4. 4
Nomenclature
Conceptual Design
Moment Coefficient for longitudinal trim
Distance to centre of gravity
chord
Lift coefficient
Moment coefficient at zero AOA
Dimensional Selection
Taper ratio
Tip chord
Root chord
Aspect ratio
Fuselage length
Statistical correction values for fuselage length
Take-off weight
Wetted area
span
exposed wing area
Reference wing area
Propeller diameter
Statistical correction values for propeller
diameter
Propeller tip speed for static aircraft
Rev/s
Propeller tip speed for aircraft in motion
5. 5
Aerofoil Parametric Study
Coefficient of moment for canard
Moment coefficient at zero AOA
Moment coefficient at AOA
Angle of Attack AOA
Pitching moment due to canard deflection
Canard/elevator deflection
Lift and Drag Calculations
lift
density
S Wing Area
Coefficient of lift
Forward velocity
Taper ratio
Tip chord
Root chord
. . . Exposed mean aerodynamic chord; wing
characteristic length
Reynold’s Number
Airplane correction factor
Exposed wing area
Wing parasite drag coefficient
Fuselage parasite drag coefficient
Canard parasite drag coefficient
Induced drag coefficient
Total drag coefficient
6. 6
Performance Calculations
Cruise velocity
Stall velocity
Assumed maximum velocity
Maximum wing lift coefficient
Takeoff velocity
Flare velocity
Flare radius
ℎ Flare heigh
Thrust at takeoff
ℎ Brake horsepower
Propeller efficiency
E UAV endurance
R range
Flight Performance
R Turn radius
Load factor
Turn rate
Stall velocity at turn
Minimum turn radius
Pull up radius
Pull up rate of turn
Pull down radius
Pull down rate of turn
TOP Takeoff parameter
Coefficient of lift at takeoff
Landing distance
Obstacle clearance
Density ratio
8. 8
Introduction
Project: Tailless UAV
Project Goal: To design, construct and perform a flight test on the Tailless UAV
Plan of Action: Using the information gathered from research on tailless aircraft construction, design
a Tailless UAV prototype using dimensional procedures and construct the prototype based on the
design.
The conventional tailed aircraft is ubiquitous in the modern era; after many years of
research, design and trial-and-error, such configuration is widely accepted to be the most efficient.
This design is complexity with simplicity in design; in one structure a multitude of passive and active
actions on the aircraft is incorporated. Tail surfaces provide control as well as stability, although it
may have disadvantages that, with current technology, cannot be removed until a drastic,
unconventional redesign of tail is considered.
Tailless aircrafts exhibit the lack of a tail, instead compensating for it with a different flight
control configuration to maintain a, more or less, similar flight behaviour. Due to the reduction of
surfaces exposed to the flow of air, tailless aircraft present a much lower drag coefficient when
compared to their tailed counterparts. Multiple types of tailless aircraft exist and in this project the
type to be constructed is a standard swept-back aircraft with canards.
Since its introduction in the early 1900s, tailless aircrafts have never been applied in the
aviation industry to the magnitude of today’s standard aircrafts. The advantages it presents in real-
time applications seem to stray far from its theoretical advantages; nevertheless, this means that its
holistic design has never approached its zenith and many opportunities for its improvement are still
available.
This report will encompass the theoretical aspect of a tailless aircraft. Using multiple
literature sources, the conceptual design of the Tailless UAV will be justified and the analysis of its
aerodynamic performance will be presented. This will include lift and drag calculations and
9. 9
estimated performance calculations of the UAV. The calculation sequence to be used will be in the
generalised sense; that is the constants to be used will have the assumption of perfect construction
parameters but this will provide an approximation of Tailless UAV performance.
The design of this tailless aircraft will mostly be based on knowledge gained on aircraft
design in the 3rd
semester. The dimensional analyses to be performed is the result of research on
aircraft conceptual design.
10. 10
1.1 UAV Applications
With the added advantages of having a tail-less configuration, the use of UAVs has the potential to
become a fundamental component of monitoring and activities performed to measure, report and
identify the parameters of a test subject. To contribute to the development of the possible uses of
UAVs, this report will present: the feasibility of UAV application, extent of its application and the
possible advantages and hindrances that might be met in the application of UAVs.
For the purpose of monitoring; the use of balloons, kites and blimps would not be suitable
for their lack of control to cover large areas. Multicopters on the other hand can only go over short
distances due to their limited battery life. Fixed-wing aircrafts exhibit greater endurance due to their
gliding capabilities. In addition, fixed-wing aircrafts can be made using parts from hobby model
aircrafts, significantly reducing costs and complexity. If applied to smaller communities within
developing countries, UAVs as compared to quadcopters would present a faster learning curve as
UAVs can function as either fully or semi-automatic.
1.1.1 Monitoring of Atmospheric Conditions
The use of low-cost and simpler drones to monitor atmospheric conditions can give data can
be just as accurate as the ones collected by scientists. Weather balloons are high-altitude balloons
that carry measurement equipment to obtain a range of wind data. Its maximum altitude is
controlled by the amount of gas within the balloon and may reach up to 40 km.
The main disadvantage with the use of high-altitude balloons is that the balloon expands
due to the decrease in pressure up to a point where it explodes; measurement equipment is then
lost. Replacing weather balloons, at lower altitudes, with UAVs gives the mission repeatability
1.1.2 Geospatial Analysis and Mapping
Owing to the fact that most fixed-wing aircrafts fly at low altitudes of 30-300m, pixels can be
down to an order of centimetres rather than metres. The feature of having high-spatial resolution
can significantly improve the quality of maps. Through this way; maps are more meaningful even dirt
roads, which can be indistinguishable from satellite imagery can be identified.
11. 11
Coupled with 2D or 3D mapping software, the photos taken by the UAV can be switched
together to create a detailed map of a subject area. AutoCAD Map 3D or Pix4d are 3D mapping
software that could be used, albeit at a rental price. For 2D mapping, the most popular open source
software that could be used is Google Earth. With this users simply need to geotag the photos that
was taken by the UAV and overlay it onto Google Earth’s database and filling in blanks or improving
its quality.
