The goal of this guide is to give the reader an introduction to the different parts of a quadcopter and how those parts interact with each other. Each part is given its separate section with explanations on different conventions used and what should be taken into consideration when buying that part. In each section I tried to maximize the information presented without making that section too lengthy.
This guide is for people who
- Want to pick their own parts without having to search all over the internet for what different numbers mean.
- Want to make sure their parts will work with each other.
This guide is not for people who
- Want a step by step guide on how to build a quadcopter from a list of preselected parts.
The website www.hobbyking.com is used in this guide because of its large selection of parts at low prices.
All parts you need to fly are:
1. Frame + Additional parts for mounting such as velcro and zip ties 2. Motors (4X) 3. Propellers (4X) 4. Electronic Speed Controller (4X) 5. Battery 6. Power Distribution Board 7. Battery Charger 8. Flight Controller 9. Radio and Receiver
Remember to have fun and register your quadcopter with the FAA.
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Step 1: Frames
Quadcopter frames come in a large variety of layouts, sizes, and materials. The 2 main layouts are:
1. Racing 2. Utility
If you plan on doing acrobatic maneuvers such as flips and/or First Person View (FPV) flying, a racing frame would be your first choice. If you want to add accessories such as a camera for aerial photography, a utility frame would be a better choice.
The size of the frame will usually be denoted by a number such as 150, 200, 450, etc. This number is the diagonal length in millimeters from motor to motor (see above picture).
Some materials used in quadcopter frames include:
1. Plastic 2. Glass Fiber 3. Aluminum Tubing 4. Carbon Fiber Tubing 5. Carbon Fiber Plate
Material selection is largely based on how much you want to spend on a frame. A cheap heavy frame will reduce flight time, but will be less expensive to replace if it breaks.
Additional parts to make mounting components easier are shown above (links in the picture notes).
Frame used in my build: Frame
Step 2: Motors
Almost all quadcopters use a type of motor called a "brushless motor". The general naming convention of brushless motors goes as follows (using the motor from my build)
- Turnigy Multistar 2209-980Kv
The brand and model is Turnigy Multistar. The first number, 2209, is broken down into 2 parts:
1. 22 is the diameter, in millimeters, of the stator (the copper coils inside the motor) 2. 09 is the height, in millimeters, of the stator
The second number, 980Kv, is the revolutions per minute (RPM) the motor will spin at when 1 volt is applied to it. The Kv number is one indicator of how powerful the motor is.
Example: 980Kv * 12.6V = 12,348 RPM
Different sized motors will have different bolt patterns (see pictures above). The builder will have to do some research in the frame and motor descriptions to make sure they are compatible. If the builder picks a motor size recommended by the frame, chances are the motor and frame will fit.
Motors used in my build: Motors
Mounting bolts for motors (see note below): Bolts
Note: Some motors on Hobbyking might NOT come with the required mounting bolts. Mounting bolts are the bolts that hold your motor to the frame (the ones used in the bolt pattern). Larger motors like mine seem to use size "M3" while smaller racing motors seem to use size "M2". If you want to avoid having to buy mounting bolts, check the product pictures for 2 sets of bolts (the smaller bolts are for mounting the propeller).
Step 3: Propellers
Propellers come in sizes ranging from about 3 inches to 10+ inches in diameter. Propellers are often plastic but some more expensive propellers are made of carbon fiber.
The size of the propellers will have a direct affect on noise, flight time, and performance.
Large propellers are more suited for utility quadcopters because they will:
1. Be less noisy 2. Give longer flight times
Small propellers are more suited for racing quadcopters because they will:
1. Make the quadcopter more maneuverable
To keep the quadcopter from spinning, 2 clockwise and 2 counterclockwise propellers will have to be installed on the correct motors. This is the same reason why a helicopter has a small rotating tail rotor.
Hobbyking does a good job recommending propeller sizes when you go to buy a frame. Being 1 inch above or below the recommend propeller size should not be a problem, as long as the propellers have enough clearance between themselves when mounted on the motors.
