Solar Challenger

Future starts now

Tim van Leeuwen & Jesper Haverkamp

Hermann Wesselink College Advisor: F. Hidden March 2010

Abstract

Main goal of this project was to make calculations and respective designs to create an electric airplane prototype, capable of powering its flight either entirely or partially using solar

2010 energy. This project intended to stimulate research on renewable energy sources for aviation.

- In future solar powered airplanes could be used for different types of aerial monitoring and unmanned flights.

First, research was done to investigate properties and requirements of the plane. Then, through a number of sequential steps and with consideration of substantial formulas, the aircraft‟s design was proposed. This included a study on materials, equipment and feasibility. Finding a balance between mass, power, force, strength and costs proved to be particularly difficult. Eventually predictions showed a 50% profit due to the installation of solar cells. The aircraft‟s mass had to be 500 grams at the most, while costs were aimed to be as low as €325.

After creating a list of materials and stipulating a series of successive tests, construction itself started. Above all, meeting the aircraft‟s target mass, as well as constructing a meticulously balanced aircraft appeared to be most difficult. Weight needed to be saved on nearly any element. We replaced the battery, rearranged solar cells and adjusted controls. Though setbacks occurred frequently, we eventually met our goals with the aircraft completed whilst

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim weighing in at 487 grams.

– Testing commenced with verifying the wings‟ actual lift capacities. Results were satisfying. In addition, further testing on drag and propulsion was gratifying as well. Finally, the aircraft truly took to the skies, but sadly crashed due to flaws in steering. Testing on solar cells however, was disappointing. Instead of the expected 50 %, we only managed to achieve 10 % profit. In addition, one can pose the question if leaving out the solar cells entirely would have

meant saving such considerable weight, that there would have been more profit after all. Final

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– costs of the project were €515.

Ultimately we can conclude purely solar powered flight is impossible, at least with the materials available and taking Dutch climate into account. Further developments in solar technology might create possibilities for solar planes in future. For now, in order to install solar cells, too many aspects of the plane are sacrificed to save weight. This for example

resulted in a frame far too fragile. Solar Challenger Challenger Solar

– Still, it should be noted that the plane we manufactured was a prototype only. Many adjustments can be made. During the project we have seen that there is quite some room for improvement. That is obvious, as this was the very first airplane we ever build. We gathered enormous amounts of knowledge and we hope that in future this knowledge will be used to continue working on solar powered planes. For if development continues, solar powered aircraft might truly be used in future. Bear in mind: Future starts now.

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Introduction

As we both enjoy aviation and are considering a study involving the aircraft industry, it had

soon become clear we wanted to do our research project about a topic related to flying.

2010 Though aviation is a complex part of technology, we thought our expertise on physics and our

- passion for flying would guide us through this project. Our first concern was finding a topic both interesting, challenging and future-proof. Due to current turbulence in aviation we decided on the following:

The desire to fly is nearly as old as humanity itself. Ever since we walked the earth, we longed to get airborne, just like the birds above us did. In 1783 this dream became reality1. “Historians credit France's Montgolfier brothers with the first pioneering balloon flight”2. Aviation‟s next revolution was in 1903, when Orville and Wilbur Wright took off with their „Flyer 1‟ and flew 36 metres with their plane3. Flyer 1 was powered by a petrol engine, just like later aircraft. Nowadays, aviation accounts for three percent of all CO2-emissions produced by mankind4.

This doesn‟t seem much, but more important is that profit of commercial aviation strongly relies on the oil price. Due to high prices5 of crude oil lately, profits of commercial aviation have been diminished and aviation industry is now looking for alternative energy sources to

propel modern-day aircraft. Options that are being considered are bio fuels, hydrogen and Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

6 – ethanol . An option which is rarely considered is solar energy, an option we wanted to investigate.

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Solar Challenger Challenger Solar

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1http://adventure.howstuffworks.com/first-flight-attempt.htm 2Robert Lamb, 2008 3http://www.wright-brothers.org/History/Just%20the%20Facts/1903fly.htm Research Project Project Research 4http://www.rotterdam- airport.nl/nl/generalmenu/Over_Rotterdam_Airport/In_de_samenleving/Feiten_en_cijfers 5http://images.angelpub.com/2009/03/1606/oil-price-chart-1-12-09.png 6http://www.faa.gov/news/conferences_events/aviation_ forecast_2007/agenda_presentation/media/9 - %20Rich%20Altman.pdf 3

Table of contents

Front page Page 1

2010 Abstract Page 2

Introduction Page 3

Table of contents Page 4

Introduction phase Phases Page 5 Main goal, purpose and expectations Page 6 Research questions Page 7 Requirements Page 8

Design phase Design proposal Page 9 Construction proposal Page 30 Test proposal Page 32

Tim van Leeuwen & Jesper Haverkamp Jesper & Leeuwen van Tim

– Construction phase Media attention Page 35 International aspect Page 36 Construction Page 41

Test phase

Test results Page 54

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– Conclusion phase Conclusion Page 60 Evaluation Page 62

Additional sources Page 68

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Acknowledgements Page 69 – Jesper‟s log Page 70

Tim‟s log Page 73 Research Project Project Research

Phases

In order to minimize chances of failure, we set up the following scheme. It divides up the

project in five different phases, all having their own planning, goals and requirements:

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- Phase Elements Goal Introduction phase Determine main goal, research Provide a starting point for our questions, requirements, planning. project. Design phase Research, orientation, plans, Set up a design proposal, calculations, proposals. construction proposal and test proposal. Construction phase Description of construction itself: Give an accurate description of the what succeeded, what went wrong progress of our project. and in which way did we alter our designs and plans. Test phase Observations and experiences Provide an accurate description of during testing and test results. occurrences during testing. Conclusion phase Interpretation of test results, Describe what can be learned from conclusion, evaluation, this project, why it succeeded or recommendations for future not and how this project can be

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim projects. used later.

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– Research Project Project Research

Main goal, purpose and expectations

The main goal of this project is to make calculations and respective designs to create an

electric airplane prototype, capable of powering its flight either entirely or partially using

2010 solar energy. This project intends to stimulate research on renewable energy sources for

- aviation. Hopefully this will result in the environment no longer suffering due to emissions of burning oil products. In future solar powered airplanes could be used for different types of aerial monitoring and unmanned flights. Due to their light weight, silent engines and infinite flying time, they might also be used as spy planes in inhospitable areas.

By doing broad research and making appropriate calculations, we hope to design an aircraft which is actually able to fly. Our first concern is composing the right electrical system to be used in our aircraft. Selecting suitable equipment and making useful drawings and schemes will provide us with the basis for our project. Extensive testing will show how effective our system functions in different circumstances. Once completed, our circuit will be combined with the aircraft‟s frame.

If we manage to correctly set up our calculations, the aircraft should be able to fly. In case testing shows the aircraft is not able to take off, we will first investigate how we can improve the plane‟s properties. Though, when nothing seems to help anymore, we will slightly shift

our main goal and try to create a controllable, energy efficient vehicle using all equipment we

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– gathered so far. This will only be done in case all goes wrong.

This project runs over an extensive period of time, which will provide us with sufficient opportunities to do research and create designs. We will make a strict planning and a precise proposal to make sure our project will run smoothly. Assuming we will be able to make accurate calculations, our expectations are that we will actually produce an aircraft capable of

flying on solar power. Even though we try to plan and predict everything as well as possible,

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– setbacks might occur. To prevent failure, we shall make sure there is enough room for unexpected events. ger ger

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Research questions

From our main goal we can derive the main research question involved in our project:

2010 Is it possible to create an electric airplane prototype capable of using solar power to partly or

- entirely power its flight?

Sub questions

In order to answer our main question completely, we need to look at several sub questions:

1. Is it possible to let the aircraft fly on solar power only? 2. How do you make sure no precious energy is spilled when the solar panels generate very little energy? 3. How do you deal with the cells’ varying output in cloudy or sunny circumstances? 4. Which extra equipment is needed to make the solar cells function properly? 5. Which circuit is needed to make the plane remote controllable? 6. Which equipment and components are needed to control the plane?

7. What will be the plane’s size, mass, speed?

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– 8. Which airfoil do you use, how big is it and how does it work? 9. How much lift do you need? 10. Which engine and propeller do you need? 11. Which solar cells generate most electricity with fewest mass and how big are they? 12. How do you mount the solar cells on the aircraft (inside or outside, wing or body)? 13. What will be the structure’s design?

14. Which materials do you need to construct the plane?

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– 15. Where do you place all electrical equipment, making sure the aircraft is balanced and what will the fuselage be like? 16. What will be the shape of the tail and elevator and how are they controlled? 17. In which order are you going to construct the plane? 18. Which effect does the position of the solar cells have on the efficiency of both the plane and panels?

19. How much profit do the solar cells provide? Solar Challenger Challenger Solar

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Requirements

Before writing a design proposal, a complete set of requirements is needed. In this way we

know which limitations there are during construction. Not only will these requirements be a

2010 guideline throughout our project, they will provide us with a starting point as well. After all,

- mass, power, size and costs of an aircraft are all related. You need to fill in one first in order to determine the others.

Element Requirements Notes Available time At least 100 hours of which 50 are before the Construction will be summer holidays, 20 after the summer before and during summer holidays. holidays. Available Nearly everything as long as we can afford it materials and it‟s available in shops (on the internet) and not custom made. Plenty of tools are available. Number of Two Experts, teachers and participants other sources not included. Final Between 1.0 and 1.5 metres in width in order to Length and height depend product’s size not let it be too small or too big. These on mass and balance,

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim measurements can vary slightly if needed. which will be determined

– later. Number of One (prototype) products Budget No more than €400 in total as long as no sponsor has been found. Environment Outside No rainy circumstances

JeT Productions Productions JeT Media attention www.solarchallenger.tk, website with our

– progress, sponsors, TU Delft?

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Design proposal

When designing, there are three things to be considered. First there is the main goal, secondly

there are the research questions and thirdly there are the requirements. When combined, those

2010 three elements form the basis of making a design proposal. To start out, we use the

- requirements and see how we can implement them in our main goal and research questions.

The requirement we are currently most interested in, is the model aircraft‟s size. We intend to construct an aircraft with a span measuring 1.5 metres. In this way the aircraft will not be too large to handle and at the same time it will be large enough to provide us with enough room for mounting solar cells and other equipment without space becoming too crowded. We will use this very measurement as a basis throughout the design proposal.

Jesper Haverkamp Haverkamp Jesper To design the plane in an organized way, we set up a plan consisting of a number of steps. These steps deal with several sub questions and will be filled in as we go:

Step 1: Designing the right basic electrical system (no sizes, properties, etc. included). Step 2: Research on the size of the aircraft and probable mass. Step 3: Feedback on the engine, solar cells, battery etc. Step 4: Final decision on mass and thus the size of the aircraft.

Step 5: Designing the final electrical system including properties and components.

Tim van Leeuwen & Leeuwen van Tim

– Step 6: Determining where to place the solar cells. Step 7: Designing the wing and doing a final check on lift, mass, size, etc. Step 8: Determining construction materials. Step 9: Designing the aircraft itself, keeping mass, centre of gravity, etc. in mind. Step 10: Calculating final costs

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– Step 1

Before continuing with calculations involving the size of the aircraft, we will look at the electrical system involved. After all, our plane would be useless without properly functioning electronics. This implies we will start out with answering sub questions 1, 2, 3, 4, 5 and 6:

1. Is it possible to let the aircraft fly on solar power only? Solar Challenger Challenger Solar

2. How do you make sure no precious energy is spilled when the solar panels generate very – little energy? 3. How do you deal with the cells’ varying output in cloudy or sunny circumstances? 4. Which extra equipment is needed to make the solar cells function properly? 5. Which circuit is needed to make the plane remote controllable? 6. Which equipment and components are needed to control the plane?

To start, we will answer question 6. A properly controllable plane needs several pieces of Research Project Project Research equipment7.

7http://www.mvccolumbia.nl/hoebeginik.htm#07 9

First there are a transmitter and receiver, which are used to send and receive signals from a control panel. The receiver, located inside the plane, will send signals to elements called servos. They can move the rudder, ailerons and elevator. Besides, the receiver also controls the engine throttle. We will come back to question 6 in more details later, when we know more about the mass, size and power of the aircraft.

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The answer to question 1 was very obvious once we investigated the power consumed by an - engine. A website8 showing engine characteristics listed a considerable number of engines. All of those appeared to consume quite a lot of energy. Besides the fact that our engine needs an enormous amount of power (which will unlikely be generated by our solar cells due to Dutch climate9) the engine also needs a steady energy flow. We don‟t want our aircraft to crash due to one cloud and for that reason we will use a battery combined with solar cells.

Then the answer to question 2: When the solar panels are not generating lots of energy, we must prevent energy from flowing from battery to solar panels. Therefore we will install a diode between the solar panels and the battery. The diode will unfortunately consume some power, but this is the only way to get things working. In order to keep voltage loss as low as possible, we are going to use a „Schottky diode‟. This specific type of diode only uses 0.1-0.2 volts compared to a regular diode which contributes to the loss of 0.7-1.7 volts10.

Since we found a solution to question 1, the answer to question 3 has already been given.

Using a battery will not only help us keeping the plane airborne when limited energy is being Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

delivered by the solar panels, but it will also make sure that whenever the output of the solar – cells drops (for example due to a cloud passing by) the engine still receives enough power.

Knowing all the information we gathered so far, we can draw a circuit basically showing the electronics inside the aircraft, which answers question 5 up to a certain extent. Since we don‟t know anything about power, mass, battery size etc. yet, we are not able to draw all details. The following scheme just provides us with a basic idea of which elements are needed to

JeT Productions Productions JeT control the aircraft, thus giving us a starting point for calculating the aircraft‟s mass in future.

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Receiver Servo Solar Cells + Battery + ntroller

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- - Servo –

Servo

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8http://www.rctechnics.eu/-c-130.html 9http://www.nlplanet.com/nlguides/dutch-climate 10http://www.absoluteastronomy.com/topics/Schottky_diode 10

Step 2

Having completed the basics of our circuit, we can resume calculations about the aircraft‟s size. When combined with the circuit, we can derive the engine‟s, battery‟s and solar cells‟ requirements. As proposed in „Requirements‟ (page 8), we intended to construct an aircraft

with a span measuring 1.5 metres. The influence of the wingspan on the plane‟s other 2010

measurements will be investigated next. Research questions involved are: -

7. What will be the plane’s size, mass, speed? 8. Which airfoil do you use, how big is it and how does it work? 9. How much lift do you need?

These three research questions are related to each other as much as can be, namely lift comes with speed and determines mass and size, but it relies on the airfoil used. We will look at the aircraft‟s size first.

Size We determined the aircraft‟s span should be about 1.5 metres. In order to make calculations and construction of the wings

easier, we change the span into 1.6 metres. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

The ratio between span and chord – (illustrated11 right) in average model aircraft is between 1:7 and 1:812. In our airplane this would imply:

Width is 1.6 : 8 = 0.2 metres

JeT Productions Productions JeT Knowing both the wing‟s width and span,

– we can calculate the wing‟s surface area. This size will later be used in several calculations.

Surface area= 1.6 metres × 0.2 metres = 0.32 square metres

Solar Challenger Challenger Solar

– Airfoil t t Not only surface area is important for a well functioning wing, but having a correct airfoil is important too. It is the airfoil‟s shape that provides the aircraft‟s lift. All airfoils rely on same principle13, Bernoulli‟s principle. It14 describes the relationship between velocity and pressure in a moving liquid or gas:

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11http://www.myaeromodelling.com/wp/wp-content/uploads/2008/01/ar.jpg 12http://www.mvccrash.nl/overons/00000097940bbf72d/ 13http://library.thinkquest.org/27948/bernoulli.html 14http://www.daviddarling.info/encyclopedia/B/Bernoullis_law.html 11

P + ½ρv2 + gρh = k

P = Pressure (Pa) ρ = Density (kg / m3)

v = Velocity (m / s)

g = Acceleration due to gravity (m / s2) 2010

h = Distance from reference, measured in opposite direction of the gravitational force (m) - k = constant (kg / ms2)

The formula proofs that if gravity, air density and position remain unchanged, pressure will drop when flow velocity increases. In other words: if you have an airflow of high velocity and low velocity under the same circumstances, the area containing the high airspeed, will show a lower pressure. This implies that if the air flowing over the wing moves faster than under the wing, the air pressure above the wing will be lower, thus sucking the wing up into the sky.

