Executive Summary -...
Transcript of Executive Summary -...
VTOL Aircraft
Final Report
Team 10
Calvin College Engineering 339/340 Senior Design Project
Tyson Butler, Brent Homan, Darbi Meyer, Derek VerMerris
10 May 2018
Executive Summary
Team 10, consisting of four mechanical engineering students, sought to design an aircraft
capable of vertical takeoff and landing (VTOL). In areas of limited take-off space, and with
standard RC aircraft technologies becoming outdated, the team hopes to renew the potential for
technological advancement with this product. This advancement ranges from the ability for inner
city hobbyists to fly aircrafts with full flight capabilities, to areas such as drone delivery or drone
disaster support. The project incorporates vertical take-off, static flight, kinetic flight, and
vertical landing through an internal weight distribution mechanism. This provides stability
control with smooth weight transfer, while allowing for the flight of larger aircrafts in areas with
restricted take off space. The project was completed through Senior Design (ENGR 339/340) in
the fall and spring semesters of 2017 and 2018.
Table of ContentsExecutive Summary.................................................................................................................................... iii
Table of Figures..........................................................................................................................................vi
Table of Tables..........................................................................................................................................vii
Table of Equations....................................................................................................................................viii
1. Introduction.........................................................................................................................................1
2. Project Management............................................................................................................................4
2.1 Team Organization............................................................................................................................4
2.2 Schedule............................................................................................................................................4
2.3 Budget...............................................................................................................................................4
2.4 Method of Approach..........................................................................................................................5
3. Requirements.......................................................................................................................................6
4. Research..............................................................................................................................................7
5. Task Specifications and Schedule........................................................................................................8
6. Design.................................................................................................................................................9
6.1 Design Criteria...................................................................................................................................9
6.1.1 Design Norms.............................................................................................................................9
6.2 Design Alternatives.........................................................................................................................10
6.2.1 Fuselage/Body..........................................................................................................................10
6.2.2 Internal Weight Distribution Mechanism (WDM)....................................................................12
6.2.3 Electrical Control System.........................................................................................................13
6.2.4 Flight Control Mechanisms.......................................................................................................14
6.3 Calculations.....................................................................................................................................14
6.3.1 Thrust........................................................................................................................................14
6.3.2 Lift............................................................................................................................................14
6.3.3 Drag Forces..............................................................................................................................15
6.4 Design Decisions.............................................................................................................................16
6.4.1 Aircraft Framework..................................................................................................................16
6.4.2 Weight Distribution Mechanism...............................................................................................17
6.4.3 Motors......................................................................................................................................17
6.4.4 Batteries....................................................................................................................................18
7. Testing...............................................................................................................................................19
7.1 Internal Weight Distribution Mechanism Testing............................................................................19
7.2 Airframe Testing.............................................................................................................................19
7.3 Electrical Component Testing..........................................................................................................19
7.4 Vertical Testing.........................................................................................................................20
7.5 Horizontal Testing.....................................................................................................................20
7.6 Final Flight Testing....................................................................................................................20
8. Conclusion.........................................................................................................................................22
8.1 Results.............................................................................................................................................22
8.2 Improvements..................................................................................................................................22
8.3 Final Thoughts.................................................................................................................................23
Acknowledgements...................................................................................................................................24
References.................................................................................................................................................25
Appendix A: Calculations.........................................................................................................................26
Appendix A.1: Thrust Calculations.......................................................................................................27
Appendix A.2: Lift Calculations............................................................................................................29
Appendix A.3: Drag Force Calculations................................................................................................30
Appendix A.4: Weight Calculation........................................................................................................31
Appendix A.5: Calculation References..................................................................................................32
Appendix B: Components.........................................................................................................................33
Appendix B.1: Controls Components....................................................................................................34
Appendix B.2: Internal Weight Distribution Components.....................................................................35
Appendix C: Flight Design References.....................................................................................................36
Appendix D: Manufacturing Process.........................................................................................................37
Appendix E: Arduino Code.......................................................................................................................39
Table of FiguresFigure 1: Lead Screw Design.......................................................................................................................12
Figure 2: Belt and Carriage Design.............................................................................................................12
Figure 3:Final Design of WDM...................................................................................................................13
Figure 4:Free Body Diagram of Forces on Wing........................................................................................15
Figure 5:Full Solidworks Design Model.....................................................................................................16
Figure 6:Manufacturing of WDM................................................................................................................17
Figure 7:Electrical System...........................................................................................................................20
Figure 8:Vertical Take-off...........................................................................................................................21
Figure 9:Horizontal Flight...........................................................................................................................21
Figure 10:Thrust Calculations......................................................................................................................27
Figure 11:Graphical Representation of velocity requirement......................................................................28
Figure 12:Lift Calculations..........................................................................................................................29
Figure 13:Drag Calculations........................................................................................................................30
Figure 14:Angle of Attack...........................................................................................................................32
Figure 15:Controller.....................................................................................................................................34
Figure 16:Full Body with controls...............................................................................................................34
Figure 17:WDM inserted in plane...............................................................................................................35
Figure 18:Electrical Control Box for WDM................................................................................................35
Figure 19:Airfoil Design..............................................................................................................................36
Figure 20:Wing making design....................................................................................................................37
Figure 21:Milled Fuselage...........................................................................................................................37
Figure 22:Fuselage being milled..................................................................................................................37
Figure 23:Templates for wire-cutting wings................................................................................................38
Figure 24:Logic Diagram.............................................................................................................................39
Table of TablesTable 1: Required Velocity to achieve lift.................................................................................................28
Table 2: Weight Calculation......................................................................................................................31
Table 3: I.C.A.O. Standard Atmosphere Table..........................................................................................32
Table of EquationsEquation 1......................................................................................................................................14
Equation 2......................................................................................................................................14
Equation 3......................................................................................................................................15
Equation 4......................................................................................................................................15
1. IntroductionThe development of a VTOL aircraft involves the design of a weight distribution mechanism,
systems control interface, and the optimization of a body design. This process was completed by
Team 10 of the Calvin College Engineering Department's senior design class to achieve the
overall goal of creating a working model of a small-scale aircraft. This aircraft would have the
ability to alter between vertical and horizontal flight; achieved via the shifting of an internal
mass. Initially, it was decided the internal mass would be shifted using a lead screw or belt
mechanism controlled by a small electric motor and other necessary control systems. The
propulsion of the aircraft is supplied from two electric motors; one mounted on the front crest of
each wing.
