FinalDesignReport

FINAL DESIGN REPORTAER E 461

Prepared forPeng Wei

By

Team EclipseNeal CrooksAlicia Ekman

Shawn MauritzJon Miller

Zhe Xu (Steve) OehMark Ritter

Tom SchleismanAlek Szoka

December 7, 2015

Abstract

Our team was given the project of designing a UAS that is capable of completing the given mission. We developed a customer oriented system through the use of market studies, customer feedback, and analyses of the structure, sizing, weight and balance, propulsion, drag, energy maneuverability, performance, stability and control, noise, cold weather operation, cost, maintenance, advanced technologies, and CFD. The result is a UAS design that meets or exceeds all mission requirements.

Table of Contents

Section Page

1. Introduction…………………………………………………………………………….... 2

2. Market Analysis…………………………………………………………………………. 3

3. Customer Survey……………………………………………………………………….. 6

4. Current Product Problems……………………………………………………………... 8

5. Project Drivers…………………………………………………………………………... 9

6. Concepts……………………………………………………………………………….... 13

7. Concept Matrix………………………………………………………………………….. 14

8. Concept Modeling Process…………………………………………………………….. 15

9. CFD and Drag Estimation……………………………………………………………... 20

10. Propulsion Selection……………………………………………………………………. 32

11. Thrust Analysis………………………………………………………………………...... 37

12. Structure Layout Analysis………………………………………………………………. 40

13. Weight, Balance and Center of Gravity……………………………………………….. 48

14. Aircraft Sizing and Endurance Analysis………………………………………………. 50

15. Material Properties…………………………………………………………………….... 52

16. Energy Maneuverability Analysis………………………………………………………. 53

17. Tail and Control Surface Sizing and Stability…………………………………………. 54

18. Advance Technology Highlights……………………………………………………….. 57

19. Cold Weather Operation……………………………………………………………….. 66

20. Noise…………………………………………………………………………………….. 67

21. Cost Estimation for Manufacturing and Maintenance…………………………….......68

22. Project Status………………………………………………………………………….... 71

23. Plan for Next Semester……………………………………………………………….... 77

24. Team Organization Operation………………………………………………………….. 78

25. Summary………………………………………………………………………………... 81

26. Appendices…………………………………………………….………………………... 82

1

1. Introduction

Our team has been tasked with designing an unmanned aircraft system that meets the following requirements:

● Fixed wing UAS● $500 Budget● Capable of carrying a payload of a GoPro Hero4 Session● Flight endurance of 15 minutes or greater● Cruise speed of roughly 30 mph● Fly under 500 feet● Ability to operate in cold and icing weather● Made from currently existing technology

In a brief summary, are mission is to design a fixed wing unmanned aircraft system tasked with agricultural mapping. Our UAS will have a payload of a GoPro Hero4 Session camera. It will be able to be in continuous flight for at least 15 minutes with a cruise speed near 35 mph. Our aircraft will be able to operate in cold and icing conditions. We will use a budget of $500 and use currently existing technology to design a UAS that is capable of completing this mission.

This report has been split into multiple sections. The Market Analysis section explores current products that meet the requirements of our mission. Feedback from potential customers is covered in the Customer Survey portion. Project Drivers covers the assigned mission and the main factors when choosing configurations and designs. The initial design concepts are presented in the Concepts section and then compared in the Concept Matrix section. Design Process outlines the selection of our airfoil and body shape. The technical subtopics follow this section each with a section of their own. Project Status presents the design heading into Aer E 462. Finally, Plan for Next Semester gives a description of what we will accomplish next semester, and Summary wraps up the report. Appendices contains all relevant sources, codes, equations, etc.

2

2. Market Analysis

Our team has studied 3 popular products that are on the market today which fit our mission profile.

AgDrone from Honeywell

Figure and technical specifications from http://www.honeycombcorp.com/

● Fixed Wing Drone● Takeoff Weight: 4.75 lb● Material: Composite construction with Kevlar Exoskeleton● Wingspan: 49 in● Autonomous Flight and Landing● Hand Launch● Coverage: Up to 858 acres● Cruise Speed: 29 mph● Communication Control Range: 2.8 miles

3

Crop Mapper from Delair

Figure and technical specifications from http://www.delair-tech.com/packages/crop-mapper/features/

● 2 hour endurance● 100 km range● Autonomous flight● Catapult-style launcher● Electric motor● Wingspan: 65 inches

Lancaster by PrecisionHawk

Figure and technical information from http://www.precisionhawk.com/

● Weight: 5.3lbs● Wingspan: 4.9ft● Payload: Capacity - 2.2lbs Swappable● Precision Hawk’s proprietary AI detects weather conditions and creates its own optimal

flight path while in the air.● Electric motor

GPS

4

Trimble GPS are commonly used in agriculture. Trimble products have the ability to talk with each other and communicate on the same maps. A complaint brought up from farmers is the fact that some products have their own GPS system and are unable to communicate with other equipment. Using a Trimble GPS in our UAV would allow it to incorporate itself into already existing infrastructure the customer has in place.

5

3. Customer Survey

From class lectures, interviews with agriculture students, and online research, our team has developed an understanding of what customers are looking for when purchasing a UAV.

Most customers value a durable, reliable, and useful aircraft. The UAV must be able to pay itself off in a reasonable amount of time, and require minimal maintenance. Farmers spoke mostly on the desire for a high end camera system with infrared imaging, and mapping capabilities. Precision flight is valuable for inspecting equipment and infrastructure, and taking detailed photos at both high and low altitudes.

The following survey was given to multiple participants to determine customer needs and preferences regarding our product. The participants interviewed include Taylor O’Bryan, an agriculture major, Ashley Kohagen, an agricultural engineering major, and Douglas Todey, an environmental studies major. A summary of their answers is seen below.

1. To your knowledge, how are UAVs used in agriculture? UAV’s are used to scout fields. The drones image crops and fields to look for color patterns, water patterns, weed populations, crop height, storm damage, drainage, and more. These images give farmers a better idea of what is going on in their field, and how to change habits to improve performance.

2. What would you want a UAV to do other than image crops in visual light?

O’Bryan would like UAV’s to take images from multiple places and track where each image was taken. Todey would like the UAV to image in the Infrared spectrum and look for and track moisture content across a field. Kohagen would like the UAV’s to have either an internal mapping system, or be connected to an external mapping system that can track crop height and field moisture. The ability to track moisture is important for farmers to know where water waste is present and where there is a lack of water hindering crops.

3. What are three main features you look for when considering purchasing a machine produce for agriculture?

Cost was mentioned by two of our participants. Kohagen said cost was less important if the product was quality and would last a while. Durability and lifespan was mentioned by all three participants. Quality of material, accuracy, and flexibility of use was also mentioned.

4. Would you be more willing to purchase a UAV if it had unique features?

Each participant said yes, as long as the features were useful.

6

5. Would you be willing to pay a little more for collapsible features to aid in storage and transportation?

Each participant agreed to this. A desire for a case that could fit in a combine or tractor was also brought up. Ease of storage is an added bonus.

6. Would you be willing to pay more for a safety parachute in the case of unexpected stall?

Each participant said they would be willing to pay either for this, or another way of insuring the aircraft. Whether this comes as a safety parachute, or monetary insurance, a desire to protect themselves against a loss of the aircraft was present.

7. How important is autonomous flight to you, as compared to remote control? Each participant prefered a pre-planned flight path and autonomous flight. However, this was not overly important to them and they were confident at least one person on the farm would be able to learn how to fly the aircraft if needed.

8. Without considering limits such as cost, practicability, or if you believe it’s possible, what features would you add to a UAV?

The participants brought up a desire for imaging, video, mapping capabilities, the ability to follow a combine or tractor, motion sensors, temperature sensors, time tracking, ability to assess drainage, ability to connect with external soil maps, and ability to connect to external weather conditions such as precipitation mapping and drought conditions. Having a GPS and ability to take quality pictures despite visibility was also mentioned. The ability to retrieve the information easily from the aircraft, and the ability to customize the aircraft and software to the owner’s field was also a popular demand.

The information gathered from this study can be used to fine tune our aircraft to the needs of a farmer or environmentalist. UAV’s can be used for more than just the imaging of fields. They can be used to track water and soil patterns, look for lost animals, and track invasive species.

