Introduction: Build ANY Professional Multicopter
Have you ever wanted to take to the skies, but didn't know where to start? This is the guide for you! It's a step-by-step simplified, yet comprehensive guide teaching you to build not only one, but any multi-copter you dream, from the grounds up.
Before I got into flying, I've always wished someone created a comprehensive guide of everything I needed to know or buy, so I don't have to wait and order missing items. Through trial and error, I have learned many things, and I hope that this guide helps you build your own multi-copter with only one click ( and very little errors )
This is a rather long guide, but contains everything one needs to know to build any multi-copter, with treasures from beginners to professionals. If you are excited to build and fly, you may skip ground school and check out the links at the bottom of Step 4 and Step 5.
Step 1: An Introduction to Flight
First of all, what is a multicopter? A multi-copter refers to any aerial vehicles that has multiple motors in various possible configuration able take-off, have a controlled flight, and land. Having a controlled flight entails being able to move in the following ways:
Thrust = Thrust is the downward push of air provided by the motors to lift a multi-rotor
Yaw = In multicopters, yaw is the ability to rotate the quadcopter 360˚, picturing it as being level with the skids or landing gears down. In traditional planes, this is usually controlled by the rudder, allowing the plane to point it’s nose left or right.
Pitch = Pitch controls the forward and backward movement of a multi-rotor. By applying more thrust on the front motors, a multi-rotor tilts and moves forward, while the opposite applies to backwards motion.
Roll = Roll controls the ability to move side to side, either left or right.
These are controlled by varying the speeds of each of the motors to attain each of the controls.
This website shows a beautiful animation that demonstrates each of these concepts for a quadcopter:
Up next, how different multicopter configurations are able to perform these flight controls.
Step 2: Multicopter Motor Configuration
Different multicopter configuration behaves differently and will have variable controllability in each of the flight control mechanisms (yaw, pitch, roll, thrust). Here are the common multicopter configurations
Quadcopter: These are the traditional drones you would see flying around. There are two possible configurations, X or +.
Tricopter: These are especially good at yaw control, however due to a missing motor, it uses a servo to control yaw, albeit better.
Hexacopter: These are like quadcopters, but with 6 motors instead, for added reliability, in the case of engine failure, and thrust, for carrying heavier loads.
Octacopter: Like the hexacopter, it has extra motors for even more added reliability and thrust. However, it features 8 motors.
Y6: This multi-rotor also 6 motors but they are mounted in such a way that it uses a tricopter frame with one motor on top and another at the bottom.
Monocopter, Bicopter, Pentacopter: These single-motor, dual-motor, and 5-motor multicopter configuration do exist but are highly impractical. In the case of a bicopter, it cannot achieve a stable hover, due to torque applied by both motors, so it will continually spin on it's axis. On the other hand, a pentacopter can achieve a stable flight, but the additional motor does not reap any benefits, even worse, when only one of the motor fails, it crashes. The monocopter is a whole new story, it has been recently discovered that it is possible by researchers at ETH Zurich, as seen in this video.
Now that you have a basic understanding of multicopter flight, we can begin understanding RC multicopters components.
Step 3: Gathering the Materials
- Motor and Propeller http://amzn.to/2nxuk5m
- ESC http://amzn.to/2nxzazh
Transmitter and Receiver (Tx/Rx)
Different transmitters have a different number of channels. Channels are the number of "controls" there are to control. The most basic one has 4 channels, which is limited to flying up to 4 motors ( or 3 motors and 1 servo). Each motor/servo requires 1 channel. I recommend using either the fleshy i6 or turnigy 9x transmitter, both for around $50 at hobby king
This is the brain of the operations, it tells the motors what to do from your stick inputs from the transmitter. I recommend using the KK2.1 as it is the simplest and easiest to use flight controller, in addition to costing only $20 at hobbyking.
Brushless DC motors are typically use for RC flight due to their high torque and greater efficiency over brushed DC motors. Though, brushed motors can also be used with a brushed electronic speed controller.
What are the Kv number?
As you search through for your motor you will find they each have a kv number. First of all, one of the greatest misconception is Kv stands for kilovolt - it does not. Kv is the revolution per minute (RPM) achievable by the the motor per voltage fed into the motor. Thus, Battery voltage * Kv number = RPM
The higher the Kv, the smaller the propellers it takes. Thus, larger drones tends to have smaller Kv motors.
