motors are being used for the propulsion system
Servo Motor
of Omni-Wing. Since, brushless DC motors are
Weight 12 g
smaller and weigh less than equivalent DC
brushed motors and they also generate less RF
electromagnetic interference.

The objective of the analysis is to find out the most

optimum propulsion package for aircraft and that
has been done using eCalc, which is basically an
airplane setup and propeller calculator. The
results are accurate up to ± 10%. The whole
system analysis is based on the estimation of
power to weight ratio of 60-75 W/lb[ CITATION
Par16 \l 1033 ] which has been taken from the
Watts per Pound Rule
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Sudhir Chaturvedi
of an empennage section. The outcomes of this
project are just theoretical analyses which needs
to be validated from actual fabrication and flying of
the Omni-wing.

FUTURE SCOPE

As per the emerging exposure that the world is

receiving today in terms of UAVs, the flying wing
has a vast scope in the present as well as in the
coming era. The extent of some highlighted
Figure 24: motor characteristic curve on full opportunities for the flying wing is stated below:
throttle
1. The designers and engineers can look up to
The motor characteristic graph shows curve non- conventional and nature inspired
between five motor performance characteristics blueprints.
and the amount of current being supplied by the 2. The fabrication material can be made more eco-
battery pack at full throttle. These characteristics friendly using bio-fabricating technologies.
are depicted by different colors in the graph 3. The stealth and combat capabilities can also be
representation. features to explore.
4. The surveillance and mapping incorporation can
1. The golden yellow line shows the electric power be done using AI and ML.
in 1 W, which should constantly increase.
2. The blue line shows the efficiency of motor in
percentage, should become constant after some
time. ACKNOWLEDGEMENTS
3. The violet line shows the maximum revolutions First and foremost, we would like to take the
in 100 rpm, should not decrease below 10000 opportunity to express our sincere thanks to our
rpm mentor Dr Sudhir Kumar Chaturvedi for his
4. The brown line shows the loss in input power in constant support and guidance in the project. We
1 W, should be minimized. would also to express our gratitude towards him
5. The green line shows the motor case for giving us this opportunity to have a great
temperature in °C, should be minimized. knowledgeable experience working under him in
an amiable and enthusiastic environment.

We are grateful to the University of Petroleum and

CONCLUSION Energy Studies, for providing us the chance of
All the inputs that have been employed and their pursuing Bachelor of Technology in Aerospace
respective outcomes provide an insight into yet Engineering with Specialization in Avionics in a
another way of modelling and simulating the beautiful as well as competitive environment with
design configurations of an Omni-Wing suitable for required amenities.
various applications. This design particularly
depicts the most optimum sizing of a flying which We are also highly grateful to the CEO of Flying
is capable for high endurance as well as high
Machine Arena, Dr. Rafaello D'Andrea for the
performance statistics throughout the flight. The
sizing was derived with the help of MATLAB major inspiration to opt this particular project and
programming which was further simulated using also for his research and experimental data, which
XFLR-5 which verifies the previous results and we will utilize in the maneuverability of our UAV.
finally modulated in XFLR-5 itself. The power
house sizing was based on empirical and Last but not the least, we are very thankful to our
experimental assumptions initially, which were parents, family members, and friends for keeping
then verified using eCalc flight performance and us encouraged and showing their constant
motor characteristics simulations. Comparing it
support. Without their help, this work wouldn't
with other UAVs, this type of aircraft is more
aerodynamically refined, hence providing more have been made possible.
velocity at the expense of less relative
aerodynamic drag, though it comes at a cost of
short period longitudinal stability rising due to lack
11 Modelling, Sizing and Simulation and Omni Wing aircraft by MATLAB, XFLR5 and e Calc Programs

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