7

4. Current Product Problems

The responses from our customer survey and our study of agricultural mapping drones currently on the market show a couple key problems: drones require too much storage space and maintenance, and they need to be useful enough to justify their cost. Most of this usefulness comes in the form of software and systems which are not the focus of this course, as well as the ability to see the entirety of the owner’s field. This drone will focus on reducing cost, reducing space, and durability to meet customer satisfaction.

As you can see from the pictures and information in the Market Analysis section, all of these products require a lot of storage space. From our survey, aircraft requiring less storage space is very important to our customers to the point that they are willing to pay more. In addition, many farmers are not afraid to spend large amounts of money. They also believe that if a drone can accomplish a job which a human previously had to do that could have the risk of falling or injury, they drone has already paid itself off from potential hospital bills or loss of life. Examples of this are building and grain inspections.

To combat these problems, we focused on creating a design that reduced storage space (collapsibility) and is programmable for different missions (autonomous flight software) in order for the design to be able to carry out as many tasks as possible.

8

5. Project Drivers and Requirements

We have examined each of the mission requirements and their effects on our design. This section will explore how each mission requirement shaped our final design.

1. Fixed Wing UAS Drone

Through our market analysis we found that quadcopters are a popular platform for agricultural imaging. Obviously, requiring a fixed wing eliminates this cheap and simple option. Fixed wing aircraft are more complicated than quadcopters in the following aspects: takeoff and landing, dimensions (specifically for storage), propulsion, and aerodynamics.

With regards to takeoff and landing, we explored the following possibilities. Rail launching systems are common and effective for drones similar to ours. However, the extra design and manufacturing efforts required to build a rail launch system, along with the added costs, make this option unfavorable. Launching drones by hand (essentially throwing them into flight), is another popular launching mechanism. Since our UAS will be lightweight, and this option requires no added work or costs, hand launching is very attractive. Launching from a runway is the last option we explored. This will require our aircraft to have a combination of wheels and skids. Although this does add minimal work and cost, most autonomous flight software works best with runway takeoffs and landings.

Storing an aircraft, no matter how small, is cumbersome due to the wingspan and length of the fuselage. Space is often at a premium for farmers. In addition, small, lightweight aircraft can be easily damaged while in storage, especially from snapped wings and bent tails. As a result, it is very important to reduce the dimensions of our aircraft while it is being stored. To do this, we have looked into foldable wings and a collapsible fuselage, which will be covered in more depth later.

Propulsion is a key component to any aircraft. We found that virtually every drone similar to ours in application used a single propellor and motor for thrust. Later in this report, we explore the differences between gas motors and electric motors, and different kinds of propellers.

Finally, aerodynamics is the last aspect we considered from the fixed wing requirement. We emphasized the importance of selecting the best airfoil for our mission by running CFD analyses on multiple airfoil types. The center of gravity is another big factor when analyzing aerodynamics. We will use ANSYS and CAD to make sure that our components (the battery, motor, camera, servos, etc.) are placed so that the center of gravity is in the correct location.

9

2. $500 Budget

In addition to our $500 budget, we also have access to the Aerospace Department’s lab and materials. With these resources, we have planned to focus on flight software, cheap materials, an electric motor, and budget friendly design features.

Autonomous flight software, while expensive, is very user friendly. Having the ability to set the flight path through waypoints is well worth the extra cost. This feature not only makes flying our aircraft extremely user-friendly, it also makes it very easy to set the most efficient flight path for every flight. This will let us accomplish more during our missions. While radio control is cheaper, it is harder to use and users cannot set the most efficient flight path for their UAS.

We will attempt to save the most money when dealing with building materials. This will be accomplished by using as much as we can from the Aerospace Department’s labs, and by purchasing cheap materials when we have to. Materials such as foam, balsa wood, plywood, 3D printed plastic, and fiberglass are all cheap materials that are commonly used in drones similar to size in ours. As a result of this, we are confident that it is safe to save costs in this area.

We will pick an electric motor and battery that are provided by the department. Electric motors and their batteries require little maintenance, perform well in cold weather, and only need to be recharged after use. This contrasts well against gas motors, which have trouble starting in cold weather and require fuel. By picking an electric motor, we will be saving our customers money and maintenance.

Developing selling-point design features for our UAS is the most challenging aspect of working with a $500 dollar budget. While working on our design we emphasized low maintenance, simplicity, and user-friendly features. Additionally, we explored concepts such as an emergency parachute and collapsible wings and fuselage.

3. Payload of a GoPro Hero4 Session Camera

Weight: 74gSize: 1.5x1.5x1.4 inchesFrames per Second: 60, 50, 30Resolution: 8MP (Default), 5MPVideo Format: H.264 codec, .mp4 file formatBattery Life: 1.5 - 2 hrsPorts: Micro USB (charging, connect to computer), MicroSD (memory card)Transfer Photos: Via USB cableWaterproofTime Lapse Feature: Automatically captures a series of photos at timed intervals of 0.5, 1, 2, 5, 10, or 30 seconds

10

As shown above, the weight and size of this camera make it very aircraft friendly. In addition, the adjustable frames per second, high resolution, battery life, time lapse feature, and waterproof feature mesh perfectly with our mission requirements. We explored placing the camera inside and outside of the fuselage, and ultimately decided on inside. This will not affect the aerodynamics of our aircraft and will also protect the camera.

4. Flight Duration of at Least 15 minutes

To make sure that our aircraft will be able to meet this requirement, we will examine the motor, weight, and size.

Motor selection is vital when considering the flight duration of an aircraft. In general, gas motors are able to support longer flight times. However, they are generally heavier and bulkier than electric motors. When choosing a motor, we considered the higher endurance of the gas motor against the smaller size and weight of the electric motor.

Weight reduction also helps lengthen flight time. We will use light materials, such as foam and balsa wood, to make our aircraft as light as possible. Reducing size will also help reduce the weight and thus help the flight time. By selecting the airfoil that provides the most lift at our projected operating conditions, we will be able to design our wings with the smallest possible wingspan.

5. Cruise Speed of Roughly 30 mph

The motor and propellor were our primary concern with this. Later in this report we show and explain the data that led us to select an electric motor with a single propellor. Additionally, we present our drag estimation. With this data we are confident that our design will be able to sustain a 30 mph cruise speed.

6. Fly Under 500 feet

For this requirement our primary concern are complying with FAA regulations. FAA regulations for model aircraft operations are as follows:

● Must fly below 400 feet and remain clear of surrounding obstacles.● Must keep the aircraft within visual line of sight at all times.● Must remain well clear of and not interfere with manned aircraft operations.● Cannot fly within 5 miles of an airport.● Cannot fly near people or stadiums.● Must weigh less than 55 lbs.

For the intended purposes of our aircraft and for the mission we were assigned, we will comply with all FAA regulations.

7. Ability to Operate in Cold/Icing Conditions

11

A more in depth analysis of our plans to meet this requirement is found later in this report in the section Cold Weather Operation. In summary, cold temperatures and resulting higher air density will help the performance of our aircraft. Our customers will have to charge the battery and store the aircraft in normal temperatures due to the effects of the cold temperatures on our materials. We do recommend that our UAS is not used when the average wind speed exceeds 10 mph. Our aircraft will be able to operate in icing conditions due to a protective skin of fiberglass coated with a deicing finish.

8. Built from Currently Existing Technology

All of the components and materials of our aircraft are available for purchase and we have obtained quotes for many of the items. In addition, the unique features of our design, primarily the collapsibility and the emergency parachute, are possible through manufacturing.

12

6. Concepts

Delta wing design considered in early weeks. Drawing by Jon Miller

V-Tail design. Drawing by Jon Miller.

Hershey Bar Design - Conventional tail with collapsible features. Drawing by Jon Miller

13

7. Concept Matrix Analysis (Alicia Ekman)

Three designs were considered for our UAV. A delta wing, V-tail, and collapsible conventional tail design were put under review, and compared with a concept matrix. Delta wings were considered because of their efficiency, durability, and marketable look. Despite these considerations, delta wings perform poorly at low speeds where our aircraft would be flying at, are much more difficult to manufacture, require more complex control systems, and are more expensive due to the higher amount of material. Because of these disadvantages, the delta wing design scored poorly as compared to the other two designs.

