Transmittal Letter

Hayden D’Addonahayden.daddona@uqconnect.edu.au

(+61) 457 951 358

Friday, 23th October 2015Michael Shiel and Brendan ChenProject A LeadersUniversity of QueenslandBrisbane QLD, 4072

Dear Mr Shiel and Mr Chen,Please find attached P03 Glass’ Final Report. This report was completed to fulfil the requirements ofENGG1200 with regard to the design of a Micro Air Vehicle (MAV) prototype. An area of innovationthe team wishes to bring to your attention is the use of 3D printing technology for the production ofthe Micro Aerial Vehicle, details of which can be found in section 4. This section identifies ease ofmanufacture, cost effectiveness and time usage as contributing factors to the use of 3D printing. Thisconstruction method greatly simplified the project task for the group.

If you have any queries regarding the report don’t hesitate to contact our team via the attached email.

Regards,

Hayden D’Addona

On behalf of P03-Glass,Hayden DAddonaOliver DarvasTe Otinga KopaAsher LeungAlex ShoungKeh Xian De

St LuciaUniversity of Queensland

University of Queensland

ENGG1200: Project A

Final Report

October 24, 2015

P03: Team Glass

Hayden D’Addona Oliver Darvas Xian De Keh Te Otinga Kopa Asher Leung Alex Shoung

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Executive Summary

The task was to design, build and demonstrate a prototype Micro Aerial Vehicle (MAV). The develop-ment process started with MATLAB and Simulink calculations. These calculations were then used tosimulate the flight trajectory of the MAV. The results are as follows:

• Lift coefficient = 0.069,

• Drag coefficient = 0.578,

• Mass of MAV = 75g,

• Flight distance = 30.21m, and

• Flight time = 1.8105s (trajectory model assumes point mass).

What followed was the build phase. The MAV was 3D printed as its individual components andassembled separately. This allows for parts to be replaced easily after being damaged. The nextphase was flight testing. The prototype failed to fly during initial testing however after shifting thecentre of mass forward and repositioning the wings the MAV was able to glide an average of 23 metresconsistently. The following results were recorded from flight testing after the improvements were made:

• Maximum flight distance = 26.8m,

• Maximum flight time = 5s,

• Cost of MAV= $1.50,

• Total mass = 75g,

• Length = 20cm,

• Width = 30cm,

• Height = 5cm, and

• Durability = 10 test flights plus toss testing.

The MAV design is a success as it minimises cost and manufacture time while maximising durability,flight distance and flight time. In order to further increase the potential of the aircraft it is recommendedthat calculations be used to optimise the cost of the MAV by minimising the volume of material neededas much as possible without affecting the flight results. Furthermore, redesigning the model to improveassembly would make the design more time and cost-effective.

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Contents

Executive Summary i

Contents ii

1 Introduction 11.1 Task Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Contents of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 Project Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Virtual Model 22.1 Tensile Member . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Approximations for Lift and Drag Coefficients using ANSYS . . . . . . . . . . . . . . . 22.3 Launch Rig Simulation (MATLAB Simulink) . . . . . . . . . . . . . . . . . . . . . . . 32.4 Trajectory Simulation (MATLAB Simulink) . . . . . . . . . . . . . . . . . . . . . . . . 32.5 Predicted Performance for Demonstration Day . . . . . . . . . . . . . . . . . . . . . . 4

3 Structural Model 53.1 Quick Release Plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.2.1 Airfoil Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.2.2 Other Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 Construction Process 84.1 Simplicity of Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.2 Manufacturability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.3 Fabrication Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.4 Successes and Difficulties Encountered . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.5 Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

4.5.1 Critical Evaluation of Costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104.5.2 Critical Analysis of Performance against Cost . . . . . . . . . . . . . . . . . . . 11

5 Reflections 115.1 Team Reflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115.2 Effectiveness of Organizational Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 12

5.2.1 Tutors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125.2.2 Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125.2.3 Problem Solving Sessions Workshop MATLAB & Creo . . . . . . . . . . . . . 135.2.4 Online tools - Blackboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5.3 Key Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.3.1 Early Prototype Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.3.2 Communication Between Team Members . . . . . . . . . . . . . . . . . . . . . 135.3.3 Team Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145.3.4 Using All Resources Available . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145.3.5 The Importance of Organisation . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6 Conclusions 15

7 Recommendations 15

8 References 16

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1 Tensile Member Calculations 171.1 Material Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171.2 MATLAB Script for Plotting Stress-Strain Relationship . . . . . . . . . . . . . . . . . 18

2 MAV Performance Calculations 192.1 Lift and Drag Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.2 Physical Model Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202.3 MATLAB Script for Declaring Performance Parameters . . . . . . . . . . . . . . . . . 202.4 Launch Rig Modelling (SIMULINK) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212.5 Trajectory Modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