The Team consists of four mechanical engineers: Tyson Butler, Brent Homan, Darbi Meyer, and
Derek VerMerris. Through the accumulation of wide variety of skills and backgrounds, Team 10
aimed to create a fully operational model that demonstrates our intellectual and practical
strengths as a team.
Tyson was born and raised in Littleton, a
small town sitting directly west of Denver,
Colorado on the foothills of the Rocky
Mountains. From the time he was very
young, Tyson has pursued a diverse array
of passions including engineering, biology,
and a lifestyle rooted in the outdoors. After
graduating from Dakota Ridge High
School in 2014 and receiving his
International Baccalaureate (IB) Diploma, Tyson found himself at Calvin College as a 2014
recruit for the men's lacrosse team. It was Tyson's hope to discover a rigorous engineering
education and a genuine Christian community. During the Summer of 2015, Tyson began his
first internship at Biomass Controls in Putnam, Connecticut. After his experience with Biomass,
Tyson offers experience in 3D modeling, prototype fabrication, control system testing, coding
and system analysis. Presently, Tyson works as a design and testing engineer at Temper, Inc.
During his time at Temper, Biomass and Calvin college, Tyson has found a passion for research,
design, and development, and offers hands on, design based, and analytical experience.
Brent grew up in the greater San Diego
area in the town of Oceanside, CA where
he attended Vista High School. He began
his hands on and manufacturing
experience in high school during the
restoration of his 1963 VW Bug which
led him to pursue his passion of
Mechanical Engineering. His experience
continued in College as he held two
different internships providing him with very valuable practical experience. The first internship
was at Best Metal Products in Grand Rapids, MI where Brent learned his first official
manufacturing experience as well as design and sales engineering for the company. Following
this experience, Brent went on to work for Highlight Industries in Wyoming, MI where he
assisted in assembly building robots and large stretch wrapping machines. Brent has also
obtained a sustainability designation during his time in the Calvin Engineering Program, and
seeks to use his knowledge of renewables and manufacturing work to contribute to the
completion of this project.
Darbi grew up in Granger, Indiana and
went to Penn High School. Her first
experience in engineering was at Calvin
College, but has always been interested
in how and why things work the way
they do. She spent the past two
summers interning at Cook Nuclear
Plant in Bridgman, Michigan. The first
summer was spent in Programs
Engineering looking at plant equipment qualifications and reliability. The second summer was
spent in Systems Engineering where she worked with the secondary systems of the plant in the
production of power. Darbi was on the Calvin College Varsity Swim team for four years and an
active member of Calvin’s Society of Women Engineers.
Derek grew up in Dorr Michigan on
the family Friesian horse farm where
he encountered many different types of
agricultural machinery and many
mechanistic solutions to physical
problems presented in this world. His
desire to build machinery, tools, and
vehicles started very early in life and
was able to do so through the unique
opportunities given to him from living on a farm. For the past three summers Derek has interned
for Yanfeng Global Automotive Interiors as a product engineer and process innovation intern.
Derek will be a hydraulics engineer for Buhler Prince in Holland Michigan upon graduation.
2. Project Management
2.1 Team OrganizationTeam 10 was advised by Professor Ned Neilson of the Calvin College Engineering Department.
Professor Neilson oversaw the development of the project and assured Team 10 met all goals and
learning outcomes as outlined by the Calvin College Engineering Department. Tim Bangma, a
design engineer at Unist, also mentored the team in their project, while serving as a sponsor for
the team. Other Calvin College engineering professors and faculty also contributed to the
progression of the project through assistance in their areas of expertise.
