DIY Quadcopter

In my previous Instructable, I've explained how to build a quadcopter (Design, Build and Improve a Quadcopter). I started with a QAV250 DIY quadcopter and changed the frame. Initially using a fan duct, later without. Finally the frame size was doubled from 5 inch propellers to 10 inch propellers.

I've made this "beginner DIY quadcopter", to learn how to fly. Flying a quadcopter isn't that hard. But combining various actions requires much practice (pitch, yaw and roll at the same time).
This quadcopter has the same size as my previous large quadcopter. Due to the large 10 inch propellers, It won't fly with very high speeds. This makes this an easy to fly quadcopter. And, after a while, It's always possible to increase the maximum speed of the quadcopter.

I ended the previous Instructable (after 30 steps) with some possible improvements. And this quadcopter contains some of these improvements. The first improvement is the flight controller. It's upgraded to a 10DOF controller. This means, It constantly measures 10 different values:

Gyroscope:      Senses rotational movement (3 axis). 
Accelerometer:  Senses changes in movement (3 axis).
Magnetometer:   Senses the variations in the magnetic field (3 axis). 
Barometer:      To detect changes in altitude (1 axis)

My previous quadcopter only contained a gyroscope and accelerometer (6DOF). And it required a constant adjustment of the height. This upgrade makes setting the height possible. To concentrate fully on steering.

The second improvement is the weight of the quadcopter. This quadcopter weighs about 700 gram (including the battery). This is 500 gram less than my previous build, and this extends the flight time.

This is a compact quadcopter. This means a lot of components in a small area (100 x 50 x 80 mm, 4 x 2 x 3 inch). It's not that hard to build, but it requires some solder and assembly skills.

Building a quadcopter requires the following parts:

• Frame
• Transmitter
• Receiver
• Flight controller
• Battery
• PDB (Power Distribution Board)
• ESCs (Electronic Speed Controller)
• Propellers
• Motors
• Charger

The frame for this quadcopter is made with a 3D printer. And the motor arms are made from aluminium tubes.

Construction:

• Aluminium tube (8 mm)
• bolts and nuts (3 mm)
• threaded rod (3 mm, 4 x 80 mm)
• Insulation tape
• Battery Velcro Cable Tie Down Straps

Electronic components:

• Flysky I6 2.4G 6 Channel Transmitter and Receiver
• Naze32 10DOF Flight Controller or CC3D OpenPilot Flight Controller
• ZOP Power 1500mAh 11.1V 40C Battery
• XT60 Power Distribution Board
• Flycolor Raptor BLHeli 2 - 4S 30A Opto ESC
• Emax 2216 motors (2x CW and 2x CCW) with propellers

All parts are commonly available items. Total costs for all electronic components is about $200.

The frame for this quadcopter is designed with Fusion 360. It's an easy to learn CAD program. The basics of this program is explained in the Autodesk Fusion 360 Youtube channel.

All parts are printed with an 3D printer.

There are 6 different parts:

1. Motor mount (Lower part, 4x)
2. Motor mount (Upper part, 4x)
3. Body lower part (PDB and ESC)
4. Body middle part (Battery)
5. Body upper part (Flight controller)
6. Cross bar (4x)

I've used the eCalc website for all calculations. This makes it possible to make calculations in advance. These calculations provide an overview of the quadcopter. The total weight is about 700 gram (I've put all individual parts on a balance scale.).

The expected flight time is about 11 minutes with a 1500 mAh battery. My 2200 battery gives a flight time of 13 minutes. This is not linear because of the additional weight of 100 gram.

Although this is a light quadcopter, it's not a very fast quadcopter. This is because the quadcopter uses 10 inch propellers. The maximum speed is about 34 km/h (21 mph) with a 6.9 m/s rate of climb.

In order to increase the speed, it is possible to use a 4S battery. This adds some weight to the quadcopter, but a higher voltage is more efficient. The expected flight time will be 14 minutes, with a maximum speed of 50 km/h (31 mph).

It's also possible to build this quadcopter with smaller motors and propellers. This saves some weight for the motor arms, motors and propellers. The aluminium weights about 50 gram per meter. Shortening 4 arms by 7 centimeter saves 14 gram. Use of Emax RS2205 2600KV motors saves (63 - 29) 34 gram per motor. And the 5030 propellers are lighter than the 1047 propellers. The total weight will be about 500 gram (with battery).

Using a 3S battery with 5030 propellers gives a maximum speed of 80 km/h (49,7 mph). Switching to 4S increases the maximum speed to 104 km/h (64,6 mph).

But for a real fast quadcopter, the propellers need to be even smaller. This allows the motors to spin at a higher speed (this is explained in my previous Instructable). The same calculations with a 4045 propeller and a 4S battery gives a maximum speed of about 160 km/h (100 mph).

This will be a compact quadcopter. It contains many electronic components, which have to be connected with each other. And there are many wires between these components.

Although it seems a tangle of wires, there is still some logic. The third image shows all electronic components of a quadcopter. The receiver (on the left) is connected to the flight controller. All signals from the transmitter are passed to the flight controller.

The flight controller is the heart of your quadcopter. It constantly measures the 10 axes (10DOF). And gives control signals to the ESCs (just like a servo motor). The ESCs translates these signals to the corresponding motor speeds.

All power comes from a battery. That is connected to the power distribution board. This board provides power to the ESCs. There is also a DC to DC converter for a 5 volt output, required for the flight controller and receiver.