List of Figures

1 Strain of Brass Samples of Various Thickness Under Load . . . . . . . . . . . . . . . . 22 Dimensions of Release plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 The MAV on the release plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 The MAV on the release plate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 Engineering Drawings of the MAV . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Manufacturing Process Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 Data Specifications of Various Materials and Thickness . . . . . . . . . . . . . . . . . . 178 Comparison of Different Materials Under Load . . . . . . . . . . . . . . . . . . . . . . 19

List of Tables

1 Relevance of Design Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Comparison of Trajectories at Different Launch Speeds . . . . . . . . . . . . . . . . . . 43 Successes & Difficulties Encountered During Prototype Construction . . . . . . . . . . 104 Lift and Drag Parameters for the MAV . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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1 Introduction

1.1 Task Definition

The MAV was designed and built from suitable materials to maximise flight duration and distance.The MAV is stable in the air and proved to be durable over a number of tests. The MAV was built tocomply to the following constraints:

• The MAV must have a width no greater than 300mm, length no longer than 600mm and a heightno greater than 300mm,

• The mass must be no greater than 250g,

• Cost no greater than $100,

• Must not start with any form of stored energy (batteries, pre-loaded elastics, etc.),

• The lowest part of the MAV must not be any lower than the quick release plate (Reidsema, 2015),and

• The quick release plate must be made from aluminium. The tensile member can be made frombrass, carbon steel or aluminium. Its dimensions must be within 150mm x 20mm.

1.2 Objectives

The objective of this report is to summarise the design and building processes taken in the developmentof the MAV. It includes an analysis of the final design, recommends further improvements, and featuresmultiple reflective pieces. The report provides information on the engineering process of the design ofthe prototype.

1.3 Contents of Report

The report covers integral factors of the design including explanations of Dynamic and StructuralModels created with MATLAB and Creo. The construction process is also covered along with allcalculations, design drawings and justifications. Reflections are also contained pertaining to numeroustopics such as the groups teamwork, the effectiveness of organisational structure and key lessons learnedby individual group members.

1.4 Project Scope

Table 1 lists all possible factors involved in this project as in scope factors that will be addressed inthe design and build process and out of scope factors that will not be addressed.

Table 1: Relevance of Design Factors

In Scope Out of Scope

Calculating lift & drag coefficients Propulsion systems

Designing profile of MAV Construction of the launch rail

Optimise wing profile & the number of wings Steering system to control MAV direction

Selection of materials for the MAV, quick releaseplate and tensile member

Use of CNC machine

Designing the quick release plate & tensile mem-ber

Choosing Material to manufacture the tensilemember

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2 Virtual Model

2.1 Tensile Member

With the data specifications of the potential tensile member materials (aluminum, brass and steel)presented in Figure 7 (see Appendix 1.1), a MATLAB script (see Appendix 1.2) was written to plot agraph of strain vs retraction distance. To prevent the tensile member from yielding, the tensile stress at0.2% yield was reduced by a reasonable amount as shown in line 17-19 of Appendix 1.2 such that thereis a safety margin on the maximum retraction distance that could be applied. Brass was chosen for thetensile member because at a gauge width of 13 mm it doesn’t plastically deform within the expectedretraction distance, yet the extension is large enough to be detected by the Optical Strain System (OSS).

To further investigate the properties of brass, a plot of the retraction distance against the strainwas produced for various gauge widths (10 - 15 mm) in Figure 1 to determine the best gauge width.

Figure 1: Strain of Brass Samples of Various Thickness Under Load

From this graph it was decided that a gauge width of 13 mm would be most suitable. It would allow fora maximum amount of strain of 0.001425 at retraction of 2.5 m (maximum usable retraction distanceof the launch rig) and the metal would not plastically deform. Between the two given thickness of thebrass tensile member, 0.390 mm is preferred over 0.250 mm as this would allow a larger launching force(since force is proportional to area for a fixed Young’s Modulus) , thus a greater range is achieved bythe MAV.

2.2 Approximations for Lift and Drag Coefficients using ANSYS

After some background research on MAV designs, the prototype MAV was designed digitally as avirtual CAD model in Autodesk Inventor. This was used to develop a trajectory simulation. To dothis, the lift and drag coefficients had to be found. The prototype MAV model was loaded into ANSYSand ran through a few ’virtual wind tunnel’ tests at different angles of attack in a given wind speed of22 ms−1 (close to the estimated launch speed). The raw data is presented in Table 4 in Appendix 2.1.The lift and drag coefficients were calculated with equations 1 and 2, where wing area A = 0.015 m2,density of air ρ = 1.225 kgm−3 and velocity v = 22 ms−1.

Cd = 2D/(ρAv2)(NASA, n.d.) (1)

Cl = 2L/(ρAv2)(NASA, n.d.) (2)

The virtual model was validated through wind tunnel testing of the physical prototype (Appendix2.2). An angle of attack of 5 was chosen for the launch angle due to it’s high lift-to-drag ratio of

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approximately 8. The lift and drag coefficients at this angle of attack were 0.58 and 0.07. There wasonly a 1.6% discrepancy between the simulated value from ANSYS and the results of wind tunneltesting.