2.2 ScheduleFor this project, work was divided as a means of outlining several fundamental deadlines over
the course of the year; including minor milestones that Team 10 aimed to achieve. Some of the
major scheduling objectives the team confronted included preliminary research, initial design
decisions, prototype design and calculations by the end of first semester. Prototyping for the
internal weight distribution mechanism, fabrication of all additional components, construction of
several prototypes, and testing of completed prototypes was completed during the spring
semester. To address immediate or small-scale milestones, the team typically met once a week;
at which point these smaller tasks were properly addressed, and divided among team members to
be accomplished.
2.3 BudgetThe budget for this project remained below $750; as allotted by the Calvin College Engineering
Department. The total cost of the project was $722 leaving $28 leftover. This was accomplished
using as many available parts available from previous engineering projects to prevent
unnecessary expenses. The budget dictated many design decisions; particularly regarding what
components were available to the team. Expensive components including motors, electronic
speed controllers, and other electrical components were protected to meet the allotted budget by
developing careful and realistic testing methods. Vendors for the project include Amazon,
Lowes, Hobby Lobby, and Tower Hobbies.
2.4 Method of ApproachTeam 10 considered numerous design alternatives for the aircraft and other similar products as a
means of designing all components to meet all necessary design and operation parameters for the
outlined VTOL aircraft. Based on the capabilities and necessities of the aircraft that was created;
it was important not to simply follow the designs of other VTOL aircrafts on the market. With
this consideration, our method of approach was divided into several distinct decision-making
steps. The first decision was the style of the internal weight distribution mechanism housed in the
fuselage of the aircraft. This mechanism was designed to be stable, lightweight, and be as space
efficient as possible. This mechanism and the decisions made can be seen in the Section 6 of the
report. Once this mechanism was designed, created and tested; the design of the plane fuselage
and airframe was able to undergo construction. The mechanism was designed before the fuselage
of the plane to outline and define necessary sizing constraints to allow for the storage/housing of
electrical components, while minimizing the overall size of the frame. As specified, the VTOL
aircraft was designed to be capable of vertical takeoff, static flight, kinetic flight, vertical
landing, and sustained flight during the transition from static to kinetic flight.
3. RequirementsThe aircraft was engineered to operate in moderate wind conditions, as it is rare for RC
enthusiasts to encounter a windless day. The aircraft must also maneuverable and responsive in
vertical take-off and landing trajectories. Some conventional aircrafts have the ability to hover
vertically, and as a result, could potentially land vertically with the proper landing gear;
however, it takes many years of skill to achieve this type of flying ability and it is a rare ability
amongst enthusiasts. As defined requirement for the project, the plane should be flyable by any
average RC plane enthusiast; ultimately, for those with limited flying capabilities to reduce the
risk of crashing. Additionally, a flight time of five minutes was defined to be an appropriate
minimum operating period, and it was a goal to achieve a greater flight time before the battery is
fully depleted. Similarly, the aircraft was designed with consideration for easy disassembly of
the aircraft into key components for transportation, maintenance, as well as replacement of parts
in the event of a crash. The aircraft is also safe to use, as it is our goal to have a product that
instils confidences in the end user's flying abilities. The final product was less than $750 dollars
to complete as a prototype, and can be competitive with current products already on the market
with regard to price and performance. The aircraft was designed to be propelled by two electric
motors powered by a lithium ion battery. This aircraft design sought to leverage the use of
components already existing on the market to achieve a new type of take-off and landing
recently only reserved for helicopters.
4. ResearchThere are many aspects of aeronautical engineering Team 10 was not familiar with, so research
began with the basics and advanced from there [1]. One focus of the team was finding other
existing products on the market currently that had similar capabilities of our aircraft or were
similar in design. This initially achieved using Google as a search engine, as well as research of
competitive product websites and patent searches. Two products, the Convergence VTOL PNP
[2] and X-vert VTOL BNF Basic [3], were determined to share recognizable similarities, but
both products still differed greatly from the design envisioned by Team 10. Research then
focused on the components needed for the completion of the aircraft as well as the overall weight
and cost. Knowing weight would be one of the biggest factors of the design, it was important to
get an initial estimate for feasibility calculations. To reduce the cost of components, available
parts on campus were inventoried from campus supplies and previous campus projects. Patent
research proved to be helpful in demonstrating that weight transfer within in aircraft can greatly
affect the flight pattern of a small RC aircraft. One interesting patent was for a small quad-
copter. Though the outlined product was not influential to the design Team 10 intended, the
drone uses four adjustable weights on a track, similar to one design alternative the team has
considered, to control the flight of the aircraft [4]. Initial feasibility calculations including lift,
thrust, and drag were completed with the aid of online research, such as tutorial pages offered by
NASA’s Glenn Research Center [5] [6], and textbooks including Fundamentals of Thermal-
Fluid Sciences [7].