Most DIY quadcopters have the ESCs placed on top of the motor arms. I've decided to place them inside the frame. As a result it is possible for the motor wires to go through the motor arms. These are 8mm aluminium tubes. And the 3 wires neatly fit inside.

All motor arms have a length of 20 centimeters. This Gives enough space for the 10 inch propellers. Use 3 mm bolts to connect the motor to the motor arm.
All motor arms are connected to the lower frame part. Use the cross bars for additional strength.

The ESCs used for this quadcopter are OPTO ESCs. This means there is no direct electrical contact between the controller and the motors. As a result there is no 5 Volt output from the ESC. This means we need a Power Distribution Board (PDB). This provides a 5 Volt output.

Solder the ESCs wires to the PDB. Make sure these wires are pointing towards inside the frame (second image). There is little room inside the frame. Don't forget to solder a wire to the 5 Volt (red) and ground (black). This is used to power the flight controller and the receiver.

The ESCs and PDB are placed inside the lower frame part during assembly.

The middle piece of the frame is used as an battery compartment. The battery is the heaviest part of the quadcopter. That's why I've placed it in the middle.

The velcro cable tie is too large for this quadcopter. I've shortened it, and attached it to the frame. This way, the velcro doesn't touch the wiring beneath the battery.

The tube (front) is used for protecting the signal wires.

The upper part of the quadcopter contains the receiver and the flight controller. These parts will be placed inside the frame. Use the supplied vibration pad to attach the flight controller to the frame. Mount the flight controller upside down on this part. The plate will be inverted, while assembling.

The receiver is placed in the receiver-compartment (on the left).

Before assembling the quadcopter, we need to check the motor directions. This has to be done before soldering of the motors to the ESCs. This quadcopter has a compact frame, there is no room for banana bullet connectors.

There is a difference between LibrePilot and CleanFlight motor configuration. The left front motor is number 1 in LibrePilot, and number 4 in CleanFlight. That's why I've marked all motors and ESCs:

1. Gray
2. Blue
3. Black
4. Red

Connect all ESCs with the assigned motor. Connect the signal wires with the Flight controller. The flight controller is lying upside down. So start from left to right, with the black wire (ground) upwards. Connect the red 5 Volt wire to a middle pin (it doesn't matter which one). And don't forget to connect the ground wire (near the other ground wires).

Start CleanFlight and open the motor settings screen. Connect the battery and test the motor directions. change 2 out of 3 wires, if the motor is rotating in the wrong direction. There is no need to save the configuration settings. This step is only done to check the motor directions.

Now it's time to assemble the different parts. Start with placing the PDB and the ESCs. Use some tape to keep the ESCs on place (temporarily). Solder the motors to the ESCs. Do this one by one. All wires need to be shortened, there is little room inside the frame The two crossbars provide additional room for the wires.

Place the battery holder on top of the cross bars. Make sure the signal wires (and the 5 volt and ground) are going through the tube. Fasten the bolts for the lower part. The arms shouldn't be able to move.

Connect the ESC and power wires to the flight controller (just like the previous step). The remote controller requires the following wiring:

Channel 1    io_1 pin 3     Throttle
Channel 2    io_1 pin 4     Roll
Channel 3    io_2 pin 3     Pitch
Channel 4    io_2 pin 4     Yaw
Channel 5    io_1 pin 5     User Defined
Channel 6    io_1 pin 6     User Defined

Tie the wires neatly together. There are 2 mounting holes for the wires.

Finally place the upper part above the battery compartment. Use 8 nuts. Make sure all nuts and bolts are tightened.

After the assembly, it's time to change the CleanFlight settings. Although LibrePilot might be easyer to work with, I start with using CleanFlight, This is the default firmware for this flight controller (If you have bought a CC3D controller, then read my previous Instructable about configuring the controller).

There is no wizard like in LibrePilot. Start with connecting the flight controller to a computer, and start CleanFlight. Use the connect button to establish a connection. The first step is to calibrate the accelerometer and the magnetometer.

After calibrating, it's time to configure the receiver. Connect the battery to the quadcopter (with no propellers attached!). The Flysky receiver requires channel mapping "AETR4321". Test the remote controller before proceeding.

There are 2 channels left on the transmitter (four are used for the different flight controls). I've assigned switches to channel 5 and channel 6. And these channels are asigned to AUX3 and AUX4 in CleanFlight. These AUX-channels can be asigned to 'modes' (third image). The first switch has 2 positions, and I use it to arm and disarm the quadcopter.
The second switch has 3 positions. Position 1 enables Angle mode. Position 2 and 3 enable Horizon mode. Position 3 also enables the barometer for altitude locking.

Horizon and Angle mode are 2 diferent assisted flight modes The the flight controller always attempts to level the quadcopter automatically. Horizon (self-level) mode is the easiest to fly, because when you leave the stick at the centre and not controlling it, your drone just level itself and stays there.

After configuring the CleanFlight software, it's time for a first flight. And it is worth noting that the quadcopter weighs little. The thrust to weight ratio is almost 3. This can be noticed while flying.

Afterwards, this video was made in Acro mode. That's why the quadcopter was more dificult to control, than using a CC3D controller with OpenPilot.

The second flight was made in the CleanFlight horizon mode, without altitude lock.

Now it's time to start flying with this quadcopter. I have no idea if it can make flips, but time will tell...

G o s s e _ A d e m a