2.3 Launch Rig Simulation (MATLAB Simulink)

A MATLAB script (Appendix 2.3) was created to declare all the constants and initial conditions(masses, lift and drag coefficients etc.) for the launch system model and trajectory simulation (section2.4). Appendix 2.4 presents the Simulink code used to model the launch rig. In this code the followingassumptions were made:

• The rail of the rig produces no friction with the sled and has a usable max length of 2.5 m,

• The energy losses due to heat is negligible,

• The air density remains constant, and

• Constant angle of attack.

The drag force experienced by the MAV-QRP-Trolley system was not neglected as this would contributesome damping effect. Hence, the forces acting on the MAV-QRP-Trolley system were the elastic forcesprovided by the elastic cords and drag (namely contact and aerodynamic friction). The elastic force isdependent on displacement and the drag force is speed dependent. The position and speed outputswere fed into the elastic force function block and the drag function block respectively. From this model,the initial launch velocity of approximately 25 ms−1 was obtained. Nevertheless, this value would beslower in real world conditions due to the presence of environmental factors such as wind and energylost as heat. A more reasonable launch velocity would be around 20 ± 2 ms−1 and this range of valuesshall be used as this would provide a much more realistic representation when simulating the flightpath of the MAV. One key thing to note that for this rig model, the elastic force is given by 26dext

instead of 26dext + 21.1 (Shiel, 2015) because the MAV-QRP-Trolley system would be moving evenwhen there is no extension applied to the elastic cord.

2.4 Trajectory Simulation (MATLAB Simulink)

In the Simulink code for trajectory simulation (Appendix 2.5), a clock is set up in coordination with astop command to determine the time of flight, e.g. the stop command stops the simulation when theheight output reaches 0 m. A standard launch angle equation would only give a parabolic trajectorywhich is unrealistic because it did not take into account lift and drag forces acting on the MAV. Thelift force always acts perpendicularly to the MAV whereas the drag force acts in parallel, so bothforces were resolved into their respective horizontal and vertical components which were representedin Horizontal Forces and Vertical Forces function blocks. This simulation also outputs a horizontaldisplacement from initial launch position as well as an XY graph of the trajectory as shown in Appendix2.5.For this trajectory model, a few assumption were made as follows:

• Uniform air density of 1.225 kgm-3,

• Absence of wind,

• Trajectory only lies in one plane (does not veer sideways), and

• MAV is treated as a point mass.

The resulting flights for different launch conditions were thus explored in table 2During rig testing, the shape of trajectory of the physical prototype MAV did perform according towhat was expected thus informing that the simulation is pretty close to the real conditions in whicha maximum flight time of 4.8 s with a maximum range of 26.8 m were achieved. This test resultcorresponds to a launch velocity of approximately 18 ms-1. The 10.8% deviation from the simulated

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Table 2: Comparison of Trajectories at Different Launch Speeds

Launch velocity (ms−1) Time of flight (s) Horizontal range (m)

18 1.797 30.06

19 2.160 37.32

20 2.630 46.42

21 3.180 56.77

22 3.753 67.20

horizontal range was understandable due to the extra external factors like wind, temperature of theair, random errors that were ignored in the simulation. However, one unexpected result was that thesimulated time of flight deferred 62.6% from the actual flight time during testing. This could be treatedas a good sign in terms of performance for the MAV in real world conditions. To further improve itsperformance, a higher launch velocity would be favoured such that a greater time of flight and rangewould be achieved.

2.5 Predicted Performance for Demonstration Day

The performance of the MAV on Demonstration Day is expected to yield the following outputs aspredicted from the virtual model and validated through physical testing:

• Time of flight, t = 4.0 ± 1.0 s

• Launch distance, d = 25 ± 2.0 m

Due to some wind factors during testing, it was found that on a relative windy day the MAV didnot follow a trajectory which lies in a single plane. Instead, the MAV veered off sideways and thiscould have resulted in extra lift and drag forces acting sideways which the trajectory model could notsimulate (motion simulated only confined to a single plane in 3D space). This may have caused theincrease in time of flight by a factor of approximately 2.5 from the flight duration obtained from thesimulation when tested at launch velocity of 18 ms−1.

As for the predicted launch distance, the average of launch distances achieved during rig testingwas calculated after removing a few outliers and chosen for this prediction. An error margin of 2.0m was included to take external factors and random errors into account such that to provide a morerealistic and accurate value.

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3 Structural Model

3.1 Quick Release Plate

The quick release plate was designed so that the the fuselage could rest at a 5°angle for launch. Thefuselage has a little hollow which the point of the plate inserts into to prevent premature take off(figure 3). The plate has been designed so that the front of the fuselage leaves the plate at the sametime as the rear, preventing the MAV nosing down (figure 4).The dimensions of the plate are presented in figure 2

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Figure 3: The MAV on the release plate

Figure 4: The MAV on the release plate

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3.2 Specifications

The following lists provide design details with accompanying justification for their selection.