The V-tail design mimics a standard RC plane, but with a more unique tail design. We hoped to reduce drag and improve efficiency with this design. The V-tail is found to decrease stability of an aircraft. This feature is a positive for users looking to perform aerobatics, or that need their aircraft to be more maneuverable than normal. Because we are using imaging systems, our aircraft needs a decent amount of stability, so the decrease in stability is presented as a disadvantage. Historical data shows that while V-tails do decrease drag, a larger tail area shows the wetted area remains roughly unchanged. Also, due to unmoving parts and a more complex shape, the V-tail requires a more complex control system than a conventional tail. With all factors taken into account, the concept matrix shows that the V-tail design, gave no benefit to our project over a standard RC plane.

With the first two designs not showing any significant advantages, and some disadvantages over a standard RC plane, we decided to try a similar shape as a standard RC plane with additional features. A conventional plane with collapsible functionality was eventually decided on. The wings will be able to fold in on themselves, and the tail can collapse into the fuselage to create ease of storage and transportability. More recent designs include the possibility of a parachute as well, which would add to safety and marketability. Despite being slightly more costly and more complicated, the marketability and benefit from these features shows that this is our best design option.

14

8. Concept Modeling Process (Jon Miller)

During the initial design process we decided to research previously used agricultural UAVs for possible inspiration. We designed a couple of initial concepts including a V-tail, delta wing, and simple Hershey bar wing. After putting these three designs into our concept matrix, we decided on the Hershey bar wing initial design pictured above. The simplicity of the overall structure appealed to us because it would make calculations much easier and more accurate as well as easier to conceptually manufacture which would greatly reduce cost. However, we wanted to expand on this concept and make this somewhat standard UAV extremely user friendly from a design standpoint. Through our research we uncovered two primary issues with many UAV models that we believed we could solve with some ingenuity. The first was a storage issue while the second was a landing and failsafe issue. The first issue would be simply solved by making our aircraft collapsible, which will be shown and discussed later. The second issue would be solved by installing a remotely activated parachute in the fuselage which would safely allow the plane to land without damage to the plane. This will also be shown and discussed later.

As we continued our research into weighting, sizing, power consumption, thrust, lift, and drag our model continued to develop. From our previous knowledge we understood that elliptical wings are more efficient with respect to lift and drag which is why we modeled the wing below and ran our analysis.

Hershey Bar Design with elliptical wing

15

ClarkY elliptical wingAfter running the analysis for both the elliptical wing and the simple Hershey Bar wing which is show in detail in the CFD section, we decided to go with the simple Hershey Bar. This was due to the fact that the difference between the efficiency of the two wings were almost negligible for the velocities in which it would be used for while the manufacturing ability would be extremely easier for the simple Hershey Bar. After deciding on both the wing airfoil, structure and overall shape we moved to fine tune the fuselage by making sure it would hold all necessary components and also be relatively aerodynamic.

Fuselage Component Structure

16

Wing and Body Configuration After constructing the body we then moved to the construction of the control surfaces of the tail sections. The sizing of these surfaces will be covered later but an important factor that determined these specifications was the distance between the quarter chord of our wing and the quarter chord of the horizontal stabilizer. Increasing this distance also help us avoid potential wake effects caused by the wing upon the horizontal stabilizer.

Final Extended ConfigurationThis Final configuration also addressed both issues. The fuselage is large enough to hold a compact parachute and both the wings and the body collapse which will be discussed later.

17

Final Collapsed Configuration

Materialized Final Configuration

18

Final Configuration in the field

9. CFD Analysis and Drag Estimation

During the design process of the UAV, many CFD simulations were run in order to determine the aerodynamic quantities of various wing designs, body designs, and full model designs. The first CFD simulations reviewed different airfoil shapes at different angles of attack to determine which shape would be best for this application. Each wing was created using a chord length of 10 inches and a wingspan of 48 inches and run through an array of angle of attack simulations. The airfoil designs that were chosen are common airfoil types for UAVs of similar size.

This simulation ran each wing at the cruise speed of 30 mph and at angles of attack from -4 to 10 degrees. These results were then plotted using CL vs alpha and L/D vs alpha plots and compared between the different designs. These results are shown below.

19

Based on these plots, it is clear that the Clark Y airfoil would work best for this application because of the larger CL values for every angle of attack and an L/D max at the target cruising angle of 2 degrees. A sample of the CFD models for each airfoil type is shown below. These photos are of the models at 10 degrees angle of attack.

Clark Y

20

Clark Y

Clark Y CFD at 10 degrees angle of attackNACA 2412

21

NACA 2412

NACA 2412 CFD at 10 degrees angle of attack

22

NACA 0012

NACA 0012

NACA 0012 at 10 degrees angle of attack

23

E168

E168

E168 at 10 degrees angle of attack

Once the Clark Y was chosen, a modified version of a Clark Y wing was made in order to compare it to the zero taper wing used previously. The modified design is shown below.

24

Modifies Clark Y

A simulation was then run at the same situation as with the standard Clark Y done previously. Comparison plots between each design are shown below.

Based on these plots, there is a slight improvement between the modified design and the standard design. However, the increased manufacturing difficulty makes these small improvements not worth it. Therefore, the full design uses the standard Clark Y wing.

25

Once the wing was chosen, a simulation was run on the wing-body model. As the name implies, this model only included the wing and the main body of the aircraft so that the aerodynamics of the body shape could be evaluated. This model was run through the angle of attack sweep at cruise similar to the other simulations. Pictures of the results are shown below. These photos are of the model at 10 degrees angle of attack.

As shown by the circled area above, the wing/body connection point on the front of the wing causes a slight separation of the airstream, reducing the performance. This was fixed by filleting the connection point to make a smoother path for the airstream to travel. Another problem that was found during CFD analysis was that there were a few sharp corners that caused problems during meshing. This is shown below.

26

Image of pre-filleted nose

Pre-filleted Vertical Stabilizer

27

Pre-filleted section where the wing meets the fuselage

These areas were filleted as well in order to produce better CFD results on the final model. Using this data, the final model was developed and tested in CFD using the same analysis as before. Pictures of the results are shown below. These photos are of the model at 10 degrees angle of attack.

CFD Model (sharp edges filleted)

28

CFD of whole aircraft

CFD of whole aircraft

Based on these results, the major areas of drag were the bottom of the vertical tail and the back of the fuselage. These locations of higher drag are expected. The only concern that arose from this simulation is the lack of significant velocity differences on the horizontal tail. This could be caused by the fact that the tail is too close to the main wing and is getting downwash from the main wing, reducing the performance of the horizontal tail. For the final design, the tail was moved farther away in order to reduce this effect, as well as reduce the tail surface areas. A T-tail design was also considered. The final results of the lift and drag are shown below followed by a plot of the results versus angle of attack.

29

AOA (Deg) L (N) D (N) L/D

-4 4.119046 0.989839 4.161328

-2 10.80708 1.083635 9.972987

0 17.26722 1.311733 13.16367

2 23.61134 1.665685 14.17515

4 29.79763 2.140126 13.92331

6 35.67445 2.72727 13.08065

8 41.03893 3.419193 12.00252

10 45.56778 4.222839 10.79079

The estimated weight of the model is about 5 lbs which is about 22.2N. Based on the lift/drag plot, the minimum L/D occurs at 2 degrees angle of attack and at that point, the lift is 23.6 N which is about what our weight is. Based on this data, the steady level cruise flight will occur at a 2 degree angle of attack at a cruise speed of 30 mph, as desired.

30

10. Propulsion Selection

When choosing a power system for a UAS there are four main things to look at the propellor, motor, electric speed controller (ESC), and the battery. The main selection criterion when making our selections were whether or not the components were available in the lab. We started from the motor knowing the plane weighs about 5 pounds, we selected a motor rated for a range of 4 to 7 pounds. We made sure it was an outrunner because outrunners produce lower RPM at higher torque than inrunners due to the way they are made. This enables an outrunner to spin a larger prop without a gearbox.This means no maintenance, quieter operation and cheaper purchase price (no gearbox). With this in mind we selected the E-flite Power 46 Brushless Outrunner Motor. It can produce up to 925 watts of power and has a 670 Kv rating. kV stands for Revolutions per minute / per volt. A 1000kV motor will spin 10,000 RPM on 10V. This rating is calculated when the motor has no load. kV rating has nothing to do with how much power the motor can produce. It represents how fast the motor wants to spin. The kV rating is useful to help determine the size of the prop.