1.1.3 Change Mapping and Monitoring
Adding upon high-spatial resolution, images from drones would enable monitoring of many
traits and features of an ecosystem, which would normally be inaccurate through other forms of
data collection. These would include: being able to closely monitor changes in soil positioning
around erosion prone zones, allowing for early detection of possible landslide sites; identification of
individual animal and tree species by pairing images with species databases; as well monitoring
deforestation or forest growth. Even though some information can be collected using ground
surveys alone, such as endangered species count, UAV mapping can be done over greater distances
under less time for more meaningful data as well as swifter response. [1]
Monitoring of illegal activities can be enhanced by the use of UAVs as the monitoring
procedure is not only restricted time-based interval imagery but as well as video capture. Rocky
terrains of mountains or flooded areas could be monitored by UAVs
Changes due to environmental factors: erosion and rising sea levels
Changes due to socioeconomic factors: deforestation
Status of animals: endangered species count and migration patters
12. 12
2.1 History of Tailless Aircraft
Long before the first aircrafts flew, plants have been doing for many millions of years. Seeds
have to navigate their way around their environment in order to survive and begin the cycle anew,
some may require animals to the job for them but some only needs a little push to start.
The seeds of the tree Liane have two curved, clear wings on its sides. Growing mostly ever
on the highest branches of the tree, the winged seed becomes dislodged by a breath of air and
begins a seemingly perfect flight; gliding its way to where it can root.
Figure 1 – Liane seed and its wings, served as an inspiration to 20th century inventors
- Early inventors and aviators used the Liane seed as a model for an aircraft that can fly just as
well and in 1904 Igo Etrich designed a glider that flew a range of 900m. Over the course of the 20th
century the application of tailless aircrafts was sporadic. Around the first half of the century, the
most distinguishable use of the tailless configuration was Me 163 Komet. Designed by German
inventor Alexander Lippisch, the Me 163 was a fighter aircraft that utilised a rocket as a form of
propulsion. It had a maximum speed of 959 km/h and was used extensively during the 2nd
World
War due to its performance. [2]
13. 13
The Allied Forces, on the other hand, responded to the Me 163 with an experimental aircraft
built as an evolution of the original and first-ever flying wing design: Flying Wing X-216H. Designed
by American inventor Jack Northrop, the Northrop N-1M displayed adequate flight performance and
modularity due to its simple design.
Decades after the 2nd
World War should minimal changes in the overall design of the tailless
configuration but an increase in interest in the design became apparent as its potential to become
an efficient aircraft became more popular. It wasn’t until 1968 that the Tupolev Tu-144 was
introduced as the first transport aircraft to travel at supersonic speeds; two years prior was the
introduction of the SR-71 Blackbird, regaled as the fastest air-breathing manned aircraft at its time,
achieving a top speed of 3,540 km/h. [3]
Figure 2 – SR-71 Blackbird, fastest manned air-breathing aircraft has no tail section to minimise drag
One needs only to look at the advancements made by the tailless configuration in the past
century to know that it still has a long way to go for the design to mature. Nowadays, it is mostly
only ever used on hobby remote controlled planes or small private aircrafts. Advancements in
technology in tailless designs is hindered not by its apparent disadvantages but rather by lack of
interest.
14. 14
3.1 Parametric Study
3.1.1 Orbiter UAV
Overview, Aims & Objectives
The Orbiter UAV is a compacted and lightweight designed UAV mostly used for military and
homeland security missions. It can also be used for Over The Hill reconnaissance missions, Low
Intensity Conflicts and Urban warfare operations as well as any close range ISR(Intelligence,
Surveillance and Reconnaissance) mission.
The Orbiter UAV can be transported, assembled, launched and operated by just two persons after
minimal training. The entire Orbiter UAV fits into a backpack and no additional personnel need be
deployed.[4]
Parameters and Specifications
Parameters and
Specifications
The Orbiter
Wing Span 2.2 m
Fuselage length 1.0 m
Weight (UAV) 6.5 kg
Pay load weight 2.5kg
Endurance 2-3 hours
Max. Altitude 18,000 ft
Range(Video/Radio) 15/50 km
Navigation GPS or INS
Figure 3 – Orbiter UAV, utilises winglets for directional control
15. 15
3.1.2 McDonnell Douglas X-36 UAV Fighter Aircraft
Overview, Aims & Objective
As part of the experimental X-Project, the McDonnell Douglas X-36 is a jet prototype
that was designed for flight without the conventional tail configuration found on most
aircrafts.
In its experimental flights, the X-36 was built to a scale of 28% of a standard fighter
aircraft and controlled from ground by a pilot in virtual cockpit. This virtual cockpit provides
real-time view of the UAV from a nose-mounted camera.
Being relatively unstable in the yawing and pitching axes, the X-36 employed an
advanced active control system to maintain its attitude throughout its flight. For directional
control a thrust vectoring nozzle was used, while a canard and split ailerons was used for
rolling and pitching.
Its lack of stability was made up for its highly manoeuvrable control, throughout its
experimental phase the X-36 has 31 successful flights, most of which surpassed the flight
goals set. However, despite the success of its research program; no development on the X-
36 has been announced since the end of its research in 1997. [5]
Figure 4 - X-36 employs canards and tailless configuration in flight
16. 16
3.1.3 Proposed Model
Overview, Aims & Objectives
Our model reflects a basic tail-less UAV, but with an addition of canard system configuration. Our
main objective behind the addition of canard wing configuration is for stability and control. Instead
of having an elevator at the tail; our prototype will have its elevators on the canard wing.
Canard wing is a design where there is an additional wing usually smaller than the actual wings
towards the leading edge of the aircraft. This additional wing can be used to share the lift generated
for the aircraft, for control, for stability or for trimming the aircraft.
Compensation for vertical stabilizer (Tail) by using TVC (Thrust Vectoring)
From some deep research about it we have to come a conclusion that one of the very effective way
to compensate for a vertical stabilizer and a rudder is to add a thrust vectoring feature on our tailless
UAV.
Thrust vectoring is a feature where the engine, in our case a propeller can have a lateral movement
on a single engine aircraft or in a twin engine the engine speed is controlled independent to each
other to generate a yawing effect. In our single engine UAV we use an engine mount which has the
capability to move sideways. This movement can help the aircraft tail to slip to the other side of the
moment of the engine creating the exact effect of a rudder. This can also provide directional stability
when the aircraft is effected by any unexpected disturbances like wind. Thrust vectoring in real life
can be found on high speed aircrafts where using a control surface can be ineffective due to the
speed.
17. 17
Specifications
Parameters and Specifications Proposed
Prototype
Wing Span 2.0 m
Fuselage length 1.0 m
Weight (UAV) 5.0 kg
Pay load weight 2.0 kg
Endurance 1-1.5 hours
Max. Altitude 12,000 ft
Range(Video/Radio) 15/20 km
Navigation GPS
18. 18
3.2 Comparison
Having researched about different types of UAVs with (Tail-less designs), we have decided to
compare the parameters and specifications of those to our proposed prototype design.