3.2.1 Airfoil Design

• The MAV is a high wing cantilever monoplane with elliptical wings of moderate aspect ratio andslight dihedral angle. The wingspan is 300mm, with an aspect ratio of 6.

– High wings keep the centre of lift above the centre of mass, preventing tilting during flight.

– The shape of wings was chosen to lower drag, while achieving a reasonable amount of lift(NASA, 2010).

– Moderate aspect ratio compromises between having a large surface area for maximum liftand low area for minimum drag.

– Various wing designs were tested in the virtual wind tunnel. This design performed best.

• The airfoil has a low camber symmetric cross section based on the NACA 4415 profile.

– Has a higher stall speed than a cambered wing (Laitone, 1997).

– While symmetrical wings produce little lift for small angles of attack (AoA), they are easierto manufacture and are more stable if the AoA varies, as it will throughout the trajectory.

• Wings have an AoA of 3° which is increased to 8° during launch. They have a transitional filletat their base, separation separation separation of flow around the fuselage.

– The transitional fillet removes hard edges around the fuselage above the wings, hencepreventing separation of flow and turbulence occurring over this section.

– Having a non-zero angle of attack relative to the fuselage enables the symmetrical wings toprovide lift even if the MAV is horizontal.

3.2.2 Other Components

• The nosecone is a paraboloid, and is printed as a solid component. The tip is left flat, and thecurve is completed with a moulded bluetak cone.

– By being solid, the the centre of mass moves forward, helping the craft recover from a stallby preventing the AoA continuing to rise over the trajectory.

– The shape ensures minimal drag at the expected speeds.

– The more pliable tip acts as a shock absorber, minimising damage upon landing.

• The fuselage is 200mm long from nose to tail. The thickness is only 4mm at the tail to keep thecentre of mass forward.

– The short length minimises flexing along the fuselage. This keeps the flight more stable.

– Having such a thin fuselage towards the back helps bring the centre of mass forward.

– The MAV is released from the plate without interfering with it (either being nosed down orup) due to its relatively short length.

• The empennage consists of a tailfin and high mounted vertical stabilisers

– Having the empennage mounted at the same height as the wings allows the top of thefuselage to be printed flat against the printer bed, improving the ease of manufacture.

All components were 3D printed in PLA plastic. This was found to be more durable than printing inABS. They were all designed in Autodesk Inventor, which enabled small changes to be made to thedesign quickly and easily. Altered components could be printed instantly and tested physically. Hencethe use of this software enabled rapid prototyping, leading to quick progress and greatly improvedmodel performance. The dimensions of the MAV are provided in Figure 5.

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MAV - Project A

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Figure 5: Engineering Drawings of the MAV

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4 Construction Process

4.1 Simplicity of Design

MAVs are used for many situations worldwide, making the simplicity of their design vital so that manycan be manufactured quickly and efficiently. The profile of the MAV (see Figure 5 in section 3) thatwas designed took into consideration simplicity of design. The four simple design components are:

• Nose,

• Fuselage,

• Tail, and

• Wings.

The simplicity in the way that these components were designed allows for it to be easily reprinted.In comparison, other materials such as balsa wood and styrofoam consume time when shaping thesematerials to the specified design, making them less simple and efficient than 3D printing the design.The assembly of the design was with the use of super glue for gluing the nose, tail and wings to thefuselage. The nose and tail were attached to the fuselage and then the wings last to determine wherethe appropriate centre of lift would be for maximum flight performance of the prototype. The simpleand effective design makes for a high quality plane to achieve the specified requirements.

4.2 Manufacturability

The ability to design an MAV that is easily manufacturable and produce an effective aerodynamicprototype is also beneficial in worldwide situations. A 3D printer was used to manufacture thecomponents for the prototype because it was simple, efficient and effective in manufacturing thenecessary components. It was a more accurate process and consumed less time (with the total time ofmaking the components being approx. 2hrs) compared to traditional manufacturing methods. Newcomponents could be easily reprinted when damaged or broken. In comparison, manufacturing theprototype from materials such as balsa wood or styrofoam would require more time consuming processes.It would have been a tedious process to shape accurate, symmetrical wings by hand.

4.3 Fabrication Process.

The fabrication processes involved in building the prototype, quick release plate and tensile memberwere simple. The quick release plate was built by submitting a file of the design to the University ofQueensland and it was machined by a CNC machine. The tensile member was built in the ABB STC(Student Technology Centre) by selecting the required material and following the specified instructions.The process flow chart below shows the steps taken in construction the prototype, quick release plateand tensile member. The fabrication process is graphically described in Figure 6.