For this reason wings are shaped in such a way that air moves faster along the upper surface. This is done through making the air above the wing move a longer distance in the same time than the air underneath the wing. Therefore the wing‟s upper surface is more curved than its lower

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim 15

surface. – Throughout the years many airfoils have been developed16. Every single one of them had excellent properties for different purposes, like low or high speeds, or stability. Concorde‟s wing was quite different from a Boeing 747‟s for example. Still, there is no such thing as „the perfect airfoil‟. Properties needed simply depend on the characteristics of the 17

JeT Productions Productions JeT aircraft. Our plane just needs a simple and ergonomic airfoil. It will be „Clark-Y‟ :

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– Clark-Y basically is an airfoil with a flat bottom and a curved top. Not only have there been many experiments about this type of wing, it is also easy to construct. The following table19 shows certain numbers defined as lift coefficient. These statistics will later be used in calculations on lift.

Research Project Project Research 15 http://www.yes mag.ca/focus/flight/bernoulli.gif 16http://www.ae.illinois.edu/m-selig/ads/coord_database.html 17http://upload.wikimedia.org/wikipedia/en/6/6a/Clark_y.JPG 18http://www.gliders.dk/clark_y.htm 19http://www.gerritentiny.nl/documenten/Microsoft%20Word%20-%20VLIEGEN4.GER.pdf 12

Angle of attack Lift coefficient 0 0.29 1 0.36 2 0.43 3 0.50

4 0.57

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- 5 0.64 6 0.71 7 0.78 8 0.85 9 0.92 10 0.99 11 1.06 12 1.12

Speed Before we determine the aircraft‟s mass, we will take a look at its speed. Investigation on several model aircraft shows the approximate flying speed is between 25 and 100 kilometres per hour. 20 Taking into account the limited capacity of our solar cells, we aim to let the aircraft fly at 30 kilometres per hour.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– 30 kilometres per hour= 30 × 1000 metres : 60 minutes : 60 seconds = 8.3 metres per second.

Mass & lift At this very point in our investigation there are two options. Either we determine the probable mass of the aircraft and try to design the appropriate plane in order to gain enough lift or we

determine the lift we will probably gather and try to match the corresponding weight. We

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– choose the latter, since it is easier to make a plane lighter than to increase its lift. Making a plane lighter can be done through removing several pieces of equipment or replacing them by lighter ones (saving on the battery for example). On the other hand, trying to increase lift takes a great effort, because it requires redesigning and manufacturing the entire wings.

Lift can be calculated precisely through „aviation‟s most important formula‟21:

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L = ½ c ×  × A × v – L = Lift in Newtons c = Lift coefficient (no unit) = Air density (kg / m3) A = Wing‟s surface area (m2)

v = Velocity (m / s) Research Project Project Research

20http://www.aeroclub-drachten.nl/pagina's/modelvliegen.html 21http://www.grc.nasa.gov/WWW/K-12/WindTunnel/Activities/lift_formula.html 13

This formula should not be confused with the formula for calculating drag22. This formula is based on the same parameters, although when calculating drag the „drag coefficient‟ is used and the letter A represents the frontal area of the object.

From our previous investigation we can derive the wing‟s surface area and the plane‟s velocity. The lift coefficient is taken from the table previously shown by assuming that the

2010 23

angle of attack is larger than one degree at take off. At ground level the air density is - approximately 1.23 kg / m3. When filling in all numbers the results are as follows:

L = 0.5 × 0.36 × 1.23 × 0.32 × 8.32 = 4.88 N

The lift generated by our wings will be able to compensate for 4.88N of gravitational force. Since 9.81 Newtons of gravitational force correspond to one kilogram of mass24, we can calculate the mass of our aircraft:

4.88 N = 4.88N : 9.81N/kg = 0.497 kg

The second calculation shows us the answers to sub questions 7 and 9. When travelling at take off speed the wings of our aircraft generate 4.88 N of lift, thus being able to lift 497 grams. We will make a slight margin concerning mass. Therefore our target mass will be 450 grams.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Reynolds number – Besides determining if our wings generate enough lift, we must also know if our wings actually generate lift at all. Namely, gently and laminar airflow over a wing will only start at a certain velocity. In addition, when flying too fast, the airflow will also become too irregular and turbulent. The speed range at which the airflow will be smooth and laminar, can be estimated using a value called the Reynolds number.25

JeT Productions Productions JeT Reynolds number is a value given to the flow conditions around objects. For any object the

– optimal Reynolds number differs, but as a rule of thumb we can assume the Reynolds number is supposed to be between 5.0 × 104 and 2.0 × 105 for aircraft wings27. The Reynolds number can be calculated through the following formula28:

Re = ρ × v × L × μ-1

Re = Reynolds number (no unit) Solar Challenger Challenger Solar

– Ρ = Density (kg / m ) v = Velocity of fluid or gas (m / s) L = Travelled length of fluid or gas (m) μ = Dynamic viscosity (Pa × s)

22 http://en.wikipedia.org/wiki/Drag_equation 23http://en.wikipedia.org/wiki/Density_of_air Research Project Project Research 24 http://en.wikipedia.org/wiki/Mass 25http://home.earthlink.net/~x-plane/FAQ-Theory-Reynolds.html 26http://en.wikipedia.org/wiki/Reynolds_number 27http://www.personal.psu.edu/lnl/097/belgium.pdf 28http://www.aerodrag.com/Articles/ReynoldsNumber.htm 14

The air density is 1.23 kg / m3 as determined previously (page 14). The travelled length of the air is just over the wing‟s chord: 0.205 m. The dynamic viscosity differs according to temperature and air pressure. At room temperature it29 is 1.85 × 10-5 Pa×s. When filling in all numbers, the results are as follows:

Minimum speed = Re × p-1 × L-1 × μ = 5.0 × 104 × 1.23-1 × 0.205-1 × 1.85 ×10-5 = 3.8 m/s 2010

- Maximum speed = Re × p-1 × L-1 × μ = 2.0 × 105 × 1.23-1 × 0.205-1 × 1.85 × 10-5 = 14.7 m/s

Fortunately our take-off speed is within those boundaries. The airflow over the wings should be smooth and laminar.

Step 3

Having determined mass, size and the electrical system, we no longer need to estimate things, but we can calculate values precisely. The first thing to do now, is to combine mass and size with the electrical system. In this way we can start to create a list of materials and equipment needed.

Parts included in the electrical system are the battery, servo engines, controller, engine and

solar cells. These elements are linked in the following way: The size of the aircraft determines Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

the engine‟s size. The engine requires certain power supply, which determines battery size – and controller size. Because of this order we will look at a suitable engine first. The sub question involved is:

10. Which engine and propeller do you need?

JeT Productions Productions JeT Engine

– Engines vary in certain ways30. There are engines for high speed and engines for much force at lower velocity. Namely, the power of an engine is described in rotations per minute per volt. The lower this number, the more powerful the engine. A slow turning engine will be able to pull heavier aircraft at lower speeds, whereas fast turning engines will pull lighter (stunt) aircraft at higher speeds. Compared to other model aircraft, we intend to fly rather slow. Therefore we will use an engine with a low volts to turns ratio.

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– Initially we found an engine which met some of our requirements: a speed 400 engine. Then we discovered there are several other types of engines31. On one hand there are brushed engines (e.g. speed 400), on the other hand there are brushless engines. The latter is a modern invention and consumes considerably less power than the initial one. Brushless engines come in two types32: inrunner and outrunner.

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29http://www.ce.utexas.edu/prof/kinnas/319LAB/Book/CH1/PROPS/GIFS/dynair.gif 30http://adamone.rchomepage.com/guide5.htm 31http://www.dynetic.com/brushless%20vs%20brushed.htm 32http://www.rcuniverse.com/forum/outrunner_versus_inrunner%3F/m_2371948/tm.htm 15

An inrunner consists of a several magnets covered by a metal casing. This creates a powerful engine, which unfortunately produces lots of heat, thus loosing efficiency and requiring a cooler. As we cannot afford extra mass, we decided to go for a less powerful, but more efficient „brushless outrunner’. Taking mass and all other requirements into account, the

following engine33 seems most suitable to us:

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2208/17 Brushless Outrunner 1100KV - Element Value Price: €14.50 KV (RPM / V) 1100 Voltage 6-12V Nominal current 3-6A Maximal current 8A (max 60 s) Efficiency (at 4-7A) 74%

No load current (at 10V) 0.6A

Internal resistance 225 mΩ

Axle diameter 3mm

Dimension (Øxl) 27.5 x 26 mm Mass 36 g

Recommended model mass 200-500 g Maximal propeller 8.5 x 5 inch

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Propeller – As shown in the scheme above, a recommendation has been given on the maximal propeller size, with the first number being the propeller‟s maximal diameter and the second being maximal lead. A propeller with its lead being similar to its diameter is best suited for fast flying airplanes, whereas a propeller with small lead and larger diameter is excellent at providing maximal force, thus being perfect for heavy, slow flying aircraft. 34 As our plane flies rather slow, the following propeller35 seems most suited:

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– Master Airscrew Electric Propeller 8 X 5 Price: € 3.35

Element Value Mass Unknown

Diameter 20.3 cm Solar Challenger Challenger Solar Lead 13 cm

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To be absolutely sure this propeller is perfectly suited to propel our aircraft, we can apply the following formula and rule of thumb 36, which shows the relation between speed, rotations and lead. The propeller‟s speed must be two to three times as high as the airplane‟s take-off speed.

Research Project Project Research 33http://www.rctechnics.eu/220817-brushless-outrunner-1100kv-p-1692.html 34http://www.zininmijnleven.nl/hobby/propellors/index.htm 35http://www.rctechnics.eu/electric-propellor-p-116.html 36http://www.modelbouwforum.nl/forums/%5Bfaq%5D-modelvliegen-electro/21998-welke-spoed-moet-mijn- prop-hebben.html 16

vprop = l × f

v = Velocity (m / s) l = lead (m)

f = Rotations per second (Hz)

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Our engine is rated to provide 1100 rotations per minute per volt. As our system functions at - 8.5 volts (see below), we expect to operate at 9350 rotations per minutes, which is 156 rotations per second.

Propeller speed = l × f = 0.13 metres/rotation × 156 rotations/second = 20.3 m/s Ratio propeller speed : airplane speed = 20.3 / 8.3 = 2.45

The propeller we selected should be perfectly suited, since its speed is approximately two and a half times as high as the aircraft‟s speed. Therefore its torque is sufficient to propel the aircraft.

Batteries The engine requires a voltage ranging from six to twelve volts. This voltage should be provided by both our solar cells and our battery. Another key aspect of the battery is mass.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

In our quest for suitable batteries we first had a look at lithium-ion polymer batteries due to – their excellent power to mass ratio. However, LiPo batteries bring notable risks with them, such as spontaneous combustion when overloaded 37. LiPo batteries work best at a steady power supply, but since the output of our solar cells varies heavily, we decided not to take the chance of our airplane catching fire in mid-air, but doing extra research on alternative batteries instead.

JeT Productions Productions JeT The second option is nickel-metal hydrate batteries. These batteries have the disadvantage of

– being much heavier than LiPo batteries, but their reliability made us favour nickel-metal hydrate batteries over LiPo batteries. We will install seven „high output‟ batteries, producing a total of 8.4 volts, weighing in at 175 grams and having a capacity of 2500 mAh38. This capacity means that the cells will be able to provide a continuous current of 2.5 A during one hour.

Solar Challenger Challenger Solar

– Solar cells (1) The solar cells should provide enough power during flight to extend flying range drastically or even power the aircraft entirely. Just as with all materials used on our plane, mass is a crucial element, so the solar cells can‟t be too heavy. The research question involved is :

11. Which solar cells generate most electricity with fewest mass and how big are they? Research Project Project Research

37http://www.rctoys.com/pr/2006/10/20/safe-use-document-thunder-power-lithium-polymer-batteries/ 38Battery packet, HEMA Photo batteries 17

There are very few companies selling single solar cells. Cells are often being integrated in glass, something that would contribute far too much weight. Eventually we found a German company, Lemo-Solar39, selling single cells. Fortunately their shop contained a variety of cells, including one that meets our requirements:

Single solar cell 2010

Price: €10.60 -

Element Value Dimensions 100 x 100 mm Soldering strip Tinned, 2 mm Polarity front Minus Polarity back Plus Nominal voltage 0.5 V Nominal current 3200 mA Maximal output 1600 mW Mass 6.4 g

Because of the chosen batteries and the 0.1-0.2 volts lost over the diode, solar cells we use on the airplane must have a total output of 8.5 volts. This would require seventeen solar cells.

Besides the financial aspect, seventeen solar cells will also weigh too much and will probably Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

not fit in the airplane (more information in step 6). Therefore we will need smaller solar – panels besides the ones mentioned above. The cells will be soldered together with flexible wiring. This will be no problem, as the cells are already equipped with soldering strips.

Solar cells (2)

JeT Productions Productions JeT Single solar cell

Element Value – Price: €3.- Dimensions 29 x 78 mm Soldering strip Tinned, 2 mm Polarity front Minus Polarity back Plus Nominal voltage 0.5 V Nominal current 630 mA

Solar Challenger Challenger Solar Maximal output 340 mW

– Mass 1.6 g

In total we plan to use twelve solar cells measuring 10 by 10 centimetres and six cells measuring 29 by 78 millimetres. When adding properties of all solar cells, the results are as follows:

Research Project Project Research Mass: 12×6.4g + 6×1.6g = 87 g

39http://www.lemo-solar.de/default_1.htm 18

Output: 12×1600mW + 6×340mW = 21240 mW ≈ 21 W Engine power: 5A× 8.4V = 42 W

This implies that under ideal circumstances the solar cells will provide 50% of the engine‟s

power supply. Of course this would be an utopia, since we didn‟t take power loss by the

receiver, servo‟s and controllers into account. Tests will eventually show how close we can 2010

get to our 50% energy reduction goal. We will go into more details about testing in the „Test - proposal‟.

Servos The next step after investigating the right materials for energy supply and propulsion, is finding the right equipment for controlling the aircraft during flight. This equipment includes the receiver, engine controller and servos. First, we have a look at the servos, devices operating the plane‟s ailerons and rudder40, which control vertical and horizontal movement. These machines come in different sizes and shapes. Since our plane is lightweight and forces on the aircraft won‟t be tremendous, we decided to go for the lightest servos41:

Micro Servo 3.7 grams Price: € 7.50

Element Value Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Dimensions 19.7 x 17.44 x 8.37 mm Mass 3.7 g

Speed (4.8V) 0.1 sec / deg

Torque (4.8 V) 0.5 kg / cm Operating voltage 4.8 – 6.0 V

eT Productions eT Productions

–

Solar Challenger Challenger Solar

– Research Project Project Research

40http://www.rc-airplane-world.com/rc-airplane-controls.html 41http://www.rctechnics.eu/micro-servo-gram-p-2497.html 19

Every flap, rudder or aileron needs a servo to operate. A regular airplane is co ntrolled using ailerons42 for rolling movements, the elevator43 for up and down movements and the rudder44 for crosswind compensations. This is illustrated by the drawings on the previous page45.

We are unlikely to fly at high wind speeds due to expected fragility of our aircraft. Therefore

we will eliminate the servo for the rudder. It will not only save us weight by not using a servo,

but also through the removal of wiring. The total mass of our servo engines will be: 2010

- Mass: 3 × 3.7g = 11.1 grams

Engine regulator Next up in the controlling equipment is the engine regulator. It controls throttle given by the engine. Again, this part should weigh as little as possible and should be able to cope with current and voltage in our circuit. We found the following suitable engine regulator46:

12A FLY Brushless ESC Element Value Price: € 16.95 Operating voltage 7.2-12 V Continuous load 12 A Peak load 15 A (Max 5 s) Dimensions 22 x 18 x 5 mm Mass 7.1 g

Low voltage turn off 47 Automatic Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Receiver Of course the airplane doesn‟t control itself. We want a person on the ground to be able to remotely control the aircraft. For this reason, we need a remote controller and a receiver. The controller will send signals to the receiver, which will instruct the servo engines and the engine regulator. We found the following suitable parts48:

JeT Productions Productions JeT

– E-Sky receiver, 6 channels, 35Mhz Price: € 13.50

Element Value Frequency 35 Mhz

Mass 14 g Solar Challenger Challenger Solar

Dimensions 45 x 23 x 13 mm – Voltage 5 V Current 11.5 mA Antenna Length 100 cm

42http://www.rc-airplane-world.com/image-files/rc-airplane-ailerons.gif 43http://www.rc-airplane-world.com/image-files/rc-airplane-elevators.gif 44http://www.rc-airplane-world.com/image-files/rc-airplane-controls-rudder.gif Research Project Project Research 45http://www.rc-airplane-world.com/image-files/rc-airplane-controls.gif 46http://www.rctechnics.eu/12a-fly-brushless-esc-p-393.htm 47Once voltage drops below 7.2 volts, the controller switches off power to the engine, thus preventing batteries from discharging too much. 48http://www.rctechnics.eu/esky-ontvanger-kanaals-35mhz-p-1367.html 20

Remote control Both the sender and receiver should function at the same frequency. Therefore our options for choosing a suitable remote control were slightly reduced. Additionally there are great differences between remote controls operating at the same frequency. Some are equipped for

controlling helicopters only, whereas others are best suited for controlling petrol powered

planes only. This difference originates from different controls needed for different planes. A 2010

helicopter for example does not have a retractable undercarriage, while a large aircraft does. - Eventually we found the following49:

E-Sky remote control, EK2-0404A Price: € 29.95

Element Value

Channels 4 Frequencies 35, 40, 72 MHz Energy source 8 x 1.5 AA battery Servo reverse Manually Voltage indicator Automatic, Led Dimensions 185 x 205 x 55 mm Colour Black

Antenna length 100 cm Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Usage Airplane, helicopter, Glider –

Step 4

We can now make a decision on size and mass of the plane. At the start of our research project, the wingspan we were striving for was 1.6 metres. Looking at the dimensions of the

JeT Productions Productions JeT equipment we will be putting in the airplane, there is no reason to change this plan.