3.3 Application
The benefit of a tail-less UAV concept compared to a conventional UAV with tail configuration is a
reduction of both parasitic and induced drag at cruise flight mode, which makes it more economic to
operate.
So from an operational point of view the tail-less concept should be just as flexible as any
conventional UAV having tail, but more economic.
It can cover more distance for the given amount of charge, due to less drag.
Parameters and Specifications The Orbiter MD X-36 Proposed
Prototype
Wing Span 2.2 m 3.15 m 2.0 m
Fuselage length 1.0 m 5.5 m 1.0 m
Weight (UAV) 6.5 kg 560 kg 5.0 kg
Pay load weight 2.5kg - 2.0 kg
Endurance 2-3 hours 1.5 hours 1-1.5 hours
Max. Altitude 18,000 ft 20,200 ft 1,000 ft (est.)
Range(Video/Radio) 15/50 km 15/25 km 15/20 km
Navigation GPS or INS GPS GPS
19. 19
4.1 Conceptual Design of Tailless UAV
Literature used
Much of the conceptual design phase of the Tailless UAV comes from the book: Aircraft
Design: A Conceptual Approach, 5th
Edition by Daniel P. Raymer. The graphs and formulae used are
generally applicable to standard conventional aircraft and like in most calculations in this report, the
values obtained would give an approximation on the practical performance of the UAV.
The constants that are justified in the Conceptual Design chapter will be backed against
graphs and tables taken from the same book.
4.2 Longitudinal Stability Compensation
The main problem that would arise from the omission of the aircraft empennage would be a
lack of longitudinal stability. An aircraft that is longitudinally stable would respond from a sudden
change in angle of attack with a pitching moment that would counteract the change and force the
aircraft nose back into its original position [6]
For tailless aircraft, the longitudinal trim requirement is:
= 0
That is:
= × + = 0
Equation 1
Where is the static margin is the lift coefficient and is the moment
coefficient at zero angle of attack.
If, during the conceptual stage, the static margin is assumed to have a conventional value
between 0.1 and 0.2, then the mainplane must be able to provide a at a large enough value to
counteract the value of . This problem is made more complicated by the fact that the value of
has a linear relationship with ; therefore, trimming moments have to be obtained from more
unconventional methods when it comes to tailless aircrafts, these are: Large aerfoils, 3-
dimensional manipulation of wings and active controls.
20. 20
4.2.1 Swept-back wing
A swept wing is a wing design wherein the wing is deflected backwards or forwards at an
angle from the root. In tailless aircrafts, this has the advantage of increasing the effective wing
lengthwise. The control surfaces, in this case, would be installed near the tips of the wings where the
distance between it and the aircraft’s centre of gravity is the greatest; allowing for a more effective
moment arm and longitudinal stability. In additional, swept-back wings can be used alongside wing
twist to induce washout.
For this project the swept-back angle on the UAV would be 43 degrees. This value would be
a compromise between a sufficient lift curve slope and an effective moment arm. The value for the
degree of wing sweepback is justified in the Design Chapter.[7]
4.2.2 Large Aerofoil, Pitching Moment Aerofoils
In essence, any type of aerofoil can be used on a tailless aircraft so long as there is no
discrepancy with the sweep-back and wing-twist. However, in order to minimise the amount of drag
experienced by the aircraft, the wing twist should be kept at a minimum and an aerofoil that has a
value of moment coefficient enough to negate the moment due to lift has to be chosen.
Such an aerofoil, in theory, should have a reflex camber; that is, the aerofoil curves upwards
towards the trailing edge of the aerofoil. This would result in having a moment acting on the
aerodynamic centre of the aerofoil to be zero.
However, a reflex aerofoil would be too complex to construct for this project and it was
decided that the aerofoil to be used is the Eppler 1212; to be discussed in detail in the chapter
‘Aerofoil Parametric Study’.
4.2.3 Wing Twist
In order to maintain control over the aircraft’s longitudinal stability, it is necessary that the
wing’s aerodynamic centre lie outside the 42.4% of the length of the wing from the root. The
idealised lift distribution by Prandtl, described it to be shaped as a curve; with most of the lift
emanating from near the roots of the wings; in tailless aircrafts, however, the introduction of a wing
twist can help with the control of the aircraft as the moment arms of the wing control surfaces are
much longer with the new aerodynamic centre.
Additionally, the wing twist places more of the lift on the tips of the wings. Instead of having
a semi-circular distribution of lift, the shape would be more of an ellipse. The tips, at zero angle of
attack, would provide a downward lift that would counteract the nose-up tendency resulting from
the lack of tail. [8]
21. 21
4.2.4 Active Control
A fly-by-wire system is wherein the aircraft’s conventional manual controls are replaced with
an electronic network; should the pilot provide a needed flight control, the deflection of the cockpit
controls are converted into electrical signals that are the interpreted by the flight computer to
decide the appropriate amount of control surface deflection.
The incorporation of the fly-by-wire system into the aircraft reduces pilot input and load as
actions can be done independently. In the regime of automatic stability, the fly-by-wire system
works alongside on board gyroscopes to determine any aircraft disturbances within its three axes
and perform the necessary changes in flight control surfaces deflection to return the aircraft back to
its original position.
4.3 Pitch Control
4.3.1 Canard
Canards are a design configuration wherein a smaller wing is located in front of the
mainplane, it presents multiple advantages in lift production, control, stability and trim. In this
project much of the focus on the canard is on its contribution to control and stability.
One of the canard’s main advantages is its influence over stall safety. In the canard design
aircraft, the canard’s parameters can be altered in such a way that it will stall before the mainplane;
essentially making the aircraft proof against stall. [9]
Figure 5 – Control canard on a tailless aircraft
22. 22
Aerodynamically, the canard can induce a vortex that would interact with the mainplane,
this vortex would increase in strength as it travels rearwards and augment lift production. In terms
of drag, an airplane with a conventional tail configuration normally suffers a downward load exerted
by the horizontal tail; due to this, the mainplane has to provide more lift in order to counteract the
download and keep the aircraft in a level position. This problem would result in the designing of an
aircraft with an even greater wingspan, which contributes a significant amount of drag. The canards,
however, would solve this problem as both surfaces produce a force upwards and the omission of
the tail, or most of it, would present a significant reduction in drag.
Canards, on the other hand, despite its theoretical advantages in terms of control and
stability still present issues when applied in aircrafts.
