RC Arduino Rubber Band Glider

Looking outside the window, there is a good chance you may spot large commercial airplanes soaring through the air with their powerful jet engines, which are becoming a bigger talking point at time passes with the growing concern of the consequences of climate change due to the amount of carbon dioxide commercial planes produce leading to more discussion as to how to make the aviation sector more efficient. Perhaps a helping solution is to look into gliders, which focus on optimising energy efficieny to achieve the same lift using the same energy.

In this instructable, i will show how anybody can create not only their own glider, but a rubber band powered one that can be remotely controlled. This tutorial requires basic skills using cardboard without the need of a 3D printer or laser cutter, and the electronics can be bought cheaply and are easy to use and upload code.

So what is a rubber band glider? You may have created one in your childhood and is a simple concept to understand. In the bottom left photo, a drawing illustrates how a continous servo rotates anticlockwise causing the attached rubber band chain to store this energy as elastic potential energy, the same concept as if you were to pull and stretch a rubber band and let it go, causing it to launch forwards. The only difference is that in this situation, the energy is exerted in circular and not linear motion. As the propeller is fixed in place by either resting it on the floor or stopping it with your hand, the rubber band chain connected is twisted, and energy is stored up.

When the propeller is released, this elastic potential energy is transferred to kinetic motion in the opposite direction (clockwise) in which it was twisted, causing the propeller to turn rapidly, creating thrust in which the glider will use to produce lift using the wings. So thats the jist of the design; now, what you need to make this:

The glider body

• Single corrugated carboard (amazon uses this to package large delivieries in boxes)
• Thin card (amazon uses this to package smaller items in envelope size)
• A 2-3 inch propeller
• Multiple rubber bands
• A steel paperclip
• Wire (that can be bent easily - i used brass wire)

The electronics

• Lipo battery (2s or 1s, a 2s needs a 5v regulator, a 1s needs a boost voltage converter) I used this one as it is light and small, as capacity is not essential
• Voltage regulator/booster (not a linear regulator due to its inefficiency) I used this one but there are smaller ones but for a higher price. It also comes with a useful voltmeter
• Two arduino nanos with data cables to upload code
• Two Nrf24l01 modules I used this one that also comes with two nanos
• Continous 9g servo
• Normal 9g servo
• Analog joystick
• Switch
• (Optional for prototyping) Breadboard
• Male to male, male to female jumper wires

Tools

Pencil, pen, marker

30cm ruler, 15 ruler, measuring tape

Blade cutter

Cutting board

Superglue

Soldering iron with solder (optional - a clamp stand to make soldering easier)

What makes this glider intresting is that it is remote controlled using two Arduinos and two Nrf24l01 modules.

In the video, it demonstrates how on the transmitter side of the electronics, a switch controlles whether the continous servo should rotate or not at maximum speed. On the same side, a analog joystick controlles a normal servo which will be attached to the rudder of the glider, causing it to turn between the angles of 30 degrees and 150 degrees, where 90 degrees is the rest position of the joystick when the rudder is not angled. The increased drag caused by the angled rudder should cause the glider to turn the opposite direction to the force that is being applied onto the rudder.

On the receiver side of the electronics, a 2s lipo battery (tinkercad doesn't have lipo batteries so i just used a 9v battery instead) provides a voltage of 8.4V (at full capacity) in which the voltage regulator decreases that voltage to a stable 5V efficiently, while also monitoring both the input and output voltage. The 5V output can then be used to power both servos, the Arduino Nano and the Nrf24l01 with no worries.

"Oh but why don't you use the Vin pin on the Arduino and use the onboard voltage regulator instead of wasting space and weight with the external regulator?" - It seems reasonable to use the Vin pin if it accepts 5V to 12V, but the problem is that the Nano uses a linear regulator to regulate the voltage, which are incredibly inefficient (50%), and when using servos that draw up to 250ma each when operating, watts of power are wasted. Your arduino will soon fry up! If you use a switching regulator instead which are up to 95% efficient, there should be no problem.