– Element Mass (grams) Now we‟ve decided on the parts to be used, we can also Engine 7.1 give a more informed prediction of the mass of the Battery 175 plane. All the parts we just summed up add to a total of Servos 11.1 335 grams, well below our target mass of 450 grams. Receiver 14 However, we haven‟t included all elements yet (such as the frame, wiring and unforeseen additional mass). In

Solar Challenger Challenger Solar Propeller 5

– Engine 36 addition, we aren‟t certain yet about the mass of the Wiring 10 propeller, but we estimate it weighs 5 grams. We reserve 70 grams for the frame, a reasonable amount Solar cells 1 76.8 50 Solar cells 2 9.6 according to experts on internet forums . Furthermore Frame 70 we reserve 10 grams for wiring and 10 grams for Unforeseen 10.4 unforeseen mass. All these numbers add up to a total of 425 grams, so we should be well under our target mass.

Total 425 Research Project Project Research

49http://www.rctechnics.eu/esky-zender-kanaals-35mhz-ek20404a-p-2784.html 50http://www.modelbouwforum.nl/forums/bouwverslagen-vliegen/59216-bouw-van-een-fijn-zwevertje.html 21

Step 5

The electrical system has now been completed. Knowing mass, size and properties we are able to draw the final circuit:

2010

- + - + +

Solar cells

Batteries:

Haverkamp Haverkamp Solar Cells: Batteries:

0.5 V each, 1.2 V each,

3200 mA 2500 mAh

18 in series: 7 in series: 9.0 V 8.4 V - 3200 mA 2500 mAh

Tim van Leeuwen & Jesper & Leeuwen van Tim

–

Controller Receiver Servo M

Servo

JeT Productions Productions JeT

Servo – -

Step 6

Solar Challenger Challenger Solar

– 12. How do you mount the solar cells on the aircraft (inside or outside, wing or body?)

With the solar cells being a critical part of the plane, it is logical to have a good thought about the solar cells‟ position in the plane. The solar cells account for a large part of the total mass, so their position has to be well considered to keep the plane balanced, both on the ground and during flight. Since the plane‟s fuselage will be very slim and the solar cells measure 10 square centimetres, it is most obvious to place the solar cells on the plane‟s wings. With the

Research Project Project Research plane being 160 centimetres in wingspan, we have plenty of space to place all solar cells. In addition, placing solar cells on the tail will not only be impossible due to the tail‟s size, but the plane‟s centre of gravity will also be shifted too much to the back.

We have to determine whether we will place the solar cells on top of the wings or inside the wings. The choice was made quickly: we will place our solar cells inside the wings, since it offers multiple advantages:

 The assembly of the solar cells becomes much easier. If we would place the solar cells on

top of the wings, we would have to attach the solar cells to the covering foil which might

2010

- pierce the foil and possibly ruin lift properties.  Placing the solar cells inside the wings will leave aerodynamic properties of our wings intact, whereas putting solar cells outside the wings would drastically increase the drag of the wings and could reduce the lift they provide.  Placing the solar cells inside the wings largely eliminates the risk of damaging the highly vulnerable solar cells, since they will now be protected by foil.

The schematic drawing below gives an impression of the right wing:

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

–

The six big yellow squares represent the six big solar cells in the wing; the small yellow squares represent the smaller cells. We will leave some space between the solar cells to place the ribs of the wing. All these ribs will give the wing its structural integrity. In step 7 we will go into more details about the construction‟s design.

JeT Productions Productions JeT

– Step 7

13. What will be the structure’s design? 14. Which materials do you need to construct the plane?

Now that the solar cells‟ placing has been determined, we can make a list of all the additional

Solar Challenger Challenger Solar equipment we will be placing in the wings. Parts that will be put in the wings are:

–  Solar cells  Servos  Wiring  Foil  Ribs & cornices

 Triplex beams Research Project Project Research  Axle for aileron  Ailerons

Our plane‟s wings will have a wingspan of 160 centimetres, a width of 20 centimetres and an expected height of 2.5 centimetres. To prevent the wing from bending we will place two triplex beams running through the wings. The front and rear cornice have already been pre- shaped51. In the diagram below you can find an overview of the wing. The numbers above the

wing represent the rib that is placed there:

2010

The ribs will be made out of balsa wood, the lightest type of wood known to men52. Each rib measures three millimetres in thickness. We will cover the wings using a covering foil called Mylar. This material can be applied to the wing loosely, but will be tightened around the

frame by ironing it53. It weighs approximately seven grams per square metre and is strong Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

enough to lift the aircraft. –

Cross section 1 The drawing below shows one of the wing‟s regular ribs. The yellow circles represent holes in the ribs for wiring. The black rectangles in the middle of the wing represent two triplex girders running through the wing. On top of these we will mount the solar cells. Besides

JeT Productions Productions JeT providing a base for the solar cells, the girders also give the wing structural integrity. The

– black semi-circle and triangle show the pre-shaped front and rear cornice. The blue rectangle shows the position of a solar cell in between the ribs.

ar Challenger Challenger ar

Sol

–

Our solar cells will be mounted inside the wing. This requires the ribs to be placed eleven centimetres apart, for else the solar cells won‟t fit. We also need to make sure there is enough room to construct the ailerons. Besides, some space must be kept free to install a servo engine. These demands result in three alternative ribs which will be used in the aft of the wing: Research Project Project Research

51http://muco-modelbouw.nl/index.php?lang_id=1&c_id=590&ref_change=outside 52http://pldaniels.com/flying/balsa/balsa-properties.html 53http://www.modelbouwforum.nl/forums/verlijming-constructie/44864-mylar-folie-hoe-verwerk-je-dat.html 24

Cross section 2 In the second cross section we see the servo‟s placing in the wing.

2010

Cross section 3 The third cross section represents the last rib before the aileron, the element in the wing which allows us to steer the plane. You may notice an extra beam just before the hole for the aileron. This beam provides a surface around which the covering foil can be wrapped.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Cross section 4 – The fourth cross section is the rib that can be found in the part of the wing where the aileron is placed. As you can see, the rear cornice of the wing has been cut off. Instead we will place the aileron there. In addition, the large solar cell isn‟t shown, because in this part of the wing we will locate the smaller cells instead. They are too small to rest on top of the triplex beams. Therefore they will be suspended on top of a little piece of rope attached to the triplex girders.

JeT Productions Productions JeT

– 4

Step 8 & 9

Solar Challenger Challenger Solar

– Fuselage The aircraft‟s fuselage is among the most important parts of the plane. All electronic equipment is to be installed here. Moreover, wings and landing gear are connected to the plane‟s fuselage. As weight and balance are crucial to an aircraft, it is important to make a detailed drawing showing where all equipment will be placed. To monitor the balance the plane‟s fuselage will be suspended by one thread during construction. In that way a flaw in

Research Project Project Research balance will be noticed quickly as the plane flips over when not properly loaded. Sub questions involved in parts 8 and 9 are:

15. Where do you place all electrical equipment, making sure the aircraft is balanced and what will the fuselage be like? 16. What will be the shape of the tail and elevator and how are they controlled?

Fuselage

First up is the fuselage. Since drag is an important factor when concerning the engine‟s 2010

capacity, we should keep drag as low as possible. We intend to construct a frame measuring - seven centimetres wide. In order to keep the structure both light weight and strong, we shall construct a triangular shaped fuselage. The fuselage will be 28 centimetres long, thus providing us with enough room to place all electrical equipment. However, our seven AA batteries measure54 five centimetres each. Therefore they can‟t be installed in one line. The entire scheme of our plane‟s fuselage can be found below. Due to heat produced by several pieces of equipment55 the back side will be left open.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

–

JeT Productions Productions JeT As shown in the drawing, the centre of gravity is to be located at ⅓ of the wing‟s depth. This

– is a rule of thumb56 for building aircraft. With the equipments‟ mass being so low and exact mass of the frame yet unknown, it is impossible for us to calculate the momentum for each element in the plane. Therefore the scheme shown above will be used as a guideline to position all equipment.

Once our aircraft has been completed, its centre of gravity will be determined precisely by

slightly moving the equipment inside the plane‟s fuselage. Another rule of thumb57 is to rather

Solar Challenger Challenger Solar

– position the plane‟s centre of gravity slightly too far in front than too far to the rear. This is due to the plane getting in stall position too easy when the centre of gravity is located in the rear.

Research Project Project Research

54http://en.wikipedia.org/wiki/AA_battery 55http://www.modelvliegclub-swentibold.nl/To_BEC.htm 56http://www.modelbouwforum.nl/forums/zweefvliegen/74239-afstellen-zwaartepunt-zwever.html 57http://www.fms-spaarnwoude.nl/home/content/view/272/88888915/ 26

The fuselage‟s frame will be constructed with balsa wood and covered with Mylar foil. However, due to safety reasons, we will manufacture the fuselage‟s base out of a plate of balsa wood, for else the equipments‟ heat will melt the Mylar foil. The frame itself will feature triangular shaped parts. The holes in between the 2nd and 3rd and between the 4th and

5th triangle are points to attach the wing to the fuselage. As shown in the diagram below, the

main gear will be placed slightly in front of the centre of gravity. This will make the aircraft 2010

fall over to the back when landed. A little wheel mounted underneath the tail will prevent the - aircraft from sustaining damage. Besides, when on the ground the aircraft will always stand in a tilted position, thus providing more lift at take off (see diagram page 13).

Another important element of our aircraft is the positioning of two supporting triplex beams for the wings. They can be seen in the diagram below. The triplex beams will be attached to the landing gear, to provide maximum support for our wings. The beams will measure 10 x 5 millimetres.

Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen

Tim van Tim

–

Tail and elevator Up so far there are still two vital airplane parts we haven‟t mentioned. They are the horizontal

JeT Productions Productions JeT and vertical stabilizer, better known as tail and elevator. They provide stability for our

– aircraft. In addition they are vital elements in controlling the plane. Just like the fuselage, elevator and tail will be constructed with balsa wood and Mylar foil. Strength is once again provided by triangular shaped balsa frames.

The tail‟s and elevator‟s size are determined by the wing‟s area. The ratio58 between elevator and wing is 4:1, whereas the ratio between tail and wing is 25:1. This implies the areas of

both the tail and elevator will be as follows:

Solar Challenger Challenger Solar

– Wing area: 1.6 × 0.2 = 0.32 m² Elevator area: 0.32 × 0.25 = 0.08 m² Tail area: 0.32 × 0.04 = 0.0128 m²

Elevator size: 60 centimetres wide and 13 centimetres in depth.

Tail size (triangular): 18 centimetres in depth and 15 centimetres high. Research Project Project Research

58http://www.auf.asn.au/groundschool/umodule6.html 27

The tail will be connected to the fuselage with a triplex beam. For extra structural integrity the beam will run all the way from tail to engine. The diagram below shows the entire aircraft, including the tail, wings and fuselage.

2010

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

As a final check we will calculate the balsa wooden frame‟s mass. Every rib will weigh half a – gram. Twenty ribs weigh 10 grams. Triplex beams, front cornice and rear cornice will weigh approximately 30 grams. In addition, the fuselage and landing gear weigh 20 grams, compared to 10 grams for the tail. Mylar will come in with just several grams. This adds up to a total of 70 grams.

JeT Productions Productions JeT Step 10

– As our design proposal has nearly been finished, we can now determine the costs of our project. Our budget is €400. The table below shows we should be well under that amount.

Element Cost Solar cells 1 € 127.20

Solar cells 2 € 18.00

Solar Challenger Challenger Solar

– Engine € 14.50 Propeller € 3.35 Remote control € 29.95 Receiver € 13.50 Servos € 22.50 Engine controller € 16.95 Battery € 25.00 Research Project Project Research Frame € 35.00 Wiring € 5.00 Unforeseen € 14.05 Total € 325.00 28

Another crucial issue is weight. Having a clear picture of which elements we will be using, it is time to add up the masses of all individual components. The results show we are still well on track to reach our target mass.

Element Mass (grams)

Engine controller 7.1

2010

- Battery 175.0 Servos 11.1 Receiver 14.0 Propeller 5.0 Engine 36.0 Wiring 10.0 Solar cells 1 76.8 Solar cells 2 9.6 Frame 70.0 Unforeseen 10.4 Total 425

= estimated

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

–

JeT Productions Productions JeT

–

Solar Challenger Challenger Solar

–

rch Project Project rch Resea

Construction proposal

After having done thorough research on the plane‟s design, it is time to start thinking about

construction itself. Just as we did in the design proposal, we set up a plan dealing with the

2010 order of construction:

- Step 11: Research on where to order construction materials. Step 12: Determining the order of construction.

The sub question being answered is:

17. In which order are you going to construct the plane?

Step 11

To start with, we will order the parts of the electrical system. We try to keep mailing costs as low as possible. Therefore we must order as many items as possible at the same supplier. We composed the following list of materials needed. All supplies will be ordered on the web.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Electronics All the electronics are to be ordered at rctechnics.eu. Their shop features a broad range of items, all good quality products according to people on internet forums. The following items will be ordered at rctechnics.eu:

 Receiver

 Engine regulator

JeT Productions Productions JeT

–  Servos and wiring  Engine  Remote control

Construction materials

Just as the electronics, the propeller and landing gear wheels will be ordered at rctechins.eu. Solar Challenger Challenger Solar

Unfortunately this shop doesn‟t sell other construction materials. In addition, finding a web – shop which sells and ships balsa wood is extremely difficult. Eventually we found a supplier in Groningen, who could offer us balsa wood and beams for the ailerons and rudder: netshop.nl/shop/krikkem. Glue is available at a local DIY shop and batteries will be bought at the local HEMA. In contrast, Mylar is not available in any shop in Holland. At last we found a shop in Great Britain selling Mylar: indoorflyer.co.uk. The shopping list for construction materials is as follows:

Research Project Project Research  Propeller (rctechnics.eu)  Landing gear wheels(rctechnics.eu)  Balsa (netshop.nl/shop/krikke) 30

 Beams for ailerons and rudder (netshop.nl/shop/krikke)  Glue (Praxis)  Mylar (indoorflyer.co.uk)  Batteries (HEMA)

Solar cells

2010

- As told in our design proposal, the solar cells will be ordered at lemosolar.de.

Step 12

Once we receive our supplies, we will put together the electrical system. After composing it, we will run several tests as described in the „Test proposal‟. We will collect data we need and make amendments to the system if desired. After such possible adjustments we will make a new estimation of the plane‟s mass and, if needed, adjust the wings‟ size or the plane‟s design.

With the electrical system being complete, it is time to focus on the plane‟s body. A crucial element here is design and construction of the wing. This is the next step in our process of construction. We will construct two separate wings out of balsa wood, place solar cells on the correct places and then wrap the wings with Mylar foil to secure their shape.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Once completed, we can test the lift the wings generate. The test is described in our „Test – proposal‟. If the wings don‟t produce the lift required, we will have to make adjustments.

With the wings and electrical system now completed, we will construct the rest of the aircraft, which consists of the elevator, tail and fuselage. Next, we will mount the electrical system in the plane‟s fuselage, glue the landing gear onto the plane and determine the centre of gravity.

The last step in construction is to fasten the wings to the fuselage. If needed, we will move JeT Productions Productions JeT

items inside the plane in order to get the centre of gravity in the right position. – If all goes well, we have built a complete plane by now and we can start testing. If required,

adjustments will be made during and after testing.