4.3.2 Elevons
Figure 6 – Combination of elevon deflection for aircraft control
Elevons merge the purpose of the aileron and the elevator into one control surface. They are
installed at the trailing edges of the wings and its operation is as such that when the two elevons are
simultaneously deflected in the same direction, a pitching force is induced; meanwhile, a differential
deflection of the elevons would cause a rolling motion.
23. 23
Elevons would an ideal compromise for the lack of a tailplane and would be more effective
in pitching and rolling control if the wings are at a slight dihedral. However, elevons pose problems
in lift production as lift is disrupted when they are operated, as well as reduced control effectiveness
due to mixed control. [10]
For this project, the control surface to be used is canards. There are two distinct types of
canards: lifting-canard and control canard; the control-canard type was chosen due to the lesser
requirement of lift in the design due to its low structural weight.
24. 24
Selection
5.1 Dimensions
5.1.1 Sweepback
Figure 7- Sweepback angles vs taper ratio
Since taper ratio is:
= =
0.17
0.6
= 0.283
Equation 2
where is the tip chord and is the root chord
and aspect ratio is:
= =
2
0.77
= 5.19
Equation 3
Using these values, the degree of sweepback was determined using the table above. Since
the aspect ratio was 5.19, the last line (triangle) was used, with a taper ratio of 0.283; the final value
used is 43 degrees sweepback. [11]
25. 25
5.1.2 Fuselage Length
The calculation for the take-off gross weight is taken from the prerequisites outlined for the
design of the tailless UAV given at the start of the semester. The calculated weight of the aircraft
around the conceptual stage is 3.5 kg, in addition to this, it was required that the UAV be able to
carry a payload of 5kg. [12]
For the calculation of fuselage length, it is assumed that the overall take-off weight of the
aircraft is 8 kg. Fuselage length is calculated using the formula:
=
Equation 4
The constants a and c, are statistical values taken from multiple types of aircrafts. The values
can be read from the table below:
Figure 8 – Determining fuselage length using statistical correction constants
Sailplane-powered is closest to the pusher-type Tailless UAV, but since the Sailplane-
powered assumes a piston-powered propeller the value is averaged with Sailplane-unpowered for a
closer approximation.
26. 26
For Sailplane-powered:
= 0.383 × 8 .
= 1.04
For Sailplane-unpowered:
= 0.316 × 8 .
= 0.86
Averaged Fuselage Length:
=
1.04 + 0.86
2
= 0.95
In order to simplify the construction of the fuselage, the length is increased to 1 meter
27. 27
5.1.3 L/D Estimation
Since the UAV’s canards are only designed to be as control surfaces, its effects on lift will be
ignored in the initial L/D estimation. Similarly, in the design stages of conventional tailed aircrafts,
the influence of the tail is ignored, focusing only on the lift production of the mainplanes; therefore,
the same sequence will be followed L/D estimation for a tailless aircraft.
The relationship of lift and drag depends mainly upon the wing span and the area of the
wing wetted by the flow of air. For this estimation a revised form of aspect ratio will be used:
=
Equation 5
In contrast to the previous aspect ratio calculation, the wetted aspect ratio calculation will
be in the order of meters in order to be applicable to the following graph; reference area is assumed
to be equal to wing area.
=
4
0.62 × 2.04
0.77
= 2.43
According to the graph below, for fixed-gear propeller aircraft, the maximum L/D is at
around 14; during UAV flight, it should keep to the corresponding velocity for more efficient
performance. Since it is a propeller aircraft, then compromises must be made for apparent losses
due to propeller operation and flight at 86.6% of the max L/D will be used in test flights. [13]
Figure 9 – Estimation of maximum lift/drag ratio using statistical values
28. 28
5.2 Propeller Location
In the conceptual design stage of the tailless UAV, out of the possible propeller placements
that could be used two types were considered: fuselage mounted tractor and fuselage mounted
pusher. A fuselage mounted propeller is advantageous in regards to drag reduction as the overall
wetted area of the aircraft is reduced. [14]
Figure 10 – Comparison of pusher and tractor propellers
5.2.1 Tractor Propeller
In a tractor configuration the propeller and its engine are mounted at the front of the
fuselage; under propeller rotation, the aircraft is the effectively pulled forward.
The main disadvantage of the tractor configuration is that the aircraft flies in disturbed air;
the eddies formed by the forward mounted propeller strike the mainplanes at its rear causing a
significant increase in skin friction drag. Additionally, a different method of cooling the engine has to
be employed for the same reason: the flow rate of air over the engine is hindered.
The canards would be completely useless when placed beside a forward mounted propeller
as its use of a control surface would be effectively eliminated.
5.2.2 Pusher Propeller
As opposed to the tractor propeller, the pusher configuration is wherein the propeller and
its engine are mounted at the rear of the aircraft. Alongside the advantage of fuselage mounted
propellers, the use of tractor propellers can further decrease the length of the fuselage and reduce
overall skin friction drag.
The pusher propeller moves the centre of gravity of the aircraft farther into the rear of the
fuselage; which can possibly be counteracted by further increasing the sweepback of the wing to
increase the moment arm of the control surfaces. Moreover, mounting the propellers at the rear of
the aircraft increases the efficiency of the mainplanes as they move over undisturbed flow of air; a
problem most commonly seen in tractor configurations.
29. 29
A disadvantage of the use of pusher propeller works in the opposite way as in the tractor
configuration; the propeller loses efficiency as it has to move over air that has been disturbed by the
body of the aircraft before it.
5.3 Propeller Sizing
Details behind the shape of the propeller blade and its helical twist are not considered in the
initial stages of the design of the tailless UAV, these parameters would be considered in the later
design stages involving thrust.
At the initial stages of design, the propeller diameter must be determined. In a theoretical
sense, the larger the propeller diameter the more efficient it should be; however, this is limited by
multiple constraints such as increased loads on the motor mounts and ground clearance. The main
factor to be considered in the selection of propeller diameter is the rotational speed of the propeller
at its tips. This should be kept well below sonic speeds to avoid inducing shock waves. [15]
Figure 11 – Determining propeller diameter using statistical correction constants
The table shown shows the correction constants used for propeller calculations; the value of
gives an approximation using statistical information on a range of propellers. Propeller diameter
would be a function of motor brake horsepower and can then be calculated using the formula:
= √
Equation 6
Using data from AT2814 motor manual and the value of is for two blades, in metric; then:
= 1.7 × √0.496
30. 30
The diameter for each propeller is then:
= 9 ℎ
The value obtained from the propeller diameter obtained in the previous equation should be
juxtaposed against the tip speed:
=
Equation 7
= × 246 × 0.75 = 579 = 176
Assuming a forward speed of 5 m/s
= +
Equation 8
= 176 + 5 = 176 /
31. 31
Material selection
6.1 Wood
The preferred material for the construction of the Tailless UAV model is Balsa wood, due to
its ubiquity in model aircrafts, it appears to be the most appropriate due to its feather-light build
against its high degree of mechanical strength.