Following the motor manufactures recommendations of having a prop from 12x8 to 14x10. The prop sizes have two numbers that are important. The first number is the diameter (in inches) and the second number is the pitch. These numbers are usually molded into the front of the propeller. Diameter - The size of the propeller (total length) measured in inches. The diameter of the propeller depicts the thrust generated.The second number pitch is a little harder to understand. The number indicates how far the propeller wants to travel forward in one revolution. A higher pitch propeller is meant for higher speeds and will be less efficient at slower speeds. It is similar to a bike or car in a higher gear. The acceleration is going to be less but the top speed is going to be greater. A lower Pitch prop is going to grip better and give you a faster acceleration however, it has a lower top speed.

With this basic knowledge know We used an easy online calculator with some of its helpful recommendations to calculate the following useful information seen below. Knowing we have a direct drive motor I we decided to go with the yellow recommendation of a 13x8 APC Electric E Propellor would provide the proper amount of thrust for our aircraft. Knowing if we need more thrust in the future we can always go to an 13x10 for .5 oz more thrust. seeing that it is an APC prop we will know it has consistent power throughout its entire RPM range. This makes it a great all around sport prop. Though, it may be one of the noisiest and most highly engineered props you can buy. Its weakness; A jack of all trades is a master of none.

Aerobatics was chosen because it was the closest option to our design. The inputs were taken from our CAD model and selected component ratings.

31

Some other useful information:Estimated Flight Duration: 16 to 27 minutesStall Speed: 21.5 mph (with top speed of 59 mph)Battery Size: 4S 6600 mAhPower Into/Out of Motor: 522.7 W in / 392.0 W outSuggested ESC Rating: 47A to 54AAs you can see, all of the calculated values match our selected component ratings and mission requirements.

32

Continuing on with the manufactures and calculated recommendations with a motor this size we are required to go with a 60 Amp brushless ESC.This ESC will have battery elimination circuit(BEC). The BEC is what powers the receiver (RX.) Unless you are powering your receiver from a separate battery, you will need to make sure your ESC has a BEC built in.

The manufacturer also recommends a 4S-5S Lipo battery, and the calculator saying we should use a 6600 mAh battery. We decided the Multistar High Capacity 4S 6600mAh Multi-Rotor Lipo Pack was our best option due it being a Similar size and weight as batteries of much lower capacity. The battery has a capacity of 6600mAh set up in a 4S1P / 14.8V / 4Cell configuration. The constant discharge is 10C while its peak discharge for a duration of 10 seconds is 20C. The battery pack is able to do this all at the size of 142 x 49 x 35mm weighing in at 537g. We looked into using a larger capacity battery, however the increased weight was too great.

We also decided to use the Adrupilot as our receiver to control our servos and motor. Placed below are pictures of each component that will make up our propulsion system.

Figure: Multistar High Capacity 4S 6600mAh Multi-Rotor Lipo Packhttp://www.hobbyking.com/hobbyking/store/uh_viewItem_B.asp?idProduct=56848

Figure: E-flite 60-Amp Pro Switch-Mode BEC Brushless ESC

http://www.e-fliterc.com/Products/Default.aspx?ProdID=EFLA1060

33

Figure: Power 46 Brushless Outrunner Motor 670Kvhttp://www.horizonhobby.com/airplanes/motors/power-46-brushless-outrunner-motor--670kv-eflm4046a

Figure: APC 13x8E Thin Electric Propeller http://www.motionrc.com/apc-13x8-thin-electric-propeller/

http://www.ardupilot.co.uk/Figure: Adrupilot Autopilot control system

34

Figure: Example of Power System and Adrupilot put together to be fitted in fuselage

35

11. Thrust Analysis Using another online calculator with move variables to get a closer approximation of our power system you can see we entered in our components in the figure below from the limited list of products they had. We went with a slightly larger battery so the data may vary a little bit.

Figure: Data generated by http://ecalc.ch/motorcalc.php

When comparing some of these numbers with the previous calculator you can see the estimated flight duration of 16 to 27 minutes maybe closer 17 minutes of mixed flight time. But the battery is well beyond its load limit and remains around 6C with a current draw of about 40 Amps and 14.7 volts. Our power input and output may vary a bit but should be within 520 to 580 watts in and can max out at 720W. Along with 390 to 450 watts out with a max of 557 W of power out. The motor should have an efficiency of 77.3% and should only reach a temperature of 160 F when operating and maximum power spinning the prop at 8096 RPM.

With a wing loading of 19.3 oz/ft^2 or a cubic wing load of 9.4 the estimated stall speed is 22 mph and the max speed at steady level flight will be around 55 mph. The estimated vertical speed is 18 mph with a rate of climb at 1985 ft/min. This is all done with a power to weight ratio of 150 W/lb or a thrust to weight ratio of 1.45:1. Being the the most efficient at about 75% throttle or power. You can see additional motor characteristics in the following graph.

36

Figure: Graph generated by http://ecalc.ch/motorcalc.php

Using the equation above a excel spreadsheet was created to generate a table of data to create the graph below showing Thrust vs Airspeed an APC E 13x8 prop at 8000 RPM.

37

Figure: 13x8 Prop at 8000 RPM

Aircraft Airspeed, V0 (m/s)

Aircraft Airspeed, V0 (mph)

Dynamic Thrust, F (N)

Dynamic Thrust, F (g)

Dynamic Thrust, F (kg)

Dynamic Thrust, F (oz)

Dynamic Thrust, F (lb)

0 0 26.6631201

2717.953 2.717953 95.87308 5.992054

13.4112 30 13.4648757

1372.566 1.372566 48.4159 3.025987

The plot shows the max speed with a 13x9 prop is about 60 mph. The data above shows a static thrust in the first row and dynamic thrust in the second row for our cruise speed of 30 mph. With a known error of about 16% shows some promise when comparing these results with the previous calculator stating we should have a static thrust of 3278 g or 115.6 oz and a stall thrust of 2063 g or 72.8 oz. Our thrust at 30 mph should be 59.1 oz. It is also calculated to have a pitch speed of 61 mph which is should in the graph and a tip speed of 313 mph and a specific thrust of 0.16 oz/W. This UAS should be able to perform well and above than the stated requirements.

38

12. Structure Layout Analysis

Using ANSYS, deformation and stress were calculated on the Clark-Y airfoil selected for this design. Because the wing is made of solid foam, the lift force was dispersed on both sides of the ¼ chord of the wing to avoid unrealistic deflections due to only placing the resultant force on the ¼ chord. The total lift and drag forces applied were the forces calculated in the CFD analysis for steady level flight. Figure 12.1 below shows the meshed Clark-Y model with applied forces before solving for deflections and stresses.

Figure 12.1: Clark-Y Airfoil Model

39

Figures 12.2 and 12.3 below show two views of the calculated displacement from the applied lift and drag forces. As expected, the maximum displacement occurs at the tip of the wing. According to the solution, this maximum displacement has a value of 10.42 inches.

Figure 12.2: Deflection, Front View

Figure 12.3: Deflection, Angled View

40

Figures 12.4, 12.5 and 12.6 below show views of the calculated Von-Mises Stress from the applied lift and drag forces. As expected, maximum stress occurs at the root of the wing.

Figure 12.4: Von-Mises Stress, Front View

Figure 12.5: Von-Mises Stress, Top View

41

Figure 12.6: Von-Mises Stress, Angled View

Whether or not the foam material fails under flight loading is irrelevant. The deflections for this model are too severe to sustain steady level flight, and the airfoil must be reinforced.

42

A second reinforced model of the same wing was created in ANSYS using two ¼ inch diameter aluminum rods running throughout the length of the airfoil. One was placed at the ¼ chord where the resultant lift force is, and the other at the 2/3 chord because it is roughly halfway between the quarter-chord and trailing edge. Figure 12.7 below shows the meshed, reinforced Clark-Y model with the same applied lift and drag forces.

Figure 12.7: Reinforced Clark-Y Airfoil Model

43

Figure 12.8 below shows new calculated displacement from the applied max lift and drag forces. The maximum displacement again occurs at the tip of the wing, with a significantly smaller value of 3.61 inch.

Figure 12.8: Reinforced Deflection, Front View

Due to the foam airfoil and aluminum rods having significantly different properties, figures 12.12 and 12.13 below show the Von-Mises Stresses on the foam airfoil and aluminum rods independently.

