# Design, Build and Improve a Quadcopter

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## Introduction: Design, Build and Improve a Quadcopter

First Prize in the
Drones Contest 2016

In this Instructable I'll describe my first self-build quadcopters. I'll begin with a brief introduction about quadcopters. And a description of all parts, using an existing "DIY quadcopter Kit" as an example. Then I make some calculations about these quadcopter. This way we know, before the build, what to expect from this quadcopter. Then I repeat these steps, for another multirotor model: a hexacopter.
I have ordered the necessary parts on the basis of these calculations. Here I have been taken into account that most parts will be reused, for the build of a second quadcopter.

After these steps, a quadcopter is made according to the plan. And after building the quadcopter and the first flights, the flight results are compared with the calculations.

Then I investigate how to change and improve a quadcopter. The first change will be a new frame (Which I create on my own way). And before the making of improvements, I made calculations about the speed and flight time. In this way, we can retrospectively determine whether the changes have made the desired effect. This way I have made some improvements to my quadcopter, aiming mainly to extend the flight time.

As a conclusion, the size of the quadcopter is doubled. With reusing of most parts from the first quadcopter. And even of this model I have made all calculations in advance. The end result is an unusual self-build quadcopter.

After reading of this Instructable, it should be possible not only to create your own quadcopter. But also to determine (in advance) the expected properties of the quadcopter .

All in all, quite a lot of different steps. And especially for building a first quadcopter. But with the necessary preparation, and by taking small steps. I managed to design my 'own' quadcoper.

## Step 1: Gearbest

Before the writing of these instructable, I had no experience with quadcopters. And I want to thank Gearbest for providing some of the necessary quadcopter parts. Without mail from their Online Marketing Department, I wouldn't have build this kind of quadcopter.

The mail contained a link to "Multi Rotor Parts". And initially I started designing my own quadcopter, with all necessary parts. And this were more components than expected by Gearbest. Afterwards it turned out that it was intended to choose a single product. And to write a review.

Instead, my proposal contained the following components:

• Building of a quadcopter (using 5 inch propellers).
• Modifying the frame.
• Try to increase the flight time.
• Doubling the size of the quadcopter (towards 10 inch propellers).

In retrospect quite a lot for someone without "flight experience".

I am therefore grateful that Gearbest has left me completely free while creating this Instructable.

I have taken into account that everyone should be able to build this quadcopter. That's why I've tried to minimize the number of required parts. I also opted for commonly available items. This makes it possible for anyone, with the help of this Instructable, to make a similar quadcopter. And at the end of this Instructable, I will give a list of all materials used.

## Step 2: Safety

In this step, I can copy the warning of my first Instructable: "This is not a toy."

Some steps in this Instructable are about adjusting parts of a quadcopter. These are partly structural and partly electrical. These modifications result in changes in flight behavior. This can be both positive and negative. Assume that the quadcopter always can crash during one of the flights.

Check the wiring after changes in the electronics. The used Lipo batteries can supply a lot of current in a short time. Always remove the battery before altering the quadcopter. A short circuit can result in a fire.

Maintain a safe distance to your quadcopter. Take local regulations into account. Don't fly near other people, airports or (public) buildings. And keep the quadcopter always in sight.

## Step 3: Q250 Quadcopter Example

The Q250 quadcopter has all required items and it's sold as an DIY kit. It contains, as any quadcopter, the following main parts (image 1 and 2):

1. Frame
2. Transmitter
4. Flight controller
5. Battery
6. PDB (Power Distribution Board)
7. ESCs (Electronic Speed Controller)
8. Propellers
9. Motors
10. Charger

### Frame

The frame is used for holding/mounting/carying all other items. There are many different types and sizes of multi-rotor frames. The third image shows the three mostly used configurations: The Quadcopter, the X-Copter and the Hexacopter. In addition to these configurations, there are some other less common types.

This is a so called X-Copter, and these type of frames are build for speed and acrobatical movement.
The distance between the motors is 250 mm (Q250) and the propellers should match the size of the frame. This frame is build for using 5" propellers.

The transmitter and receiver are used to communicate with the quadcopter. They must match, and your quadcopter should only respond to your controller. It's mainly used for flight control. But you can also use it for controlling an attached camera.

### Flight Controller

There are different types of sensors. And the most important are:

```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)```

The gyroscope only measures changes in the angles. This is required for leveling out your quadcopter. The accelerometer measures the direction in which the quadcopter is going. These sensors are the minimum required for a flight controller. These controllers are called 6DOF flight controllers. All measured values are changes relative to the previous position.

The magnetometer measures the variations in the magnetic field of the earth. And provides an electronic compass. This way we measure the angles relative to the earth. The barometer is used to measure barometric pressure, which in turn can detect changes in altitude. Flight controllers, which have all 4 sensors, are called 10DOF flight controllers.

A fifth sensor could be GPS (Global positioning system). With a GPS system added, the quadcopter always knows its exact location.

The flight controller which comes with the Q250 is a 6DOF controller. The pilot must adjust the height and the direction almost continually.

### Battery

Most quadcopters use LiPo (Lithium Polymer) batteries. These batteries not only differ in the ammount of energy stored (mAh, the ammount of current the battery can deliver for 1 hour). Batteries also differ in voltage. Most quadcopter batteries are 7.4 volt, 11.1 volt or 14.8 volt. They are refered as 2S, 3S and 4S types (the number equals the number of cells placed in series).

``` 3.7 volt battery = 1 cell x 3.7 volts (1S)
7.4 volt battery = 2 cells x 3.7 volts (2S)
11.1 volt battery = 3 cells x 3.7 volts (3S)
14.8 volt battery = 4 cells x 3.7 volts (4S)
```

Some batteries also have an P-value (3S2P), this means the number of cells in parallel. This doubles the capacity, but also the weight.

The supplied battery has a capacity of 2200mAh, with a C value of 25. And contains 3 cells. This means it is able to give 2.2 Ampere (at 11.1 volt) for 1 hour. But it can deliver up to 55 Ampere (25 x 2.2).

### Power Distribution Board

Next part is the power distribution board (PDB or ESC connection board). The battery delivers power to the 4 ESCs and several other items (e.g. flight controller). This board connects them all together. With this quadcopter the PDB is integrated in the frame.

### Electronic Speed Controller

The flight controller determines the required speed of the motors, but is not capable of handling high currents. This is the task of the Electronic Speed Controller (ESC). The ESC gets it's power from the power distribution board. While the required speed-signal is deliverd by the flight controller. That's why there is one ESC for each motor.

The "12A"value, in our ESC example, means that it is capable of delivering 12 Ampere. This is the Continuous current: 12A. There is also a Burst current( for 10 seconds ): 15A.