Solar Challenger Challenger Solar

– Research Project Project Research

Test proposal

To make an organized test proposal we have to follow the steps we‟ve set ourselves:

2010 Step 13: Determining what needs to be tested and in which order.

- Step 14: Set up plans on how to run tests, where and with which materials required.

Step 13 & 14

Throughout the project several tests need to be run. We will investigate the following data:

 Solar cells’ output and profit  Lift test  Drive test  Flight test

The solar cells‟ output and profit 18. Which effect does the position of the solar cells have on the efficiency of both the plane

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim and panels?

– 19. How much profit do the solar cells provide?

To answer the two sub questions concerning the solar cells‟ profit, we came up with the uctions uctions following test setting. After we ordered components such as solar cells and the engine, we will compose the electrical system. At this point we haven‟t started construction of the plane yet. First, we will fully charge the batteries, connect them to the engine and then let the engine

run at full throttle. We will record the time it takes for the batteries to run out. In order to

JeT Prod JeT

– minimize errors, we will redo the test three times.

In a second test we will add solar cells to our electrical system. We make sure the solar cells receive plenty of light and then we let the engine run at full throttle again. We will write down the time it takes for the batteries to run out and compare this to the previously clocked time. In this way we will be able to tell something about the profit of the solar cells.

Solar Challenger Challenger Solar A third test aims to determine the effect of Mylar foil on the solar cells‟ output. We will run – the second experiment again, but now, we will place Mylar foil over the solar cells. This will probably decrease their power supply. Through this experiment we will be able to say something about the influence of the Mylar foil.

Unfortunately the solar cells‟ output strongly depends on weather. If time is available we will do the second and third test several times in both cloudy and sunny conditions. Unfortunately 59

Research Project Project Research a photo meter to measure sunlight intensity is not available.

59 http://en.wikipedia.org/wiki/Photometer 32

Lift test Once construction of the wing has been completed, it is time to test lift. At this point we still have two separate wings. Before both parts are glued together, we will take one of the wings and attach it to a force meter. This composition will be mounted into a freely moveable frame.

The frame, composed of K‟nex parts, will be fit on a bicycle‟s basket.

2010

One of us will cycle at 30 kilometres per hour, the intended take-off speed. Speed will be - measured with an odometer on the bicycle itself. If calculations have been correct, the force meter should measure a difference of approximately 2.5 Newton. Of course we will take into account influences that could disturb our test, like wind, loss of surface area due to K‟nex frame, etc.

Drive test Eventually we reach a point where the aircraft is finished. We will have determined the centre of gravity and will have made sure the controls function properly. Before it is actually time to take off, we will perform several driving tests. We will position the airplane on a smooth surface, for example a gym floor. Then we will slowly increase throttle to let the aircraft „taxi‟.

Now it is time to make final adjustments. Drive tests might show deviation in driving

direction, lack of power or other defects. Once those problems have been solved, we will do a Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

final driving test. We will keep increasing throttle until the tail will get airborne. Namely, the – tail coming off the ground is a first indication of taking off. This is because the mass of the aircraft is no longer supported by the wheels, but by the wings. The centre of gravity is slightly behind the wheels, thus making the aircraft falling over to the back. When the mass of the aircraft is no longer supported by the wheels, but by the wings, the centre of gravity is at ⅓ of the wing, thus balancing the aircraft. This process is shown by the following pictures60/61.

JeT Productions Productions JeT Taxiing Take-off –

Flift Fn

Solar Challenger Challenger Solar

– Fn Fg Fg

Research Project Project Research

60http://media.photobucket.com/image/ph-pba/AirKas1/PH-PBA_GRQ_12-07-09kj.jpg 61http://farm4.static.flickr.com/3135/2768004875_d48345f8bc_o.jpg 33

Flight test At this point in our research project we know whether or not our wings produce enough lift and the engine and propeller generate enough power to propel the plane. Still, there is one big challenge left: flying.

According to people on internet forums, flying a model aircraft is a very difficult discipline. It 2010

requires extensive expertise and experience with flying. As we don‟t want to crash our aircraft - during its maiden flight, we will bring in an experienced person from a flying club. He will fly our aircraft at first. With his help we will eventually learn how to control the plane.

The last problem that needs to be solved is finding a suitable runway. As our plane is probably going to be fragile, it is unlikely we can take off from any parking lot. Currently we plan to use an artificial turf field as a runway.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

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Media attention

Website

2010 We intended to launch a website on the internet. Here people would be able to follow our

- progress and see pictures of the airplane. However, we didn‟t want to spend any money on an expensive internet domain, so once the free testing period had expired, unfortunately the amp amp website was cancelled.

Sponsors

Since this project is quite costly, we had to take a look at possible sponsors. Being environmentally friendly is a major aspect in our project. We searched for companies that present themselves as environmentally friendly. Companies we ended up looking at were Triodos and ASN bank. However, Triodos only sponsors five major projects on a yearly basis and the ASN bank rejected our proposal.

Another effort we made was with the company that supplied us with solar cells. We asked them if they were willing to provide us with solar cells or give us discount on solar cells in

return for some promotion. Luckily, they gave discount on the solar cells, but mailing costs

Tim van Leeuwen & Jesper Haverk Jesper & Leeuwen van Tim

– proved to cancel out our „profit‟.

Logo

Just like any plane, ours will feature a company logo on its tail. We chose to create the

following logos:

JeT Productions Productions JeT

– Aircraft Construction Company Airline

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„JET‟ is not only a synonym for airplane, it also represents our initials: J(esper) E(n) T(im). The globe shown on the logo represents JET‟s internationally orientated roots.

Research Project Project Research

International aspect

As part of our internationally orientated education, our research project should include a piece in which we discuss how our research project is internationally relevant. We think our

research project is internationally relevant, because it is based on a world-wide hot topic.

2010

Energy demands

The issue of meeting the worldwide energy demands is currently high on any politician‟s shortlist. Right now we are able to fulfil our needs, but knowing we consume 85 million barrels of oil a day62, it is clear we will run out of our energy supplies one day. That day is coming closer by the minute. Engineers worldwide are searching for alternatives to meet our demands. Their focus mainly lies on the renewable energy sources, such as wind and solar power63.

Their reasoning to focus on these sources of energy is simple: such sources won‟t run out for billions of years and are capable of meeting the world‟s energy demand. Covering 10% of the Sahara desert area with solar cells for example would be sufficient to supply energy to the whole world64 and wind turbines in shallow coastal waters could account for 20% of energy

demands in the USA65. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Solar power thus is an interesting option. Recent years have seen solar power production climb with a staggering 40% per year66, but when looking at statistics showing67 shares in total energy supply, we will notice that solar power production does not even account for one percent. We should realise that there still is a long way to go.

Our solar powered plane could let people come to realize just what the possibilities of JeT Productions Productions JeT

renewable energy sources are, especially solar cells. If we can make a plane fly using solar – power, other possibilities are nearly endless! People might consider placing solar panels on their roof or on their carport to supply part of the power for their houses. There are a lot of advantages to solar panels: four square metres of solar panels supply 10% of the annual energy consumption of an average household 68. In addition, solar panels could recover69 their costs in about ten years and solar panels can increase the value of your house, since a home becomes friendlier to the environment and has considerably lower energy costs.

Solar Challenger Challenger Solar

– Not only is solar power being looked at as an option to supply energy we use in our households, solar power has also come into picture for powering vehicles. This mostly shows through all sorts of contests being held for technical institutions.

62http://peakoil.blogspot.com/2006/03/peak-oil-is-closing-in.html 63 http://en.wikipedia.org/wiki/Renewable_energy 64http://en.wikipedia.org/wiki/Desert#Solar_energy_resources Research Project Project Research 65http://www.motherearthnews.com/Renewable -Energy/Offshore-Wind-Power.aspx 66http://en.wikipedia.org/wiki/Solar_power#Development.2C_deployment_and_economics 67http://www.iea.org/textbase/nppdf/free/2008/key_stats_2008.pdf 68http://www.milieucentraal.nl/pagina?onderwerp=Zonnepanelen 69http://www.olino.org/articles/2006/07/31/de-terugverdientijd-van-zonnepanelen 36

Solar cars

The most serious option being looked at is solar energy to power cars. With hybrid and plug- in electric cars being introduced to the market, solar power becomes an interesting option to

supply energy. A famous contest between solar powered cars is the World Solar Challenge, a

race across the Australian desert being held every two years70. This race catches worldwide 2010

attention. Technology used in cars involved can be replicated in other cars. -

In recent years the race has become well-known in The Netherlands because of success of the Technical University of Delft with their NUNA71 solar powered car. The TU Delft has won the World Solar Challenge four times in a row72, each time with a modified and upgraded car. When the team entered competition with NUNA 1, they won the race with an average speed of 92 kilometres per hour73. Two editions later NUNA 374 won the World Solar Challenge with an average speed of 103 kilometres an hour75. In fourth edition NUNA 4 won with an average speed of 93 kilometres an hour, even though this car had only 6 m2 of solar panels,

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim 2 76

instead of 9 m used in previous editions . – Cars competing in the World Solar Challenge distinguish77 themselves from normal cars because of their extremely low drag and low mass. The cars are very aerodynamic (up to 6 times more aerodynamic than cars driven today) and have a very low rolling resistance, thanks to thin and well lubricated wheels. Moreover, the cars are as light as a feather compared to normal cars. Namely, a regular car usually weighs78 around 1000 kilograms, 79

JeT Productions Productions JeT whereas the newest version of the NUNA (NUNA 5) weighs just 160 kilograms. Solar

– panels used on these cars are of very high quality and have an extremely high output compared to normal solar cells. Although the NUNA 5 doesn‟t have the luxurious items we

might want in our cars, such as a radio or air conditioning, we can still learn a lot on how to lenger lenger make our cars lighter and how to lower their drag. Besides, we can learn how to incorporate solar cells in our cars. All these aspects could make present day cars more fuel efficient.

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70http://www.wsc.org.au/ 71http://www.tudelft.nl/live/pagina.jsp?id=a43ae927-9cc7-4716-ab01-c4795f6c11a3&lang=nl 72http://www.globalgreenchallenge.com.au/wsc-evolution/previous-winners 73 http://en.wikipedia.org/wiki/Nuna_1 74http://c0378172.cdn.cloudfiles.rackspacecloud.com/12227_15070993902.jpg Research Project Project Research 75 http://en.wikipedia.org/wiki/Nuna_3 76 http://en.wikipedia.org/wiki/Nuna_4 77http://nl.wikipedia.org/wiki/Categorie:Zonnewagen 78http://www.cbs.nl/nl-NL/menu/themas/verkeer-vervoer/publicaties/artikelen/archief/1999/1999-0361-wm.htm 79http://www.nuonsolarteam.nl/2009/06/nuna5-onthuld/ 37

Solar boats

Solar power has become an interesting option for small boats too, mainly due to the Frisian Solar Challenge held in 2006 and 2008 80. The organizers of this event wanted to create a

counterpart of the World Solar Challenge and have done so by making solar powered boats

race on the very same water used for the famous „Eleven cities‟ speed skating race81. 2010

- Since small boats need a relatively small engine to power them (a five horsepower engine is sufficient to power a small vessel82) an electric power source is a serious option to be considered. A solar panel might just be the ideal way to power the engine since most boats have a large area to place the solar cells on and spend all their time outdoor in sunlight.

The hydrodynamics used in the Frisian Solar Challenge can be applied to commercial yachts as well, no matter what size they are. A streamlined hull is a key element for a vessel to achieve low fuel consumption and streamlining is just what the Frisian Solar Challenge is all about. Powering freighters using solar power is no realistic option since big carriers require tremendous power83. Giant kites would be more suitable to propel these ships84. Still, we could reduce global carbon dioxide emissions drastically by making vessels more

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim 85

efficient, since naval traffic accounts for five percent of – worldwide CO2 emissions, nearly twice as much as aviation.

Solar planes

Last of all, attempts have been made in the last decades to power aeroplanes using solar cells.

JeT Productions Productions JeT One of the biggest organisations researching the feasibility of a solar powered plane is NASA

– with their ERAST program86. This program resulted in four prototype electrical planes (NASA Pathfinder87, NASA Pathfinder Plus, Centurion88 and Helios89) which all four flew using solar cells. The planes got increasingly bigger as the project went on and several records, such as the altitude and endurance records 90, were broken. These planes, however, were unmanned planes, steered through radio controls. Although Helios could carry up to 230

kilograms of mass, there was no place for a pilot.

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80http://www.frisiansolarchallenge.nl/ 81http://www.frisiansolarchallenge.nl/route-en-reglementen/route 82http://www.s malloutboards.com/choose.htm 83http://www.howstuffworks.com/floating-city1.htm 84http://iloapp.seamanshiptutor.com/blog/blog?ShowFile&image=1201089418.jpeg 85http://www.guardian.co.uk/environment/2007/mar/03/travelsenvironmentalimpact.transportintheuk Research Project Project Research 86http://www.nasa.gov/centers/dryden/history/pastprojects/Erast/index.html 87http://en.wikipedia.org/wiki/NASA_Pathfinder 88http://www.dfrc.nasa.gov/gallery/movie/Centurion/HTML/EM-0003-01.html 89http://www.pvresources.com/en/helios.php 90http://askmagazine.nasa.gov/pdf/pdf11/48741main_FIG1.pdf 38

Planes that did succeed in carrying a person with it were Sunseeker91 and Solar Challenger92. In 1981 Solar Challenger crossed the Channel93, whereas in December 2008 Sunseeker was the first solar powered plane to cross the Alps. In 2010

the successor of Sunseeker, Sunseeker II94, will make a tour across Europe to demonstrate the possibilities of the plane.

2010 Solar Challenger

- In June 2009 a new solar powered plane was revealed95 to the world: Solar Impulse96. This plane has a wingspan of 64 metres (larger than most commercial aircraft97), can carry one person and weighs just 1600 kilograms. If all tests go according to plan, the successor of Solar Impulse will make a flight around the world in 2011. The designers reckon this will take approximately 25 days, since the plane flies at just 90 kilometres an hour.

The examples above illustrate that it is still impossible for mankind to transport hundreds of people in a plane over large distances using solar energy. One of NASA‟s aircraft could carry three persons, but the ride wouldn‟t be very comfortable due to the plane‟s shape. Also speed

is an issue: whereas current planes have a cruising speed of 900 kilometres per hour, solar Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

powered planes travel at approximately 80 kilometres per hour. At this speed a trip from – London to Sydney would take about 216 hours, or 9 days! To keep aviation the way it is today, we have to use fossil fuels, just because the amount of energy they deliver is unmatched.

Investigation aircraft

JeT Productions Productions JeT

– Although solar powered airplanes are not useful for passenger transport at this moment, it might offer new possibilities to other brands of aviation. Solar planes have features common planes don‟t have. The most useful ability is that solar powered planes could stay airborne forever, for they, rather than carrying their fuel with them, gather their energy while flying.

This ability provides lots of opportunities for solar powered planes. NASA already fitted their

Pathfinder plane with measuring devices to observe coral reefs around Hawaii, forest Solar Challenger Challenger Solar

– regrowth after damage by a hurricane and sediment concentrations in coastal waters . As the examples illustrate, solar powered planes could be used for research because of their long flight time, low flying speed and ability to fly at nearly any altitude.

91http://solar-flight.com/sunseeker/index.html 92http://www.donaldmonroe.com/gallery/albums/solar-challenger/sc126_01.jpg 93http://www.donaldmonroe.com/gallery/solar-challenger/ Research Project Project Research 94http://solar-flight.com/sunseekerII/index.html 95http://www.solarimpulse.com/sitv/pictures.php?lang=en&group=media 96http://www.kennislink.nl/publicaties/solar-impule-vliegt-op-zonlicht 97http://en.wikipedia.org/wiki/File:Giant_planes_comparison.svg 98http://www.nasa.gov/centers/dryden/news/FactSheets/FS-034-DFRC.html 39

Commercial use of solar planes

Solar powered planes have been tested for commercial use as well. In 2002, NASA‟s Pathfinder Plus was fitted with communication relay equipment and was sent to fly at an

altitude of 19 kilometres. From there it was able to send television signals back to earth,

making the plane equivalent to a radio tower with a height of 19 kilometres 99. 2010

Military purposes

World-wide military organizations could also be interested in solar powered aircraft. A solar powered plane satisfies many of the needs of military organizations. It doesn‟t use any fuel, is silent because of the electric engines, can fly at high altitudes (which makes it difficult to detect on radar), can fly without refuelling, is relatively cheap compared to modern day planes and can fly unmanned so no human lives are risked. All these properties will make a solar powered plane desirable. Also, military organizations can mount a camera or measuring n & Jesper Haverkamp Haverkamp Jesper n & devices on the plane to use it for purposes like observation, an aspect of warfare which has become more and more important the last decades.

