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

© 2018

Team 10

Calvin College Engineering Department

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standard RC aircraft technologies becoming outdated, the team hopes to renew the potential for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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Appendix A: Calculations

Appendix A.1: Thrust Calculations

Figure 10:Thrust Calculations

Table 1: Required Velocity to achieve lift

Figure 11:Graphical Representation of velocity requirement

Appendix A.2: Lift Calculations

Figure 12:Lift Calculations

Appendix A.3: Drag Force Calculations

Figure 13:Drag Calculations

Appendix A.4: Weight Calculation

Table 2: Weight Calculation

Appendix A.5: Calculation References

Table 3: I.C.A.O. Standard Atmosphere Table

Figure 14:Angle of Attack

Appendix B: Components

Appendix B.1: Controls Components

Figure 16:Full Body with controls

Figure 15:Controller

Appendix B.2: Internal Weight Distribution Components

Figure 17:WDM inserted in plane

Figure 18:Electrical Control Box for WDM

Appendix C: Flight Design References

Figure 19:Airfoil Design

Appendix D: Manufacturing Process

Figure 20:Wing making design

Figure 21:Milled Fuselage

Figure 22:Fuselage being milled

Figure 23:Templates for wire-cutting wings

Appendix E: Arduino Code

The code that was written for the control of the internal weight distribution mechanism was written in C, and can be referenced within the documents section of our website. The state diagram for this logic can be seen below.

Figure 24:Logic Diagram