5. Task Specifications and ScheduleTo accomplish the task of creating a vertical take-off and landing aircraft, the design and
construction was broken into sections and steps. The first step of this project was to design the
weight distribution mechanism. By creating the design of this aspect first, Team 10 was able to
better assess the complexity of this project, as well as the size constraints that had to be
considered. Creating a working model involved fine tuning of the relationship between power
output and weight, which was better analyzed once the overall size capacity was known. This
design phase was expected to take about two or three weeks.
Once the design of the internal mechanism had been created, the design of the fuselage of the
plane was to be created based on the size constraints set. Implementing the internal mechanism
and the motors occurred after prototyping and testing had been conducted for the fuselage of
each prototype. This design and prototyping process was expected to take one month. In
conjunction with the design of the fuselage for the aircraft, the wings of the plane were modeled
using Solid works. Wing fabrication was scheduled to be completed in phase with the fabrication
of the fuselage to assure geometric constraints were met and to utilize available time.
After the finalization of a body design prototype, the internal mechanism was then installed into
the plane. Following this installation, the team moved into three phases of controlled flight
testing. The first phase was a vertical test to ensure thrust capabilities and adjust trim. The
second phase was a horizontal test in order to gain information on lift capabilities and fine
adjustments. Following these two phases, additional aspects of the aircraft were put completed
for a full flight test including the vertical take-off and the center of gravity shifted transition.
This phase of the project occurred during the last month of the semester.
With the assembly of the aircraft completed, the focus of the team was then directed to testing
and improvements of aircraft flight dynamics, control and fluidity. The task of the project was to
design an aircraft that can sustain static and kinetic flight with the capability of vertical take-off
and landing. Once a working model had been created, most aspects of the task were completed,
but as Calvin Engineering Students, Team 10 aimed to base our project on trust, and
transparency which led us to continue to improve the model until we felt it is the best
representation of our work that we could deliver within the time constraints of the project.
6. Design
6.1 Design CriteriaBased on the specific capabilities required for this project, Team 10 used different design criteria
than what would be used for a traditional aircraft. One of the biggest criterion considered in the
design was weight. With the complex mechanism integrated within the aircraft, it was necessary
to assure weight was minimized to retain adequate thrust capabilities for sustained flight. This
was a major influence in not only component selection, but also in design decisions. In addition
to the weight constraints, Team 10 also had a limited budget which influenced design decisions
as well. With this financial constraint, Team 10 weighed the importance of certain components
and then selected components accordingly. Regarding most traditional aircrafts, the completed
aircraft incorporated many differing capabilities including an altered body profile that supported
this vertical flight. The criteria listed above influenced the decision process and led to the current
design that was implemented in the prototyping process.
6.1.1 Design Norms
While all the design norms discussed in this course are important when looking at this project,
Team 10 chose three to focus on specifically: Trust, Transparency, and Integrity. Through our
education at Calvin College, we have learned the importance of integration of faith and
engineering. As a team, we ensure that our mentors and customers can trust that our project has
the capabilities we claim it to have. In addition, Team 10 sought to maintain trust in each other
and the aspects of the project we worked on individually. Similarly, Team 10 also sought to work
with transparency throughout the entirety of the project. This was done through a consistently
updated website with which our mentors and potential customers had the ability to track our
progress. Our designs and design decisions should be something in which those interested in our
project should be able to keep up with and track. Finally, we also committed to integrity through
the construction and design of this project.
6.1.2 Christian PerspectiveFor this project, Team 10 has chosen a guiding verse that was referenced as a guiding principle
for the entirely of this project:
For as in one body, we have many members, and each member does not serve the same
function. So we, though many, are one body in Christ, individually made one of another,
having gifts that differ according to the Grace given to us. (Romans 12:4-6)
This verse speaks of the different gifts that we all have as Christians, and that none of these gifts
are greater than any other gift—as a gift serves not but oneself, but another. Each gift is
important in its own way, and each contributes its full magnitude to the Kingdom of God.
Through the following of this verse, Team 10 can recognize the different, and equally important,
gifts and strengths that each of us bring to the table, and how this diversity of strengths is what
allowed us to complete this project.
6.2 Design AlternativesThe design of a VTOL aircraft can be considered in terms of four main mechanisms/sections: (1)
the fuselage or body, (2) the internal weight distribution mechanism,(3) electrical control
systems, and (4) flight control mechanisms.
6.2.1 Fuselage/BodyThe design of the fuselage, or body, of a VTOL aircraft incorporated considerations of weight,
lift, balance (center of gravity), and spatial constraints for internal electrical components and the
necessary internal weight distribution mechanism. As an initial approach, materials for the
construction of the body were determined with the goal of maximizing the structural integrity of
the plane while minimizing weight. Final fabrications of the body were completed using an
available mill on campus from Solidworks design files. With this approach, it was necessary to
be able to mill the selected body material(s) to meet all modeled geometric parameters. More
specifically, the fuselage was designed to fuse seamlessly with the cross section of the main
wings. With this consideration, the body of the plane was constructed as upper and lower
sections and manually assembled to accommodate the milling process. With the plane fabricated
using two mirrored/conjoining sections, internal supports and slip fittings for the wing inserts
were easily added. The final design of the body was determined after the specified testing period.