Model aviation

Tim van Leeuwe van Tim

Our solar powered plane could also inspire a whole new branch to be formed in the mode l – flight industry. Right now model flight industry is mainly based on aircraft with an electric engine or a combustion engine and few planes with an electric engine charge their batteries using solar cells. After having shown flying with solar cells with a relatively small budget is possible, our plane could inspire many people around the world to build an aircraft of their own. When we posted questions on a forum asking whether other people, whom mostly had extensive experience with model aircraft, thought our project was feasible, we got numerous

JeT Productions Productions JeT reactions of people asking us to let them know if and how we had succeeded, so they could try

– building a plane of their own.

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99 http://en.wikipedia.org/wiki/ NASA_Pathfinder#Atmospheric_satellite_tests 40

Construction

Electrical system

When all electrical components had been received, we made an appointment at Jesper‟s place

2010 to construct the electrical circuit and run some tests. These tests included operating the engine

- at full throttle to see how long the batteries would last when fully charged and some weighing of the components to see if their masses matched those of specifications. Below you will find an account of our findings during construction of the electrical system.

Electrical components Constructing the electrical system wasn‟t much of a problem, since all components included a clear manual. The construction process was straight fo rward as well. All components simply had to be linked together according to scheme. Then we ran the first test. Results of the endurance test can be found in the „testing‟ part of this document.

After having constructed the electrical

system and having done the first engine test,

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– we had some time left. We decided to get ourselves a scale and weigh the components we already had. We wanted to achieve two things: in first place we wanted to check the mass we were given by the manufacturers of components we had received. In second place we wanted to check if our assumptions of unknown masses of components had been right. Overall the test turned out pretty dissatisfactory, with most components proving to be heavier than we thought they would be. Below you find a table showing components‟ masses.

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– Element First plan (grams) Actual mass (grams) New plan (grams) Engine controller 7.1 8 8 Battery 175.0 220 50 Servos 11.1 20 20 Receiver 14.0 11 11 Propeller 5.0 11 11

Solar Challenger Challenger Solar Engine 36.0 43 43

– Wiring 10.0 60 70 Solar cells 1 76.8 76.8 120 Solar cells 2 9.6 9.6 0 Frame 70.0 150 165 Unforeseen 10.4 10.4 2 Total 425.0 619.8 500

Research Project Project Research = estimated

In the second column you find data that was shown in the design proposal. It displays masses we started with during this project. The third column shows the actual masses as measured during testing. It appeared all components we measured turned out to be heavier, with batteries, frame and wiring being significantly heavier than assumed. With the total mass

being over 600 grams now, we were forced to think of a new plan.

2010

This new plan was all about saving weight, since 600 grams was way above our maximum - take-off weight. The easiest way to save a lot of weight was changing power source. In the beginning of the project we decided to go for NiMH-batteries, because we thought they were more reliable than LiPo-batteries. Because of disappointing results during mass testing we were forced to go for a LiPo-battery after all.

The decision to use a LiPo-battery brings three drawbacks however. First of all capacity of the LiPo-battery is smaller, so we won‟t be able to run the engine for as long as we could using NiMH-batteries. A second drawback concerns the reliability100 of the power source: LiPo- batteries are prone to exploding101. We will have to be careful. A third drawback is the need for alternative charging equipment102. LiPo batteries can‟t be charged using regular chargers. They require equipment dividing power equally over the battery‟s numerous segments.

Still, we decided to continue our testing with the NiMH-batteries. We would build the entire plane and then replace the battery. Once we changed the power source into a LiPo-battery, we

would attempt to make the plane roll and eventually fly. In this way we keep risks of Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

something going wrong with the LiPo battery as low as possible. – We wanted a battery as light as possible, yet powerful enough to supply sufficient energy for our airplane. In the end we found the following 103:

Conrad energy LiPo Pack 7,4V/ 800 mAh/ 10C

JeT Productions Productions JeT Price: €19.95

– Element Value Mass 38 grams Dimensions 50 × 30 ×10 mm Capacity 800 mAh Voltage 7.4V

Solar Challenger Challenger Solar Plug Mini Tamiya

– As shown, voltage of the LiPo-battery is not equal to the voltage of NiMH-batteries. ject ject Therefore we would have to alter the number of solar cells in the wings in order to get an equal voltage from both the solar cells and the battery. If we don‟t, either the battery or solar cells will blow up.

Research Pro Research

100http://www.norfolkhelicopterclub.com/index.php?option=com_content&view=article&id=59&Itemid=66 101http://www.utahflyers.org/index.php?option=com_content&task=view&id=22&Itemid=28 102 http://www.seven-segments.com/index.php?action=pageshow&id=67&idcat=44 103http://www.conrad.nl/goto.php?artikel=229994 42

Number of solar cells = 7.5 : 0.5 = 15

In total the solar cells will provide us with 7.5 volts, 0.1 volt more than the LiPo-battery. This difference will be cancelled out by the Schottky diode, which consumes approximately 0.1-

0.2 volts. After finding out we would now need fifteen solar cells, we had to choose which

type of cells we would use. We will now use big solar cells only, measuring 10 cm by 10 cm. 2010

Fifteen such solar cells would fit in our wings exactly. Still, in order to keep the centre of - gravity in the correct position we would have to put seven solar cells in each wing and one solar cell in the middle of the wings.

Wing construction

One week after testing the electrical system we met again to start construction of the wings. First, we decided to manufacture various ribs of the wing, which had to be cut out of a board of balsa wood. Cutting demanded much Balsa wood precision and carefulness, since balsa wood is very vulnerable and thus can be broken easily. Because of this the first part of the afternoon was spent on considering options to cut ribs, e.g. cutting it with scissors,

sawing it with a fretsaw or cutting it with a Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Stanley-knife. After some testing on leftover – pieces of wood, we went for the Stanley- knife, for it proved to be easiest to cut corners. In addition it turned out to be very precise.

Since we couldn‟t cut sections randomly, we needed some kind of template. We printed a

JeT Productions Productions JeT model of the wing (page 12) and used it as a template. In the end we were able to construct

– twenty solid ribs. We then marked spots where supporting beams would have to be placed.

Since we now finished the ribs and already had the front and rear cornice available, we tried to visualise the wing. When we laid down all the components of the wing we noticed straight away that all aligned perfectly. This was greatly satisfying.

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– Research Project Project Research

That very afternoon we also had some discussion on which rear cornice to use. Originally we planned to use a cornice measuring 10 by 15 millimetres. Now, we also had a cornice available measuring 5 by 3 millimetres. Both of us were worried that when using the smaller one, contact area would be too small for gluing ribs and cornice together. Eventually we used

the smaller one, but, to be able to use this cornice, we would have to make incisions in the

wood in which to glue the ribs. This increased the contact area for the glue. 2010

- After cutting ribs, it was time to make incisions in the correct positions.

We started with holes through which we would run wiring for the solar cells and servo engine (1). This didn‟t prove to be too difficult since the holes didn‟t have to be at an exact position and could vary in size. We did decide to make only one big rectangular hole instead of the three holes shown on the picture. Main reason was that cutting such small holes with a Stanley knife is pretty difficult, while cutting straight went so smoothly that we could easily

manufacture a rectangular hole. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Next, we set out to construct the incisions through which the main supporting beams should run (2). Making these incisions proved to be way more difficult since more accuracy was required. All the incisions had to line up perfectly in order to make the wing straight and uncurled.

We already marked places on each rib where incisions would have to be made (the red dots).

JeT Productions Productions JeT We did so by lining up all ribs, locking them in a clamp and drawing a perpendicular line

– across the ribs using a try square. Since not all twenty ribs fitted properly in the clamp, we split the ribs in two groups, one group of nine ribs for every wing. The two ribs left were put away to be used as spare parts or test parts later.

After cutting holes, we tried to fit the ribs over the supportive beams. The holes proved to be too narrow. Some filing made sure the holes became a bit wider, allowing the support beams

to fit neatly.

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– When fitting the beams, we discovered that the incisions were not deep enough. To compensate, we made small incisions in the supporting beams. This plan gave the advantage that the ribs could no longer slide over the supporting beams and we had a larger surface area to glue the parts together.

Next we had to make the hole for the piston which would connect the aileron to the servo

Research Project Project Research engine (3). By now we had already ordered the beam, which was made out of carbon, and we discovered its amazing low mass. It weighed so little, that it would be better to place the servo engine at the beginning of the wing, eliminating the need for relatively heavy wiring.

Unfortunately the new plan demanded a hole in every rib, so again we fitted the ribs in the clamp and we drilled a hole at the right place. Again we faced a minor problem: some of the ribs fractured because the new hole required to be drilled very close to the edge of the rib. Luckily cracks were only minor, so we could fix the problem with a piece of tape. As a

precaution measure, we used some tape to reinforce the unbroken ribs.

2010

- Ribs, including holes

When we put the beam through the newly drilled holes we discovered that there was too much friction, because the holes were too small. When neglected, this would possibly result in the

servo engine not being able to turn the aileron. Again we used a file to widen the holes a bit.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– The only thing left to do now was think about the ribs between the ailerons. Initially we planned to cut off a part of them, but still leave the hole for the beam in place. After we saw the beam was still strong enough without the extra support, we decided to cut the ribs at the place the closing bar would be placed as shown below. This had the advantage that the

ailerons could be constructed out of a single piece of wood.

JeT Productions Productions JeT

– Original plan New plan

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Research Project Project Research With all ribs finished, we could start gluing the ribs to the supporting beams. This was done pretty quickly and we soon could start attaching the front cornice and rear cornice as well.

The front cornice was glued fairly easy but the rear cornice proved to be time-consuming. It turned out the ribs didn‟t align perfectly at the back, so we had to make small incisions in the rear cornice. This gave us the additional advantage that contact surface between the ribs and

the rear cornice drastically increased. After we inserted the beams for the ailerons, fabricated

closing beams, and measured the ailerons, we had ourselves complete frames for the wings.

2010

Landing gear

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– With wings completed now, we could think of how we would let the plane stand on its own. The metal frame accompanying the supplied wheels proved to be far too heavy, so we had to come up with another solution. By now we had also discovered that when only supported in the middle, the wings would bend down. We decided to build two small gears underneath the wings. They would be installed at one third of each wing. In this way the plane would be supported by wheels during taxiing and supported by its wings during flight. In both situations

forces on the plane are equal and located at the same spot.

JeT Productions Productions JeT

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Fg Fg Fg

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F F g Fg g

Research Project Project Research

Wing construction (2)

Still, we had two separate wings. We somehow had to connect the left wing to the right wing, whilst maintaining structural integrity. We decided to cut off half of both supporting beams in

order to increase surface area. We then glued together both parts and inserted pins into the

beams to create both a glued and mechanical joint. This process is illustrated in the diagram 2010

below. -

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

–

Tail construction

JeT Productions Productions JeT

– Construction on the tail started out with a triangular wooden beam which connects the tail section to the wings. We then manufactured the horizontal and vertical tail section by using a few sticks of balsa wood as a frame. A small rear wheel had to be

attached to this beam as well. Construction

Solar Challenger Challenger Solar

– was easy and fast.

Sequentially, it took us a long time to figure out how we would have to control the elevator. We had to think of a way to convert the circular motion of the servo search Project Project search engine into the up and down motion of the elevator. Obviously we couldn‟t use the same

Re system as we did in the wings. Not only there was no space available to mount a servo engine near the tail, but in addition, mounting the servo engine at the rear would make locating the centre of gravity even more difficult.

Eventually we found out that we would need a so-called push-rod to control the elevator104. A push-rod is a device that links the elevator with the servo engine. It took us a while to figure out exactly how the push-rod functioned. When we had put it together, we came up with an alternative idea, which might save some weight. We could replace the push-rod with an

ordinary piece of iron wire. In the end this turned out not to save any weight at all.

2010

When testing the beam connecting the tail and - Work in progress wings on strength, we noticed the beam gave way more than we liked. We decided to glue another triangular beam on top of the one we already used. With this final adjustment the tail had been completed.

Fuselage construction

Our plane‟s fuselage is where we would put most of our electronics. Earlier on we had decided to construct a balsa wooden frame with a sheet of wood at the bottom to put all the electronics on. As we now had expertise on construction using balsa

wood and balsa glue, we knew that just a few Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

beams would be enough to carry the electronics. – First however, we had to think about where we would want to put all our equipment on the wooden sheet. It involved some puzzling, because we changed batteries and several wires proved to be quite short. Secondly, we had to think about how the fuselage‟s interior would affect the centre of gravity of our plane. After all, our initial plan (see page 28) on positioning electronics had been changed drastically. We determined placing of all equipment by balancing the plane on one finger.

JeT Productions Productions JeT

– Balancing the plane

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Research Project Project Research

104http://www.airfieldmodels.com/information_source/model_aircraft_hardware/pushrods_and_pull_pull_control s.htm 48

When the engine runs at full throttle, it will produce quite some thrust, which has to be transferred to the plane. To accomplish a smooth transfer, we decided to mount the engine to the plane at two points. One attachment will be connecting the engine to the main beam running from wings to tail. The other attachment will be between the engine and the sheet of

balsa wood at the bottom of the fuselage.

2010

We do not want to take any risk with the LiPo battery. Since the near engine regulator can - become very hot105, we chose to mount it on the bottom of the wooden sheet. Here it will not be able to contact the LiPo-battery. In addition, it would be cooled by the airflow generated by the propeller.

To fix the servo engine regulating the elevator to the fuselage, we had to cut a hole measuring the exact size of the servo engine in the wooden sheet of the fuselage. First we fixed the servo engine upside down to reduce drag, but later Servo in the wing we chose to mount it straight, since it would then be easier to fit the push-rod.

With this servo engine in place, we looked at how to mount the other two servo engines into the wings. Unfortunately screws available were too short. Therefore we filed a hole in

the first rib of the wing, just large enough to Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

squeeze through the heads of the servo – engines. Finally we fixed the servo engines into position using glue and new screws.

Mylar foil

JeT Productions Productions JeT The plane‟s frame had been completed now. Next steps would consist of putting solar cells in

– place and wrapping the wings and tail with Mylar foil. Since Mylar foil was delivered much earlier than the solar cells, we decided to cover the tail with Mylar foil first. This section of the aircraft is relatively minor. It was perfect for us to get used to working with Mylar.

We were informed one should apply glue to the ribs and then wrap Mylar around the frame106. So we did. By heating the Mylar foil, it was supposed to shrink and wrap itself tight around

the frame. First, we attempted to heat the foil using a hairdryer, but this turned out to not be

Solar Challenger Challenger Solar

– hot enough. Though we had read one should use an iron to heat the Mylar foil, we tried the hairdryer first, since we didn‟t want to damage the Mylar foil. Ultimately we went for the iron, but we decided to keep some space between the iron and the foil. Even this didn‟t work out. We finally discovered what really to do. Jesper touched the foil with the iron. Instantly the foil shrank. We put the iron on the lowest temperature and ironed the foil with it. Using

this technique, we managed to cover the vertical and horizontal tail section with Mylar foil.

earch Project Project earch Res

105 http://www.rctechnics.eu/download/MAN-HM-FLY.pdf 106 http://www.modelbouwforum.nl/forums/verlijming-constructie/44864-mylar-folie-hoe-verwerk-je-dat.html 49

Ironing Mylar Before (right) and after ironing (left)

2010

After this, we could mount the rudder itself. We glued two small wooden segments onto the aft of the elevator to support the rudder‟s axle. We did have to solve one small problem, since the tail had deformed slightly under the force of the Mylar foil and was now slightly bent.