44

Figure 12.12: Reinforced Von-Mises Stress, Foam Airfoil

Figure 12.13: Reinforced Von-Mises Stress, Aluminum Rods

Using the calculated maximum stresses of 21.65 psi for the foam and 22132.9 psi for the aluminum rods, the factors of safety were then calculated using the following equations:

45

Where is the failure stress of the material and is the maximum stress calculated using ANSYS. The factors of safety for the foam and aluminum rods are 3.62 and 4.22, respectively, as shown in table 12.1.

Table 12.1: Determined Values for Reinforced Clark-Y Airfoil

Material Max Displacement

(in)

Max Stress(psi)

Failure Stress(psi)

Safety Factor

Foam Airfoil 3.61 21.65 40.32 1.86

Aluminum Rods 3.57 22132.9 48008 2.17

13. Weight, Balance and Center of Gravity Parts Weight (grams) Weight (lb)

Camera System

GoPro Hero4 Session 74 0.163

Build Materials

Foam/Renshape 900 1.984

Foam Glue and Epoxy 400 0.882

Fiberglass Cloth/Mat about 400 about 0.882

Carbon Fiber Cloth 100 0.220

Tail Tubing 28 0.062

Monokote 84 0.185

Power System

Battery 537 1.184

ESC 60 Amp 76 0.168

Motor Power 46 298 0.657

Prop Shaft Extender 21.3 0.047

Propeller 18 0.039

Prop Spinner (cone) 8 0.018

Control System

46

Controller/Transmitter Not Included Not Included

Receiver 10 0.022

LargeServos 42 0.093

Small Servos 10 0.022

Control Links/Pushrods 5 0.011

Control Horns 5 0.011

Hinges 9 0.020

Autopilot and Stabilization System

Ardupilot 26 0.057

Gyro 11 0.024

GPS 25 0.055

Parachute 20 0.044

Battery Charger Not Included Not Included

Empty Weight 392.8 g .866 lb

Fixed Weight 1196 g 2.637 lb

Center of Gravity

If we set the origin at the tip of our aircraft, the center of gravity is located at the following location (the x direction is from the tip to the tail, the y direction is from the bottom of the aircraft to the top, and the z direction follows the wingspan):

x: 5.27 inchesy: 0.21 inchesz: 0.00 inches

This puts our center of gravity in front of the aerodynamic center and nearly in the center of the fuselage, which is favorable for our aerodynamics and control.

47

14. Aircraft Sizing and Endurance Analysis

Takeoff Gross Weight (TOGW)The takeoff gross weight sizes the vehicle. We considered the takeoff gross weight (TOGW), or WTO to be: (Anderson_124)

WTO = Wfuel + Wfixed + Wempty

The fixed weight (Wfixed) consists of the following: (The weight is above at the “Weight and Balance” section)

1. GoPro Hero4 Camera System2. Battery 6600 mah3. ESC 60A Electronic Speed Controller4. Motor Power 465. Prop Shaft Extension, Propeller, & Propeller Spinner6. Receiver7. Large and Small Servos8. Control Links/Pushrods, Control Horns, & Hinges9. Parachutes

As our design is powered by electric motors, the fuel weight (Wfuel ) is zero.

The empty weight (Wempty ) consists of the structure of the plane such as fuselage, vertical & horizontal stabilizers and wings. The total volume of the structure is 783.94in3 or 0.454ft3, the total weight for the structure of the plane is 0.681 lb using the foam weight of 1.5 lb per cubic ft. Also, the design included MonoKote, a light weight plastic shrink wrap film used to cover and form the surface of the aircraft, which has a weight of 84g or 0.185 lb. Hence, the empty weight for the designed UAV is at 0.866lb.

Table 14.1

Weight: (lb)

Fixed weight (Wfixed) 2.637

Fuel Weight (Wfuel ) 0

Empty Weight (Wempty ) 0.866

Takeoff Gross Weight (WTO) 3.503

From the calculation above, the takeoff gross weight (TOGW) for the designed UAV is at 3.503 lb.

48

Endurance

The endurance calculates the maximum length of time an aircraft can fly at specific cruising speed. Our design is powered by a Multistar High Capacity 4S 6600mAh Multi-Rotor Lipo Pack. To calculate the endurance, we need to know the battery’s capacity in amp hours and the average amp draw. For this specific battery, the battery’s capacity is 6600mAh, while the battery is capable of providing a constant discharge of 10 Amps.

Using the numbers above, we take the battery’s capacity in amp hours, then divide that into the average amp draw and then multiply by 60. That will give you the total flight time in minutes.

Battery Capacity: 6600mAhAverage Amp Draw: 10A Flight Time: 39.6 minutesFlight Range: 19.8 miles

The battery selected has a peak discharge of 20A. Considering the battery is at peak discharge, our design has a flight time of 19.8 minutes. The endurance or flight time of our UAV fulfil one of the mission requirements of our design, which is a flight duration of at least 15 minutes.

Battery Capacity: 6600mAhPeak Amp Draw: 20A Flight Time: 19.8 minutesFlight Range: 9.9 miles

49

15. Material Properties

The main material used in our design is foam, which will be used for the fuselage and the wings of the UAS. There are a few reasons for this selection. First, foam is very lightweight and easily repaired. Second, foam is flexible and allow us to use another material to cover it to strengthen the structure of the aircraft. Third, foam is low in cost and it helps us to keep out budget under $500.

There are a few types of foam: Expanded Polypropylene foam (EPP), Expanded Polyolefin foam (EPO), Expanded Polystyrene foam (EPS), and XPS, an extruded version of EPS. XPS is most commonly used in UAVs as it improved the surface roughness and higher stiffness and reduced thermal conductivity. Therefore, the design of our design uses the extruded version of EPS (XPS) because of its superior strength comparing to other types of foam.

Monokote is a lightweight plastic shrink wrap film used to cover and form the surface of the aircraft. The decision to go with Monokote is because it is light and cheap. Monokote will provide the much needed strength and shape to the design. To prevent punctures, we will use fiberglass on the bottom of the aircraft to reduce damage from landing and takeoff.

There were a few initial ideas of using composites, fiberglass, and balsa wood to be the main structure of our UAV. But the ideas were rejected because these materials are expensive or heavy in weight. Using foam as the main structure of our design certainly give us a much lower weight, and this was clearly illustrated in the takeoff gross weight of 3.503 lb.

50

16. Energy Maneuverability Analysis

Energy Maneuverability is how easily an aircraft can change its energy state. At any time in the aircraft’s flight with a given velocity and altitude, the aircraft has a specific energy given by the following equation.

he=h+12V 2g

Specific excess power is given by the following.

Ps¿V [Tcos(α+i)−D ]/W

This is a measurement of the change in the excess power at any given point in the flight. Plotting the specific power versus thrust will allow us to see what thrust is needed to accelerate, remain at steady level flight, or decelerate. A code was created to plot thrust vs specific power given flight criteria inputs of angle of attack, incidence, and flight path angle, drag, velocity, altitude, and weight.

Results were found using the following inputs. Our aircraft weighs approximately 5 lbs with a

α=2deg¿=0.5degγ=0degW=5lbs

D=0.3745lbsV=30mphHeigh t=450 ft

Drag was found from the CFD analysis of the full body at 2 degrees angle of attack. The results are shown below in Table 16.1.