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Figure 6: Manufacturing Process Flowchart

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4.4 Successes and Difficulties Encountered

Throughout the construction phase of the prototype there were many successes and difficultiesencountered and lessons learnt from these challenges. These are shown in Table 3.

Table 3: Successes & Difficulties Encountered During Prototype Construction

Successes Difficulties Lessons Learnt from Difficulties

Each component of the prototypewas printed to a high quality tothe specified design requirements

Gluing the two pieces for thewings. The thin wings meant lesssurface area for the glue to stickonto and for the wings to be ableto attach securely.

Learnt that it would be sim-pler to design a wing profile asone component instead of twoindividual pieces. This wouldmake for a more secure attach-ment onto the MAV and the wingwould be stronger.

Constructing the componentsfrom 3D printing allows for themto be symmetrical, which is im-portant when the MAV getslaunched.

Attaching the fuselage of theMAV to the quick release plate.The piece removed from the bot-tom of the fuselage was notprinted to the correct dimensionsso there was a tight fit onto thequick release plate.

Learnt that measurementsshould be doubled checked be-fore printing to save the wastageof material and that accuracy isimportant. Also the machinesare not always precise and canbe inaccurate sometimes.

The tensile member was built tothe required specifications calcu-lated. Worked well as a team tomake the tensile member. Hadclear communication and knewwhat was needed to be achieved.

Assembling each of the compo-nents onto the fuselage using su-per glue. Tape and blue tack wasused to attach wings and tail toadd further support. Also com-ponents broke or got damagedduring practice runs.

Learnt that should consider otherfastening methods when assem-bling the MAV, as blue tack addsextra weight and isnt as secure assuper glue. Also that we shouldhave printed extra componentsto have on stand by for when acomponent does break or becomedamaged.

4.5 Costs

4.5.1 Critical Evaluation of Costs

The expense that was involved in manufacturing the MAV was very low compared to that of othermaterials. The simplicity of the design and processes that were used to manufacture the prototype weretaken into consideration in the designing stage of the project build, with the 3D printing fabricationprocess chosen because of its effectiveness, efficiency and low cost. The total cost of the prototype wasonly $1.50 and the extremely low cost was to do with the MAV being produced using a 3D printingmachine. There were minimal materials used in the construction process. These materials were:

• Super Glue,

• Tape, and

• PLA plastic (3D printer plastic).

Each component was printed separately, with the total time taken to print all components beingapproximately 2hrs. The other components of the design and manufacture process (quick release plateand tensile member) involved no costs as the materials were supplied by the University of Queensland.In comparison, materials such as balsa wood and styrofoam can be seen to be more expensive thanthat of 3D printing. An approximation of the cost of balsa wood and styrofoam were calculated usingthe same design with the cost of these materials being:

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• 3D printing ≈ $1.50,

• Styrofoam ≈ $2.10, and

• Balsa wood ≈ $4.50 (Bunnings, 2015).

4.5.2 Critical Analysis of Performance against Cost

Section 2.4 shows that the approximation of the prototypes trajectory simulation is 30.06m in 1.797secsfor an approximated 75g MAV. It can be seen that prototypes performance is remarkable for itsextremely low cost. In comparison, if other materials were chosen such as balsa wood or styrofoam andmanufactured in the same design a different trajectory simulation is achieved. Assuming that the massof the prototype to be 60g when using balsa wood or styrofoam, it can be seen that the trajectorysimulation models the MAV to travel 39.3m in 2.49secs. It is evident that the lighter weight model hasa better performance as it flies further for longer. Comparing the cost to build each of the prototypesthe performance of the 3D printed model can be seen to be greater than that of the others as it wascheaper and only travelled approximately 9m less than the other prototypes made from balsa wood orstyrofoam, which were more expensive to build.

5 Reflections

5.1 Team Reflection

One of the most used methods of project management used was group meetings. They served as aplatform to communicate mutual goals, allocate work and discuss how our team wanted to progressforward. Reflecting on the earlier stages of the semester, we realise that our procedures for thosemeetings were inefficient, due to the lack of communication and organisation. As all team members haddifferent roles and responsibilities, when it came to discussing completed work, we realised the necessityof communication and organisation to be able to complete assessment to the highest quality by thedue date. It has also become apparent to us that if effective communication were to occur, we wouldhave been able to further minimise errors as the project progressed. Our team has highlighted that forfuture group work, it is important that a foundation is laid where all team members understand theproject timeline and assessment allocations so that in the early stages group productivity is optimised.

Another key area was communication. In reflecting on this, the necessity of having a team leaderand having clear communication between all team members made for a successful project with allgoals being achieved. It is recommended for future group practices, that a foundation on a mutuallyagreeable style of leadership be laid at the start of the project to achieve goals and have a successfulproject. An example from our team was that individuals in our group preferred a leader to initiatediscussions about reports, followed by team members picking sections based on their strengths tomaximise the success of the report. It is believed that with this recommendation, team performancewill increase and execution of the project will be to a higher standard.