With the rudder positioned, we could install the push-rod to attach the servo engine to the elevator rudder. At the aft we had some trouble mounting the push-rod to the rudder. Moreover, cutting the push-rod at the right length was extremely difficult. This proved to be a

time-consuming job. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Final result

JeT Productions Productions JeT

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Link between elevator and push-rod

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– Solar cells

Up so far we seemed to be able to keep to our tight planning. Then we hit a major delay concerning the solar cells. Due to holidays in Germany, they were delivered three weeks late. Once delivered, we immediately wanted to join all solar cells together. We went about by soldering them using the soldering strips. This wasn‟t done however before we tested a solar cell‟s output by using a multimeter. This test really satisfied us, since the solar cell proved to

Research Project Project Research provide us with an even higher voltage than expected (0.6 volts instead of 0.5 volts). Although the electric current may still vary, this reading could be considered a good sign. Another positive finding was that the solar cells turned out to be as heavy as specifications told us. We were yet another step closer to achieving our goals. 50

Whilst trying to solder the solar cells, we stumbled upon some problems. It appeared the solar cells couldn‟t be soldered. At first we assumed our old soldering equipment was to blame. Then, after using state of the art soldering equipment offered by Computer Services Alphen, we were still puzzled by unconnected solar cells. It turned out ordinary solder tin was not suitable for soldering solar cells. We would need soldering tin containing silver. We had

nearly bought this expensive substance, when an expert on soldering noted that the strips on 2010

the solar cells had probably been chromed, which implied that they couldn‟t be soldered at all. -

Not only did these events consume considerable amounts of time, also this setback meant we would have to resort to more primitive methods when connecting the solar cells. We figured out that the easiest way to link all solar cells would be to place wires between the cells and tape the wires to the cells using duct tape. Before we could do this however, we had to glue the solar cells to the two supporting beams. Otherwise they would come off when sticking tape on them. Drilling new holes The wires demanded new holes in the ribs, which we drilled between the front cornice and the first supporting beam. Wiring all the cells demanded great care since the cells proved to be extremely fragile.

Another setback occurred when we discovered our

wiring was so stiff, it would rip itself off the solar cells. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Luckily we still had servo extension cables left, as we – had replaced wiring by carbon beams. Those cables were much more flexible, thus perfectly suiting our demands. The new wiring

When we tested all cells after they were connected, we found out the circuit wasn‟t complete. One cell had

JeT Productions Productions JeT cracked and thus disconnected the circuit. We solved

– this by taking the tape and the wire off the cell and attaching the wire to the solar cell again behind the crack. When all solar cells were tested outside, we found out that the fifteen solar cells produced eight volts, 0.5V more than we expected.

Last thing we had to do concerning the electric circuit

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– was to include the Schottky diode in the circuit. Figuring out which way to mount the diode took some time, since All cells in place our multimeter didn‟t function properly. After soldering the diode into our circuit, the last thing we had to do was to wrap the diode in duct tape, so our circuit wouldn‟t shortcut when the diode touched one of the solar cells.

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5151

Mylar foil (2)

With all solar cells and the diode in place, we could finish the wings by wrapping them with Mylar foil. Because of the experiences we had while applying Mylar to the tail section, this

was done quickly. However, we couldn‟t apply Mylar foil to the wings in one go. First we had

to cover the wing sections at which the ailerons are located, because we could only mount the 2010

aileron itself after these sections had been covered. -

We had to choose whether we would literally wrap the Mylar foil around the wings or apply two big strips of Mylar foil, one for the top and one for the bottom half. Eventually we decided to wrap the wings at the ailerons sections and to cover the rest of the wings in two parts. After we had applied the foil, we heated it with the iron to let it shrink. Something concerning we noticed, was that the shape of the wing altered when we ironed the segments in front of the ailerons. Because of the shrinking foil, wrapping

van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van around the aileron‟s closing beam too tight,

the wing had become a little dented. Luckily the ironing didn‟t affect the shape of the rest of Tim Tim

the wing. –

Finishing off

Finishing off consisted of mounting the wings to the fuselage to create one completed aircraft. The joint between fuselage and wings is the plane‟s most important joint, since it deals with

JeT Productions Productions JeT the greatest forces in the aircraft.

– Before we could mount the wings to the fuselage however, we had to determine the centre of gravity for both wings and tail. This was done by balancing the fuselage on our fingers. We knew the wings had to be placed on the fuselage at one third of their chord. Next we had to check whether in fact it was possible to mount the wing at this position. It turned out not to be possible to mount the wing in the desired

spot, since wiring for the servo engines

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– would be too short to reach the receiver. To fix this problem we positioned the receiver slightly to the back and moved the wings one centimetre forward to make sure the servo engines‟ wiring would reach the receiver. This action would not be harmful for the plane‟s centre of gravity, for we could still

Research Project Project Research alter the centre of gravity a little by positioning the wheels in the proper place.

Once position of the wings on the fuselage had been decided, we prepared to fix the wings in place. First we had to file minor segments out of the fuselage to make sure contact area between the wings and the fuselage would be as big as possible. Next, we turned the wings upside down and laid them on the table, so we could glue the fuselage onto the wings. We

applied a good amount of glue to both segments. Still, in order to provide extra strength to the

joint, we wrapped around duct tape as well. 2010

- Finally we went to mounting the wheels. We had already decided we would place the wheels at some distance from each other. In the end we placed the wheels under the fourth rib of each wing. Because the wings had been covered in Mylar foil by now, we would have to glue the wheels onto the foil and reinforce them by sticking pins into the wood. However, we still found the wheels to be unstable, so we mounted them with an extra supporting beam to prevent them from wobbling forwards and backwards. With these reinforcements in place, we lifted the airplane and put it on the ground, where it proudly stood on its own wheels, finally

finished. Most important, the plane‟s final mass was 487 grams!!

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

–

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Without reinforcements With reinforcements

–

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Our plane when suspended Research Project Project Research

Test results

Electrical system testing

2010 During a first test on the electrical system we investigated how long the batteries could keep

- the engine running at full throttle. This was the first part of a series of tests in which we wanted to investigate the difference between using and not using solar cells as an additional power source. During the second test, we would redo the first test but with solar cells included. Comparing both runs would give us an indication of the extra flying time the solar cells provided.

Our first test didn‟t run as smooth as we had hoped for, since the engine shut down abruptly several times. This was caused by not tightening all wiring very securely due to the test setting being temporally. Although we had mounted the engine securely to a wooden board, a wire disconnected once in a while. Now and then the engine shut off. After reconnecting the wiring we were able to continue testing. In the end we found out that using battery supplies only, the engine could run for about 15 minutes. At this point we still used NiMH-batteries, so when we would repeat the test with solar cells, we would have to use NiMH-batteries as well.

Unfortunately we hadn‟t received the solar cells yet, so we weren‟t able to run the test with

solar cells immediately. When we had finally received the solar cells, we found that we could

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– run the test in an alternative way as well. Earlier on, we had calculated that the engine would consume about 42 watts of power and that the solar cells would produce 21 watts of power under ideal circumstances. We had also found our solar cells‟ output was 8 volts under reasonably sunny conditions. The only thing left now was to determine the electric currents produced by the solar cells. This was done by completing the circuit with the solar cells by inserting a small light bulb between the wires of the solar cells and measuring the current that

went through it. The current turned out to be only 0.3 Amps in sunny autumn conditions. This

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– meant:

Power of solar cells = 8V × 0.3A = 2.4W

Using another calculation, we could now find out how much the solar cells would contribute to the total power supply. First we needed to measure the engine‟s power consumption. We

presume that during flight the engine will run at about 75%, which means that the current is Solar Challenger Challenger Solar

3.5 Amps, as shown in the table. – Engine speed Current (Amps) No load current 0.166 25% 0.513 50% 1.2 75% 3.5

Research Project Project Research 100% 6

Amount of energy supplied by solar cells = 0.3A :3.5A × 100% = 8.6%

This value is way under what we had estimated, since we had expected that under ideal circumstances solar cells would account for 50% of the total energy supply. Still, this setback didn‟t mean the end of our project. We can still charge batteries using the solar cells when the plane is on the ground and the solar cells can provide a little extra power during flight. With

the data we gathered, we can also calculate how long it will take to recharge the batteries

using solar energy under reasonably sunny circumstances: 2010

- Time to charge = capacity of battery : current of solar cells = 800 mAh : 300 mA = 2.67 hours = 2 hours and 40 minutes.

Charging the batteries for 2 hours and 40 minutes will fully load them and will allow us to fly for about a quarter of an hour. This is shown through the following calculation:

Flight time= capacity battery : energy consumption= 800 mAh : 3500mA= 0.228 hours = 14 minutes

This would mean that we could fly for about 14 minutes. When we take the solar cells into account, which we had found out to generate 300 mA, the calculation for the flying time is as follows:

Flying time= capacity battery : energy consumption= 800 mAh : (3500-300)mA= 0.25 hours

= 15 minutes Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Extent flying time = (0.25-0.228) : 0.228 × 100% = 9.6% – Our flight time has been prolonged with 1.2 minutes, which is an extension of 9.6%

Lift test

JeT Productions Productions JeT After testing the electrical system, it was time for a lift test. Initially we had thought of a

– construction to place one wing in a K‟nex frame and cycle with it. However, when we er er manufactured the wings, we decided to construct the wing segment as a whole. This meant we had already connected the wings when we installed the solar cells and applied the Mylar foil. Because of the fragility of the wings it was irresponsible to carry out the initial plan. We were forced to think of a new plan. We decided to finish the entire plane before performing the lift test.

Solar Challeng Solar

– Because we would now be testing with the complete and extremely fragile aircraft, we had to come up with a new setup for testing. Since we didn‟t want to test lift with a moving plane we needed to perform the test with the plane standing still. This implied we would have to blow air over the wings. We thought of several options, such as placing the airplane on a big wooden board which would be placed on scales and then positioning fans in front of the aircraft. When turning on the fans, we should see a decrease in weight indicated by the scales.

Research Project Project Research Another option was to hang a force meter from the ceiling and then hang the board under the force meter. The force meter should show a drop in reading when the fans would be turned on. In the end however, we did decide to use the force meter, but we made the plane hang underneath a wooden stick attached to the force meter instead (see picture on following page) 55

We lifted the plane with four belts wrapped around the wing and the wooden stick. This would make sure no unnecessary forces worked on the plane as it hovered. A last

thing to think of was to make sure the plane

wouldn‟t start swinging once the fans were 2010

turned on. We resolved this by fixing a small - piece of wire to a hole in the nose cone.

We still needed to arrange fa ns. We were told our school possessed two big fans. When testing the fans however, we discovered that maximal wind speed they could produce was six metres per second, or 21.6 kilometres an hour. This was short of our take off speed, which is over eight metres per second. Still, at these wind speeds we should already see some lift.

When setup was finally complete, we could start testing. First results were disappointing. At a fairly low wind speed (about two metres per second) the wings didn‟t seem to

provide any lift. This confirms calculations Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

on the Reynolds number (see page 15). – Then we increased wind speed (the fans turned out to accelerate the air to four metres per second at full power), which showed some results. In total the wings generated about 0.4 N of lift, nowhere near the 5 N of

JeT Productions Productions JeT lift we need. However, when we tilted the

– aircraft to 15° (maximal angle of attack) we found the wings already generated 1.2 N of lift.

These results were promising, since we found out that not every part of the wings had wind blowing over it. The fans didn‟t have a range large enough. In addition, the suspension cables covered several inches of wing. This implied we were only able to use 60% of the wing. Furthermore, we had assumed the plane‟s speed would be higher at take-off. In fact, we

calculated the speed of our plane would be twice as high as the wind speed produced by the

Solar Challenger Challenger Solar

– fans. This would mean that the lift of our wings would be four times as high, since the variable „speed‟ has a quadratic influence in the lift formula.

1.2 N × 4 = 4.8 N 4.8 : 60% × 100 = 8 N (at 15°) 0.4 N × 4 = 0.8 N 0.8 : 60% × 100 = 1.3 N (at 0°)

After this test we may conclude that our wings should be able to generate enough lift to let the

Research Project Project Research plane fly. Only, the angle of attack needs to be bigger than expected. This could be due to the shape of the wing not being perfectly according to plan, as explained on page 52.

Drive test

After the successful lift test, we went on to the next test: driving. The first part consisted of making sure all controls worked properly and making sure the plane would be remotely

controllable. The test was performed at school, where we showed the plane to our supervisor

and other interested people. However, we couldn‟t perform the actual driving test yet since we 2010

had discovered a problem. Because the wheels were placed some distance from each other, - the middle part of the airplane had slightly dropped, which meant there was very little clearance between the propeller and the ground. If we would drive at such a speed that the tail would lift off, we would risk the propeller hitting the ground, possible destroying the propeller and the aircraft itself.

It was clear an adjustment would have to be The supporting wheel made, which we did by installing a third wheel in the middle of the plane to support the fuselage. This adjustment meant that the propeller now had a clearance of about a centimetre. In addition, the third wheel was placed slightly to the front, so risk of the plane toppling over was largely eliminated. Putting the plane on the ground had shown

however that the wheels were prone to Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

movement to the left or right. This problem – was overcome by placing reinforcing beams to the wheels.

With all the problems concerning the landing gear now sorted out, we could perform the drive test. We had managed to find a fully flat floor, namely the floor of the school‟s auditorium. This room was large enough to drive the plane without the risk of crashing and was long

JeT Productions Productions JeT enough to drive in a straight line.

– During the test we stumbled on some more problems though. It turned out that our plane didn‟t drive in a straight line. The cause was quickly found. Friction in each wheel had to be exactly equal in order to let the plane drive in a straight line. This friction could be adjusted by tightening or loosening the nuts that held the wheels. It resulted in another problem though. Tightening the wheels too much would make friction too big to let the plane drive. Loosening

the nuts too much in order to decrease friction, resulted in the nuts coming off because of the

Solar Challenger Challenger Solar

– vibrations caused by the engine. Whenever the nuts came off, so did the wheels. This sent our plane spinning several times.

When we had found the right setup, it was time to perform the driving test. It was an absolute success. With the engine not even at full throttle, we could see the tail coming off the ground, a first indication of the plane taking off. Luckily, we were able to catch this moment on camera (see page 65).

Research Project Project Research

Flight test

With the first three tests now completed and all results suggesting that our plane is capable to fly, it was time to get airborne. Weather conditions made us postpone the maiden flight

several times. Eventually, on the 3rd of March 2010, flight JET001 was ready for take-off.

2010

After having made some adjustments on the wheels and doing some checks on controls, we - hit our last problem. One of the ailerons malfunctioned, probably due to a fractured joint between its axle and the servo engine. We had to keep this aileron in place through tape. Steering the aircraft could only be done now using the sole remaining aileron.

We gently opened throttle, made the airplane role and then opened throttle fully. Within seven metres the plane took to the skies, reaching an approximate altitude of six metres. Then the nose pitched up, the aircraft stalled and crashed just moments after take-off.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Initially we were greatly satisfied. Our hard work had paid off, our calculations, predictions – and constructions had been correct. Later we started wondering why the aircraft stalled so quickly. There were two possibilities: either the plane‟s centre of gravity had been shifted too much to the back or the plane was steered into a stall position.

It appeared we are to blame for the aircraft‟s crash. In order to not let

JeT Productions Productions JeT the propeller hit the athletics track

– used as a runway, we ordered the rudder to push the plane‟s nose up as much as could be. Being so excited by the plane actually taking off, we forgot to move the rudder into neutral. The plane steered itself

into stall position. Disaster was

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– inevitable.

Another noticeable fact was the aircraft taking off so quickly. It had not yet reached a speed anywhere near the 8.3 metres per second required. When looking at the formula for lift, this situation can easily be explained:

2 Research Project Project Research L = ½ × c ×  × A × v

Analysis showed the angle of attack was about twelve degrees at take-off, whereas in our calculations we had assumed it would be one degree. At twelve degrees the lift coefficient is 1.12, compared to 0.36 at one degree. In addition, when taking off, head wind speed was approximately two Beaufort, which corresponds to 1.7 metres per second. This results in:

Take-off speed = √(½-1 × 1.12-1 × 1.23-1 × 0.32-1× 4.88) – 1.7m/s = 3.0 m /s 2010

- Off course the Reynolds formula (page 15) predicted we cannot fly at speeds lower than 3.8 metres per second. It should be noted that the velocity mentioned above is the ground speed. The airspeed is the plane‟s groundspeed, plus its headwind. For our take-off situation this would be 4.7 metres per second. That would perfectly be possible according to the Reynolds formula.

The noticeable difference in angle of attack therefore explains why our plane took to the skies so quickly. Moreover, the angle of attack might have been even higher than the angle used in calculations. Namely, the angle of attack is said to be zero degrees in the following situation107

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– We assumed zero degrees would be the following situation.

JeT Productions Productions JeT

– This would imply the values used for the angle of attack in all our previous calculations were too low, which would confirm an ever lower take off speed.

In the end, the low flying speed and high angle of attack turned into a devastating stall and crash. Luckily damage was only minor and mostly concerned the landing gear. Most

important after all: our solar powered plane had taken off.

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Research Project Project Research

107http://marlongofast.tripod.com/zipped_aeronotes/clarky.htm 59

Conclusion

It is now time to draw conclusions. Extensive tests and respective calculations showed our

model aircraft is capable of flying, even partly solar powered. Tests also showed the wings are

2010 capable of producing the desired amount of lift. Furthermore, observations showed the engine

- is capable of propelling the aircraft to take-off speed. Most satisfying of course was the moment when the plane truly took off.