Its low density is the result of the tree having large cells filled mostly with just water, once
dried out the wood has a spongy texture that easily gives way under a utility knife but still provides
sufficient strength and durability against impacts and loads. As compared to other materials, balsa
wood is widely available in hobby shops in the UAE, easy to work with as shaping is not time
consuming and is suitable to work with using tools available in the university workshops.
On the other hand, balsa wood is susceptible to failing under torsional and shear loads; in
this case the spars of the wings will be pinewood shafts. This material still possesses a light-weight
structure but better stress resistance. Moreover, the root ribs has to be attached midway of the
fuselage and would carry most of the drag imparted on the tailless UAV; in this case, the root rib will
be constructed out of plywood. Although it slightly heavier, the use of plywood is a safety net
against any wing damage. [16]
32. 32
6.2 Required Equipment & Tools:
Surgical Knife: There is simply no way you can work with balsa without a nice knife and sharp blades.
Ensure that your blades are always sharp, a blunt blade makes working with balsa a lot harder but
it's still sharp enough that you can cause yourself some serious damage from overexerting.
Gorilla Glue: Strongest Glues for Balsa Wood. Gorilla glue is more costly than other brands of glue,
but it is worth the extra cost. Gorilla Glue takes longer than average to dry, but forms a strong and
rigid glue joint.
Razor plane: A razor plane will let you shave down your fuselages, leading edges and trailing edges
with such ease that you will never touch sandpaper for anything other than the finishing shaping.
Steel ruler: Such a simple tool yet very important. Don't try use plastic or wooden rulers as the balsa
knife will typically slice right into them.
Aluminium extrusions: Get L and square extrusions of about 1" size on each side. Cut the 1m length
into various smaller lengths and keep them handy, they make excellent right-angle braces for when
you're gluing in fuselage sides, ribs etc.
33. 33
Aerofoil Parametric Study
7.1 Canard
The canard design essentially moves the tailplane of a conventional aircraft and moves it
fore the wing. The position of the centre of lift, can then be found behind the centre of gravity.
The nose down tendency of a canard configuration is cancelled out by the apparent lift
created by the canard itself. Due to its far smaller size, canards are designed to have a greater
aerofoil camber than that of the wings. In the case of the tailless UAV in this project, however, the
centre of gravity would be projected farther into the rear of the aircraft due to the addition of a
thrust vectoring system at the propeller base. The value of coefficient of lift would not be so
important since the aerofoil required should fit for a control canard and not a lifting canard.
For this project, three aerofoil designs have been considered: ht08-il, ag47ct02r-il and
dga1138-il
The ht08-il is a symmetrical aerofoil with maximum thickness of 5% at 20.2% of the chord.
Ag47ct02r-il and dga1138-il, on the other hand, are asymmetrical aerofoils. The former has a
maximum thickness of 5% at 22.5% of the chord; while the latter has maximum thickness of 6.9% at
30% of the chord.
Figure 12 – moment coefficient against AOA for ht08-il at RN=500000
34. 34
Due to the canard being only used as a control surface, only the moment coefficient is
considered in the aerofoil selection process. Shown in the graph above is the juxtaposition of values
of moment coefficients for the three aerofoils against angle of attack. The ht08-il shows a larger
value of moment coefficient against the other two counterparts and thus making it suitable for
control canard application.
Figure 13 – Aerofoil shape for ht08-il
Since the wing’s generated lift force is much greater than that of the canard’s, a significant
pitching moment has to be created in order to cancel out the nose-down tendency of a canard
configuration. [17]
The longitudinal static stability of a canard equipped aircraft can be represented by the
equation:
= + ∙ + ∙
Equation 9
where: is the coefficient of moment at zero AOA
change in coefficient of pitching moment with respect to AOA
change in coefficient of pitching moment with respect to elevator
deflection
Further derivation would show that the values , and are all dependent upon
the coefficient of lift the canard exhibits. It is imperative that the longitudinal static possibility should
be large enough for the aircraft to cruise smoothly and decrease sensitivity to environmental factors.
35. 35
7.2 Wings
In the unique design of the canard configuration, two qualities have a major impact on the aircraft’s
overall performance: lift curve slope and pitching moment.
Since the canard uses aerofoils with a large camber, its coefficient of lift increases at a much
faster rate than that of the wing. This would reduce the stability margin of the aircraft as the neutral
point moves forward and giving the mainplane a steep lift curve can counteract this. The lift curve
determines the limits of the movement of the neutral point with respect to a change of angle of
attack; if it were steeper the neutral point will remain farther aft.
The pitching moment of the aircraft determines the location of is forward centre of gravity.
To avoid overloading the canard, the pitching moment must be set accordingly.
For the tail-less UAV, four aerofoils were considered for the mainplane: Eppler 1212, MH-60,
MH-61 and MH-64
The MH-60 series consists of models: 60, 61 and 64; used primarily for tail-less aircrafts.
They exhibit relatively high lift coefficients and low moment coefficients and a thickness of 10.12%
36. 36
Figure 14 – lift coefficient against AOA at RN=500000
where purple is Eppler 1212, green is MH-61, Orange is MH-60 and lighter orange MH-64
Note the near similarity of the values presented by the aerofoils of the MH-60 series. As for
the Eppler 1212, the values of lift coefficients continue to increase until around 16 degrees. In
contrast to previous choice for the aerofoil for the canard, the Roncz 1046, it would stall at around
13 degrees. Thereby following the order that the canard should stall before the mainplane.
Juxtaposing the four different aerofoils against one another, it appears that the Eppler 1212
satisfies conditions set by the relationship between the canard and the mainplane.
37. 37
Figure 15- Moment coefficient against AOA at RN=500000
where purple is Eppler 1212, green is MH-61, Orange is MH-60 and lighter orange MH-64
As before, only minor differences are seen between the aerofoils of the MH-60 series. With
the values they present for the relationship between coefficient of moment and alpha, it can be said
that these aerofoils are inherently unstable. The Eppler 1212, on the other hand, present a mostly
negative value of moment coefficient for a given angle of attack, becoming only positive at around
15 degrees. The pitch down tendency would present a load on the front canards, but with overall lift
production of the Roncz 1046, this can be cancelled out and at the same time, provide the tail-less
UAV with more stability.