Table 16.1

he 480 ft

Thrust at Ps=0 0.3751 lbs

Max Ps 31.87 ft/s

51

17. Tail and Control Surface Sizing and Stability The vertical tail and horizontal stabilizer sizes can be found based off of the distance between the center of gravity and the aerodynamic center of the tails themselves, as well as the wing span, area and mean chord length. These surfaces need to be designed such that they are big enough to cause a strong enough moment about the center of gravity to offset the moment caused by the aerodynamic center. They cannot be too large though because that will cause unneeded drag on the UAV which is detrimental to performance. Due to the design of our UAS the distance from the center of gravity to the aerodynamic center of the tail is short, and the wingspan is quite large. The moment arm (distance from cg to ac of tail) is 24.8 inches and the span is 60 inches, with a chord length of 10 inches. This gives us an aspect ratio of six. The next part to determining the size of the horizontal and vertical tail is to determine a tail volume for each. Standard values for these for prop driven aircraft are .7 for the horizontal tail and .04 for the vertical tail (Anderson_436). With these numbers we get a horizontal tail area or 169.355 in^2 and a vertical tail area of 57.6 in^2. From here we calculate the span of the horizontal tail and the height of the vertical tail, to do this we need to choose an aspect ratio for each of them. Beginning with the horizontal tail an aspect ratio of 2 has been chosen. This was chosen because aspect ratios for tails need to be smaller than that of the wing itself. This will allow the tail to have some control over the craft if the wing stalls due to a higher stall angle than the wing. Our wing aspect ratio is six, we chose two for the horizontal tail because it decreased the size of the span while keeping a reasonable value for aspect ratio. The vertical tail is somewhat different, the aspect ratio still needs to be small however there is a set range that is typically used. That range is 1.3-2, we chose to use 1.5 for our aspect ratio. This will yield a horizontal tail span of 18.4 inches and a vertical tail height of 9.3 inches, note the vertical tail is based on a height as a tip to tip measurement does not mean anything for a vertical tail. (Anderson_438-440) The root and tip chords can now be found based on the areas, spans and taper ratios. We decided to design the horizontal tail so there was no taper to it. This means that our root chord and the tip chord have the same length, thus the taper ratio is 1. The vertical tail we wanted to taper as much as possible for aesthetics. We allowed a taper ratio of .335 for this, it allows for a large taper but also leaves room for the rudder to go all the way up the tail. This yields values of 9.2 inches for the horizontal root and tip chords and a vertical root chord of 9.28 inches with a tip chord of 3.1 inches. (Anderson_438-440) These seem to be large values for a tail and stabilizer however if we examine the design we will see that the moment arm, the distance from center of gravity to aerodynamic centers, is small compared to the size of the wing span. This means that the tail will need to be larger in order to offer enough lift to create a moment that will allow for control to be effective. The elevator, rudder and aileron sizing can be estimated as follows, elevator 20% of the horizontal stabilizer, the rudder is 10% of the average vertical tail chord, and the ailerons are 20% of the wing chord

52

length. This makes the elevator chord 1.84041 in the rudder chord length is 0.495742 in and the aileron chord length is 2 in. If we look at the figure below we can see the moment created by the horizontal tail with zero elevator deflection. Our cruise angle of attack is two degrees, at that angle of attack out tail creates a negative moment which is what we want for control and stability. (Nelson)

Figure: moment created by the tail versus angle of attack A preliminary look into stability for the UAV shows that it will be stable using an angle of incidence for the wing of .5 degrees and an angle of incidence for the horizontal tail of -2 degrees. If we examine the pitch moment coefficient Cm vs alpha, the slope of the curve must be negative, as can be seen in the figure below it is. Also for stability, cm_alpha_tail must be less than zero, ours is -.041. These are only preliminary looks into stability of the craft, a more in-depth look will be done in the future. (Nelson)

53

Figure Pitch moment coefficient versus angle of attack

54

18. Advance Technology Highlights

Control of Craft

The main technology highlight that will separate our UAV from the rest will be the autonomous control system that we will implement. We plan to use the ardupilot mission planner through an Arduino system using the pixhawk. The mission planner has several key benefits that will help the success of our UAV. The system will allow for waypoints to be selected based on an uploaded Google Maps, Bing, or Openstreetmap. The system will load the map and then allow the user to select the waypoints as well as a home location used for takeoff and landing. The waypoints will have a latitude and longitude that is uploaded from the map as well as an altitude selection. After a certain set of waypoints have been uploaded they can be saved so that the exact same set of points can be reloaded at a later time and flown over again. This will benefit farmers who wish to see the same section of their property time after time. There is also an auto grid system that is a built in feature, it will allow for a farmer to put in 4 corners, the distance desired between input commands and then the system will generate a grid that can be flown over. (Oborne) Another benefit of this system is that it has a set of commands that can be used as inputs to the aircraft. These include things such as speed control, loiter, servo control, camera control, and several other commands that could prove useful. If a speed control is used properly we can slow the craft down at each waypoint so that a more quality picture can be taken, it will also allow us to slow the craft at our last waypoint for parachute deployment. The servo control can be used for a number of things should we wish to control anything outside of the normal function of the craft. The biggest plus is the camera control, this will allow the farmer to tell the program when and where he/she wants the pictures to be taken. This will also help with the parachute deployment because it can be programed so that conditional statements are met, meaning that if the system for some reason fails it will deploy the parachute automatically. (Oborne) This system will allow farmers to easily do flights and know exactly where the pictures are being taken, and it will allow farmers who do not know how to fly a UAV to purchase our craft because it will not require any previous flight experience. It allows for several missions to be run back to back and also for missions to be saved so they can be run exactly the same a second time. The only downfall is that there will be a need for internet connection, however the benefits outweigh this. All in all this is the best way for someone to easily control a system of this nature with little to no experience.

55

Solar Power

Making sure that our UAV can fly for the full amount of time of 15 minutes is a key design criteria. We decided to look into the possibility of putting in a solar panel on the top of our fuselage to add battery life to extend flight time. Our battery is a 14.8 volt battery with 6600 mAh, if we use a 3x6 inch solar panel and point it directly into the sun we can get approximately 10 Watts per hour (Solar Calculator). If we assume a loss factor of 2.5 when charging with the solar panel and a flight time of 15 minutes we will charge our battery .25 percent, with a total battery charge time of 97.68 hours. For the cost of the solar panel and the added weight and drag getting an extra .25 % charge is not worth it. Also that assumes that it is mid-day and cloud free conditions with the solar panel pointing directly at the sun, if these conditions are not perfectly met then we will get even less extra energy from a solar panel. (Estimating) For those reasons, we will not utilize solar panels.

Collapsibility

Storage of a small UAV could pose a problem to anyone who is attempting to store one, they are oddly shaped and could be damaged if not kept in a safe place. In order to make storage somewhat easier with the UAV it has been decided to make it collapsible. This will allow it to be stored in a smaller area as it will take up less space. In order to do this our tail section will slide into the main body of the fuselage. It will do this via the circular attachments from the fuselage to the tail. The wings will also fold downward next to the fuselage reducing the chance that they will be damaged in anyway when not in use. Our craft will go from taking up an area of approximately 5ft by 4ft (20 Square feet) to taking approximately 3ft by 2.5ft (7.5 square feet), this will reduce the area needed by 12.5 square feet making storage significantly easier.

56

Extended Simple dimensions

Collapsed Simple Dimensions

57

Parachute

We have decided to change the style of landing for our craft from the typical wheels on runway to using a parachute system. This will allow us to be able to build the craft without any landing gear, saving us drag or the problem of making retractable landing gear. It will also act as a failsafe should the autopilot system malfunction in anyway. If for any reason the autopilot malfunctions the parachute can be deployed for an emergency landing. It will most likely land in the farmer’s field in this case, however retrieving the craft is much easier than needing to replace it because it was lost or damaged beyond repair. Our preliminary design for the system will attach in a small compartment on the top of the craft. There will be a hatch covering the compartment that will be controlled by a small servo. Storing the parachute in this fashion will cause no extra drag for the craft as it is inside of the fuselage. The parachute will need to attach to a point on the top of the craft that is as close to the cg as it can be made to ensure that the craft will land on its belly. We will need at minimum two attachment points to ensure that the craft does not tip over during its descent, however if three attachment points can be used it will help stabilize the descent. If three connection points are to be used one will be in front of the wing and two will be behind the wing. Using a system of this fashion will cause the craft to impact the ground with more force than if landing gear were used which could cause damage. We believe that the craft will be able to absorb the impact with no damage due to it being wrapped in either carbon fiber or fiberglass. If we can use a slightly larger parachute than necessary it will also slow the craft down to a speed where the force of impact is reduced to a more manageable amount. Also using three attachment points in a triangular setup will keep the craft from landing on a wing or the tail. The parachute will deploy when the craft reaches its home location of (0, 0, z). The autopilot system will be programmed to reduce thrust to stall speed upon approach to home location and open the hatch encasing the parachute upon arrival. The altitude at the deployment can be varied based upon wind conditions however should remain above 100 feet, this will allow for enough time for the parachute to deploy and slow the descent to the desired speed. The parachute should be sized so that the craft will fall between approximately 11.5 and 14.8 feet per second, as a general guideline, we have increased this to 10-16 feet per second. These values will have a small enough impact force that the plane should be able to withstand. If we choose a descent speed of 10 feet per second this will give us the least amount of impact force, however it will increase the size of the parachute needed to slow to that speed. At 10 feet per second the diameter of the chute needed is 73 inches and the force of impact will be 15.3 lbf assuming a Cd of 1.5. If we assume on the lower end of typical values for Cd, say .75, the necessary diameter will be 103 inches and the impact force will stay the same. If we up the descent rate to 16 feet per second the size of the parachute needed decreases to 62 inches for a Cd of .75 but the impact force increases to 25.5 lbf. If the Cd is increased back to 1.5 the diameter reduces to 44 inches. The following figures show the necessary diameter of the parachute as a function of coefficient of drag at each velocity as well as a function of velocity for each coefficient of drag. (Apogee Components)