Multiple prototypes were constructed throughout the project for testing and design optimization.
After several iterations of testing numerous prototypes were severely damaged. To address the
issue, carbon fiber and aluminum supports were used to reinforce weaker areas.
The fuselage of the plane was responsible for housing electrical components and the weight
distribution mechanism. Electrical components controlled the exterior micro-servo motors,
internal weight distribution mechanism, supplied power, regulation of power, and receiving
controller signals. All electrical components (excluding exterior components) were housed near
the nose of the fuselage. Behind the electrical control system, the weight distribution mechanism
(WDM) ran axially along the length of the fuselage. The size and operation requirements of the
WDM were determined at the beginning of the prototyping phase.
The largest consideration for the design of the whole aircraft was the shape, form and scale of the
wings and tailfins. The surface area had to be large enough to accommodate the general size of
other components via generated lift. As there is a linear relationship between lift and surface
area, wings were optimized through testing and further analysis with regard to weight, scale,
motor placement, and other aerodynamic criteria. Numerous types of traditional airfoils were
considered as well; with desire for maximum lift and low drag forces. As seen in Figure 7 of
Appendix C, multiple airfoil designs were considered. The plane operated at moderate speeds
(<10mph on average), thus it was necessary for the airfoil design to incorporate considerations
for maximized lift, as well as a generally symmetric design to prevent any non-symmetric forces
during vertical flight. With these considerations, it was decided that the wings would have a
symmetric profile (Appendix C Figure 7). With the symmetric profile, the flyer can generate
significant lift by inducing slight angle of the wings relative to the direction of flight.
Final fabrication of the wings for the plane incorporated a hot-wire cutting method. A hot-wire
cutting apparatus was available in the engineering shop. This apparatus consisted of a long wire
that was supplied by a current from a power supply, which heated due to the wires resistance and
small gauge. Aluminum templates (cross section) were milled for the cross sections of the wing's
airfoil and used as surfaces for tracing the hot-wire through a pre-sized section of polycarbonate
foam. The process results in a closely dimensioned wing with minor surface imperfections. Wing
surfaces were finished and shaped appropriately with knives and sand paper.
6.2.2 Internal Weight Distribution Mechanism (WDM)The objective of the weight distribution mechanism is to vary the center of gravity from the tail
of the plane in vertical flight to a position in line with aircrafts "natural" center of gravity
(generally located between the main wings). To minimize additional weight added to the plane,
the battery as well as a small stepper motor served as the transferring mass. The WDM was
designed with a focus on smooth/steady weight distribution, weight minimization, and in-flight
responsiveness from the controller.
Three different designs were considered for the mechanism. The first design was a lead screw or
worm gear that would transfer the weight. This design was modeled in Solidworks and can be
seen below in Figure 1. This idea was dismissed due to weight and spatial concerns.
Figure 1: Lead Screw Design
The next design considered was a track with belt and pully to move a carriage holding the
battery. This design was modeled in Solidworks as well and printed using 3D PLA material. It
was determined that this method of weight distribution did not provide the holding torque
required to keep the weight in place during flight as well as needing additional components to
tension the belt which could add unnecessary weight to the plane.
Figure 2: Belt and Carriage Design
The final design option for the WDM was a linear gear and pinon that moved the battery and
stepper motor along a track within the plane. The linear gear, pinion, and track were all 3D
printed with PLA 3D printing material. The battery and stepper motor were held on a Plexiglass
slide that fit within rails of the track. This design allowed the stepper motor to be included in the
total weight that was transferred, and reduce the number of components of the mechanism. This
design can be seen in the Solidworks drawing below, Figure 3.
Figure 3:Final Design of WDM
6.2.3 Electrical Control SystemThe aircraft was controlled through the means of two separate power supplies; one controlling
the electric motor controllers, ailerons, and motors, with the other one powering the internal
weight distribution mechanism. The reason for isolating the power supply within the WDM is
because the voltage draw from the motors and servos will create an oscillating supply and causes
the stepper motor to struggle in its motion. A stepper motor works by having two coils that
alternate voltage between them, and therefore an inconsistent power supply causes issue with the
alternating between the coils. All controls from the plane are sent between the controller and the
receiver that is mounted on the aircraft. All actions for flight capabilities are programmed into
the controller, and then respond accordingly based on the input that the component is connected
to. Utilizing this capability, Team 10 was able to connect the WDM into this connection in order
to allow it to be controlled by the controller. The switch that this was programmed into is
constantly sending a signal back and forth between the controller and the receiver. When the
switch is moved, the signal changes, so the WDM was programmed to read the signal and
activate whenever it reads a specified change in the signal’s value.