One conclusion we can draw is that purely solar powered flight is impossible. In theory the maximum power our solar cells can produce is 21 watts, nowhere near the 40 watts required. Unfortunately our solar cells produced far less than the 21 watts they were meant to produce. Main reason for this is Dutch climate. Moreover, difficulties in connecting the solar cells contributed to power loss as well. Therefore flying on solar cells only is not possible. At the most, solar cells will lengthen flight with 10%. When used as a charger for the battery, it will take the cells two hours and forty minutes to fully load the battery. Maybe in future solar cells‟ efficiency will be higher. For now, technology is not advanced enough.

A second conclusion concerns the weight aspect. With the solar cells already having a mass of 120 grams, it was extremely difficult to not exceed our target mass of 500 grams. Current solar cells have a power to weight ratio far too low. In order to fit the number of solar cells

required, we were forced to cut weight on many other elements. In the end, we managed to

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– create a plane weighing in at 487 grams, but the aircraft was extremely fragile.

A third conclusion is that it is impossible to fly a solar powered plane using NiMH-batteries. This power source proves to be too heavy. The current battery pack in our airplane, a LiPo battery, weighs about 40 grams, whereas the original NiMH-battery pack weighed 225 grams. That is nearly half the mass of the entire plane! Even though LiPo batteries bring considerable

risks with them, it still is the best option for our aircraft. One simply needs to be very careful

JeT Productions Productions JeT

– when handling the plane.

A fourth conclusion is that our methods of testing worked well and our calculations and expectations have been correct. Especially the lift test gave results we expected. Although the angle of attack needed to be bigger than expected, the wings still generated enough lift. This confirms formulas we used have been both correct and accurate. Moreover, provided data has

been correct. Also we constructed the wings in a proper way. Therefore tests results were Solar Challenger Challenger Solar

satisfying. – The most satisfying test was of course when the aircraft truly took off. Cheer went up as we realised our assumptions, calculations, measurements and constructions had been correct. But most satisfying after all was that the plane took off completely balanced. Analysis showed the aircraft took to the skies at a far lower speed than expected due to factors like wind and the angle of attack. Sadly the aircraft‟s fragile frame didn‟t fully survive the crash landing.

Research Project Project Research A final conclusion we can draw is that even though they can‟t be used to entirely power aircraft, solar cells are a serious option when trying to extend flight times of airplanes. As we have seen, solar cells can keep our plane in the air for a nine percent longer period of time.

However, we can pose the question whether the weight savings following the exclusion of solar cells wouldn‟t have had the same effect, since the plane would have been much lighter without solar cells. In future projects further research could be done on this topic.

Last of all it should be noted that this version of our model aircraft is only the first version to

be built. This project has, more than anything, learned us a lot about building model aircraft 2010

and has provided us with valuable experiences to use in future projects. -

per Haverkamp Haverkamp per

Tim van Leeuwen & Jes & Leeuwen van Tim

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– Research Project Project Research

Evaluation

Our research project has provided us with numerous experiences and insights to be used later

when constructing a better, second version of our plane. Our experiences and insights include

2010 knowledge about what materials we should have used, what should be done differently and

- which parts of the plane we could have upgraded.

What should be done different, what didn’t go as well as could be?

Weight savings Mass of our aircraft has been a key factor in the project. Put simply, we have been trying to save weight on every part of the plane. In the end, we have been pretty successful in doing so, but there are some aspects of the plane on which more weight could have been saved.

First of all, we could have saved quite some weight on the two supporting beams in each wing. Initially we decided on using triplex beams as girders. While constructing the wings, now being familiar with the strength of balsa wood, we decided to use balsa wooden beams instead. They saved us relatively much weight, while proving to be strong enough as well. When connecting the ailerons to the servo using a carbon beam, we found out that we should

have used yet another type of material instead. We could use these carbon beams to replace

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– the supporting balsa beams, as they are as strong as balsa beams, but weigh half as much.

The carbon rods can also solve another problem concerning the wings. Since the balsa beams were not long enough to run over the full length of the wings, we were forced to build each wing individually and then glue the both of them together. The joint between the two wings proved to be a very fragile one. Using two long carbon rods will eliminate the need of making

a joint at all.

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– Talking of the frame, we have to note that a more realistic estimation of masses should be made at the start of the project. In the beginning we didn‟t exactly know what the mass of balsa wood was. We estimated the frame would eventually weigh 70 grams. When the plane was finished though, we ended up with a frame weighing nearly 160 grams.

The frame wasn‟t the only part of the plane that was heavier than expected. Numerous Solar Challenger Challenger Solar

components, such as the engine, batteries, propeller, engine controller, servo engines and – wiring turned out to be heavier than expected or promised. In future projects we should be more pessimistic about components‟ masses, which would result in solely positive findings rather than mostly negative findings.

Structural improvement

Because we did our utmost best to save weight, we might have pushed it a bit too far on some Research Project Project Research aspects of the plane. This affected the strength of the plane. During lift test we noticed that our tail looks pretty fragile, especially at high wind speeds. The rudder does seem to function, but the tail section can only be described as wobbly. The connection we made between tail section and wing is a bit too weak. 62

A second structural improvement is the landing gear. During the design of the plane we hardly spent any attention on the landing gear. This proved at the end of the construction phase, when we were faced with the problem of what to do with the landing gear. We managed to construct a suitable landing gear but it wasn‟t actually up to its job. This was

demonstrated when our plane crashed during its test flight. After the crash most damage was

done to the landing gear. Besides, we suffered a minor lapse in concentration whilst mounting 2010

the wheels. This resulted in us placing one wheel slightly more forward than another. It - shouldn‟t be a real problem, but as mentioned before, our plane tends to drive in a curve. The placing of the wheels might have to do with this.

Second of all, suspension of the wheels could have been more secure. Because we didn‟t have enough nuts and bolts at our disposal, we mounted two wheels using pins. This resulted in the wheels getting into a tilted position easily, thus creating more friction. Using bolts of the right dimension on every wheel would have increased the stability of our plane and would have reduced friction.

A third improvement involving the landing gear is making sure distance between wheels and suspension is wide enough. Currently we put a piece of balsa wood between the wheel and the supportive structure. The wooden parts separate the wheels from their suspension, but dramatically increase friction. Instead, we could have used some of the tubing left over from the push-rod to maintain distance between wheels and supporting structure. This would have

resulted in significantly lower drag and increased stability. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– A last improvement to the wheels, is to make the wheel supports higher, in order to give the plane a bigger ground clearance. This would eliminate the need to construct a third wheel (thus adding extra mass and friction) and would make it safer to drive the plane.

A final structural improvement has to do with materials available. As we had to build the plane all by ourselves and in our own house, we didn‟t have every material and tool at our

JeT Productions Productions JeT disposal. Because of this we had to resort to using pins and other „primitive‟ materials. If we

– would have had more materials available, we might have been able to manufacture a more rigid aircraft.

Solar cell improvements Our plane‟s solar cells can also be improved in several ways. When doing our project, we

discovered how fragile solar cells are. Unfortunately we learned by failure. During our project

Solar Challenger Challenger Solar

– several pieces of solar cell cracked, due to too much pressure being exerted on the cells. This might have resulted in the cells supplying a far lower current than the 3300 mA they should ject ject have provided according to specifications. Solar cells we used simply were too fragile.

Next time we should consider using a different type of solar cell. The high-performance cells we used are originally designed to be placed on cars or in glass solar panels; places where they would have had support all over. We just had two supporting beams. This resulted in a

Research Pro Research serious amount of pressure being exerted on the cells. In future we could use solar which are more flexible and fracture less easily. Currently those cells are not available.

A second method to provide more support for the solar cells is to simply add more supporting balsa wood or use a different construction material. Some model planes are built using a sort of polystyrene foam to fill up spaces between the wooden frame. In future projects this method should be used. It will allow the solar cells to be laid onto the foam. Another proposal

is using a different airfoil. The wings should have a flat rear on which to put the solar cells.

2010

A second improvement of our solar cells is the connection between them. We faced problems - with soldering and had to resort to connecting solar cells with ordinary tape and wire. This wire seems to disconnect occasionally, thus stopping the electrical circuit. Tape blocks some of the precious sunlight as well. Next time we should go for soldering strips Lemo Solar offers. This will result in better connections between cells.

Cost savings Another aspect of the project we could have improved on, was the cost aspect. After the project we still had numerous materials left we hadn‟t used at all. Not all balsa wood we bought was used for example. The final costs of this project are:

Element Costs (€) Element Costs (€) Balsa 41.09 Battery (NiMH) 8.95 Glue 10.16 Receiver 13.50

Engine controller 16.95 Servos 30.00 Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

Propeller 3.35 Wiring 7.80 – Shipping costs 54.96 Engine 14.50 Battery holder 3.50 Remote control 59.00 tions tions Landing gear 22.95 Switch 5.95 LiPo battery 19.99 LiPo charger 29.99 LiPo balancer 12.99 Solar cells 135.00

Diode 1.12 Mylar 6.00 JeT Produc JeT

Belts for testing 4.95 Pushrod 12.30 –

TOTAL 515.00

Parts that cost a lot were accessories for the LiPo-battery. Initially we planned on using a battery balancer when charging the LiPo-battery, but when the battery was charged, we found

out it either didn‟t work or was unnecessary. Charging can be done without a balancer, Solar Challenger Challenger Solar

although it drastically shortens the battery‟s life expectancy. – Another part we didn‟t use was the adapter, which would transform the 230V mains into 12V. When we received the adapter however, it turned out 230V mains was not transformed into 12 volts, but into 8 volts. We had to send back the adapter and resort to using a car battery charger. Although we did get our money back, we had to pay shipping costs.

The remote control and receiver also gave us some problems. We wanted to order a separate Research Project Project Research controller and receiver, but when the receiver had been delivered, we discovered we would need a crystal to place in the controller and receiver. It turned out the easiest way of getting a pair of crystals was to order a set containing a controller, a receiver and a pair of crystals. This left our initial receiver unused. 64

Another financial improvement is the shipping costs. During the project we ordered materials from several companies in several stages. Of course we intended to order all materials at the same time, thus having to pay only once. However, as we needed several unforeseen parts such as the LiPo battery, ordering was done in several stages. We can save quite some money

on shipping costs next time, as we now know which elements are really needed.

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- Test improvements Last part of our research project that could be improved, is testing. Improvement mainly lies in the lift test. We went about it as well as we could, but still it wasn‟t a very professional setup. It would have been better if we had been able to test the plane in a wind tunnel, using a device producing smoke, so we could take a look at the airflow. However, we didn‟t have a wind tunnel at our disposal and arranging one would have been very expensive.

Or so we thought. Thinking „it is always worth a try‟, we sent an e-mail to the faculty of Aerospace Engineering at the TU Delft in which we presented our finished Solar Challenger. In the e-mail we requested using one of the faculty‟s wind tunnels. A bit to our own amazement the faculty replied by stating that „the use of the wind tunnels for these purposes can rarely be accepted. However, since our project looked very complete and we even had a complete prototype, the faculty was happy to make an exception for us‟. Because our Solar Challenger would need to be tested in the biggest wind tunnel, which has a full schedule until

July, we‟ll have to wait some more time to perform this test. This will give us the opportunity Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

to fix the plane after the crash during the test flight. – A second improvement for testing, is the time of the year. As this project was finished in October, we had to deal with Dutch autumn weather during testing. This especially affected the test concerning the solar cells‟ output, because the angle of the sun‟s rays in autumn differs from the angel in summer and the sun‟s rays aren‟t as intense either. For this reason we can‟t say for sure what the solar cells‟ maximum output is. Besides, recharging the battery in

JeT Productions Productions JeT summer will take less time than recharging during autumn.

– Another improvement to be made when measuring the cells‟ output, is to have a light meter available. Using such a device enables us to draw a graph about voltage and current produced by the solar cells under various light intensities. Right now we can only describe weather as „sunny‟, „cloudy‟ or „reasonably sunny‟.

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– Camera data A last setback we encountered during test phase had to do with our camera footage. We filmed all tests we ran, including the plane‟s driving test. Video footage would have enabled us to show fragments of video in our presentation. Furthermore it contains the evidence of the existence of our plane in case something bad happens to it. However, even though we explicitly requested the TOA to put the video on computer immediately, it didn‟t happen. When we returned after bringing home the plane, we discovered video recordings were lost.

Research Project Project Research They were erased by accident.

What went well?

We have seen quite some elements to improve during our research project. On the other hand we also came across several techniques and designs which we think should definitely be

repeated in future projects.

2010

- Mylar foil One of the absolute successes of this project, is the use of Mylar foil. When we received the roll of foil, we thought we could have used kitchen foil as well. It was only when we applied the foil when surprise came in. We were especially shocked when Mylar foil turned out to shrink so well when being heated by an iron. Mylar foil is one of the key factors in the success of the project.

Wing shape Another good design used in our project, is the airfoil. Our choice to use a „Clark-Y‟ wing profile has been a very good one, for numerous reasons. First of all, the ribs of the wing were relatively easy to construct when compared to other airfoils. Second of all, the ribs connected well to the front and rear cornice and proved to be strong. Our wing frame together with the Mylar foil has proven to generate enough lift, thus sending our plane skywards.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– Engine & propeller The choice for an engine was a very difficult one, especially due to so many types being available. This choice we made turned out to be a very good one. The engine fits nicely in the frame, the propeller has the correct ratio with the frame and the engine doesn‟t consume too much power. More importantly though, the engine is capable of propelling our aircraft to high speeds.

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– Controls & steering Controls are one of the most crucial aspects of the plane, since the plane is helpless without them. After extensive research, a suitable receiver and remote controller had been found. Both function properly. We haven‟t tested yet what the maximum distance between the remote controller and the receiver can be, but it certainly is more than 100 metres.

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– The servo engines turn out to function properly as well. We had some small concerns about the servo engines‟ torque, but it turned out all servo engines are capable of tilting the ailerons and elevator. One small drawback is that one of the ailerons slightly drops once in a while due to gravitational forces. Luckily this can be corrected easily.

Using carbon rods is a very good way of connecting servo engines with ailerons and is a good way to save weight. Also the push-rod is a good solution to control the rudder. Although

Research Project Project Research installing is quite tricky, it works well. Moreover, the push-rod looks professional.

Last of all, the engine controller we used also functioned properly. We haven‟t had any problems dealing with heat production or too high currents going through. 66

Our opinion

The past months, especially the past weeks, we have been working intensely on this project. It has been a great challenge to us. Setbacks occurred on a daily basis and delays were

unavoidable. Still, we eventually managed to attain our goals.

2010

This project has, more than anything, taught us lots about building model aircraft and - provided us with valuable experiences to use in future projects. We didn‟t construct a €500.- plane, we gathered €500.- of knowledge and we are very satisfied with all results.

Last of all, this project has been an absolute success. Not only has it been great fun building the plane, the reactions to the project have been overwhelming and Solar Challenger even managed to pick up a prestigious price at our school. The whole project was a great experience but of course, there was one moment that stood out specifically: the airplane

taking off. It was simply breathtaking.

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

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Additional sources

Report writing:

http://www.ruf.rice.edu/~bioslabs/tools/report/reportform.html

2010

- Research project discussion on fuel savings for commercial aircraft, including on solar panels http://www.wetenschapsforum.nl/index.php?showtopic=94691&pid=466140&st=0&

Solar powered model aircraft built by students from Puerto Rico: http://www.youtube.com/watch?v=uzu2Y2kbPZw&feature=related http://ceic.pupr.edu/html/Capstone/HybridWings/index.html

Students attempting to build a solar powered model aircraft as a research project: http://www.modelbouwforum.nl/forums/electro-vliegtuigen/66600-modelvliegtuig-op- zonnecellen-pws.html

Building the frame of a model airplane: http://anjo.com/rc/aircraft/elder/ http://www.airfieldmodels.com/information_source/how_to_articles_for_model_builders/con

struction/wing_construction/index.htm

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

– http://picasaweb.google.com/jaspapens/Charter#5154316415791691170

ns ns http://plans.rcmodell.hu/planelect.html

About model flying: http://www.mvccrash.nl/overons/00000097940bbf72d/

Forum: JeT Productio JeT

http://www.circuitsonline.net/forum/view/66253 – http://www.modelbouwforum.nl/forums/accu-laad-techniek/69411-batterij-laden-dmv- zonnecellen-2.html

Technical tips:

www.amcor-modelbouw.nl

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Acknowledgements

Solar Challenger was a success. Still, completing our project would not have been possible

without the efforts, support and help of the following people, companies and organizations:

2010

-  F. Hidden, our advisor. Though he was quite skeptical about feasibility of our project, he approved with our ideas and plans. His critical thinking and expertise prevented us from making unnecessary mistakes and taking inaccurate steps.  R.J.W. Haverkamp, Jesper‟s father. He provided us with all equipment we needed for construction. This included tools and several instruments.  P.A. van Leeuwen, Tim‟s father. He helped through critical thinking and cooperation. His tips and hints appeared to be pretty constructive. Moreover, ordering components abroad would not have been possible without his credit card.  I.M. Prange and L.C. van Staveren, Jesper‟s and Tim‟s mothers. They were willing to transport our fragile plane to and from testing locations. In addition they supported other logistics and finances.  R. van der Laan, for providing us with his LiPo battery charger and safety equipment.  Lemo Solar, a German supplier of electronics. They gave us €24 discount on the solar cells.