```          | Normal  |  Burst  |       |        |
| Current | Current | Cells | Weight |
----------+---------+---------+-------+--------+
Simon-12A |  12A    |  15A    | 1-3S  |   8 g  |
Simon-20A |  20A    |  25A    | 2-3S  |  28 g  |
Simon-25A |  25A    |  30A    | 2-3S  |  28 g  |
Simon-30A |  30A    |  40A    | 2-3S  |  28 g  |
Simon-40A |  40A    |  50A    | 2-3S  |  41 g  |```

The ESC value must match your motor and battery. 4 motors x 15 Amp = 60 Amp. The battery can handle 55A, but it's better to have a higher value for the ESC. But also keep the weight of the ESC in mind. A larger continues current might also mean a larger weight.

### Propellers

The Q250 quadcopter has 5030 propellers. The number 5030 defines two values. The first value is 5.0. This means the total length is 5 inch (127 mm). A bigger propeller means more lift, but also more workload (more power usage) for the motor.

The second value (3.0) is the pitch of the propeller. Pitch is defined as "the distance a propeller would move in one revolution" . In our example, a 3.0-pitch propeller would move up 3 inches in one revolution without any gravity. Essentially, the higher the pitch value, the faster your quadcopter will go.

### Motors

Final part is the motor. There are several items to account for. This requires reading the motor specifications:

```KV:              2300
Number of cell : 2-3S
Weight:          25 gram```

KV is a constant that tells you the RPM of the motor when a potential difference of 1V is applied with no load. The motors 3 have connecting wires. This makes it impossible to apply direct voltage on the motors (always use an ESC). A higher voltage on the ESC gives a higher voltage on the motor. Resulting in a higher generated magnetic power. Or the same magnetic power, as with the lower voltage, at a higher rotational speed. This is why a higher voltage gives a higher speed.

Using a 7.4 (2S) volt battery will give 7,4 x 2300 = 17020 rpm with no load. An 11.1 (3S) volt battery will give 11,1 x 2300 = 25530 rpm.

The Q250 example quadcopter is equipped with a 5030 size propeller. This means we have to look at these 2 lines in the motor specification table:

```voltage   | propeller | current | thrust | speed     |
----------+-----------+---------+--------+-----------+
(2S)  7.4 |  5030     |  4.4 A  |  210 g | 13530 rpm |
(3S) 11.1 |  5030     |  8.0 A  |  380 g | 18510 rpm |```

There are 4 motors. When using 2S batteries, the total thrust equals 4 x 210 = 840 gram. The Q250 Example uses 3S batteries, and the total thrust almost doubles to 4 x 380 = 1520 gram. This should be enought to lift this quadcopter.

In the next step there are some further calculations for this Quadcopter.

## Step 4: Q250 Quadcopter Calculations

Before making any calculations we need to know the total weight of the quadcopter:

```1 x Frame                       108 gram
1 x Flight controller            25 gram
1 x Battery                     167 gram (3s, other brand)
4 x ESC                4 x  8 =  32 gram
4 x Propeller          4 x  2 =   8 gram
4 x Motor              4 x 25 = 100 gram
```

This gives a total weight of 444 gram. The total lift is 1520 gram (previous step). This gives a weight to lift ratio of 0.29 (444/1520).

According the motor specifications, the motors require 8 Ampere at full power. Using a linear ratio, the assumed usage is 8 x 0.29 = 2,32 Ampere per motor. The total number of required ampere equals 9,28A during normal flight.

The example battery has an rating of 2200mAH. But you you should never discharge a LiPo pack down past 85% of its capacity, to be safe. This translates in 2200 x 0,85 = 1870 mAH for this battery

Divide this number by the power used, gives the estimated flight time in hours. 1,870 / 9,28 = 0,2 hour. This means an estimated flight time of 12 minutes.

The calculated value corresponds approximately with the expected duration of flight of an RC quadcopter. It does not seem long, but a RC quadcopter is created for agility and speed.

For checking my calculations I went looking for calculations of a similar quadcopter. At one forum I came across a reference to the eCalc website. They claim to be "the most reliable RC Calculator on the Web". After signing up I could make the same calculation as the one above. This shows, in addition to information about the expected time of flight, much more information about the quadcopter.

The results of the Gearvest DIY Q250 set are as follows:

```Min flight time:    3.6 min
Mixed flight time:  9.1 min
Hover flight time: 14.9 min

Max speed:         61 km/h (37.9 mph)
Rate of climb:     10 m/s

All up weight:    444 gram

The 12 minutes flight time, from my calculations, is between the mixed and hover flight time. And the maximum weight for this quadcopter equals 919 gram. This makes sense, because it will never take off if the weight equals the maximum lift of the motors.

## Step 5: DJI F550 Hexacopter Example

My second example is a different type of multirotor: A hexacopter. These are usually larger than quadcopters. This allows for a more stabilized flight. And therefore more suitable for taking pictures and video recordings.

The prevous example has 5 inch propellers, this one has 10 inch propellers. This requires a larger frame. And the size of this frame is 550 mm (about 22 inch).

Larger propellers are more efficient than smaller propellers. They rotate at a lower speed to achieve the same lift. And therefore require other motors. The number of rotations per minute is even less than half that of the previous example.

I found the following motor with the required specifications for this hexacopter: The EMAX MT2216 II. This motor requires a voltage of 11.1 or 14.8 volt. This translates to 3S or 4S batteries. The propeller sizes, mentionend in the specifications (second image), are a 8, 9 or 10 inch. The “45” in the propeller size is the propeller pitch.

My example uses 3S batteries (just like the 250-size quadcopter example) and 10 inch propellers. This gives the following details (from the corresponding line in the motor specifications):

```Motor type:     MT2216 II 810KV
Voltage:        11.1 V
Propeller size: EMAX1045
Current:        9.8 A
Thrust:         670 G
Power:          108,8 W
Efficiency:     6.2 G/W
Speed:          6620 RPM```

The maximum thrust for this hexacopter is about 4 kilogram (6 x 670 gram). At full load this requires a power of 650 watts. With a battery current which equals 6 x 9.8 = 58.8 Ampere.

Next parts are the ESCs. There are 10A, 12A, 20A, 30A (and up) ESCs. The maximum current is 9,8 Ampere. And having 20% extra is a good rule of thumb. This means a 12A ESC will work, but I would recommend using a 20A ESC.

The hexacopter requires a total of six 1045 propellers. These are usually sold by four, but a few spare propellers is recommended anyway.

With use of all above parts selected, we can determine the total weight (without battery) of the hexacopter:

```Frame                    424 gram
Landing gear:   4 x 18 =  72 gram
Motors:         6 x 63 = 378 gram
20A ESC:        6 x 10 = 168 gram
Power board:              15 gram
Flight control:           23 gram
Propeller:      6 * 10 =  60 gram
miscellaneous:            50 gram```

The weight of the hexacopter is 1085 gram (without battery). The maximum lift is 4020 gram.

Using a 5200mAh 11.1V 30C Battery, adds 357gram to the total weight. The total weight becomes 1442 gram. This gives a lift to weight ratio of 4020/1442 = 2,78.

The 5200mAh battery delivers 5.2 Ampere for one hour. To extend the lifetime of the Lipo battery, only 85% can be used. This gives 4.4 Ampere for 1 hour. The flight time at maximum load requires 58.8 ampere. This means this battery is empty after 4.5 minutes (60 * 4.4 / 58.8).

These 4.5 minutes are at full power. The actual load is only 36% of the maximum load. We can multiply the flight time with the lift to weight ratio for an more realistic value. This results in an estimated flight time of 12.5 minutes.

I have made the same calculations with eCalc. This results in a mixed flight time of 12.8 minutes and a hover flight time of 18 minutes. The maximum speed is about 34 km/h (21 mph).

These type of multirotors are built to carry a camera. And this means additional weight. The following table gives detailed information about flight times (minutes) when changing the weight of the hexacopter.