Figure 16 – Eppler 1212 aerofoil shape
38. 38
Construction Sequence
The ribs were constructed using templates printed out exactly as per dimensions. These
were then stuck onto sheets of balsawood and cut-out using a knife, then sanded down to an
accurate shape.
8.1 Wings
Figure 17 – Ribs attached together by a pinewood spar
Similarly the canard ribs were made out of a single template; the gap at the centre is its
attachment point into the fuselage
8.2 Canard
Figure 18 – Canard ribs attached by a pinewood spar
39. 39
Figure 19 – Close-up view of the canard ribs
8.3 Fuselage and landing gear
Figure 20 – Fuselage and wings, UAV taking shape
40. 40
Figure 21 – Landing gear attachment
Simplicity in construction was done by forming the fuselage with a flat bottom, like the ribs
it was cut-out using templates stuck onto plywood.
The landing gear screwed into a pedestal in between the wing ribs
45. 45
8.5 Onboard Equipment
8.5.1 Battery
14.8V with 3300 mah, powering the propeller, autopilot system and thrust vectoring control
system.
8.5.2 Arkbird Autopilot System
Bought from hobbyking.com, with GPS for waypoint flight. The autopilot system includes
attitude sensors that stabilise as well as control the aircraft in flight. Also has features that would
allow the aircraft to loiter around a waypoint as well as a return home function.
Dimensions: 50x38x14mm
Weight: 19g
8.5.3 AT2814 Motor
Bough from hobbyking.com, brushless t-motor. Variable rpm, with Kv=1000, alongside the
battery having 14.8 volts; the motor should run at around 14800 rpm.
Dimensions: 35x36mm
Weight: 103g
46. 46
Calculations
Literature used
The aerodynamic and performance formulae and calculations are based on the ones given
and learned in 2nd
and 3rd
semester Aerodynamics classes. Alongside these formulae, the tables from
the Aerodynamics book are used to provide the constants required. These constants obtained are
ideally used for more conventional aircrafts but the theoretical values obtained would give an
approximation of the performance of the Tailless UAV [18]
Atmospheric constants to be used in all the calculations will be standardised sea-level
values. Additionally, the velocity used in the calculations would be the minimum cruise speed so as
to ensure that the calculations for the lift and drag would be at a suitable value for design
considerations.
Temperature 288 K
Pressure 101.325 kPa
Density 1.2250 ⁄
Cruise Speed 5 /
Viscosity 1.4607 × 10 ⁄
9.1 Lift
=
1
2
Equation 10
=
1
2
× 1.225 × 0.62 × 5 = 7.977
9.2 Drag
For the wing, the overall taper ratio is:
= =
0.17
0.6
= 0.283
Equation 11
then:
. . . =
2
3
(1 + −
1 +
)
Equation 12
47. 47
. . . = =
2
3
1 + 0.283 −
0.283
1 + 0.283
= 0.425
the exposed m.a.c. stands for the wings’ characteristic length:
=
Equation 13
=
5 × 0.425
1.4607 × 10
= 145478
Using figure 11.2 assuming a typical roughness for the wing:
= 0.005
Using figure 11.3, the correction factor is:
= 1.27
the actual area of the wing in contact with the air can now be calculated using:
= × 2 × 1.02
= 0.62 × 2.04 = 1.2648
Then coefficient of parasitic drag is:
=
Equation 14
=
0.005 × 1.27 × 1.2648
0.77
= 0.013
And coefficient of induced drag is:
= =
2000
770000
= 5.19
Using figure 11.8, the airplane efficiency factor is: 0.97
=
× ×
Equation 15
48. 48
=
0.8403
× 5.19 × 0.97
= 0.04
For the fuselage:
=
5 × 0.7083
1.4607 × 10
= 242452
Using figure 11.2, assuming typical roughness for the fuselage:
= 0.007
To find K:
=
1
0.25
= 4
From figure 11.4, then:
= 1.39
=
Equation 16
=
0.007 × 1.39 × 0.62
0.77
= 0.00783
For the canards:
. . . = =
2
3
1 + 1 −
1
1 + 1
= 0.15
=
5 × 0.15
1.4607 × 10
51345
Using figure 11.2, assuming typical roughness for the canards:
= 0.0089
From figure 11.3, then:
= 1.0875
49. 49
The parasite drag coefficient for the canards is:
=
0.0089 × 1.0875 × 0.62
0.77
= 0.00779
Total parasite drag coefficient is then:
= + +
Equation 17
= 0.013 + 0.00783 + 0.00779 = 0.0286
= +
= 0.04 + 0.0862 = 0.0686
Then:
=
1
2
Equation 18
=
1
2
× 1.225 × 0.62 × 0.0686 × 5 = 0.65
Lift to drag ratio is then:
=
7.97
0.65
= 12.244
Equation 19
50. 50
9.3 Aerodynamic Performance
9.3.1 Flight Velocities
If the assumed maximum velocity of the aircraft is 20 m/s as per the parametric study, then:
= 0.75 ×
Equation 20
= 0.75 × 20 = 15 /
=
1
2
.
Equation 21
=
7.97
1
2 × 1.225 × 0.62 × 1.1481
.
= 4.27 ⁄
= 1.2 ×
Equation 22
= 1.2 × 4.97 = 5.124 ⁄
= 1.23 ×
Equation 23
= 1.23 × 4.27 = 5.25 ⁄
9.3.2 Landing Parameters
Using standard values on remote controlled aircrafts, then n=3.8 for aircrafts that weigh less than
1,867 kg, radius of flare can then be calculated using:
=
× ( − 1)
Equation 24
51. 51
=
5.25
9.81 × (2.8)
= 1
Similarly, using a standard value of 20 degrees for flare angle, then the flare height can be calculated
using:
ℎ = × (1 − cos )
Equation 25
ℎ = 1 × (1 − cos 20) = 0.06
9.3.3 Thrust to take-off
With takeoff velocity converted to ft/s, assuming standard propeller efficiency of 30% as calculated
in propeller analysis.