6.2.4 Flight Control MechanismsTo achieve static and kinetic flight modes, a flight control system was devolved through the
implementation of control systems based off traditional aircraft. General flight control
mechanisms consist of the motors (and propellers), servos, elevators, and the internal WDM. To
achieve static and kinetic flight, the use of a flight control system including an elevator rudder
Ailerons, and two motors were the implemented solution. The use of three tail fins provided
stably in yaw while in static and kinetic flight modes, as well as the combination of pitch, yaw
and roll. The addition of two motors instead of one would allow for stabilization in the
separation of propulsion mechanisms, as well as the potential for an addition plane of motion
while in static mode parallel to the belly of the aircraft; otherwise, the introduction of a
horizontal plane of motion.
6.3 Calculations6.3.1 Thrust
The very first calculation addressed was that of thrust, as the very success of this project was
dependent on the aircraft having the ability to accelerate upwards in a vertical trajectory in a
manner that overcomes the force of gravity. The generation of lift was dependent on the velocity
of the aircraft, surface area of the wings, and the angle of the aircraft relative to the direction of
travel. Online resources were used to attain the appropriate equations used to calculate lift in the
context of specific pitched props at a set rotational speed. The equation seen below takes into
account Euler's Law, the rotational speed of the prop, the diameter and pitch of the prop, and the
surface area of the prop.
Thrust Force=4.39 x10−8 RPM D3.5
√ pitch(0.00042 RPM pitch−V 0)
Equation 1
6.3.2 LiftIn addition to the other preliminary calculations performed for the Vertigo VTOL aircraft, the
aircraft’s lift capabilities were calculated from the following equation acquired from NASA,
mainly taking into account a general wing shape.
L=12
ρ V 2 A CL
Equation 2
In this equation, “L” represents the lift, which must equal the airplane’s weight in pounds to
effectively overcome gravity and to sustain flight. Rho is the density of air, which changes due to
altitude. These values can be found in Table 3: I.C.A.O. Standard Atmosphere Table located in
Appendix A.5. The velocity of the aircraft expressed in terms of meters per second is shown in
the term “V,” and “A” is the wing area of the aircraft in square meters. The Coefficient of Lift
(CL), is determined by the type of airfoil and angle of attack, and can be found using Error:
Reference source not found in Appendix A.5.
Figure 4:Free Body Diagram of Forces on Wing
6.3.3 Drag ForcesDrag calculations were also completed to verify the aircraft would not experience too much
resistive force to fly. These equations were found from NASA’s Glenn Research Center online
resource. The following equation describes the drag force experienced by the aircraft.
D=12
Cd ρ V 2 A Equation 3
Variables of ρ, V, and A represent density of air, velocity, and reference area as in the Lift
Calculations. “D” is the force of drag on the aircraft and Cd is the drag coefficient. The drag
coefficient consists of two parts, the basic drag and induced drag. The basic drag is resistance on
the aircraft due to its shape and material. The induced drag is the resistance experienced due to
lift on the wings creating a pressure differential.
Cd=Cdo+Cdi Equation 4
The overall drag coefficient is the addition of these two drag forces seen in the equation above with Cdo being basic drag and Cdi as induced drag. These calculations can be seen in Appendix A.3.
6.4 Design DecisionsThe two biggest decision factors of the design were weight and cost. The aircraft would not be
able to get off the ground if it weighed too much, and the team was required to operate with an
allotted budget. Components were selected based on these two decision factors first. With most
things related to engineering, more costly components are usually lighter, stronger and have a
greater performance delta in comparison.
6.4.1 Aircraft Framework The final design selected for the aircraft frame was a complete symmetrical design along its
lateral and vertical axis to assure optimal dynamic performance of both the wings and fuselage.
Upon testing, it was discovered that a fourth stabilizing surface, or tailfin, was unnecessary but
helpful for additional control response—if desired. Alterations to the design have messaged out
in the Solidworks model, as manufacturing different parts have yielded some light to the design.
Polystyrene foam was used to create the fuselage, wings, and tailfins. Fiberglass ¼’ tubing was
used to reduce flexure in the wings and increase rigidity of the plane. Sections were joined using
3M foam safe spray adhesive. The overall shape of the plane was designed to reduce drag and
uneven forces in vertical flight.
Figure 5:Full Solidworks Design Model
6.4.2 Weight Distribution MechanismThe weight distribution mechanism design chosen was the linear gear and pinon moved by a
stepper motor that moves the battery and stepper motor along a track inside the plane. The track,
linear gear, pinon, and stepper motor mount were 3D printed using PLA (polylactic acid), which
can be seen below.
The design included an Arduino Uno board connected to the RC receiver. The Arduino board
connected to a bread board with H-Bridge allowed the stepper motor to turn both clockwise and
counter-clockwise so the battery could travel up and down the track. C was used to code the
Arduino. The code looked for a signal coming from the controller, which was providing the
Figure 6:Manufacturing of WDM
receiver a continuous signal based on switch position. When the signal from the receiver
changed, creating a leading or trailing edge in the signal output, the stepper motor was activated
either moving clockwise or counter-clockwise a predetermined number of steps. The number of
steps and motor speed were preset into the code. Once the action was complete the motor
stopped, waiting for another change of signal to before it moved again. Through testing it was
determined that the stepper motor needed more torque to move without stalling. By increasing
the motor driver, stepping up to an Arduino Mega originally intended to control a mill, and an
Arduino shield, the necessary torque was achieved to smoothly move the mechanism.