```Weight| Mixed  | Hover | Max speed  | Rotor |
gram  | flight | flight| km/h | mph | fail  |
------+--------+-------+------+-----+----- -+
1200  |  15.2  |  23.8 |  37  |  23 | green |
1300  |  14.1  |  21.2 |  37  |  23 | green |
1400  |  13.2  |  19.0 |  36  |  22 | green |
1450  |  12.8  |  18.0 |  34  |  21 | green |
1500  |  12.4  |  17.1 |  33  |  20 | green |
1550  |  12.0  |  16.3 |  33  |  20 | green |
1600  |  11.6  |  15.5 |  32  |  19 | green |
1700  |  10.9  |  14.2 |  31  |  19 | green |
1800  |  10.3  |  13.0 |  30  |  18 | orange|
1900  |   9.7  |  12.0 |  28  |  17 | orange|
2000  |   9.1  |  11.0 |  27  |  16 | orange|
2100  |   8.6  |  10.2 |  25  |  15 | orange|
2200  |   8.1  |   9.5 |  23  |  14 | red   |
2300  |   7.7  |   8.9 |  20  |  12 | red   |
2400  |   7.3  |   8.3 |  19  |  11 | red   |
2500  |   6.9  |   7.8 |  16  |   9 | red   |```

Rotor fail is a prediction of the resulting controlability of your multicopter in case of a rotor/engine failure. Green means resistant to single Rotor Failure, orange means probable controlable for a immediate emergency landing and red means uncontrolable.

## Step 6: Q250 Remote Controller

The Flysky I6 remote controller is a 6 channel transmitter. This number of channels determines how many individual actions on the quadcopter can be controlled.
A quadcopter requires four channels for moving. This means there are 4 different ways to move the quadcopter:

1: Throttle: move the left stick forwards or backwards.

This controls the altitude. Move the stick forwards, to increase the speed of all motors. Moving Backwards, decreases the speed of the motors.

2: Pitch: move the right stick forwards or backwards.

This is used to move forwards or backwards. Move the stick forwards to increase the speed of the rear motors, and decrease the speed of the front motors. As a result, the quadcopter will move forwards.

3: Roll: move the right stick to the left or to the right.

This is used to move sideways, to the left or right. Move the stick to the left, and the speed of the motors on the right side will increase. The speed of the motors on the left is decreased. And the quadcopter moves to the left.

4: Yaw : move the left stick to the left or to the right.

This alters the direction of the quadcopter. Yaw to left, means turn to the left. All motor which rotate clockwise are given a higher speed, and all motors moving counter clockwise are given a lower speed. This results in turning the quadcopter.

It's always possible, and mostly necessary, to combine multiple actions.

All directions have a correspending trim button. This can be used to adjust the "zero" value. In normal situations this isn't necessary, because we calibrate the remote controller right after configuring the flight controller.

This controller has 6 channels. There are 2 channels left for other operations. These can be assigned to the switches on top of the transmitter. Possible actions are: changing the flight mode (auto, manual), controlling leds or use a camera and a gimmball.

## Step 7: Ordering Parts for a Quadcopter

I had the option to choose between many loose components, or one of the many DIY sets, for obtaining parts for my quadcopter. And I didn't want to use vendor specific parts (for example, a mainboard used only in a specific brand quadcopter).

My first quadcopter requires the following parts:

• Frame
• Flight controller
• Battery (and charger)
• Power distribution board
• ESCs
• Motors (2000-2500KV)
• Propellers (5")

And for the second (and bigger) quadcopter:

• ESCs (20A)
• Motors (800 - 1000KV)
• Propellers (10")

When I started with these Instructable, there were several DIY quadcopter kits on the Gearbest website. And I've chosen the Q250 set for my first example. Because it has a simple design, and it includes only easily available parts.

There are 2 other sets, on the Gearbest website, very similar to the Q250 set:

The following table shows the differces between the 3 sets:

```Part                     | QAV250 - FS I6   | QAV250 - AT9     | Q250 - FS I6
-------------------------+------------------+------------------+-----------------
frame                    | QAV250           | QAV250           | Q250
flight controller        | CC3D             | CC3D             | CC3D
battery                  | 25C 2200mAh      | 25C 2200mAh      | 25C 2200mAh
charger                  | Skyrc E3         | Skyrc E3         | Skyrc E3
power distribution board | ?                | ?                | Frame
ESCs                     | BLHeli 20A       | BLHeli 12A       | Simonk 12A
motors                   | Emax 2204/2300KV | Emax 1806/2280KV | Emax 2204/2300KV
propellers               | 5030             | 5030             | 5030

The main differences are the ESCs, the motors, the transmitter and/or the frame. Although I chose the Q250 as an example, I choose to build the UAV250, because it has 20A ESCs. These ESCs can be reused for the large quadcopters. This means the large quadcopter requires merely additional motors (EMAX MT2216) and propellers. And 1045 propellers are supplied with the motors.

My initial shopping cart contained the following items:

I myself have ordered some batteries and small parts:

I've ordered 3 batteries. And they will be used in the small and the large quadcopter. The small quadcopter requires only one battery (at the same time). But I can use multiple batteries for my large quadcopter (placed in parallel).

## Step 8: QAV250 Quadcopter Build - Part 1

The first Gearbest shipment contained the QAV250 DIY kit. And after unpacking it seems to be a real DIY kit. It lacks a fancy box. And all parts are regular parts, which are well packed in a cardboard box. And it really includes all the components you need to complete your build. DIY also means "no manual". The only manual is about building the frame.

The first picture shows all items for this quadcopter. And the other pictures in this step are about building the frame and placing the motors with the ESCs.

The first step is building the frame. But you don't have to tighten all screws. The bottom part will be removed in a further step.

The fourth picture shows all electronic components.

Connect the banana bullet connectors to the motors and the ESCs. They have to be soldered to the side with the 3 wires. Use one type connector for the motors (e.g. female) and the other type for the ESCs. Isolate the connectors with the supplied shrink wrap. You can connect the motors to the ESCs. Be aware that wires might to be changed, to make the motors spin in the correct direction. I chose not to shorten the wires. Because I want to reuse the parts for another quadcopter.

Solder the red (positive) and black (negative) wire to the (T-plug) power connector. Make sure the wires are connected to the correct side. Use shrink wrap for isolation.

The the way the propeller nut unlocks is the direction the motor should spin in. The thread is the only difference between a CW and CWW motor. Attach the motors on the frame, as follows:

1. black: front left
2. silver: front right
3. black: back right
4. silver: back left

The supplied ESCs are too large to fit between the bottom plates. The best place is on the motor arms. Place them with the 3 wires directed to the motor. But make sure they don't touch the motor. The motors must be able to rotate freely. Use zip-ties to attach the ESCs to the arms.

Turn the quadcopter upside down, and remove the bottom plate. This quadcopter doesn't have a power distribution board. Because it doesn't really require one. And there is enough wire to make all connections. Place the T-plug connector toward the rear. Start with connecting all 5 red wires. Then connect all 5 black wires with each other. Isolate all the connections. Install the bottom plate carefully.

By now, we have the majority of the frame built. The motors are attached to the arms, and they are connected to the ESCs. And we have made a power distribution system. Next step is to connect the flight controller and the receiver.

Continue with the following 3 steps for finishing the quadcopter:

• QAV250/Q250 quadcopter build - Part 2
• Librepilot Software Configuration
• Remote Controller Configuration

## Step 9: Q250 Quadcopter Build - Part 1

After building of the QAV250 quadcopter, I received a mail from Gearbest. With the question, if I could make building instructions for the Q250 quadcopter?
The only differences, between the QAV250 and Q250, are the frame and the ESCs. My quadcopter came without a battery (because of the LiPo shipping policy), but a battery (and transmitter) is included in the DIY kit.

Buiding this quadcopter is almost the same as building the QAV250 quadcopter. But there are some differences. The first step is finding a place for all components. The motors location is very clear. But there is little room between the propellers and the motor arms for placing the ESCs. For this reason I've decided to place the ESCs underneath the motor arms.

In contrast with the QAV250, the Q250 has a power distribution board. This is integrated in the bottom plate of the frame. There is no 5 Volt regulator, it's only for powering the ESCs. The fifth image show the wiring of the PDB, ESCs and motors. The ESCs provide the 5 Volt output, required for the flight controller.

Connect the banana bullet connectors to the motors and the ESCs. Be aware that these wires might to be changed, to make the motors spin in the correct direction. This can be done by changing two out of three wires. Solder the ESCs to the Power Distribution Board. Isolate all banana connectors with the supplied shrink wrap. You can shorten all wires, if you want to.

Attach the motors to the motorarms and build the frame. The front left motor must have a black bolt (CCW). The front right motor must have a Silver bolt (CW). Reverse this setup for the backside of the quadcopter.

Connect the ESCs and place them underneath the motorarms. I've used adhesive tape for temporarily fastening the ESCs. Replace this with zip ties after configuring the flight controller.

Solder the red and black wire to the T-plug connector. Then solder the battery plug to the frame.

Continue with the following 3 steps:

• QAV250/Q250 quadcopter build - Part 2
• Librepilot Software Configuration
• Remote Controller Configuration

Don't forget to replace the adhesive tape with zipties, after configuring the flight controller.

## Step 10: QAV250/Q250 Quadcopter Build - Part 2

This step is about the flight controller and the receiver. The flight controller can be placed on top of the frame (anti vibration pad). And the receiver can be placed underneath (QAV250) or near (Q250) the flight controller. Notice the arrow on the flight controller. This arrow indicates forwards! And we need to be able to access the USB plug, after placing the flight controller.

The ESCs connectors are placed on top of the flight controller (image 1), and they are numbered from 1 to 6. These numbers correspond to the following ESCs:

1. front left motor ESC (black, CCW thread)
2. front right motor ESC (silver, CW thread)
3. back right motor ESC (black, CCW thread)
4. back left motor ESC (silver, CW thread)
5. unused
6. unused

The yellow wire is the signal wire. The red and brown are the +5 Volt and the ground. The flight controller is powered by the ESCs. And each ESC has a 5 Volt output. We only need power from one ESC, but it is safe to connect them all.

The receiverport on the CC3D flight controller has the following connections (from left to right, image 4):

1. Ground
2. Power (5 Volt)
3. PWM signal 1 = Throttle
4. PWM signal 2 = Roll
5. PWM signal 3 = Pitch
6. PWM signal 4 = Yaw
7. PWM signal 5 = Flight mode
8. PWM signal 6

These must be connected to the FS-IA6 receiver. PWM signals 1 to 6 are connected to channel 1 to 6 (from left to right: blue, yellow, white, green, blue, yellow). The ground wire (black) is connected to one of the 6 ground pins. And the power wire (red) is connected to one of the 6 power pins (image 4).

After connecting and placing the receiver and flight controller, it's time to place the (charged) battery, Using the velcro straps. We connect the battery in the next step.

By now the quadcopter is almost finished. The next step is to configure the firmware of the flight controller.

## Step 11: Librepilot Software Configuration

The CC3D flight controller comes with pre-installed OpenPilot firmware. This firmware needs to be configured to meet your quadcopters need.

You'll need a mini-USB cable to connect the flight controller with your computer. And after downloading the software you can configurie the quadcopter using the Vehicle Setup Wizard.

Don't forget to remove all propellers before proceeding.

Configuring is very easy.The hardest part was finding the required software, because the Openpilot.org website isn't accessable. After a while I found out why (OpenPilot wiki): OpenPilot was a Free software unmanned aerial vehicle project for model aircraft aimed at supporting both multi-rotor craft as well as fixed-wing aircraft. OpenPilot was discontinued and reinitialized as LibrePilot.

Before proceeding it's time to bind the transmitter and receiver together. Place the supplied bind wire to the (shown in the first image) 3 connectors which are labeled B/VCC. Turn on the transmitter, and press (and hold) the bind key. Connect the battery with the quadcopter. This will give power to the flight controller and the receiver. The led indicator on the receiver starts flashing. Wait until the led stops flashing. Now remove the battery and turn off the transmitter. Don't forget to remove the bind wire.

Start the "Vehicle Setup Wizard". Before configuring the flight controller, the firmware must be updated. Choose to erase all settings, because this is a new configuration. After upgrading it's time to identify the board. This is an Openpilot CopterControl 3D board (this is automatically detected). The receiver uses PWM (pulse-width modulation) signals.

This flight controller can controll different types of vehicles. Choose the multirotor. I couldn't find the proper value for the Emax Simon ESCs: I use the default value (Rapid ESC).

This is a "Quadcopter X" configuration. Take notice of the direction of rotation of the motors These should match your quadcopter.

This ends the first part of the configuration.

Place the quadcopter on a flat (leveled) surface. The next step starts with calibrating the accelerometer and the gyroscope.
The ESCs need to be calibrated to use the full throttle range of the flight controller. Follow all 7 steps.