In the two photos, they show the wiring layout for both transmitter and reciever electronics (I had to add my own joystick and Nrf24l01 as Tinkercad doesnt support it). Once both are wired correctly, using the Arduino code i have attached, open them in Notepad and then copy and paste each code into separate Arduino IDE files and upload each code to each Arduino Nano (make sure the reciever code goes into the reciever electronic Nano and vice versa). Before uploading though, and if you have tried to, you will notice you need to download the Mirf library for the modules to work as well as the drivers which you can find very easily online. Once the libraries have been downloaded and the code uploaded, you should be good if you wired the connections correctly! I also have the code written out below for anyone who is experiencing downloading issues with the files.

Transmitter Code

#include <SPI.h>
#include <Mirf.h>
#include <nRF24L01.h>
#include <MirfHardwareSpiDriver.h>

const int switchPin = 7;
const int VRy = A1;
int YPosition = 0;

long previousMillis = 0;
long interval = 20;

void setup() {
  Serial.begin(9600);
  Mirf.cePin = 9; 
  Mirf.csnPin = 10;
  Mirf.spi = &MirfHardwareSpi;
  Mirf.init(); //initialization
  Mirf.channel = 3; //Sending channel (0~128)
  Mirf.setRADDR((byte *)"Sen01");
  Mirf.payload = 2; //transmitting 2 bytes

Mirf.config();
Serial.println("I'm Sender...");

pinMode(VRy, INPUT);
pinMode(switchPin, INPUT);
}

void loop() {
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis > interval) {
    previousMillis = currentMillis;
    
    YPosition = analogRead(VRy);
    unsigned int Angle = map(YPosition, 0, 1023, 30, 150);

    int SwitchState = digitalRead(switchPin);
    
byte data[Mirf.payload];
data[0] = Angle; //array
data[1] = SwitchState;

Mirf.setTADDR((byte *)"Rec01");
Mirf.send(data);

while(Mirf.isSending());
  }
}

Receiver code

#include <SPI.h>
#include <Mirf.h>
#include <nRF24L01.h>
#include <MirfHardwareSpiDriver.h>

#include <Servo.h>
Servo ConServo;
Servo StepServo;

unsigned int Angle = 0;
int SwitchState = 0;

void setup() {
  Serial.begin(9600);
  Mirf.cePin = 9; 
  Mirf.csnPin = 10;
  Mirf.spi = &MirfHardwareSpi;
  Mirf.init(); //initialization
  
  Mirf.setRADDR((byte *)"Rec01");
  Mirf.payload = 2; //recieving 2 bytes 
  Mirf.channel = 3; // Sending channel (0~128)
  Mirf.config();

  ConServo.attach(6);  
  StepServo.attach(3);
  StepServo.write(90);
}

void loop() {
  byte data[Mirf.payload];
  if(Mirf.dataReady()) //Waiting to receive data. 
{
  Mirf.getData(data); //Receive data to data array. 
  Angle = (unsigned int)(data[0]); //to variables
  SwitchState = (int)(data[1]);
 
  Serial.print("Servo angle = ");
  Serial.print(Angle);
  Serial.print(";    Switch state = ");
  Serial.println(SwitchState);  
  }

  if (SwitchState == 0){
    ConServo.write(0); //rotate counterclockwise full speed (0-89)   
  }
  else{
    ConServo.write(90);
  }

  StepServo.write(Angle);
}

Once you have fully tested out the electronics and made sure that they work properly, you can ditch the breadboard on the reciever electronics to save space and weight. There is no need to solder the transmitter electronics as space and weight will not be a issue if i am holding them and reduces risk of short circuiting.