=
ℎ ×
× 550
Equation 26
=
0.496 × 0.3
16.81
× 550 = 4.86
9.3.4 Endurance
According to motor specifications, the maximum continuous current drawn by the motor
is 35A and the maximum capacity of the battery 3300 mah, then the endurance in minutes of
the UAV assuming no losses can be calculated using:
= × 60
Equation 27
=
3300 × 10
35
× 60 = 5.65
52. 52
9.3.5 Range
Assuming a cruise condition at 75% of the , then the range of the UAV can be calculated
using:
= ×
Equation 28
= 15 × 5.65 × 60 = 5085
9.4 Flight Performance
Using a similar assumption, for an aircraft weighing less than 1,867 kg, then the load factor
can be taken as: n=3.8 for all subsequent flight performance calculations. Velocity used will cruise
velocity:
9.4.1 Turn Radius
=
√ − 1
Equation 29
=
15
9.81 × √3.8 − 1
= 6.25
9.4.2 Turn Rate
=
√ − 1
Equation 30
=
9.81 × √3.81 − 1
15
= 2.4 /
9.4.3 Minimum turn radius
Since stall speed is:
= 4.27 /
Then level turn stall speed is:
54. 54
9.5 Take-off Distance
Since the UAV will be flown at sea-level, then the density ratio is: = 1
Take-off distance will be calculated in English units in order to be applicable to the formulae that
follow. A statistical value, Take-off Parameter is calculated using:
=
/
ℎ
Equation 37
= 0.7
= 0.7 × 1.1481 = 0.8
Then:
=
6.39/6.67
1 × 0.8 ×
0.496
6.39
= 15.42
Take-off distance is then taken from the below graph for propeller ground roll.
≈ 33.528
Figure 26 – Determining takeoff distance using takeoff parameter
55. 55
9.6 Landing Distance
= 5 ×
1
+
Equation 38
Where is the obstacle-clearance distance, applicable only to large aircrafts; assumed to be
negligible for a UAV.
= 5 ×
2.9
0.62
×
1
1 × 1.1481
+ 0 = 26.67
56. 56
9.7 Propeller Analysis
As per the manual on the AT2820 motor, the power is 0.8 kW or 1.07282 bhp and maximum
thrust of 1.9 kg. The values obtained in the following calculations are in sequence in order to identify
propeller efficiency.
The AT2814 motor is rated at 830 rpm/v, with the battery providing a maximum voltage of
14.8V; it can then be assumed that the motor would spin at around 12284 rpm without losses due to
friction and propeller loads, in the calculations this would be converted to 204 rev/s. Constants will
be provided in English units in order to be applicable to the formulae.
9.7.2 Power coefficient
=
550 × ℎ
Equation 39
=
550 × 1.07282
0.002369 × 204 × 0.75
= 0.12363
9.7.3 Thrust coefficient
=
Equation 40
=
4.189
0.002369 × 204 × 0.75
= 0.13
9.7.4 Propeller efficiency
At cruise speed of 16.4 ft/s:
=
550 × ℎ
Equation 41
=
4.189 × 16.4
550 × 1.07282
= 0.1164
58. 58
Budget Plan
Item Estimated Cost (AED)
Balsa Wood 500
Motor 200
Battery 150
Servos (x5) 100
Landing Gears 50
Wheels (x3) 45
Radio Controller 500
GoPro HD Camera 500
GPS system and software 600
Video Transmitter 100
Lamination Monokote (x2) 110
Accessories and Tools 100
Final 2,955
60. 60
Gantt Chart Description
When we refer the Gantt chart, we can see the basic idea we have put as a group to see the
approximate timeline to complete the project. As a group with five members we might split the tasks
in between hoping to complete quicker than mentioned. If there are any major changes it will be
updated as soon as possible.
Week 1 - Week 2
Our initial weeks begin with studying and researching more about project where we could come
across different designs. After comparing these designs we will choosing the desired design and will
be considering getting the materials and parts required for it.
Week 2 - Week 4
The construction will begin as soon as we purchase the required materials for it. We might order
certain parts online where we have kept two weeks head time for shipment.
Week 4 - Week 10
During week 4 to week 8 our main focus would be on constructing the model, as decided we will
contribute the constructional tasks equally to each and every member of our group, construction of
wings will be one of very crucial stage in our construction so that might demand some more time,
like a week atleast.
Also during this period we will be doing the aerodynamic calculations and as well will be a bit busy
with our other assignments and quizzes.
Once we are done with construction and assembly we will carry out a minor testing and then a flight
test.
Week 11 - Week 13
Any faults or issues found will be fixed in the two weeks period kept before submission. During all
this time from week 4 onwards we will be regularly updating our log books as well as the final
submission report at every stage of out project
61. 61
Challenges Faced
As opposed to a standard aircraft, the literature behind the design of a tailless aircraft is
limited. The concept is such a unique idea that most of everything within the aviation industry is still
under its experimental phase; the rest of the resource pool on tailless aircrafts are from hobbyist
who rely on practical knowledge on trial-and-error in order to achieve successful flight. Of course,
both parties would keep the sequence of their design a secret; as argued the tailless design is still in
its developmental stages.
Back in September, at the very earliest stage of the design of the tailless UAV, a parametric
study was performed and the project manifested. Simple as compared to most but still poses a
daunting challenge; much of the parameters behind its design are, in essence, assumptions;
moreover, its design is something that has never been touched in the last two years of
aerodynamics.
Construction went forth and ideas came and went as understanding behind the tailless
concept grew deeper. Initial design conditions began with a lifting canard, this was then scrapped
and the design transitioned into simply a control canard using a symmetrical aerofoil. In terms of
theory, the constants and values readily available to us in the last two years became moot; it simply
wasn’t applicable but nevertheless… push forth.
Wing ribs broken and a lack of balsawood; these were some of the problems encountered
throughout the coming months. Like the hobbyists that this project is based on, everything was trial
and error; in the end, skills were honed and mastered and the UAV came into fruition. Like
construction, the AutoCAD took weeks and weeks of trial and error; the last semester’s lessons were
basic. Much of the time spent on the drawing were on YouTube, watching tutorials on how to
construct something that has never been done before. Painstaking it was at the start, yet it grew
easier and more relaxed.
Despite the challenges that arose throughout this project we managed to learn our way out
of it and as we progressed, what was learned was applied, reapplied and revised; given more time
and this project would have been a far greater success.
62. 62
Evolution of Tailless Concept
Mentioned throughout the report is the reasoning that the tailless configuration has never
achieved maturity and is still capable of rapid progression that could someday allow to it to be more
ubiquitous in the aviation industry; from the zirconia seed to the concept developed and designed
for this project numerous branches of improvements have evolved. These ideas target a more
efficient flight, as well advancements that would take the tailless configuration into the supersonic
and hypersonic regime.