After calibrating the ESCs it's time to calibrate the output levels. Follow the instructions and move the slider until the motor just starts to spin stable. You can calibrate all motors at the same time, if you want. Make sure the motor rotates in the corrospending direction. If the motor spins in the opposite direction, you have to change 2 out of 3 wires between the motor and the ESC.

This wizzard only sets the initial tuning parameters. Choose between the Generic Quad X (Q250) or the ZMR250 (Chinese QAV250 clone). Finally it's time to save the configuration.

This is the basic setup of the quadcopter. There are more advanced options. But this is enough for the first flight experience.

## Step 12: Remote Controller Configuration

The next step is configuring the flight controller. These steps are rather simple, and easy to follow. The FlySky FS I6 is an Arco transmitter with mode-2 configuration.

Move all stick according the directions given by the transmitter setup wizard, to calibrate the ranges. The directions of the sticks can be reversed in one of the final steps (if required).

Final step are the settings for arming and disarming the quadcopter. I've choosen for "Yaw left" to arm the quadcopter. This is the action required to turn on the quadcopter after attaching the battery.

## Step 13: First Flights QAV250/Q250

After building the quadcopters it is time for some flights. And I must say they are not just toys. They fly really fast, and it requires some practice to fly.
Taking off is easy. Yaw to the left for arming the motors. Then move the throttle stick slowly forwards. All motors start spinning, and the quadcopter starts flying. The moment the quadcopter flies, you know that you have calibrated the flight controller well. The quadcopter must go straight up. If it's also moving sideways, you must recalibrate the flight controller. For small adjustments, you can use the trim buttons on the remote controller.

The main difference between the quadcopters is the total weight (656 vs 525 gram, with a 207 gram battery). And I must say the Q250 responds a little better than the QAV250. This makes it easier to fly with the Q250. But both quadcopter respond very fast! It requires little movements on the remote controller, to move the quadcopter. Both quadcopters respond immediate to sudden movements of the controller sticks.

Both quadcopters have a 6DOF controller (gyroscope and Accelerometer). This means using both sticks at the same time, to keep the quadcopter under control. Keeping the quadcopter at a constant altitude, requires the most exercise. And all movements with the controller are relative to the quadcopter. A roll to the left, on the controller, results in the quadcopter moving to the left. But if the quadcopter is pointing at you, the quadcopter moves to the right! And this takes time to learn.

The supplied battery (2200mAh) lasts about 10 minutes. This is with slow flights, and with several take offs. It is almost required to buy additional batteries. And I've bought 3 additional batteries. They aren't that expensive, and now I can fly at least for 30 minutes, even at higher speeds.

Some remarks about both DIY kits, used in this Instructable.

The QAV250 has 20A ESCs. These add too much weight (80 gram) to the quadcopter. They are also too large to fit in the frame. Replace these with smaller sized ESCs. I also noticed a difference between the delivered frame and the displayed frame on the product page.

Both kits don't contain the latest motors. The EMAX mt2204 motor is succeeded by the EMAX mt2204-II (cooling series). But the used mt2204 motor is still available, and it's still a good motor.

It you're thinking of buying one of these quadcopters, I recommend buying the Q250 quadcopter. It's a cheap quadcopter, with all necessary parts. And if you really want the other frame, it's even cheaper to buy the Q250 with a separate frame.

## Step 14: Battery Charging Error

After initally charging my batteries, and a few flights, it was time to recharge the battery.

After turning on the charger and connecting the battery, the 3 leds started blinking. After a while the leds where still blinking, and it was time to read the manual: "All leds flashes red six times and stop 1 second in cycle". Cause of error: There is a 300mV difference of voltage between the battery pack. Apperently there is a maximum difference this "balance" charger can handle.

The only thing left to do is measure the voltage of the different cells (first image). The main voltage was 10.01 Volt (the battery wasn't completely empty). The maximum difference between the cells is 0,34 Volt, equals to 340mV. Which this is higher than the maximum of 300mV, which the charger can handle.

The solution to this problem is to manually charge or discharge some cells. An because discharging sounds more easy, I decided to discharge one cel. I used an old Lego motor, which takes about 120mA, while connected to one of the 3 cells. After one minute I measured the voltages again. The voltage dropped from 3.53 to 3.44 volt. With a maximum difference below 300mV.

Now the charger was able to charge the battery. I measured the voltage of the cells after charging. And the cells where balanced.

This has only happened once. And luckily it was easy to resolve.

## Step 15: Battery Charger

The charger, which comes with the Q250 and QAV250 kit, is a small charger. It is capable of the charging of 2S and 3S batteries. It charges the cells until a certain voltage (4.2 volt), and thereafter automaticly stops charging.

It is capable of delivering an 1 Ampere charging current. Which means charging of an empty 2200 mAh battery takes 2.2 hour. Because the LiPo battery can only be discharged for 85%, charging takes about 2 to 2.5 hour.

All in all the Skyrc E3 is a simple charger. Because of the price very attractive to begin with. But if you want to fly more often. It's better to buy a slightly faster charger. For example the Skyrc E4 which is capable of delivering 3 Ampere (2S-4S), or the Skyrc B6AC charger (6 Ampere, 1S-6S). The latter is especially recommended for high capacity batteries. All 3 chargers have a built in power supply.

The generally recommended charging current is equal to 1C (For the preservation of the battery). With this value it always takes an hour in order to charge the battery. For a 2200mAh battery this requires a current of 2,2 Ampere. So there is no need to buy a very big charger (The E4 charger is sufficient).

But If you are using a 5500mAh battery for a big quadcopter. It takes about 5 hours to charge the battery with this charger. 2,5 hour with the E4 charger, and 1 hour with the B6AC charger.

## Step 16: Crash Recovery

The above photos were taken after the QAV250 quadcopter hit the ground rather quickly, from about 4 meters altitude.

After some tumbling (and a few meters further) the quadcopter ended in the grass. This resulted in 2 damaged propellers, and dirt in one of the motors.

To get the sand out of the motor, remove the propellers and disassemble the motor from the frame. And blow pressured air (air duster) from the inside of the motor. This prevents entering of dirt into the bearings.

After cleaning the motor, the quadcopter worked as before. And after this crash, I can confirm that the frame is sturdy enough. And it is wise to order some spare propellers.

## Step 17: Custom Quadcopter Frame

The first image, in this step, show the "Sectansis - L160 Quadcopter". This model immediately caught my attention when I was looking for a quadcopter. Because this model has all moving parts inside the frame.

And after the previous crash with my first quadcopter, I see the advantages of this model. This design might have prevented some damage, for the motor and propellers.

The L160 is also a smaller quadcopter. It has 4 inch propellers. And is sold as an BNF kit (Bind And Fly. It includes the frame, flight controller, propellers, ESCs and Motors). Because my quadcopter uses 5 inch propellers, I can't use this frame. Instead I 've made a 5 inch version, using the Fusion 360 software:

In the next steps I will create such a frame. Just because I have a lot of experience with woodworking, I create a wooden frame. And then build a new quadcopter, using the the QAV250 parts.

The expected weight of this quadcopter frame is about 200 gram. the total surface of the upper part is 36340 square millimeter (Fusion 360). And 46490 square millimeter for the lower part. Plywood is about 600 kilogram per cubic meter (google).

Upper part: 36340 x 3mm x 600 / 1000 / 1000 = 65 gram

Lower part: 46490 x 3mm x 600 / 1000 / 1000 = 139 gram

## Step 18: Dremel Plunge Router

In my previous Instructable "Kids Room Wall Decoration". I made a wall decoration using a plunge router. In one of the steps I described how to create a butterfly, completely made up of circles. And I'm using the same technique to create this quadcopter frame. Only for this quadcopter I'm using a dremel router. Before I started, I have placed the whole on an old piece of wood. To prevent damage to my workbench.

The topside is the easiest to make. Using the powerpoint file as a template, drill 4 holes. They are the centerpoint of the circles. Start with the milling of the outer circles. And fasten the workpiece before starting the middle circles.

Always move the router against the rotation of the bit (move to the right or clockwise). That allows the bit to cut into the work, giving you full control over the router.

The bottom starts the same way as the topside. Then draw the motor arms on the workpiece. Use the router for the inner circles, but don't mill through the motor arms (12th picture). Use a fretsaw to finish the motor arms. Sand down both parts carefully.

The weight of the parts is 79 (5 mm) and 38 (3mm) gram. This is because I've used the lightest wood available from the hardware store.

## Step 19: Fan Duct

One way to improve the flight time of a quadcopter is improving the thrust deliverd by the propellers. One way to accomplish this, is by using a fan duct. This avoids leaking of air sideways. With as a result that the only remaining airflow is facing downwards. The downside is the additional weight of the fan duct. And it could change the flight behavior of the quadcopter.

A simple setup has been made, to measure the effect of a fan duct. The ESC is connected to a 12 volt power source. And since an ESC works just like any servo motor, an arduino can be used for controlling the speed. Connect the yellow line to port 8. And the brown wire to the ground. Don't use the red (+5 volt) wire. The arduino is powered by usb. A 50K potmeter is used for input (analog input 0).

This resulted in the following data:

```Value |      Propeller      |    With Fan Duct    |
|  current |  weight  |  current |  weight  |
------+----------+----------+----------+----------+
0  |   0.0    |   353    |   0.0    |   383    |
10  |          |          |          |          |
20  |          |          |          |          |
30  |          |          |          |          |
40  |          |          |          |          |
50  |          |          |          |          |
60  |   0.6    |   349    |   0.6    |   360    |
70  |   1.4    |   339    |   1.4    |   354    |
80  |   2.2    |   330    |   2.2    |   343    |
90  |   2.9    |   320    |   3.0    |   322    |```

A single fan duct adds 30 gram to the total weight. At the servo-value of 90 (half power) the applied current is 3 Ampere. The lift for the propeller only equals to 353 - 320 = 33 gram. The lift for the propellor and fan duct equals to 383 - 322 = 61 gram. So for this setup the total lift has almost doubled at half power.

I'm aware that this is not a very scientific setup. And my measured weight isn't the real lift deliverd by the motors. But it seems that the fan ducts give more lift to a quadcopter. So I'm gonna give it a try.

The fan duct is designed with Autodesk Fusion 360. And printed with an Up Plus 2 3D printer.

After painting the frame, It's time to install all parts. Since it's the third quadcopter build, there isn't really much to write about. Start with the motors and the fan ducts. Then connect the ESCs, flight controller and receiver.

At this point, the size of the ESCs, might be a problem. There is little room, but they can be placed near the fan ducts. And I've managed to keep everything inside the frame.

There is no need to reconfigure the flight controller. It still has all values from the QAV250 quadcopter. And this quadcopter uses the same components, except for the frame.

## Step 21: Custom Quadcopter - First Flight

The flight results of this quadcopter were not as expected. Compared to the QAV250, taking off takes a lot more motor power. This is mainly due to the increased weight. And probably also by the increase of the surface of the quadcopter.

The fan ducts are working. In such a way that there is increased upward force. And this makes controlling the quadcopter more difficult. Particularly at sudden lateral movements. The total weight of the quadcopter is about 740 gram. And this is almost too much for these motors.

That's why I have decided to omit the fan ducts.

## Step 22: Rotor Fail

The eCalc software makes a prediction of the resulting controllability of your multicopter in case of a rotor/engine failure. This prediction has one of the following 3 values:

Resistant: Resistant to single Rotor Failure
Controlable: Single Rotor Failure is most probable controlable for a immediate emergency landing.
Uncontrolable: A single Rotor Failure is uncontrolable and will lead to a flip-over.

I have not given much attention to this value. But it's something to consider.

While testing my custom quadcopter, one of the bolts came loose. And the corresponding screw hit the propeller. With a broken propeller as result.

By this, the next quadcopter will use self-locking nuts (or Loctite).

The first change is removing the fan ducts. They reduce the controllability of the quadcopter. They might work for a larger quadcopter, but they add too much weight for this small quadcopter. This saves about 120 gram.

The controllers are also too heavy. 4 x 20 gram equals 80 grams. The 12A Simonk ESCs have half the weight (and I've ordered some other ESCs for my next quadcopter).

I want to replace the ESCs later, so I'm using a screw terminal instead of a power distribution board. I've also removed the QAV250 power cables, this also saves some weight.

The total weight is now about 600 gram. And I can save 40 gram by replacing the ESCs.

After some initial testing in the garden, it was time to go outside for a proper flight. During a wrong landing, a piece from the upper part broke down. The 3mm plywood wood isn't strong enough (it is only 12 mm wide). I've made 2 pieces with 5 mm thick wood, so I could replace the broken piece. And I was planning to do so while replacing the ESCs.

The quadcopter was still capable of flying. And it flew much better without the air ducts. Unfortunately it crashed while we were trying to fly at a higher speed. And some parts of the 5 mm thick wood broke. And this quadcopter is now beyond repair.

All electronic components survived the crash. Even the propellers are still usable. So this frame is working, but it needs to be stronger. I can switch to a carbon fiber plate. But these are quite expensive.

With my previous quadcopter frame in mind, one of the most important parameters is the lift to weight ratio of the quadcopter.

Besides reducing the weight or the quadcopter, there are mainly two improvements to choose from. And it looks like you can only choose one of them. It's a choice between a longer flight time or a faster quadcopter.

### Flight time

To improve the flight time of the quadcopter we can simply use a bigger battery. But this gives more weight, so it's not a complete solution.
Bigger propellers have less drag than smaller propellers for a given thrust. This means they require less energy to achieve the same lift. They require stronger motors with a lower RPM. But the total setup is more efficient.
An air duct can improve the airstream. I've tested a small version with a 5" propeller. But increases the weight of the quadcopter. They might work with a large quadcopter.