6.4.3 MotorsTwo 26 mm 14 kV brushless motors, made by Great Planes RC, were selected based upon thrust
calculations. Initially larger brushless motors were selected; however due to supplier difficulties
the 26 mm 14kV motors were used. Calculations showed the new motors would provide enough
thrust to lift the plane vertically. Testing proved the motors, when paired with 6s electronic speed
controllers, gave plenty of thrust to achieve vertical flight.
6.4.4 BatteriesFor the final design it was decided to go with a 14.8 Volt 4 cell lithium polymer battery with a
storage of 4000Mah of power. The choice to go with this battery was based upon testing and
calculations that proved an 11.1V 3 cell does not provided enough power for vertical takeoff. A
separate power source was chosen for the Arduino board and stepper motor due to power
fluctuations from the various servo motors. These smaller batteries were housed in the nose of
the plane, while the large lipo battery was used as the transferring weight. Wire guards were used
to insure all battery and motor wires would not tangle during weight transfer.
7. TestingTesting was crucial for the successful flight of the aircraft. One of the biggest concerns and
places for failure was crashing. This could have resulted in going over budget and time to fix and
replace broken components. For this reason, intermediate testing was done throughout the
prototyping stage before final flight tests were conducted.
7.1 Internal Weight Distribution Mechanism TestingTesting of the weight distribution mechanism started outside of the plane and then was moved
into the aircraft once the mechanism functioned as desired. An external power supply was used
for most of the testing to preserve the battery life for the motor. Several tracks were printed to
allow one track to remain in the test plane and one track outside the plane for additional testing
of the mechanism.
7.2 Airframe TestingInitial designs for the body of the aircraft were designed in Solidworks. These were used to
create the specifications for the mill and templates for the hot wire cutter to form the wings.
Different adhesives were tested on the foam used to ensure it would adhered components without
corroding the material.
7.3 Electrical Component TestingTesting of electrical components took place simultaneously with prototyping. All electrical
components were tested before implementation to insure they function properly as well as after
they had been included into the system to verify correct wiring. All components needed to
function properly before being enclosed in the airframe. The external set up of the internal
weight distribution mechanism with isolated power supply can be seen below.
Figure 7:Electrical System
7.4 Vertical Testing Vertical testing took place first to ensure the plane could get off the ground. A nylon string was
secured from a rafter in the Engineering Building to a block on the ground to create a ridged
guide for the plane to follow. A small fiberglass tube was secured to the back of the plane and
the string was fed through to constrain the plane to vertical flight. A 11.1 V battery and small
(limited to 3s or 12 V) electronic speed controllers (ESC) were used to begin testing. It was
determined through calculations and testing that the small battery and ESC combination did not
provide adequate thrust to lift the plane. Next a 14.8 (5s) lipo battery and larger ESCs (rated up
to 6s) were installed. These provided plenty of thrust to lift the plane off the ground. First lift off
was achieved on April 9th.
7.5 Horizontal Testing Horizontal testing was done to insure the servo motors and brushless motors responded correctly
to the controller as well as to test for the plane body’s ability to maintain flight. The plane was
tossed in a horizontal position to start flight. This was done to remove excess variables
introduced by vertical take-off. The controller was trimmed during this testing to fine tune the
flight control in normal (horizontal) flight. This testing took place on April 13 th in Calvin’s Track
and Tennis Center to remove wind as an obstacle.
7.6 Final Flight Testing The final flight testing was done using no constraints, and outside between DeVos
Communications building and Calvin’s nature preserve on April 19 th. The plane successfully
took-off from a vertical position and transitioned to horizontal flight. Due to windy conditions,
this transition needed to take place shortly after leaving the ground to keep the plane from
flipping from a gust of wind. After the transition the plane was able to maintain horizontal flight
for a total flight time of approximately seven minutes. It was decided to land the plane using
traditional horizontal methods during this test due to the increasing windy conditions.
Figure 8:Vertical Take-off
Figure 9:Horizontal Flight
8. ConclusionIn conclusion, Team 10 sought to expand the potential for technological advancement of
unmanned aircrafts through the development of a working prototype that achieved vertical and
kinetic flight through the altering of center of gravity. This aircraft included a weight distribution
mechanism that moved a weight from the tail of the plane to closer to the nose of the plane in
order to bring the center of gravity from the tail to approximately two-thirds up the body of the
aircraft. Through the successful designing, building, and testing of this prototype, Team 10 was
able to prove the concept of this idea, as well as open the doors for further fine tuning of the
project, or simply further work into the idea itself.
8.1 ResultsProject Vertigo began by first outlining project specifications and later progressed to
several iterations of design, fabrication and testing. A total of three functional prototypes were
completed and tested. During the period of testing, three severe crashes occurred preventing
extensive testing from being completed. While there were issues associated with testing due to
the associated risk of crashing, five successful test flights were conducted: (i) vertical thrust test,
(ii) kinetic glide/component test, (iii) full flight test with forward center of gravity, (iv) vertical
takeoff to kinetic transition test with tail center of gravity, and (v) a final horizontal flight.