10.1 Adaptive Wing and Aeroelasticity
An adaptive or aeroelastic wing is wing design wherein flexibility is to a point wherein the
shape of the wing can be manipulated throughout the flight sequence for efficiency. Possible
advantages include a reduction of over 10% in aircraft weight, improved flight control in all three
axes, drag reduction and better response to disturbances.
In an aeroelastic wing, the wing is intentionally constructed with material that has low
torsional stiffness, while strength in other directions remain as normal. A flight computer then
controls high-speed actuators located at the trailing and leading edges of the wing, which would
deflect and morph the wing shape depending upon what is required.
In directional control, the aircraft yaws due to the resulting increase in wing-tip drag; the
control system manipulates the shape of the trailing edge of the wing so that they act as speed
brakes. The mirrored deflection of the wing on both sides causes a force that would try and twist the
other wing in the opposite direction, causing the aircraft to yaw. In roll control, the control system
manipulates the shape of the trailing edges of the wing so that they would behave as normal
ailerons do. In terms of pitch control, the aircraft’s wing has to designed with a sweepback far
enough that when the tips of the wings are twisted they would behave as normal elevators.
Aside from three-axes control, the aeroelastic wing can be used for gust alleviation. Should
the aircraft meet gusst, the control system would respond by twisting the wings downward by their
leading edges. This would cause a dramatic reduction of lift and better response against gusts.
NASA’s Environmentally Responsible Aviation is a project that aims to harness the potential
of the use of active aeroelastic wings in possible aircraft’s with reduced with fuel consumption. After
successful test of their Adaptive Compliant Trailing Edge in 2014, the company aims to go further
into research. [19]
63. 63
10.2 Blended Wing Body
Also known as flying wing or lifting fuselage, the blended wing body lacks a fuselage or an
empennage; the whole aircraft itself is an aerofoil producing lift. The idea behind the concept is to
create a lifting body with a perfect elliptical distribution of lift; in a theoretical sense, the fuselage,
landing gear, tails and the like are simply additional weight and drag contributors. The blended wing
body assumes that the only true requirement of a body capable of flight is lift and thrust,
theoretically it should produce minimal drag as opposed to a large lift due to a greater increase in
effective wing area.
Jack Northrop and Reimar and Walter Horter were the first pioneers of the blended wing
design. Northrop came up with the XB-35 while the Horter brothers designed the Ho IX; both
designed intended to recreate the elliptic wing distribution of lift by adjusting the parameters of the
aerofoil throughout its span, the tips would produce zero lift and progressing to the root, the wing
twists in order to maximise the amount of lift produced. Both designs faired successfully, with excess
of 800 km/h in speed and 90000 kg of weight for both aircrafts; however, once the 2nd
World War
came to an end the blended wing body design saw no immediate purpose, the aviation industry
transitioned into transport where the blended wing body design can normally only accommodate its
pilot in order to keep its lifting shape. [20]
Figure 27 – NASA and Boeing collaboration: X-48
64. 64
In recent years, however, the blended wing body design has made a comeback as the
conventional aircraft design has now matured. The public calls for a revolution in the aviation
industry, aviation is a major contributor to pollution due to the amount of fuel used by an aircraft in
a single flight sequence. Instead of just looking into the use of greener sources of fuel, aircraft
manufacturers seek to reinvent the future of large-scale public transport. The design of the Boeing
X-48 utilises a blended wing body but now incorporate a large cabin for passengers. The structural
and aerodynamic advantages the design contributes would result into significant savings in weight
and fuel. Following successful flight tests in 2013, Boeing now collaborates with NASA to further
advance blended wing body technology.
10.3 C-Wing
http://aero.stanford.edu/reports/nonplanarwings/LargeCWing.html
In more successful designs incorporating a tailless configuration, a feature that stands out
the most is the winglets. Instead of having its main a purpose as a method of drag reduction, these
modified winglets acts as rudders for directional control.
Figure 28 – Boeing C-wing concept
The C-wing concept derives from the use of winglets and can be essentially seen as a winglet
having a winglet. The secondary winglet is horizontal and is placed farther rear to serve as the
horizontal stabiliser; the effects of these ‘winglets’ can be made more substantial by adding sweep
to the wings. In order for the C-wing to work most efficiently, the horizontal winglet has to produce
a down-force to produce a trim force that would stabilise the aircraft.
65. 65
Since the wing is effectively increased in length but with no apparent increase in span the
drag force due to vortex is reduced and like the tailless configuration, the length of the fuselage can
be kept short. [21]
However, the c-wing design still poses issues on the structure of the wing. Its geometry
places much of the load on the lower surface causing it to twist; if the control surfaces are placed
below, then the weight penalty would cause them to flutter at high-speed flight. Additionally, this
design does not solve aerodynamic issues attributed to the wing section near the root of the wing.
66. 66
Conclusion
This project revolved around a design concept that still has a many long way to go until it
matures. With the increase of the use of aircrafts as a means of public transport as well as the
increasing want of the public newer and better method of such, understanding the concept of
tailless aircrafts as well as its potential to someday takeover the conventional aircraft as the most
widely used design. Many ideas have sprouted from the concept and these ideas would come into
fruition once each and every aspect of the tailless aircraft is understood and innovative solutions to
its disadvantages are presented.
Throughout this report the performance of the Tailless UAV was analysed using the 2nd
and
3rd
semester aerodynamics books as well Aircraft Design: A Conceptual Approach by Daniel P.
Raymer. The subsequent chapters justified the parameters chosen for the dimensions of the Tailless
UAV using the latter source.
This project could have been made better if the conceptual design was more dominant than
the parametric study. Values obtained from the parametric study are essentially assumptions and
assumptions, in this case, is only supposed to give a general idea and not the holistic one.
Implementation of better time management techniques would have allowed the Tailless UAV to be
constructed far earlier than now; giving more time for testing as well as revisions should any
problems arise. In terms of the analyses performed on the Tailless UAV, much of the constants used
on the calculations were essentially applicable only to large, conventional transport aircraft, the
results would be much more accurate if constants used are applicable to small tailless aircrafts.
67. 67
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Appendices
AutoCAD
The fuselage was constructed by drawing two spheres and interconnecting them with lines. Lines are
the revolved.
Aerofoils were drawn using coordinates, ‘pline’ command
71. 71
Plotted rib, using coordinates and ‘pline’ command
Ribs separated into upper and lower cambers using an arc and the ‘trim’ command
72. 72
Wing skin was created using 3D surf network, separate skins for the upper and lower cambers
Canard ribs were drawn using the path ‘array’ command