Electronic Speed Controller (ESC)
The electronic speed controller as the name suggests controls the speed of the motors. There are two different types of speed controllers, opto (from optoisolator) and battery elimination cirucit ESC:
An opto ESC does output power from the JST connectors, thus making it the perfect and safest ESC to use when plugging into a flight controller. It merely reads data gathered from the flight control and sends appropriate signals to the motor.
A regular ESC (or BEC ESC) on the other hand, outputs power. It has a BEC, or battery elimination circuit. This is used for RC planes since it takes the power from the battery and regulates it to from 5V to 7.2V depending on the specification. Do not use this for multi-rotors, as it can damage your flight controller.
Opto vs BEC ESC
A major advantage of opto ESCs over BEC ESCs is that when one of the opto ESCs fail, only the motor it is connected will cease to function. If a BEC ESC, on the other, fails, all the motors will cease to function, which will inevitably resulted in a wrecked drone.
ESCs also have a current rating, that is the maximum current draw it of which it is capable. When choosing the current rating of an ESC, it should be higher than the maximum draw its respective motor. Higher Kv motors tend to have a lower current draw since it uses smaller propellers, which draws less current. While lower Kv motors tend to have a higher current draw, using larger propellers.
What's all those wires for?
The ESC is the octopus of the RC avionics. It has 6 sets of wires connected. You will notice one set of three wires, is significantly thinner than all the other wires, this is the part that connects to the flight controller (more specifics on the next step). The end terminal of these wires is called a JST connector.
The side with two wires are connected to the battery. Warning: Do not reverse the polarity of these two wires, since ESC have a capacitor, it is polarized.
The opposite side with three wires are connected to the motor. Order does not matter, switching any two wires simply causes the motor to spin in the opposite direction (more on this in the step)
The size of the propeller will be dependent on the motor you choose, and a particular motor will specify which particular propellers would be a good fit. There are two types of propellers, counter-clockwise and clockwise rotation propellers.
What are the numbers on the propellers?
Propellers are identified by two numbers like 8x4. The first
number, 8, indicates length of the propeller in inches. The second number is the pitch of the propeller, where the greater the pitch the more lift it produces. Certain propellers also have more than two blades, the greater the blade, the greater the lift.
How can you tell if a propeller is clock-wise or counter-clockwise?
Propellers have top/down orientation. It is important that all the propeller numbers are facing upwards.
To distinguish if a propeller is counter-clockwise rotation or clockwise rotation, place your finger on the topside of the blade along the indent, then push that forward – that’s its rotation.
*Tip: I like to remember clockwise vs counter-clockwise by visualizing the movement of the second hand of analog clock, that would be clock-wise (literally) and the opposite is counter.
Lithium Polymer or LiPo batteries are commonly used in RC multcopters and planes, given that they are capable of a high load discharge.
Three attributes of batteries are especially important:
Cell (denoted by S)= Each cell has maximum of 4.2V and a nominal voltage of 3.7V. Three cell (3S) LiPo batteries are most common and most used for the majority of brushless motors. So a 3S LiPo can be charged up to 12.6V, but it's voltage levels are held steady at 11.1V.
Capacity = measured in mAh (milliamp hour), it is the electric power the battery has over time. Higher capacity batteries typically have a longer flight time.
Discharge rate or C rating = how fast your battery can discharge the charges stored in the battery. The essentials that you need to know with the batteries is that Capacity * Discharge Rate = Current output, so the total current draw by the motors ( and other accessories like cameras that you may have ) must be less than the current output calculated.
Warning: do not let your battery voltage fall below 80% of it's maximum charge level, or else you may damage your batteries, these batteries
There are also one-time investments that are necessary for flying.
For this particular guide, let's build a 600mm quadcopter! Keep in mind, these are not the cheapest parts list, it is intended for someone with a keen interest in pursuing the hobby and wanting a quadcopter with pizzazz. I've listed most of the parts from eBay since many of these China/HK companies offer free shipping (over Hobby King and other hobby stores) for almost, if not cheaper prices. Though, a major disadvantage is that shipping takes about a month to arrive, so be prepared to wait. I usually order the batteries from Hobby King, as they are usually cheaper and better quality, even with a whopping shipping fee. I'd like to buy either Turnigy or Zippy brand batteries.