We believe we have learnt the significance of supporting one another. Reflecting on our experi-ence at the start of the project, team members were assigned individual tasks. Although some of usmay have experienced difficulty completing this task due to a gap in knowledge, there was limiteddiscussion between members asking or offering help. Certain team members admitted this was howtheir ENGG1100 team operated, where individuals would complete only their assigned tasks. However,building on this experience, towards the middle of our team project, we decided to take the next stepforward and ensure that we all felt comfortable asking for assistance if required. We discussed howthere is no “I” in team and to achieve high standards we would need to work as a team. This made ourplanning and execution of the project a smoother, more enjoyable experience. It also made positiveimpacts on our teams performance, where more work was able to be completed in a shorter amount oftime. A recommendation to improve this in future situations would be to offer help to individuals if itappear they made need the assistance.

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Discussing our team reflection has changed our groups way of thinking, especially in terms of whatwe now believe contributes to a successful team. We have agreed that prior to commencement of theBachelor of Engineering, we believed a successful team consisted of highly intelligent individuals beingable to complete work to a high standard. However, after reflecting on our joint journey throughENGG1200, we now believe that healthy leadership, clear communication and excellent teamwork area some of the key factors to what makes a team successful. We have highlighted recommendations forfuture improvement in hopes to apply our learning from ENGG1200 and make future group experiencesmore positive, rich and enjoyable.

5.2 Effectiveness of Organizational Structure

The organisational support provided throughout this project was seen to be effective for differentareas of the course. A large degree of the learning for the course was self-directed learning. Theorganisational support provided by the course included:

• Tutors,

• Workshops,

• MATLAB/Creo Problem Solving Sessions, and

• Online tools - Blackboard.

5.2.1 Tutors

The project session tutors had a relatively minor impact on the group’s project. However, this was dueto the fact that their job was primarily to oversee our completion of the MATLAB and Creo tutorialsduring each session. The ENGG1200 Facebook group was a highly effective was to gain assistancefrom tutors/ course leaders about questions or issues with the project. It was an effective way fororganisational support recommending it for future years as it is easy to inform the cohort on issuesand questions were promptly answered by tutors.

Another recommendation towards improving organisational support in regards to the tutors could beby getting tutors to discuss the project with groups, outlining the key concepts and features for theproject to achieve a successful outcome. This would allow for a better overall project and no areas ofthe project where concepts are misunderstood.

5.2.2 Workshops

The workshops provided useful time to address key concepts of the course and expand our knowledgeon project specific content. The templates completed within the workshops allowed for differentcomponents of the course to be focused on each week (such as the memo, exam study, final report)whether it be project specific or course related. Course coordinators and the project leaders used theworkshops as an interactive lecture to address these aspects of the course (such as reflections andproject management), providing in depth knowledge and guidance along the way. This was evidentduring the initial weeks of the course as the workshops assisted in simplifying the overall scope of theproject and improved our groups approach to the task (e.g. templates D and F). The templates in theworkshops allowed my team and I to gain a different perspective on the key concepts and what wasfully required for the assessment items. The organisational support was highly effective throughout theworkshops with the course coordinators and project leaders leading us in the right direction, alongwith the power point slides that provided beneficial information. A recommendation would be to keepthe weekly completion of templates during the workshop as the support provided was a key factor inunderstanding what was required from specific tasks and being able to achieve success in completingthe project.

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5.2.3 Problem Solving Sessions Workshop MATLAB & Creo

The support given through the problem solving sessions during weeks 7 to 9 for learning MATLABand Creo, were highly effective. The tutorial videos used to walk groups through simulating the rigmodel, trajectory simulation and how to use Creo were very effective and clearly outlined the stepsthat needed to be taken. The videos along with the sufficient tutor help that was provided at thesesession was beneficial and allowed our team to achieve success and complete the required tasks. Theorganisational support at these sessions was highly effective and resulted in a productive outcome forour team, with the required assessment being achieved.

A recommendation for the future would be to persist with the tutorial videos as they were aneffective way of support for not only our team, but most teams and outlined what needed to be achievedeach session.

5.2.4 Online tools - Blackboard

The online tools (such as Blackboard and Facebook) were another useful tool of support for our group.The large degree of self-directed learning throughout the course made the use of online tools morerelied on. The course Facebook group and project specific group were very effective when a questionwas needed to be raised or an issue resolved, with tutors promptly answering. The Facebook groupsand the large amount of resources available on the Blackboard site were easily accessible tools forfinding information about unknown content and were effective methods for providing support for myselfand my project team. However, with the abundance of people in the course it was difficult in findingkey information at times, although the ”learning pathway” link was helpful in keeping up to date. Arecommendation for the future would be to create a search bar where documents or links could betyped to find the specific file on the Blackboard course page.