The video is a timelapse of me soldering all the components together, positioning all of the wires connected to the Nano pins perpendicularly in a way to reduce the vertical height of the Arduino Nano. There is no need to solder on the battery or the servos to its wires as they should come with a JST connection in which you can just insert postive and negative wires into the connection.

If you are new to soldering, make sure the electronics work before packing away the soldering iron as there is a good chance one of your connections has become loose or is shorting something.

Once the electronics are done, the glider chassis needs to be designed. In the left photo, it shows the dimensions of all the parts of the glider that are needed, in which the majority of the parts are cut out of corrugated cardboard. The top and bottom covers of the fuselage are cut out of card to save weight and are easier to glue together.

Shown in the top right photo, i used a blade cutter and a 30cm ruler to easily cut straight lines.

There is also a video of a timelapse of me cutting out all of the parts.

The bottom right photo shows which parts are which, which is important as the top and bottom covers made of card will fit only on the correct sides of the fuselage side parts.

Once you have cut out all of the parts needed, the fuselage is the first part of the glider needed to be created. Shown in the top left photo, taking one of the side parts, apply some superglue to the top edge of the part and then press down the top part made of card down onto the side piece shown in the top right and middle right photo. You should apply pressure for around 30-60 seconds to wait for the superglue to dry.

After connecting one side piece with the top cover, glue the other side piece to the top cover shown in the bottom left photo. Make sure both side pieces are parallel to each other as if they arent, the bottom cover will not fit properly on both side pieces.

Shown in the bottom right photo, apply superglue to the bottom edges of the side pieces and then press on the bottom cover onto the curved edge of the side pieces and again wait 30-60 seconds for the glue to dry, making sure that both the top and bottom pieces completely cover the side pieces. You should then be left with the main body of the glider.

Taking the fuselage that you previously created, turn it so that one of the side pieces is facing you. For future reference, the longer end of the side piece of the fuselage is the front of the fuselage and the shorter end is the back of the fuselage. Then using a pencil or pen, mark out the slots you will be cutting out of the side pieces on both sides. The dimensions and angles of what you are cutting are shown in the left photo, but bear in mind that the cardboard that i used to cut out the wings have a thickness of 3mm, which is why the slots have a width of 3mm to make sure the wings are secure. If your material has a different thickness, adjust the width of the slot you will be cutting out.

Copy the markings on the other side piece making sure they are identical. There should be one wing slot and one stabiliser slot on each side.

The reason for the wing slots to be angled shown in the left photo is so that maximum lift can be achieved when the glider is moving forwards. If the wings are angled too much such as past 45 degrees, they create too much drag and therefore decrease the speed of the glider to decrease, causing it to fall due to its lack of momentum. The stabiliser slots are not angled as their purpose is to make sure the glider stays vertically stable and not to achieve lift. The stabiliser slots should also reach the very end of the side piece.

Using the blade cutter again, cut out the slots carefully following the pink lines shown in the top right photo and once they are cut, apply superglue to the wings and stabilisers that were cut out previously in Step 3 shown in the middle right photo.

Make sure the wings and stabilisers fit in the slots cut for them and push them through the slots so that part of the wing/stabiliser is inside the fuselage (5mm-10mm) shown in the bottom right photo. This is done to secure the wings/stabilisers in place and to improve the integrity of the wings/stabilisers.

After adding both wings and stabilisers on each side, your glider should look like the bottom right photo.

By using a rudder, the glider is able to turn left and right. Shown in the left photo, take the back end of the plane with the top cover facing you and mark out the dimensions of the shape that needs to be cut out to fit the servo.

Using the blade cutter, cut out the shape following the lines shown in the top right photo and fit the bottom of the normal servo into the space you cut out. Make sure you have fit the normal servo in and not the continous servo as the mechanics for each servo is different.

Shown in the middle right photo, using superglue, attach the servo to the cardboard rudder piece (looks like a square with a right angled triangle on top of it) that you cut out in Step 3, making sure the shorter side of the rudder is closer to the front of the glider.