The following table shows the increase of hover flight time, when using a larger propeller:

```Propeller | Mixed Flight | Hover Flight
----------+--------------+-------------
8045    |   11,9 min   |   16,1 min
9045    |   11,8 min   |   18,0 min
1045    |   11,5 min   |   18,8 min
1145    |   11,2 min   |   21,3 min
1245    |   10,9 min   |   22,7 min
1345    |   10,6 min   |   24,1 min
1445    |   10,4 min   |   25,0 min```

### Speed

More speed requires faster spinning motors. This means increasing the RPM.

Choosing a motor with a high KV value. With the highest possible voltage for this motor. Will give a faster quadcopter. In the next step an example of a high speed quadcopter is given. Then I'll continue by building a large quadcopter.

## Step 25: 4S High Speed Quadcopter Example

The previous step described two ways of improving a quadcopter. And I've decided to increase the size of the quadcopter. In this step I describe what is necessary to increase the speed of the quadcopter.

The DIY kits I've used as an example have Emax 1806 or Emax 2204 motors. These can be used with 2S and 3S batteries (7,4 or 11,1 Volt). This means they are not build to be used with 4S (14,8 Volt) batteries. With the eCalc software it is possible to calculate the estimated speed with difference voltages. Even when the motors don't support the voltage used. This gives the following table for these motors:

```Battery |  MT2204-II (2300KV)  |
--------+-----------+----------+
3S      |  66 km/h  |  41 mph  |
4S      |  87 km/h  |  54 mph  |```

These high speed come with a price: It takes a lot of power. A 4S 2200MAh battery lasts only 2 minutes when flying at 87 km/h (constantly 54 mph).

To further increase the maximum speed we need a higher KV value for the motors (higher RPM equals higher speed). The motors in my example are 2300KV motors. Using an Emax RS2205-2600KV motor gives a higher speed:

```Battery |  RS2205 (2300KV)     |  RS2205 (2600KV)     |
--------+-----------+----------+-----------+----------+
3S      |  70 km/h  |  43 mph  |  79 km/h  |  49 mph  |
4S      |  94 km/h  |  58 mph  | 103 km/h  |  64 mph  |```

All above calculations are with 5030 propellers (5 inch). Increasing the size to 6 inch propellers decreases the maximum speed. Larger propellers, result in lower motor speeds. But lowering the propeller size increases the motor speeds.

Using 4045 propellers (4 inch, with a higher pitch) gives an airflow warning in eCalc. But the RS2505 2600KV motors are designed to be used with a 4045 propeller (motor specifications):

```Battery |  RS2205 (2300KV)     |  RS2205 (2600KV)     |
--------+-----------+----------+-----------+----------+
3S      |  93 km/h  |  57 mph  | 114 km/h  |  71 mph  |
4S      | 141 km/h  |  87 mph  | 159 km/h  |  99 mph  |
5S      | 189 km/h  | 112 mph  | 198 km/h  | 123 mph  |```

Calculations with Emax RS2205-2600KV motors, using 4S batteries and 4045 propellors show a maximum speed of 159 km/h (almost 100 mph). These motors are not designed to be used with 5S batteries, so 198 km/h is only theoretical with these motors.

The total weight of this quadcopter will be about 500 gram, using the following parts (this set-up has not been tested):

This requires almost all new parts! The only reusable parts, from the QAV250/Q250 kits, are the frame, the transmitter and the receiver. So building this high speed quadcopter is something for another instructable.

## Step 26: Doubling the Size of the Quadcopter - Frame

For this quadcopter I've enlarged my custom frame from the previous build. In fact I've doubled the size of the frame.

The motors I'm using for this build are the Emax MT2216 motors. These different from the MT2216-II motors by the propeller connection. The newer (MT2216-II) motors use the same connection as the motors used with the QAV250.

The MT2216 motor has two ways for connecting a propeller. It can use the general type propeller and three-hole propellers. They are deliverd with a CW and CCW propeller. And that's where I made a mistake. I just ordered 6 motors (all CWW motors, the CW motors weren't in stock). Assuming that I could mount any propeller (CW or CCW), on any motor. So the following quadcopter has 4 CCW motors.

These propellers or motors must be replaced by proper parts. So I have to order 2 (or 3) new motors, or CW accessory parts for these motors. But I will continue with the motors I received.

I've used a router to make this frame. The total weight of the previous frame was just over 100 gram (wood only). This frame will weight about 400 gram (4 times the weight). The motors are 80 gram each. And I'm not using the 20A ESCs. But 30A OPTO ESCs (4 x 9 gram). The flight controller and receiver are still the same. And I've added a power distribution board.
The 1500mAh 3S batteries weigh about 110 gram. Other items are about 60 gram (PDB, receiver and flight controller). The PDB is required because the OPTO ESCs don't have a 5 volt output.