5.3 Key Lessons Learned

5.3.1 Early Prototype Testing

Prior to rig testing, our team was confident that our MAV would fly well. This belief was confirmedthrough concept, theoretical discussions and mathematical models. However, on the first day of ourscheduled rig testing, our MAV failed to fly further than 3 metres despite numerous trial runs. Ourteam was encouraged to alter our design to generate a more appropriate centre of mass and lift. Afterthese modifications were taken, we were then able to successfully fly and believe that we have learntseveral key lessons from this experience.

We have identified the significance of early prototype testing. It has become clear to us that ifwe were to delay rig testing until a later date, appropriate modifications to our MAV may not havebeen made. We have recommended that for our future projects, it is vital that preliminary prototypetesting must occur well before demonstration. We have also come to understand that this lessoncan be extended beyond ENGG1200. For example, if we were to create MATLAB scripts for futuremathematics courses, even if we were confident in it and it has been shown to work before, it is stillvital that we run it to observe how it works in demonstration.

5.3.2 Communication Between Team Members

Reflecting on the first few weeks of our team project, we realise that we lacked communication betweeneach other. We failed to clearly communicate ideas to each other, thus making progress in the prelimi-nary memorandum and MAV construction stagnant. Our team began to notice this halfway during thesemester and decided to make the extra effort in clear, concise communication. Since then, in mutualagreement, we all have noticed our teams production and effectiveness have increased significantly andproject tasks have run smoother.

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It has become clear to us that for future projects, clear communication is a vital aspect to pro-ducing a successful team. Reflecting on this, we have all discussed how it is important to get toknow and understand your future team mates and encourage clear communication from an early stagethrough this. It has also been highlighted how clear communication skills within teams may not onlyhelp us in other courses, but also in our future industry work.

5.3.3 Team Work

Although there were minimal problems with teamwork in our journey through ENGG1200, we allbelieve we have learnt some key lessons regarding it. All tasks assigned to us were split between teammembers with all contributing a similar amount of work. The team noticed how such large perceivedtasks can be easily completed by a cooperative and well-rounded team. After completing the majorityof our assessment pieces a few days prior to the deadline, we found that our teamwork made ourjourney through ENGG1200 a more smooth and enjoyable experience.

We hope to take this into any future group practices by encouraging teamwork between individ-uals, as we now know that it will lead to tasks being completed easier, faster and possibly to a higherstandard. Reflecting on this, we have come to the conclusion that teamwork is not only vital inENGG1200 or other university courses, but also several real world applications such as group work inthe engineering industry.

5.3.4 Using All Resources Available

Our group has agreed that one of the reasons as to why we found our journey through ENGG1200relatively smooth was because we used all resources available to us. Although we didnt experienceany difficulty regarding this, our team has reflected and agreed that this is one of the key lessonsthat we will take away from this course. Furthermore, we asked tutors any questions we were havingon the days of rig testing regarding our MAV. We have come to realise that using MATLAB andSimulink once again after the model test was not required by the course, however was extremely usefulin optimising the performance capable from our MAV.

We hope to apply this key lesson to future team projects, where we aim to use all resources available,despite whether they are marked or required by the course. This is heavily applicable to generaleveryday life, where this process could make our journey through university both easier and moreenjoyable.

5.3.5 The Importance of Organisation

In the earlier stages of our journey through ENGG1200, although our team had suitable teamwork andcommunication, we lacked organisation. Despite being able to communicate with each other effectivelyand help each other when need be, we initially found it difficult to set and meet deadlines for ourselvesin terms of assessment. As the course went on and we developed as a team, we actively identified ourweakness as organisation, and aimed to improve that. By the later stages of the course, our team hadsuccessfully organised testing times which were available to everyone and our own deadlines for thefinal report and were successful in meeting them.

The main key lesson we will take away from this is the importance of organisation in a success-ful team. We all aim to apply this to future projects by taking the lead if need be, and makingteamwork less stressful. We have also identified that this can be applied and extended beyondENGG1200, where good organisation will not only help our university studies, but also our everydaylives such as sticking to a time schedule.

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6 Conclusions

The prototype was manufactured using a 3D printer and each component was printed individually andassembled as outlined in section 3. The material and design of each of the components was chosen foroptimal performance of the MAV and is outlined in section 4. Furthermore, the lightweight materialchoice and unique design will ultimately lead to achieving success and reaching the requirements formaximum flight time and distance that the MAV can travel.

7 Recommendations

Due to the scope and nature of the project, the design and model of our MAV is unsuitable for anyreal life applications, due to its simplicity and very small size. The functions of modern UAVs/MAVsprimarily include photography, aerial inspection, surveying and remote observation (MicroDrones,2015). All of these functions require both continuous flight and the implementation of camera, whichthis MAV was not designed for.