58

Figure: Diameter as a function of Cd for each possible velocity

59

Figure: Diameter as a function of V for each possible Cd If we choose values of 13 feet per second and a Cd of 1 the diameter necessary is 67.3 inches with an impact velocity of 20 lbf, we can generate the following plots to determine diameter and impact velocity:

60

Figure: Diameter as a function of Cd with constant velocity of 4

61

Figure: Diameter as a function of V with constant Cd of 1

Figure: Diameter as a function of both V and Cd

62

Figure: Impact force as a function of velocity

Camera Storage

Another advanced concept that we have decided to use involves our camera and the way in which we will be storing it on the craft. We have decided to store the camera inside of the fuselage with the lens flush to the bottom. This will significantly reduce the amount of drag that would be effecting the plane if the camera were stored on the outside. It also negates having to design any sort of bracket, or attachment point on the craft. Having the camera inside of the fuselage will also add extra protection for the camera, should there be a crash landing the foam surrounding the camera will protect it, for the most part, from the impact. In order to get the camera inside of the fuselage the dimensions will be recorded and a cut will be made in the foam fuselage using the CNC machine. This will allow us to make the cuts so that the camera is snugly fit into its spot ensuring that it will not move during flight. Having a cutout made specifically for the camera will also allow us to easily access it when the cargo bay is opened. Carrying the camera in this fashion will allow ease of access, it will keep it safe from damage, and it will cause much less drag on our craft.

63

19. Cold Weather Operation

We have examined the effects of cold weather on the motor, materials, and aerodynamics.

Gas motors can have trouble starting in temperatures that are below 40° Fahrenheit. To accommodate for this, it is recommended that users start their gas engine inside a heated space before launching their drone. The cold has little effect on the operation of electric motors as long as they are charged. Extreme cold temperatures reduce the speed at which chemical reactions can occur while also increasing electrolyte resistance, which makes charging in cold temperatures very hard.

The cold temperature does not significantly affect the foam or fiberglass. However, wood shrinks in cold weather. For this reason, we will recommend that the UAS be stored in a heated area over the winter. The wood will not shrink enough to affect the structure or performance of the UAS during its usage outside of the warm storage area.

The cold weather will help the aerodynamics of our UAS. The density of air rises when the temperature drops, and this increase in air density increases our aircraft’s lift. This will give our motor better efficiency. In fact, many RC plane enthusiasts prefer to fly on cold days when the weather conditions are calm and cool because of the increased air density.

Cold weather often brings windy conditions and precipitation along with it. Since our aircraft is small, it cannot fly on excessively windy days (winds greater than 10 mph). Iceing on our UAS add weight which will negatively affect our aerodynamics and center of gravity. To combat icing, we will recommend that our aircraft be stored in a warm area and examined before flight. Additionally, we will use fiberglass coated with a deicing finish as a protective skin against icing and other precipitation. Propylene Glycol Industrial Grade (PGI) will be recommended to deice the aircraft if needed.

In conclusion, cold temperatures alone will help the performance of our UAS. However, our customers will have to charge the battery and store the aircraft in normal temperatures. We do recommend that our UAS is not used when the average wind speed exceeds 10 mph. Our aircraft will be able to operate in icing conditions due to a protective skin of fiberglass coated with a deicing finish.

64

20. Noise

Noise of the UAVs are created by two main different sources, aerodynamic noise and propulsion system. For aerodynamic noise, the flow of the air around the control and aircraft fuselage surfaces create sound. For the propulsion system, the vibration of the structure created by the thrust of the propeller. In addition, the gust of wind, high altitude radiation, and fluctuation of temperature will all contribute to the creation of noise.

UAVs are generally operated at a lower speeds compare to commercial and military aircrafts. Noise generated are considered to be lower due to the lower speed. Noise can also be reduced by using bulk absorbing material like foam which has been used in this specific design. Foam are able to viscously dampen the acoustic wave. Also, a electrical powered UAV will be able to operate more efficiently, and create less vibration and noise compare to a UAV that uses combustion gas.

The noise of the UAVs are generated mostly by the propeller. The propeller noise is determined by the tip speed and shape. The most obvious way is to reduce the noise is to reduce tip speed and use a good tip shape. Therefore, the propeller selected in our design is a APC 13”x8” thin electric propeller. A propeller of 13” diameter is expected to generated 9,500 rpm. Using the tip speed vs RPM & Diameter Data Chart (Bollenhagen_9-10), the propeller selected has a tip speed of 329 mph, which is below the optimum maximum tip speed for achieving a low noise of 400 mph. This suggests that the propeller selected has achieved the aim of producing low noise.

65

21. Cost Estimation for Manufacturing and Maintenance

We have provided a table below with a breakdown of all the parts needed to assemble this aircraft with pricing for purchasing all materials and parts without shipping costs. As you can see, the collapsibility adds complexity with manufacturing. However, our team feels the benefits outweigh the costs. We also have provided a cost estimate with the assumed materials that will be provided by our department. For maintenance cost you can use the table to see the pricing of a part if it needs to be replaced. Any structural damage to the wings or the body will vary due to the severity of damage. In some cases we would recommend making custom orders for replacement parts, such as wings, fuselage, and tail pieces. When producing this product in a mass quantity it maybe possible to get bulk pricing on certain products and to be able to assemble and package everything for about $800 and sell it at a market price for $1000 per unit.

For common maintenance of your plane we recommend you clean your aircraft and make sure that all hinges and moving parts are properly lubricated and operating correctly.For added protection and shine you can use an automotive wax or sealant, such as Chemical Guys JetSeal Sealant which protects against water spots, contamination, road grime, and solar rays.It is important that our customers use a fully charged battery for every flight. We also advise fully discharging your batteries before storage. Before take off, make sure wing mounts are secure and all servos are working properly.

In the event your Aircraft crashes always check:Control surfaces - Pull on everything, make sure everything is secure and moves properly.Rips and tears - Examine the body of your plane closely looking for rips, tears or crinkles.Angles - Look for structural weaknesses. Check the angle of your tail and make sure it’s not crooked. Make sure angles of repaired area are the same as before the crash. Even if it is not a control surface.Power system - Check all electronic connections and make sure everything works. Turn the motor by hand and make sure it turns freely.

Always replace damaged or broken propellers. In the case of a bent motor shaft it’s best to replace it or swap the whole motor. If there is dirt in the motor remove it and remove the bell and clean it thoroughly. If the motor mount is damage you can remove it and try to fix it with glue and reinstall it. For stripped servos you need to replace them. For Loose control horn, wires or prop tighten them back down or repair if possible. For minor damage you can use foam safe CA glue for repairs. For Broken or crinkled fuselage repair with hot glue, tape, or foam safe CA. For Damaged Battery which is very dangerous get rid of it! Recycle the battery using the proper procedures and buy a new one. If you're not sure if it’s damaged check individual cell voltages frequently.

To avoid crashes always do a proper preflight check and avoid flying on windy days.