Total weight with 3000 mAh (2 parallel) batteries is about 400 + 320 + 40 + 220 + 60 = 1140 gram. Calculations with eCalc give the following data for this quadcopter:

```thrust-weight:         2
mixed flight time:     8,3 min
hover flight time:    11,5 min
all up weight:      1140   gram
max speed:            33   km/h
21,7 mph
est rate of climb:     5,7 m/s```

The maximum speed is half the speed of the Q250 quadcopter.

## Step 27: Large Quadcopter - Electronics

Building this quadcopter is the same as building the other quadcopters (and it's getting easier every build).

This quadcopter has a power distribution board. This is required because the used OPTO ESCs don't provide 5 volt. The ESCs have only two wires: signal (white) and ground (black). This PDB has 2 outputs: 5 and 12 volt.

I've updated the flight controller firmware before installing all other components. The USB port is difficult to reach after placing of the upper frame.

Total weight, without battery, is 985 gram. Adding 220 gram, for two batteries, gives 1205 gram.

## Step 28: Large Quadcopter - First Flight

Flying with this quadcopter is more easy than flying with the Q250. It's slower, but it has a good response. It's also more steady. It requires small changes from the transmitters joysticks, to fly with this quadcopter.

## Step 29: First Person View

After the previous build, I've added a camera to the quadcopter. This is a so called action camera.

One of the reasons to build a quadcoper is areal photography/filming. An other reason to use a camera is FPV (First Person View) flying. This means flying the quadcopter while looking at a video screen. This can be a small tv screen or a special goggle.

For this small quadcopters the camera must have a less weight as possible. And it must be some kind of shock proof. While looking for a camera I cam accross the RunCam 2. Although it looks and feels like a normal action camera. It is a small lightweight action camera which is designed to be used in quadcopters.

You can connect through Wifi, and change all configurations. But it also has live view, you can see the video on your celphone while flying. I choose this camera withouth selecting any FPV equipment, I only wanted to make images with my quadcopter. But this live view feature gives some kind of FPV experience.

Unfortunately is the WiFi range too short to fly FPV with a cellphone. And the video throughput by WiFi is too slow. To fly FPV with this camera, a video-transmitter and video-receiver is required. The transmitter uses the video output from the RunCam2 camera (this cable is supplied with the camera).

The camera mounted to the 3 mm frame gives a lot of vibrations in the video. It's better to attach the camera to the lower plate (5mm). But this still gives a lot of vibrations. I have to balance my quadcopter and propellers, for better videos.
Don't use double sided tape to connect the camera to the quadcopter. Use the supplied camera mount.

## Step 30: Batteries

I've ordered 3 additional batteries. These are 3S 1500mAh 40C batteries. The battery from the QAV250 kit has a T-Plug connector. The new batteries have a XT60 connector.

It looks like the newer frames, batteries and power distribution boards use XT60 connectors. Thats why I've decided to switch to XT60 connectors.

These batteries can be used with both the small and the large quadcopter. I'll use 2 (or 3) batteries in parallel for the large quadcopter. Creating one 3000mAH 80C (or 4500mah) 120C battery. The batteries can only be placed in parallel when they have exact the same voltage! Or the battery with the highest voltage will charge the other batteries. I also recommend to use batteries from the same type/brand.

It's better not to short circuit a LiPo battery. A 40C 1500mAh battery can deliver 60 Ampere (40 x 1.5). But 2 or 3 in parallel deliver a maximum amperage of 120 or 180 Ampere! So be careful.

The 2200mAh battery has a weight 220 gram, the 1500 mAh batteries are 108 gram.

## Step 31: Further Improvements

After building the large quadcopter there are still some things to improve. But I'm planning to do some flights first, for the necessary flight experience.

Some things I would like to change:

• Replace the 2 2216-CCW motors with 2216-CW motors.

• Use 5mm wood for the upper frame (instead of 3mm). Or usage of an other stronger material for the frame.

• Adding a barometer to the CC3D controller. This requires a different firmware. Probably CleanFlight. This creates an 7 DOF flight controller.

• Building of a hexacopter frame.

• Switch to 4S batteries.

• ...

• ..

• .

Even after so many steps, there is much more to do:)

The following list contains the items I've used for the succesfull steps. Some items have a newer versions available. Then I refer to the newer/updated version.

Required multirotor items for the quadcopters in this Instructable:

Given the number of steps, there aren't that much parts used. A lot of items are reused in different steps.

Materials used for the 2 frames are:

• 3mm plywood (It's better to use 5mm, but this increases the weight)
• 5mm plywood
• 3mm nuts and bolts

In addition to a plunge router and drill, only hand tools have been used to build the frame.

My Instructable contains a lot of steps. Some of my improvements have worked, and some have failed. And I know I've made some mistakes, but meanwhile I've learned a lot about building quadcopters.

Update 3 October: I've made a new DIY quadcopter (first image). I've placed the new quadcopter in another Instructable. Because this Instructable already contains 34 steps.

## Step 32: Rapid Prototyping a Multirotor

As mentioned in the step "Doubling the Size of the Quadcopter" I've received only CCW motors. I was planning to build a hexacopter, after building the large DIY quadcopter. This would not be a part of this Instructable. This Instructable is about quadcopters, and not about hexacopters.

But instead I've already built a prototype of a quadcopter. I've made this prototype before the "Large quadcopter". So all parts had to be reusable. And it's more a quick test to see if this setup would work. It's far from a finished hexacopter.

A CCW motor rotates counterclockwise. And a quadcopter requires CW and CCW motors. Or the quadcopter will rotate while flying. Like a constant YAW. This means I have to change three motors from CCW to CW. One way is firmly tightening the nut. But when the nut gets loose. Then the propellor flies up, while the quadcopter goes down.

Another solution is mounting the motor upside down. Then CCW becomes CW! This gives a hexacopter with 3 motors mounted at the top, and 3 motors mounted at the bottom (upside down). This requires less distance between the propellers. It also has effect on the airflow and stability, but they can't hit each other.

The smallest hexacopter possible, is with no distance between the CW and CCW motors. In this case the motors are above the other. It's possible to create such a multirotor out of one timber plate of 60 x 120 centimeter (2 x 4 feet, with 2 layers). But this leaves little room for all electronic components.

With this prototype both configurations are possible. The 'regular' hexacopter and the 'tricopter'. It consists of two equal parts. And each part has three motors.

In the next two steps I will build both hexacopters. It's not possible to use eCalc for calculations about these prototypes. It does not distinguish between types of quadcopters.

## Step 33: Prototype: HexaCopter

This is the first prototype hexacopter. The following parts are not in the QAV250 kit:

The quadcopter electronics might look confusing, but it's really simple. All 6 motors are connected to the 6 ESCs (three wires). The ESCs are connected to the flight controller according the motor number.
These ESCs are OPTO versions. This means they don't have a 5 Volt output. The 5 Volt has to be provided by the power distribution board. I use a screw terminal for power distribution board. This connects the battery with the ESCs. An additional non-OPTO ESC (7th, one from the QAV250) provides 5 Volt for the flight controller.

For the construction of this prototype, I used waste pieces for the frame. This resulted in a rather heavy frame. The total weight of this quadcopter is about 1400 gram. With a 3000mAh battery, the expected flight time is about 10 minutes with a maximum speed of 32 km/h (20 mph). A final version of this quadcopter must be less heavy, for a longer flight time.

Use the LibrePilot software to setup an "Hexa X" multirotor. The flight controller should be facing towards motor 6 and 1 (motor 1 is marked with orange paint).

During the first flight the hexacopter rotated counterclockwise. Tree motors were spinning in the wrong direction. After changing the motor connections, and checking them twice. the hexacopter didn't fly as expected. I thought this was caused by a difference in airflow between the CW and CWW propellers. But the second type hexacopter experienced the same problems.

## Step 34: Prototype: Tri-Copter

The entire lower part is rotated 60 degrees clockwise. And I've marked all ESC wires with colored tape. This way I can easily disassemble and reassemble the quadcopter.

Now motor 1 rotates clockwise, and motor 2 rotates counterclockwise. And they are located on the same spot (second image).

This multirotor type is known as a "Hexa Coax Y6". This is an existing configuration in LibrePilot. The flight controller should be facing towards between motor combinations 1/2 and 3/4.

The video shows the two first flight attempts. The hexacopter still rotates counterclockwise. While all motor spin in the right direction (image 3). There is also a disbalance during the flight. The quadcopter resonates somehow. This might be a PID setting in the flight controller.

I realised that this setup will take more time to build. And after finishing the frame for the large quadcopter, it was time to disassemble this prototype. Maybe after a while, when I have more time, I will build a hexacopter. But in the meantime I'll fly with the big quadcopter and Q250 quadcopter. To gain the necessary flight experience. And to create some videos.

Afterwards I think the resonation is due to the frame and the flight controller. Vibrations in the frame have influence on the flight controller. But solving this requires a new frame...

## Recommendations

• ### 3D CAM and CNC Class

138 Enrolled

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We have a be nice policy.

## Questions

i have a doubt. i already have a quadcopter. It's one of the rotor is not rotating so it does not fly. Can you explain me what will be the fault.. the other three rotors were working well

The most common fault is a wire break: This can be between the controller and the ESC, between the ESC and motor, and/or between the PDB and ESC.

I think you should have won, man. This is a unique, inclusive instructable and I really like that you are doing this. Keep up the good work

this is great caved me some time in research lots of information here.

Thanks for that detailed instructables, thorough explanation, great help!

Re your hex-rotor design, you might want to take a look at

https://www.instructables.com/id/Cheap-crash-resist...

Although you have 6 rotors, they probably do not cancel their respective torques. You might need to alter the downwash angle of the rear pair.

Very professional , highly detailed ! Thank you for important info for people who are interested building their own! You got my vote .

wow amazing

wow, impressive! very good job.

Very well done Instructable. I have bookmarked this and you have my vote. Thanks.