Given that you know the important concepts of multicopters, you may opt to design and build your of multi-rotor. Then, use this instructable to guide you to build a different and unique multi-rotor. An online tool, eCalc can help you calculate the necessary avionics for flight or you can also but Ready to Fly (RTF) or Bind and Fly (BNF) multirotors. Check out the RC groups forum as well to inspire your creations.
Remember, the multicopter you build is yours and only yours. As a maker, you should feel empowered to design it as you wish. The following build options I presented above, are mere recommendations, feel free to change the design, and make it your own!
Congratulations.You have graduated from ground school. The rest of the guide should be easy as pi!
Step 4: Assembling the Quadcopter
Assembling the Frame
Follow this manual.
Soldering the Power Distribution Board
Solder all the red wire of the ESC to the (+) pads of the circuit board. Then, solder all the black wires of the ESC to the (-) pads of the circuit board.
Take a black wire and solder one end to the (-) terminal of an XT-60 Connector, and the other end to the “XT-60 (+)” pad power distribution board. Do the same for red, but with the positive terminals instead.
Flite Test provides a great video on how to solder XT-60 Connectors
Soldering bullet connectors on to the ESC wires and Motor wires
Note: Where you place the male/female bullet connectors do not matter, but industry practice seem to prefer using the female 3.5mm golden bullet connectors on the motors and the male ones on the ESC.
Note: Colour coding on the three wires do not matter, as we will learn in the next step when we plug everything together.
Cut a small piece of heat shrink, about 1cm. Slide the heat shrink on the wire before soldering. The diameter of the heat shrink should be big enough to cover the 3.5mm bullet connector. Once you have soldered the wire into the bullet connector, cover it the heat shrink. Use the sides of the soldering iron to heat up the heat shrink or use a blow dryer at high heat.
If you do not know how to solder bullet connectors. Flite test also made a video here.
Putting the Avionics (aviation electronics) together.
1. Connect any three wires on one side of the ESC to any three wires from the motor. The motor is capable of spinning both clockwise and counter clockwise, if it is spinning in the direction you do not desire, simply change any two wires, and it will spin the other direction.
2. The remaining two wires of the ESC is not reversible, the red one is power (+) and the black one is ground (-). Connect all the ESCs in parallel, meaning all the red wires are connected together, and all the black wires are connected together.
3. Screw and velcro all the electronics onto the quadcopter.
Warning: Make sure there are no loose wire that can be cut by the propellers. I like to wrap my ESC wires around the arms or put it through the tubing when possible, so as not to get tangled with the propellers.
Wiring the KK2.1 Board and Receiver
Follow the image provided on how to wire the KK2.1 Board. This diagram is specifically for the use of opto ESCs. Use a female to female JST connectors for wiring the receiver to the KK2.1 Board and the female to male (also called servo extensions) JST connectors for wiring the ESCs to the KK2.1 Board.
Testing the motors and identifying the rotation
Place non-clear tape on the motor shafts. This will help us identify its rotation.
Warning: Do not place any propellers on the motors, as the propeller can cut your finger at high speeds.
Plug in the battery on the power distribution board. You should hear the ESC beep, meaning it has initialize properly. Bringing throttle up to 10%. At this speed, you should be able to see what rotation the motors are spinning.
We are using an X-configuration, and from this site , we know we’ll need the counter-rotating and clockwise rotating motors to be opposite each other, respectively. If the motor is not spinning in the direction you desire, simply change any two wires, and it will spin the other direction. Repeat this process for all of the motors.
Step 5: Maiden Voyage
Bring your friends with you, find a nice open field and fly!
"It is the greatest shot of adrenaline to be doing what you have wanted to do so badly. You almost feel like you could fly without the plane." - Charles Lindbergh
Let me know in the comments below if there's anything else you'd like to know. Cheers and Happy Flying!
Step 6: Moving Forward
After your first flight, you may be longing for more challenge or fun. Maybe you would like to command your quadcopter to fly in a specific pattern or to your friend's house, how would you go about doing this? The short answer is with an autopilot .
The autopilot I recommend is Ardupilot or HKpilot (clone), since it is one of the more cost-effective options and is compatible with APM or mission planner, a flight management autopilot. This flight controller is very well documented and is open source with its own software and hardware.
Customize and make it your own!
Here are some ideas for your multi-rotor add-ons.
- Payload Drop (use a servo and a rubber band)