Introduction: How to Make a Radio Controlled Paper Plane (and Learn About Electronics As Well)
Runner Up in the
Make It Fly! Contest 2017
Paper planes are fun to make. If you were bored in class, you would make them and throw it across the room, hoping that the teacher does not catch you (or the plane). But paper planes were fun while they lasted...in the air. Today, I will walk you through step-by-step on how to make a full, radio-controlled paper plane. I've always wanted a RC plane, but the good radio-controlled ones are fairly expensive and the ones you get under 20 dollars are controlled by infrared light, which means that you cannot take it outside, or else you will lose control of it, due to the sun's rays which also emits infrared light (trust me, I've lost control of too many of those already). Along the way, I will also teach you the fundamentals of electronics and let your first project lift you off to new heights. So let's get started!
Step 1: How Will the Finished Project Work?
In this instructable, I will show you how to make a RC paper plane with a complementary joystick controller. Before you turn on the plane, hold the joystick in the 'off' position, which means move the joystick all the way down and while doing that, turn on the plane. When you release the joystick, it will automatically go back to the center position, which is middle throttle, and all the way up, full throttle. If you are ready to throw your plane, put the joystick to full throttle and throw the plane. Steer left or right by moving the joystick left and right while holding your desired throttle (so that means if you are flying at full throttle, don't release the joystick, having it fall back to middle throttle and turn then, simply steer left or right while holding the throttle up). To land, simply pull the throttle to off and the plane will glide to a landing. This plane is also built to have a low battery warning. When you notice that the plane does not respond, it means that you either have fine out of range or the battery is low.
Note: when the battery is low, the motors will automatically cut out to make sure that the battery does not get damaged.
Step 2: Get Your Parts
In order to make this flying contraption, you will need:
- Paper (duh...)
- A 5v Arduino Pro Mini (I know the authentic ones are discontinued, you can get clones here: https://www.ebay.com/sch/i.html?_from=R40&_trksid...
- A FTDI board (or an Arduino Uno with a removable microcontroller (aka non-SMD version), both which you will use to program the Arduino Pro Mini): https://www.ebay.com/sch/i.html?_odkw=433mhz+rf+t...
- Various Wires
- 2x small coreless motors with propellers (you can get them here: https://www.ebay.com/sch/i.html?_from=R40&_sacat=...
- An analog joystick: http://www.microcenter.com/product/476341/XY_Joys...
- 433Mhz RF radio modules: https://www.ebay.com/sch/i.html?_odkw=2n3904&_osa...
- A small Lipo (150 mah or smaller: http://www.ebay.com/itm/2PCS-3-7V-150mAh-Lipo-Bat...
- TP4056 USB Lipo Charger: http://www.ebay.com/itm/2pcs-5V-1A-Micro-USB-1865...
- 2x 2N3094 NPN transistors (you can salvage these, but here's a link if you can't find some: https://www.ebay.com/sch/i.html?_from=R40&_trksid...
- 2x common diodes (salvageable, but here: http://www.ebay.com/itm/1N4007-1A-1000V-1KV-Recti...
- 2x 220 Ohm resistors (again salvageable, but here is a good resistor pack: http://www.ebay.com/itm/2600pcs-130-Values-1-4W-0...
- A small slide switch: http://www.ebay.com/itm/20PCS-MSK-12D19-1P2T-Togg...
- 2 breadboards
- 8 AA batteries
- AA battery holders (12v): http://www.ebay.com/itm/2Pcs-Black-Plastic-Batter... (only need one)
- 3.7v to 5v boost converter: http://www.ebay.com/itm/DC-DC-3V-3-7V-5V-Step-Up-...
- 3 inch by 3 inch foam board
- 2 in x 4 in x 2.25 in project casing (for transmitter case)
Here's the tools you will need:
- Soldering Iron (and solder)
- A computer to program the Arduino
- Your hands :)
Step 3: Stop and Learn
If you are not complete beginners and know a bit about electronics, feel free to skip to step number 7 to get to the build, but for others who want to learn about electronics, continue reading for a brief description and useful information about the parts we will be using for this build.
Arduino is a small microcontroller in which you can program and do everything you want. They come in all shapes and sizes, from ones smaller than your thumb to the size of your hand with the ability to do up to 84 million individual instructions per second. For this project, we will be using the most common Arduinos, and it includes the famous Uno board and the semi-permanent project suitable board, Arduino Pro Mini. The Uno that we will be using is especially user-friendly, as if you somehow accidentally fry your chip, you can always pop it out and replace it. If you want a more in-depth introduction, I recommend the book Arduino Workshop by John Boxall, which you can get here: https://www.amazon.com/Arduino-Workshop-Hands-Introduction-Projects/dp/1593274483 or get one at your local library.