There is no need to glue the servo in its place as if you cut the shape out accurately, the friction between the two surfaces should stop it from slipping out. To stop it falling in, the servo has a extended ledge that wont fit in the space, shown in the bottom right photo. The servo wires should also be fed through the gap so that they are accessible inside the fuselage where the Nano will be.

The propeller i used is a 2 inch 3 blade propeller and has pre-drilled holes in the middle where the paperclip will fit through shown in the top left photo.

Shown in the top right photo, fit one end of the paperclip throught the hole in the middle of the propeller and then using blu-tack, fix the paperclip end in the propeller. You can use superglue to secure the paperclip to the propeller further but i would like to reuse the propeller later and so blu-tack is a good solution.

Once the paperclip is fixed to the propeller, turn the propeller around and using scissors shown in the middle right photo, cut off the rest of the paperclip, leaving around 3cm of paperclip length left. Straighten the paperclip and then create a 90 degree bend in the end of the paperclip shown in the bottom left photo.

Then, using the superglue you have, apply a reasonable amount on the same spot on the paperclip near the behind of the propeller. Shown in the bottom left photo, try to form a ball of superglue on the paperclip so that it acts as a stopper.

Once it dries, pierce a hole in the front piece of the fuselage cut out in Step 3. The hole needs to be the size so that the paperclip can fit through but the superglue stopper cannot, shown in the bottom right photo. This means the paperclip wont be pulled through the front of the fuselage when the rubber band is being twisted (when twisted, the length of the chain shortens). In the shape of a ball, it reduces the surface of friction between the stopper and the front of the fuselage. The propeller should freely spin without much friction, making it more efficient.

There are many tutorials online as to how to make a rubber band chain but i used this one. For the chain itself, i made a chain of 7 that was just over the length between the front of the fuselage and where the continous servo will be based. You want some excess length as mentioned before, as the chain is twisted, the length shortens.

Once creating the chain, superglue one end to the bent part of the paperclip attached to the propeller on the back of the front piece of the fuselage shown in the left photo, making sure not to accidently superglue the paperclip to the front piece as then it will become fixed permenantly.

Shown in the right photo, superglue the other end of the rubber band to the end of the continous servo, making sure both ends of the chain are securely glued.

You've attached the continous servo to the rubber band chain, but where does it go?

Shown in the left photo, mark out the rectangle shown and blah blah blah i think you now know what to do! Once cut out, place the servo ledge (the part that extends out outlined back in the servo rudder) over the space and press down so that it fits through with the wires on the inside of the fuselage shown in the right photo. You can then either use blu-tack or superglue to fix the servo in place so that it doesnt shuffle around. Make sure the part of the servo that rotates is facing towards the front of the fuselage.

The servo and rubber band chain needs to be feeded through the front of the fuselage before being fixed to make sure the rubber band is chain is also inside the fuselage.

Now to add the other electronics starting with the battery and regulator. This and the next parts can become very confusing quickly which is why i have provided a illustration of where all the electronics should be placed (except the servo rudder as thats obvious). Refer back to this drawing shown in the left photo if you ever get confused but for now, focus on the front part containing the battery and regulator.

The main thing that you need to be aware of is to make sure the rubber chain doesnt get tangled/interfere with the wires of the battery and regulator as that can cause many problems. To stop this, using the card i used to create the top and bottom covers of the fuselage, cut out a rectangle of the width of the inside of the fuselage and the length of the battery and the regulator so that it acts as a divider between the rubber band and the electronics, shown in the right photo.

When adding the regulator and battery under the divider, add the regulator first as that will be further from the front of the fuselage. The battery will be closer to the front as that will be last thing to connect together before sealing the fuselage and so it makes things easier.

After fitting the electronics at the front, now things get a bit more precise and complicated. To make things much easier, cut out the shape (for the last time i promise!) shown in the top left and top right photos so that it creates a flap that can be closed/open and allows access between the outside and inside of the fuselage.