 Athletics Club Startbaan, whose track was available as a runway for our plane. Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim

 TU Delft, for the usage of the lay out and style as far as the report and presentations are – concerned.  Computer Services Alphen aan de Rijn, for using all of their soldering equipment.  A.Ch. van Steen, for donating €15 to stimulate progress and development of our solar powered plane.  All people from Modelbouwforum.nl and circuitsonline.net, for all their useful tips.

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Jesper‟s log

Day Date Start End Total Description time time time

2010 Wednesday 01-04-09 17:00 18:00 1

Orientation on subject (websites universities, forum, etc.) - 19:00 21:00 2 Orientation on subject (decision: solar challenger) Thursday 02-04-09 10:15 11:15 1 Discussion about subject (decision on solar challenger) 17:00 18:00 1 Information on feasibility (engine, solar panels) 19:00 21:00 2 Information on feasibility (propeller, balsa wood) Friday 03-04-09 11:30 11:45 0.25 Discussion with Mr. Hidden 10:45 11:30 0.75 Looking up information on costs (solar panels, engine) 11:35 11:50 0.25 Discussion about subject (time, costs, size) 16:00 18:00 2 Possibilities of electrical system (servo, battery, engine) 18:30 19:30 1 Possibilities for construction (wood, glue, foil) Saturday 04-04-09 13:55 14:10 0.25 Consultation on possibilities (Who will do what? Jesper: wing construction, loading batteries. Tim: Wireless system, servo engines) 18:15 18:45 0.5 Possibilities of the wing (construction of frame, foil)

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim Sunday 05-04-09 10:00 10:30 0.5

Take a closer look at wing design (Clark Y) – 12:00 13:00 1 Take a closer look at electrical system (batteries) 17:00 17:15 0.25 Determine planning and research questions Wednesday 08-04-09 14:00 15:30 1.5 Discuss electrical system (also on forum) 19:00 20:00 1 Read tips on forum and execute them Thursday 09-04-09 17:00 18:00 1 Found new engine and parts

JeT Productions Productions JeT 19:00 21:45 2.75 Made a list of electrical equipment, made a list of

– requirements Friday 10-04-09 8:45 9:15 0.5 Drawing a scheme of electrical system 17:30 18:00 0.5 Writing on documentation Sunday 12-04-09 9:00 11:00 2 Update website Wednesday 15-04-09 13:30 15:30 2 Start research proposal

Saturday 18-04-09 16:00 19:00 3 Determine airfoil Solar Challenger Challenger Solar Wednesday 22-04-09 13:30 16:00 2.5

– Work on research proposal Monday 27-04-09 10:00 12:00 2 Work on research proposal 13:00 16:00 3 Work on research proposal Wednesday 29-04-09 10:00 12:00 2 Work on website 14:00 16:00 2 Work on research proposal Sunday 17-05-09 14:00 15:30 1.5 Work on research proposal

Research Project Project Research 17:00 18:00 1 Work on research proposal Wednesday 10-06-09 13:30 15:30 2 Work on research proposal Tuesday 16-06-09 10:30 11:00 0.5 Work on research proposal Thursday 18-06-09 11:45 12:45 1 Work on research proposal 70

Monday 22-06-09 10:30 11:00 0.5 Work on research proposal Wednesday 24-06-09 10:30 13:00 2.5 Round off research proposal 18:45 19:15 0.5 Round off research proposal Thursday 25-06-09 8:30 9:45 1.25 Round off research proposal

10:30 13:00 2.5 Round off research proposal

Thursday 09-07-09 20:30 22:00 1.5 Order various components, update website

2010

- Sunday 18-07-09 15:00 18:00 3 Unpack components, read manuals, connect components, test them Tuesday 21-07-09 14:15 17:45 3.5 First test electrical system (engine & batteries), check mass of components

Thursday 23-07-09 15:00 16:30 1.5 Research on new battery, solar panels and mass savings Haverkamp Haverkamp Friday 24-07-09 10:15 10:45 0.5 Catch up with report 11:00 13:30 2.5 Investigation about Mylar, diode and other materials yet to order Saturday 01-08-2009 14:00 17:15 3.25 Start construction of wing Saturday 08-08-2009 14:00 17:00 3 Continue construction of wing Saturday 15-08-2009 9:00 12:00 3 Continue construction of wing Sunday 16-08-2009 10:00 13:00 3 Continue construction of wing Thursday 20-08-09 19:30 20:00 0.5 Purchase carbon beams & push-rod in Amsterdam Saturday 22-08-09 14:00 18:00 4 Continue construction of wing + investigate push-rod

elevator

Tim van Leeuwen & Jesper & Leeuwen van Tim

– Monday 24-08-09 14:00 17:00 3 Construction of tail Wednesday 26-08-09 8:30 10:45 2.25 Put wings together, start construction of fuselage Thursday 27-08-09 13:30 16:30 3 WeCo time: Continue construction of tail, wheels, fuselage 17:00 17:15 0.25 Ordering batteries and final equipment

Sunday 30-08-09 16:45 17:45 1 Making adjustments to engine mounting + preparing JeT Productions Productions JeT

wiring and electronics for new battery – Tuesday 01-09-09 20:00 21:00 1 Sending back wrong adaptor, testing LiPo battery charger and components Thursday 03-09-09 19:00 20:00 1 Purchase rear cornice + supporting wooden beam Monday 07-09-09 10:30 13:00 2.5 Continue construction Thursday 09-09-09 21:30 22:30 1 Spelling check + catch up with research project file

Sunday 20-09-09 10:00 13:00 3 Apply Mylar + finish elevator & push-rod Solar Challenger Challenger Solar Thursday 24-09-09 14:00 16:30 2.5 – Attempt soldering solar cells Saturday 26-09-09 19:00 21:30 2.5 Second attempt to solder solar cells, no results, silver tin needed. Sunday 27-09-09 19:00 22:30 3.5 Drilling new holes, gluing solar cells, connecting wire to cells with tape Monday 28-09-09 15:15 18:15 3 Soldering diode, finishing wiring, testing voltage, applying Mylar and ailerons

Research Project Project Research 19:00 20:00 1 Soldering diode, finishing wiring, testing voltage, applying Mylar and ailerons Tuesday 29-09-09 16:30 18:30 2 Applying Mylar to wing

19:00 22:00 3 Gluing landing gear, determining centre of gravity, gluing fuselage, wings and rudder together Wednesday 30-09-09 13:30 15:30 2 Transporting plane to school, showing it at school, testing

controls

16:00 17:00 1 Installing new gear, doing final checks

2010

- Thursday 01-10-09 10:00 10:30 0.5 Arranging equipment for testing 19:00 19:30 0.5 Setting up frame for testing Friday 02-10-09 8:30 12:00 3.5 Lift test, drive test 20:00 22:00 2 Spelling check + catch up with research project file Saturday 03-10-09 9:30 12:30 3 Working on file 16:00 18:00 2 Working on file 19:00 22:00 3 Working on file Sunday 04-10-09 9:00 10:00 1 Working on file 11:00 13:00 2 Testing solar cells' profit Monday 05-10-09 17:00 18:30 1.5 Working on file 19:00 22:15 3.25 Working on file Tuesday 06-10-09 17:00 18:30 1.5 Working on file 19:00 23:15 4.25 Working on file Wednesday 07-10-09 17:00 18:30 1.5

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim Working on file

– 19:00 01:30 6.5 Working on file Thursday 08-10-09 17:30 18:30 1 Working on file 19:00 23:30 4,5 Working on file TOTAL 156

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Tim‟s log

Day Date Begin End Total Description time time time

2010 Wednesday 01-04-2009 13:45 16:00 2.25 Introduction to research project, explanations on

- possibilities and brainstorming on topic 19:45 20:00 0.25 Telephone call with Jesper, idea of solar powered airplane 20:00 21:00 1 Orientation on topic, look at possible materials and parts, look up information, check out others ideas Thursday 02-04-2009 10:15 11:15 1 Discuss findings with Jesper, brainstorm on topic, come up with topics to be investigated 20:00 21:00 1 Look at feasibility of project, focussing on solar cells, mass and engine Friday 03-04-2009 11:35 11:50 0.25 Discuss finding, determine size of aircraft, discuss first materials 18:00 19:00 1 Search for materials and parts on the internet, look at engines, look at forums Saturday 04-04-2009 13:55 14:10 0.25 Telephone call with Jesper, divide first tasks for looking up information. Tim will focus on controls,

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim Jesper on wings & electrical system

– Sunday 05-04-2009 20:00 20:30 0.5 Orientation on controls, search the internet for possibilities and available materials/parts Tuesday 07-04-2009 9:45 10:15 0.5 Discuss findings on ways of controls and number of solar cells. Determine aimed mass Wednesday 08-04-2009 13:30 16:00 2.5 WeCo-time, report topic, look up parts together, investigate battery overload problems, post questions

JeT Productions Productions JeT on forums and look at answers

– Thursday 09-04-2009 9:00 9:15 0.25 Look at further answers on forum Friday 10-04-2009 10:50 11:05 0.25 Catch up with log Wednesday 15-05-09 13:30 16:00 2.5 WeCo-time: Work on research proposal Wednesday 22-05-09 13:30 16:00 2.5 WeCo-time: Work on research proposal Wednesday 20-05-09 13:30 16:00 2.5 WeCo-time: Work on research proposal, step three

(engine, batteries, propeller & solar cells) Solar Challenger Challenger Solar

Thursday 21-05-09 22:15 22:30 0.25 Catch up with log – Friday 22-05-09 9:00 10:15 1.25 Work on research proposal, step three (controls) Friday 22-05-09 10:30 11:00 0.5 Work on research proposal, step four (determining final mass & size) Wednesday 10-06-2009 13:30 16:00 2.5 Work on research proposal, finish step four and start step six (placing of solar cells) Wednesday 24-06-2009 10:00 13:00 3 Work on research proposal, step seven (design of wing)

Research Project Project Research Thursday 25-06-2009 10:00 13:00 3 Work on research proposal, step seven (design of wing) and finishing of research proposal Sunday 28-06-2009 18:00 18:30 0.5 Research on international aspect of project Monday 29-06-2009 15:45 16:30 0.75 Research on international aspect of project 73

20:00 22:15 2.25 Work on international aspect of project 22:30 23:00 0.5 Work on international aspect of project Tuesday 30-06-2009 9:30 10:00 0.5 Work on international aspect of project 10:15 10:30 0.25 Research lending solar cells

19:00 18:30 1.5 Research on international aspect of project

Wednesday 31-06-09 19:45 23:15 3.5 Work on international aspect of project 2010

Thursday 01-07-2009 20:30 23:15 2.75 Work on international aspect of project - Friday 02-07-2009 8:00 9:30 1.5 Work on international aspect of project 11:15 11:45 0.5 Work on international aspect of project 13:30 15:30 2 Research / work on international aspect of project 15:30 15:45 0.25 Start spelling & grammar check Sunday 19-07-2009 11:00 11:45 0.75 Work on international aspect of project 17:30 18:15 0.75 Work on international aspect of project (spelling & grammar check) 18:45 19:00 0.25 Work on international aspect of project (spelling & grammar check) 20:30 22:15 1.75 Work on international aspect of project (spelling & grammar check) Tuesday 21-07-2009 14:15 17:45 3.5 First test electrical system (engine & batteries), check mass of components Tuesday 28-07-2009 19:15 22:00 2.75 Adjust 'construction' part in the research project

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim document after test, research Mylar

– Thursday 30-07-2009 15:15 15:45 0.5 Buy beams at Praxis Saturday 01-08-2009 14:00 17:15 3.25 Start construction of wing Saturday 08-08-2009 14:00 17:00 3 Continue construction of wing Saturday 15-08-2009 9:00 12:00 3 Continue construction of wing Sunday 16-08-2009 10:00 13:00 3 Continue construction of wing

eT Productions eT Productions Monday 17-08-2009 13:30 15:45 2.25 Work on 'construction' part in the research project J

document – 16:15 16:45 0.5 Work on 'construction' part in the research project document Friday 21-08-2009 11:15 11:45 0.5 Send e-mails concerning solar cells and Mylar foil Saturday 22-08-2009 14:00 18:00 4 Continue construction of wing + investigate push-rod elevator

Monday 24-08-2009 14:00 17:00 3 Construction of tail Solar Challenger Challenger Solar

Tuesday 25-08-2009 22:00 22:15 0.25 E-mail for information on Mylar foil – Wednesday 26-08-2009 8:30 10:45 2.25 Put wings together, start construction of fuselage Thursday 27-08-2009 13:30 16:30 3 WeCo time: Continue construction of tail, wheels, fuselage Friday 28-08-2009 15:45 17:00 1.25 Look for suitable sponsors, E-mail ASN + Triodos for sponsoring 20:00 20:30 0.5 Order Mylar foil

Research Project Project Research Thursday 03-09-2009 20:30 20:45 0.25 Order solar cells Sunday 05-09-2009 20:00 20:30 0.5 Look at Schipholfonds as a sponsor Monday 07-09-2009 10:30 13:00 2.5 Continue construction 19:00 20:30 1.5 Update construction report 74

Monday 14-09-2009 16:30 16:45 0.25 E-mail school for information on finances Tuesday 15-09-2009 22:45 23:00 0.25 E-mail solar cell supplier for information on delivery Wednesday 16-09-2009 13:15 13:30 0.25 E-mail school for information on moving the deadline Sunday 20-09-2009 10:00 13:00 3 Apply Mylar + finish elevator & push-rod

21:30 22:00 0.5 Update construction report Monday 21-09-2009 19:15 20:45 1.5 Update construction report + start spelling & grammar

2010 check on research project document

- Thursday 24-09-2009 14:00 16:30 2.5 Attempt soldering solar cells Monday 28-09-2009 15:15 18:15 3 Solder diode, finish wiring, test the voltage of solar cells, apply Mylar to end of wings, install ailerons 19:00 20:00 1 Solder diode, finish wiring, test the voltage of solar cells, apply Mylar to end of wings, install ailerons Tuesday 29-09-2009 16:30 18:30 2 Apply Mylar to rest of wing 19:00 22:00 3 Glue landing gear, determine centre of gravity, glue wings, fuselage and rudder together, charge battery Wednesday 30-09-2009 13:30 15:30 2 Transport plane to school, show the plane, bring plane back home 15:30 17:00 1.5 Install extra wheel, do final checks on plane Thursday 01-10-2009 10:00 10:30 0.5 Arrange equipment for lift test 16:30 17:30 1 Film plane while driving, think of set-up for lift test Friday 02-10-2009 8:30 12:00 3.5 Perform lift test, drive test

Tim van Leeuwen & Jesper Haverkamp Haverkamp Jesper & Leeuwen van Tim Sunday 04-10-2009 13:00 16:00 3 Catch up with adjustments to research project

– document, check spelling and grammar 16:00 18:45 2.75 Work on 'construction' part in the research project document 19:30 21:30 2 Work on 'construction' part in the research project document 21:30 22:00 0.5 Check international aspect

JeT Productions Productions JeT Monday 05-10-2009 10:15 13:00 2.75 Work on testing part and media attention part in

– research project document 16:45 17:45 1 Write conclusion for research project document + add new data in testing part Tuesday 06-10-2009 16:30 17:45 1.25 Write about media attention, Start with evaluation in research project document Wednesday 07-10-2009 10:15 11:30 1.25 Continue evaluation in research project document

17:00 18:30 1.5 Continue evaluation in research project document

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– 19:00 21:00 2 Finish conclusion and evaluation 21:00 0:30 3,5 Order sources, finish logs, check document Thursday 08-10-2009 14:00 15:30 1,5 Working on file TOTAL 139,25

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