For the purpose of increasing the functionality of our MAV design, research into propellers shouldbe conducted to extend flight time. Producing sustained flight would require the ability to remotelycontrol the MAV which would necessitate the presence of a steering system and power source withinthe model. This would increase the functionality of the MAV, but would also require a large amountof research, design, simulation and manufacturing.

Further recommendations may also include the consideration of a wider range of materials, dif-ferent manufacturing processes, or slight changes to the design such as winglets to provide betteraerodynamics. Lighter materials such as balsa wood or carbon fibre may decrease the weight andtherefore increase the overall performance of the MAV.

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8 References

Bunnings Warehouse. (2015). Craft Wood. Accessed on 16 October 2015 from: http://www.bunnings.com.au/our-range/paint-decorating/paint-accessories/craft/wood

Dynamic Flight. (2010). Airfoils in General. Accessed 18 October 2015 from http://www.dynamicflight.

com/aerodynamics/airfoils/.

Gurit. (2015). Balsa Wood Core Material. Accessed on 19 October 2015 from http://www.gurit.cn/

Files/Documents/Wind%20Energy%20Datasheets%20(English)/Balsaflex_WE_v3.pdf

MatBase. (2015). PLA monomere (Polylactic Acid). Accessed on 19 October 2015 from http://www.

matbase.com/material-categories/natural-and-synthetic-polymers/agro-based-polymers/material-properties-of-polylactic-acid-monomere-pla-m.

html

NASA. (n.d.). Drag Coefficient. Retrieved from NASA: https://www.grc.nasa.gov/www/k-12/

airplane/dragco.html

NASA. (n.d.). Lift Coefficient. Retrieved from NASA: https://www.grc.nasa.gov/www/K-12/

airplane/liftco.html

NASA. (2010). Wing Design. Accessed on 10 August 2015, from http://www.aeronautics.nasa.

gov/pdf/wing_design_k-12.pdf

Shiel, M. (2015). ENGG1200 - Project A Brief. University of Queensland.

Laitone, E. (1997). Wind tunnel tests of wings at Reynolds numbers below 70 000. Experiments inFluids, 23(5), pp.405-409.

MicroDrones. (2015). MICRODRONES-APPLICATIONS:. Retrieved from microdrones: https:

//www.microdrones.com/en/home/

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Appendices

1 Tensile Member Calculations

1.1 Material Comparison

Test Report

Gauge Length 25.00 mmCross Head Speed 2.000 mm/min

0

100

200

300

400

500

600

700

800

0 10 20 30 40 50

Tens

ile s

tres

s [M

Pa]

Tensile strain [%]

SHIM TEST

Specimen NameBRASS 1BRASS 2BRASS 3BRASS 4Aluminium 1Aluminium 2Aluminium 3Aluminium 4Steel 1Steel 2Steel 3Steel 4

Results

Specimen label Thickness[mm]

Width[mm]

Maximum Load[N]

Tensile stress atMaximum Load

[MPa]

Young's Modulus[GPa]

Tensile stress at 0.2%Yield[MPa]

Tensile strain at Break[%]

1 BRASS 1 0.390 12.050 1,861 396 162 245 24.12 BRASS 2 0.390 12.050 1,866 397 132 242 44.03 BRASS 3 0.250 12.050 1,063 353 140 226 33.64 BRASS 4 0.250 12.050 1,022 339 100 226 33.55 Aluminium 1 0.560 12.050 1,062 157 56 144 4.86 Aluminium 2 0.560 12.050 1,058 157 119 142 4.27 Aluminium 3 0.770 12.050 1,467 158 98 138 6.38 Aluminium 4 0.770 12.050 1,478 159 69 142 6.89 Steel 1 0.200 12.050 1,889 784 225 639 1.610 Steel 2 0.200 12.050 1,903 790 196 646 2.0

11 Steel 3 0.130 12.050 1,057 675 209 565 1.1

12 Steel 4 0.130 12.050 1,083 692 194 472 1.5

Page 1 of 1

Figure 7: Data Specifications of Various Materials and Thickness

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1.2 MATLAB Script for Plotting Stress-Strain Relationship

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Figure 8: Comparison of Different Materials Under Load

2 MAV Performance Calculations

2.1 Lift and Drag Simulation

The following table presents the results of the simulation, run at various angles of attack.

Table 4: Lift and Drag Parameters for the MAV

Angle of attack (°) Lift (N) Drag (N) Lift Coefficient Drag Coefficient Lift to Drag Ratio

0 0.876242 0.167576 0.1971 0.0377 5.22893

5 2.55877 0.306044 0.5754 0.0688 8.3608

10 4.09503 0.788733 0.9209 0.1774 5.19191

15 4.32252 1.32252 0.9763 0.2974 3.2851

20 4.32533 1.79481 0.9727 0.4036 2.40991

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2.2 Physical Model Verification

2.3 MATLAB Script for Declaring Performance Parameters

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2.4 Launch Rig Modelling (SIMULINK)

2.5 Trajectory Modelling

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