66

Parts Our Price Real Price

Camera System

GoPro Hero4 Session Provided $300

Build Materials

Foam/Renshape Provided $30

Foam Glue and Epoxy Provided $5

Fiberglass Cloth/Mat Provided $20

Carbon Fiber Cloth Provided $27

Tail Tubing Provided $5.50

Power System

Battery $42.75 $42.75

ESC 60 Amp Provided $26

Motor E-flite Power 46 Provided $90

Prop Shaft Extender $15.95 $15.95

Propeller $3.80 $3.80

Prop Spinner (cone) Provided Included w/ motor

Control System

Controller/Transmitter Provided $130

Receiver Provided $30

Large Servos Provided $20

Small Servos Provided $20

Control Links/Pushrods $6.00 $6.00

Control Horns Provided $1

Hinges Provided $1

Autopilot and Stabilization System

Ardupilot Provided $120

Gyro $36 $36

GPS Included Included

Parachute Made $15

Battery Charger Provided $23

67

Extra Options

GoPro Mount Provided Included w/ GoPro

Extra Memory Card Extra $50-$80

Landing Gear Straps make -

Landing Gear Strut make -

Tail skid $2.30 $2.30

Wheels Provided $4.80

Extra Battery Extra $42.75

Spare Propellor $3.80 $3.80

Pixhawk Provided $200

Extras are not included in Pricing

Our Price Real Price

Totals $104.50 $968.00

Our expected costs equal $104.50. This leaves us with $395.5 in contingency. We are very comfortable with this budget because we will be prepared when we encounter unforeseen issues during manufacturing.

68

22. Project Status

This section briefly summarizes the previously covered engineering and technical analyses.

Below is the CAD model of our final design in its extended and collapsed configurations.

Final Extended Configuration

Final Collapsed Configuration

We will store all of the components, including the camera, inside the fuselage as shown below.

69

Components layout inside the fuselage

We chose to use a Clark Y airfoil. Below is the CAD model and CFD analysis.

Clark Y

70

Clark Y CFD analysis

Our aircraft will use the following components to generate thrust.

Motor: E-flite Power 46 Brushless OutrunnerPropellor: 13x8 APC Electric E PropellorElectronic Speed Control: 60 Amp brushless ESCBattery: Multistar High Capacity 4S 6600mAh Multi-Rotor Lipo Pack

These components, combined with our UAS design, produce the following results. These results show that our aircraft will be able to cruise at 30 mph and for longer than 15 minutes.

Flight Duration: 16-27 minutesTop Speed: 59 mphStall Speed: 21.5 mph

Our UAS will utilize collapsibility as an advanced technology. This feature will reduce storage space as shown below. Additionally, our aircraft uses a parachute to land and in case of a malfunction during flight. The parachute provides a form of insurance.

71

Extended Model

Collapsed Model

72

Our team performed a structural analysis of the wing, which is the part of the aircraft that is most likely to fail during flight. The table and pictures below show that with our intended building materials the wing will not fail when put under the predicted forces from flight.

Material Max Displacement (in) Max Stress(psi)

Failure Stress(psi)

Safety Factor

Foam Airfoil 3.61 21.65 40.32 1.86

Aluminum Rods 3.57 22132.9 48008 2.17

Reinforced Von-Mises Stress, Foam Airfoil

73

Reinforced Von-Mises Stress, Aluminum Rods

The UAS will be built primarily out of foam, aluminum, and fiberglass. The final weight of our aircraft is calculated to be 3.503 lbs. All components, including the camera and parachute, will be stored in the fuselage. With the materials provided from the Aerospace Department, our predicted costs are $104.50. This leads $395.5 left in contingency, which will be vital during the manufacturing process.

Cold weather operation and noise are not concerns. After analysis of both, we have determined that our UAS will perform better in cold weather, however it will not be able to operate when the average wind speed exceeds 10 mph. Since our aircraft is so small and operates at low speeds, the noise generated will be minimal.

As illustrated above, our design is centered around simplicity, customer needs, and effectively accomplishing the mission. We are very confident that our design will be able to meet or exceed all mission requirements.

74

23. Plan for Next Semester

This section will provide a general outline of our plans for next semester on a month-by-month basis, with the end-goal being a fully functional model of our design.

January

● Revisit design and discuss any feedback from Final Presentation.● Make necessary changes to the conceptual design.● Start work on creating a scaled model solely for wind tunnel testing.

February

● Finish scaled wind tunnel model.● Run wind tunnel testing..

○ Tests will be designed to test lift, drag, stability, and control surfaces.● Analyze wind tunnel testing results.● Finalize control system design.

March

● Make any necessary design changes as determined by the wind tunnel testing data.● Order parts.● Begin construction.

April

● Finish construction.● Run wind tunnel tests with the final model.● Run flight tests with the final model.

May

● Final Review.● Final flight.

This schedule does not include preparation for any midterm design reviews and is subject to change based on the requirements of Aer E 462.

75

24. Team Organization and Operation

Our Team is comprised of the following members with roles attached:

Neal Crooks Team LeadJon Miller CAD LeadTom Schleisman CFD LeadAlicia Ekman Weight and BalanceAlek Szoka PropulsionSteve Oeh AerodynamicsMark Ritter CAD/StructuresShawn Mauritz Controls

However our roles have been very fluid, and tasks were assigned based on interest. The responsibilities of the lead roles were as follows:

Team Lead● Ran weekly meetings.● Assigned tasks to the CAD and CFD Leads as well as general group members.● Oversaw creation of Design Review Presentations and checked that they met

requirements.● Met with the professor about Design Review and Presentation requirements and any

design process questions.

CAD Lead● Oversaw the computer aided design of all models and airfoils.● Assigned tasks to members helping with CAD.

CFD Lead● Oversaw all CFD analysis of airfoils and models.● Assigned tasks to members helping with CFD.● Compiled all CFD reports.

Meetings were held once a week on Monday nights at 7:30 p.m. in the Howe atrium. During this time we checked our progress with the schedule we set at the beginning of the semester, assigned tasks for the upcoming week, discussed issues members were facing with their tasks, and prepared for Design Reviews and Reports. During these meetings we emphasized communication and collaboration.

76

We did not face many issues as a team. The only significant problem we had was the workload of the CAD Lead and the CFD Lead. Part of this problem can be attributed to the nature of their positions, however we will work to fix it be lightening their loads next semester when the conceptual design is finished.

Overall, our team worked very well together due to open communication and contributions from all members.

25. Summary

This report summarizes the work done by our team to design a UAS that meets the given mission requirements. The concept we pursued is the result of a thorough market analysis and feedback from our potential customers. Our final design is centered around simplicity, manufacturability, and effectively meeting the mission requirements. It incorporates features that are important to our potential customers and unique to the market, such as collapsibility and a safety parachute, and utilizes autonomous flight software and a maintenance-light design to ensure ease-of-use. It is supported by CFD and structural analysis, along with analyses of sizing, drag, propulsion, weight and balance, noise, cold weather operation, stability and control, cost, and center of gravity. All of our results have shown that our UAS will perform at or above all mission requirements.

77

26. Appendices

Works Cited: Anderson, John D. "Ch 8. Design of a Propeller Driven Airplane." Aircraft Performance and Design. Boston: WCB/McGraw-Hill, 1999. N. pag. Print. Apogee Components. "Apogee." Properly Sizing Parachutes for You Rockets 149 (7 Oct. 2005): Web: https://www.apogeerockets.com/education/downloads/Newsletter149.pdf.

"Beginner Series - Power System." Flite Test. Horizon Hobby, 27 Nov. 2013. Web. 05 Dec.2015.

Carri, John. "WebOcalc." WebOcalc. Free Software Foundation, Inc., 2012. Web. 03 Dec. 2015. "Estimating Battery Charge Time from Solar." Voltaic Systems Blog Solar DIY and Device Charging. N.p., May 14, 2010 Web. 02 Dec. 2015. FliteTest. "Beginner Series - Crashing and Repairing." Flite Test. Horizon Hobby, 18 Dec. 2013. Web. 05 Dec. 2015.

Nelson, Robert C. "Ch 2. Static Stability and Control." Flight Stability and Automatic Control. Boston, MA: McGraw Hill, 1998. N. pag. Print. Oborne, Michael. "Mission Planner." Mission Planner. 3DRobotics, n.d. Web. 02 Dec. 2015. <http://planner.ardupilot.com/>. "Solar Calculator." | Weather Underground. N.p., “The Weather Channel”. Web. 02 Dec. 2015.Bollenhagen, Les. “Tip Speed vs RPM & Diameter Data Chart” The Bolly Book. Bolly Products, 1998. Web. 02 Dec 2015. http://www.bolly.com.au/1998%20Bolly%20Book%20v3.pdf

Cost and weight estimates were taken from Horizon Hobby, HobbyKing and MotionRC

78