Then turn the glider around so that the back of the fuselage is facing towards you. Before adding the Arduino Nano and wires, connect the Arduino Nano to both servo connnections as well as the regulator output wires that should be on the bottom of the fuselage. It might be a tight fit shown in the middle right photo and if the Nano doesnt fit in the space behind the continous servo, you can always extend the length of the fuselage by creating an add-on box attachment that creates more space.

So thats all the electronics execpt for the Nrf24l01 module, that will be positioned above the fuselage, though if you have the space, you can always fit the module inside the fuselage to reduce drag slightly. Shown in the bottom left photo, pull the required wires needed past the continous servo and to make things a bit more tidy, you can use wire or cable ties to make sure the wires stay together and tidy. In this case i used some spare brass wire that worked just fine.

To make sure the wires dont interfere with the rubber band chain, glue the wires to one side of the fuselage shown in the bottom middle photo. Once they are fixed in place, you can close the flap but allow the wires to pass by cutting out a small square on the side of the flap where the wires are. You can then connect the Nrf24l01 module to its wires shown in the circuit diagram in Step 1 and also in the bottom right photo. You can then either superglue or tape the Nrfl24l01 onto the top of the fuselage but make sure it doesnt make contact with the servo rudder behind it.

That's it! - For the electronics anyways. Once you've tested everything is working fine, take the front and back pieces and you can either glue them onto the front and back of the fuselage shown in the photos to complete the glider or you can tape them on so that you can take them back off easily if anything breaks which is what i ended up doing. To determine which piece is one, the back piece has a shorter height than the front piece.

This is completely OPTIONAL and if anything a bit of a disadvantage as it adds extra weight to the glider but in my opinion, adds so much character to the glider to make it worth the penalty! The video shows a timelapse of me painting the entire glider and if anyone was wondering, the inspiration for the colour of the glider was from the Porco Rosso plane shown.

Just bear in mind the cardboard can become weak and flimsy when wet with paint so try not to exert too much pressure when painting, especially on parts like the wings. Their strength is regained when the paint dries.

So, how do you fly it?

Before you fly it, the continous servo needs to transfer energy to the rubber band to be exerted in a short period of time later. To do this, flip the switch on the transmitter electronics and the servo should start turning continously. Keep this spinning for how ever long you want, (the longer the more energy) but bear in mind if you leave it too long either the propeller will be pulled through the front of the fuselage or the rubber band chain will snap. Keep the propeller fixed in place by either placing your hand there or attaching another rubber band glued to the side of the fuselage and loop it around one of the blades of the propeller to stop it from turning.

Once you feel enough energy has been stored up in the bands, flip the switch back to stop the servo and then let the glider go as well as the propeller (or unlatch the rubber band securing it in place), which should cause the propeller to turn rapidly.

On the transmitter electronics shown in the left photo, the joystick (X axis) dictates which angle the rudder is at so that you can control which way the glider turns, though i found through testing it made little difference, so either make the rudder bigger or incoroporate flaps controlled by another servo to the wings to make a bigger impact.

Anything else?

One huge tip that made a world of a difference is to make sure the centre of balance of the length of the glider is either near or on the length where the wings are attached. If the glider is tail heavy, it will cause it the glider to turn upwards, creating a larger surface area for air resistance and stopping it. If it is too nose heavy, it will plummet into the ground. To shift the position of the centre of balance, you can glue or tape coins onto the back/front of the fuselage.

If i were to do this again, perhaps i could had made the fuselage a bit more aerodynamic and maybe found other ways to reduce weight as the glider would only travel up to distances of 15 metres.

Thank you to all who viewed this as this is my first instructable created, formed out of the boredom of the summer after my GCSE's and hopefully you will have just as much fun building and designing this as i did. Please send any critisism/feedback or improvements i can make to my instructable as i would love to improve this skill.