Step 4: Transistors
In this project, we will be using the 2N3904 NPN transistor. A transistor is like a switch that is controlled with electricity. When you first look at a transistor, you can see that it has 3 legs. If you are in the UK, let the round part face you and the legs go like this: Emitter, Base, Collector. However, if you are in the US, let the round part face you and the legs go like this: Collector, Base, Emitter. The base is like the switch, collector is positive, and emitter is like the ground (or the negative part of a battery).
There are two types of transistors, NPN and PNP, both are which identical at first sight, but with a simple test with a multimeter, you can easily tell them apart. If you have a multimeter with a diode test function (it looks like an arrow) simple put the red probe on one leg and the black one in the middle. If it gives you a reading, it is a PNP transistor, however, if it doesn't, simply swap the probes around and if it then gives you a reading, then it is a NPN transistor. PNP and NPN transistors differ because they each have a different way to turn on.
NPN transistors turn on when there is a positive voltage applied to the base and turn off if ground is applied. PNP works the other way around. They turn on when their base is connected to ground and turn off when their base is connected to a positive voltage.
Transistors will be used in this case to control high-powered objects, like motors. An Arduino output can only supply 20 milliamps of current, but the motor can draw over 80 milliamps, which can fry the microcontroller, so if we use the Arduino like a human that opens and closes a switch, it will allow the Arduino to safely control the motor. But transistors also have their own limits as well. For example, the 2N3904 transistor can handle 200 milliamps of current max, which is enough for our use. However, if the transistor draws or takes too much current from the base, it will fry and release the "magic smoke". That is why we use resistors.
Step 5: Resistors
Resistors are one of the simplest electronic components to understand because they simply limit the current flowing into a device, in this case, limit the current going into the base of the transistor to avoid frying it. Resistors convert the extra energy as heat, so that means if a 1/4 watt resistor is trying to limit 30 Amps of current at 12 volts (power rule, Power (in watts)=Volts times Amps or P=VA, so 30A at 12v is 360 Watts), it would glow red and explode. But how do you know how much power a resistor is going to be facing? We use Ohm's law. Resistance is measured in a unit called Ohms. Ohm's law states that V=IR or volts equals current times resistance. That means that if you rearrange the terms to get I=V/R, you can plug in the voltage and your resistance to find out how much current will be limited. Resistors can be read by using their bands, according to a chart I drew above.
Step 6: Diodes
Finally, the last electronic component we will use for this project is a diode. As they slow down, the inertia of the motors generate energy back into the power source, which in some cases, it means a battery. This can be good and bad. If the battery was a type that can handle fast charging currents, then you are essentially recharging the battery. However, like in this case, you are controlling it with a microcontroller as well, and Arduinos don't like to be fed current. Diodes are like a one-way check valve in plumbing. They block current in one direction and allow current to flow in the other. So by putting a diode in parallel with the motor, you car giving the electricity generated another, easier, direction to flow: back into the motor. This will stop the motor faster and will protect your microcontroller. It's a win-win!
Step 7: Prepare the Radio Modules
To ensure maximum range, it is recommended to add a 12 inch solid-core wire to each of the modules (slide a wire through the ANT hole found on the board of the receiver and transmitter) as an antenna. Measure 17cm from the bottom and start winding a small 2.5mm diameter coil 16 turns in the middle. (Note, this is supposed to increase range, but this is not my idea, head over to https://www.instructables.com/id/433-MHz-Coil-load... to see where I got the idea from.) It is to be noted that the maximum working voltage of the transmitter is 3-12v, we will be using 12v for maximum power, and for the receiver, 5v.
Step 8: Back to the Build
Wire your Arduino Mega board to the joystick and the transmitter module (the smaller one) like this:
Joystick ---> Arduino
Transmitter -------> Arduino
Wiring will be shown in the images above.
Connect the receiver to the Arduino Pro Mini and wire the motors. Do this on a breadboard:
Receiver -------> Arduino
Vcc ------------> 5v
GND -----------> GND
DATA or ATAD -----> Pin 8
Wiring for the motors will be shown above.