Following all tests, Team 10 was successful in creating a functional aircraft capable of vertical
takeoff and kinetic flight, validating the concept of transferring the aircrafts center of gravity for
effective transfer of flight orientation, and developing a weight distribution mechanism to alter
the aircrafts CG.
8.2 ImprovementsUpon completion of this project, Team 10 identified a few areas in which the project could be
improved in the case of a future team taking over the expansion of the idea. One of these
improvements includes an improved method of manufacturing the body of the plane. Due to
limitations from the size of the CNC in the Calvin shop, we were unable to cut the body from the
foam in the way that we wanted to. Ideally, the SolidWorks model made would allow the top and
bottom halves of the plane to be cut in one piece, which would decrease the areas of possible
moment arm forces. Another area that can be improved with this project, is further work into the
electronics and motor control of the aircraft. Currently, vertical take-off and landing are assisted
with the altering of center of gravity, but due to the dual prop design this flight mode can be
difficult to maintain without a greater level of skill of flying. Through the implementation of
gyros or other stabilization technology, the motors can be interfaced to be more user friendly
which would allow for less skilled flyers to achieve both vertical take-off and landing.
8.3 Final ThoughtsThroughout the course of this project, Team 10 was able to use the knowledge and skills
provided to us through our Calvin education to create a working VTOL prototype. Much of the
design forced the team to use information not normally taught in mechanical engineering classes,
but through the holistic engineering education we are given at Calvin, we were able to overcome
these challenges. The team learned many new skills such as designing for rapid
manufacturing/prototyping and 3D printing, as well as continuously improving written and oral
communication skills throughout the project. In the end, the new skills learned, refreshing of old
class material, and continuous improvement of communication resulted in a successful final
senior design project.
Acknowledgements
Calvin College Engineering Department, for sponsoring the project
Tim Bangma at Unist, for mentoring Team 10 for the project
Chuck Boelkins the owner of Unist for sponsoring the project
Professor Nielsen, for advising the team throughout the project
David Malone, for assisting the team in library research
Phil Jasperse, for assisting the team with shop use and fabrication methods
Chuck Holwerda, for assisting the team with electrical component knowledge
Professor Kim, for supplying replacement parts during prototyping of the project
References[1] Weitz, Paul J. “A Qualitative Discussion of the Stability and Control of VTOL Aircraft
During Hovering (Out of Ground Effect) and Transition.” DTIC Online, Defense Technical Information Center, 1964, www.dtic.mil/docs/citations/AD0622205
[2] “Convergence VTOL PNP.” HorizonHobby, <www.horizonhobby.com/EFL11075?KPID=EFL11075&CAWELAID=320011980001297380&CAGPSPN=pla&CAAGID=37619207031&CATCI=pla-382671762385&gclid=EAIaIQobChMIyK2BnsaA2AIVybrACh1cFQG-EAQYASABEgKf1_D_BwE>
[3] “X-VERT VTOL BNF Basic.” Horizon Hobby, <www.horizonhobby.com/EFL1850?KPID=EFL1850&CAWELAID=320011980001297786&CAGPSPN=pla&CAAGID=37619207031&CATCI=pla-272081934850&gclid=EAIaIQobChMIyK2BnsaA2AIVybrACh1cFQG-EAQYAiABEgJFBfD_BwE>
[4] Vaughn, Brad Lee. Adjustable Weight Distribution for Drone. 18 Oct. 2016.
[5] “The Drag Equation.” NASA, The Glenn Research Center, 5 May 2015, <www.grc.nasa.gov/www/k-12/airplane/drageq.html>
[6] “The Drag Coefficient.” NASA, The Glenn Research Center, 5 May 2015, <www.grc.nasa.gov/www/k-12/airplane/drageq.html>
[7] Cengel, Yunus A., et al. “Chapter 15.” Fundamentals of Thermal Fluid Sciences, 5th ed.,
McGraw-Hill Education / Asia, 2017.
[8] NASA, NASA, www.grc.nasa.gov/www/k-12/WindTunnel/Activities/lift_formula.html.
[9] “Conventional Airfoils and Laminar Flow Airfoils.” Wing Design, Aviation Publishers, 2
May 2008, www.allstar.fiu.edu/aero/wing31.htm.
[10] “Romans 12.” The Holy Bible: Containing the Old and New Testaments, Oxford University Press, 2002.
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Table 1: Required Velocity to achieve lift
Figure 11:Graphical Representation of velocity requirement
Appendix A.5: Calculation References
Table 3: I.C.A.O. Standard Atmosphere Table
Figure 14:Angle of Attack
Appendix B.2: Internal Weight Distribution Components
Figure 17:WDM inserted in plane
Figure 18:Electrical Control Box for WDM
Appendix D: Manufacturing Process
Figure 20:Wing making design
Figure 21:Milled Fuselage
Figure 22:Fuselage being milled