Step 9: Set Up Your Lipo
Lipo batteries are very powerful batteries, as they can hold tons of power in a small footprint, but they can be extremely dangerous if mishandled. In short, here's a list of rules that you should follow with Lipos:
- Don't charge them over 4.2 volts or it will explode
- Don't freeze them or else the internals will short and explode
- Don't throw them in extreme heat or it will explode
- If a fire starts, don't throw water over it or it will explode even more
- Don't let the voltage drop under 3 volts or it will explode
- Don't touch the positive and negative wires to each other or it will explode
- If you do a lot more things including dropping them from a high place, compressing them, puncturing them, etc., it will explode. There are a lot of videos on youtube to prove it.
That is why we need a TP4056 Lipo charger to help increase the safety of your plane. The charger integrates a charging circuitry that carefully monitors the voltage and cuts off power when it gets fully charged and another circuit that can cut power in case something bad happens. But when we program the plane, we will integrate another battery cut-off to make sure that your plane does not become a flying fireball in mid-flight.
If your Lipo comes with a connector, carefully cut ONE wire off from the connector and strip it. DO NOT CUT THE OTHER WIRE YET, OR YOU MIGHT RISK SHORTING IT BY ACCIDENT. Then, solder the wire to the center holes (labelled B- or B+)of the TP4056 on the corresponding pad (black goes to negative and red goes to positive). After you solder one wire on, carefully cut the other wire off the connector, strip it to expose the wire inside, and solder it to the other pad. Next, get your boost converter, and solder the wires to OUT+ and OUT- on the TP4056 to IN+ and IN- respectively, on the boost converter. Solder wires to each output of the boost converter, but DON'T STRIP THE WIRES COMING OUT OF THE BOOST CONVERTER UNTIL YOU ARE READY TO SOLDER IT TO THE ARDUINO PRO MINI.
Step 10: RF Transmitter Code
First, download the Arduino IDE here if you don't already have it: https://www.arduino.cc/en/Main/Software. This is how you will program the Arduino.
Then, download the VirtualWire .zip library here: http://www.airspayce.com/mikem/arduino/VirtualWire... and install it in the IDE by going to 'Sketch' >> 'Include Libraries' >> 'Manage Libraries' >> 'Add .zip library'
Download the program below and upload the program to the transmitter Arduino by plugging it into the computer with a USB cable.
After downloading the code, secure the electronics inside the project box, making sure to drill a 1/8 inch hole for the antenna and a 1 inch hole for the joystick and hot glue everything into place.
Step 11: RF Receiver Code
Now there are two options when uploading a program to the Arduino Pro mini, if you already have an Arduino Uno non-SMD, and want to save money, read on, however, if you are using a different Arduino with a SMD chip, use a FTDI programmer, plug it in the Arduino Pro Mini, get a USB cable, and upload from there.
To upload with the Arduino Uno, VERY CAREFULLY, with a flat-head screwdriver, remove the microcontroller from the chip holder and set it to the side. Then, get jumper wires and connect the following:
Uno --------> Pro Mini
RX -----------> RX (on programming header on the top, not the side)
TX ------------>TX (on programming header on the top, not the side)
3.3v -----------> 5v
Reset ---------> RST or Reset
Then, just simply plug the Uno into your computer, set the board model to "Pro Mini 5v 16Mhz", download and upload the code.
Step 12: Build and Wire the Plane
Let's fold the plane! Follow the GIF animation above to learn how to fold a plane, or feel free to make your own, just make sure that it is a glider, not a dart-like plane that requires a hard throw to travel.
Next, roll the motors in paper tubes and tape them to hold them in place like shown in the images. The dimensions and finished tubes are shown above.
Then, solder the electronics according to the schematic shown above.
Step 13: Test to Make Sure Everything Works
Now it is time to test and make sure that everything is working as it should be.
Turn on the transmitter by sliding the switch.
Strip the wires to the boost converter and plug OUT+ into the RAW pin of the Arduino Pro Mini and the OUT- into the GND. Connect the other wire coming out of the Lipo into the A0 pin of the Arduino Pro Mini.
Test to make sure each control works, and if it does, solder and hot glue everything into place as shown in the images above (Make sure to put an extra piece of foam under the charger board to give it some height for convenience when you go charge the plane).
Step 14: Finalize
Before we start assembling, you must find the center of balance for both the plane and the electronics in order for the plane to be stable when flying. To find the center of balance of the plane, simply take a sharp pencil, insert it between the wings and find where it balances the best, as shown in the images above. To find the center of balance for the electronics, balance the board horizontally on a pencil and find the point where it balances the best. Draw a line to mark the center and match it with the center of the plane. Tape or hot-glue the electronics to the plane. Finally, turn on your plane and power up your transmitter. Set the throttle to max and throw the plane! Congratulations, you have built a fully radio-controlled paper aircraft, and learned a bit about the amazing world of electronics!
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