Propellers used in my build: Propellers
Step 4: Electronic Speed Controllers (ESCs)
You will need 4 electronic speed controllers (1 for each motor) when building your quadcopter. In short, ESCs direct the power to the motors and tell the motors how fast to spin. Many ESCs come with a Battery Elimination Circuit (BEC). The BECs will step down the voltage from the battery to a level that the quadcopter's Flight Controller and Receiver can use.
The 3 types of ESCs available are:
1. Linear BEC - Drops the voltage so the Flight Controller and Receiver do not burn out. 2. Stepping BEC - Drops the voltage just like a Linear BEC except the Stepping BEC uses a different method. 3. OPTO - These do not include a BEC. You will have to power the quadcopter Flight Controller and Receiver from another source. I would not recommend OPTO for a first build since it adds another component and more wires.
ESCs are rated to a certain amperage such at 10, 12, 20, etc. A rule of thumb is to use ESCs rated for 2X what the motor is capable of drawing.
The 3 connections that come out of the ESC can plug into the motor in any order. To switch the direction a motor is turning, you must swap 2 wires (see picture above).
ESCs used in my build: ESCs
Step 5: Batteries (Part 1)
Lithium Polymer is the type of battery used in nearly all quadcopters. Lithium Polymer batteries are a good source of power for their size and weight, unlike Lead Acid or NiMH. Lithium Polymer is often abbreviated LiPo.
The capacity of the battery, measured in milliampere-hours (mAh), is a direct indicator of how long your quadcopter will be able to fly. Racing quadcopters will use sizes around 1000 mAh, while larger quadcopters can use 5000 mAh or more. The bigger the mAh, the heavier the battery.
Lithium Polymer batteries will come in different cell counts such as 2S, 3S, etc (note the S means the cells are arranged in Series). Each cell has a voltage range:
3.0V - This is the absolute minimum the cell can handle before it becomes permanently damaged and dangerous. 3.5V - Although 3.0 is considered the minimum, it is recommended to only let the voltage drop to 3.5V. 3.7V - This is the voltage used by companies when selling the batteries. 4.2V - A 3S battery is sold as 11.1V (3.7 + 3.7 + 3.7) and can handle a maximum voltage of 12.6V (4.2 + 4.2 + 4.2).
Motors will be rated for different cell counts. A 980Kv rated up to 3S (12.6V) can spin up to
980Kv * 12.6V = 12,348 RPM
LiPo batteries come in different connection types (see picture above). The most common in the quadcopter community is the XT60 connection. The connection type of a battery does not change how the battery works. In addition to the main connection, there is a small (usually white) connection. This white connection (called a balance lead) is used to determine the voltage of each cell in the battery.
One way to avoid over discharging your battery is to have a voltage beeper attached to the white connection (see picture above).
Step 6: Batteries (Part 2)
Batteries are rated to a specific C value. This C value, combined with the mAh rating of the battery, will tell you how many Amps the battery can handle. For example, using a battery rated for 4000 mAh and 10C:
(4000 mAh) / 1000 = 4 Ah 4 Ah x 10C = 40 Amps
If your motors are rated at 9 Amps each, this battery could handle the maximum load required because:
4 motors at 9 Amps = 4 x 9 Amps = 36 Amps The load is 4 Amps less than what the battery can safely provide
Battery used in my build: Battery
Voltage Beeper used in my build: Beeper
- mAh rating - How long a LiPo will last and how heavy it will be
- 1S, 2S, 3S, etc - How many cells a battery has
- 3.5V - Recommended minimum voltage
- Voltage beeper - One way to know when your battery is low
- XT60 - Common battery connection type
- C value - The C value, along with mAh, will tell you how many Amps the battery is rated for
Step 7: Power and Signal Diagram
Shown above is how power and signal are sent to each component on the quadcopter. To split the power from the battery to the 4 ESCs (step 1 to 2), a power distribution board is required.
Power distribution board used in my build: PDB
Step 8: Battery Chargers
Special computerized chargers are needed to charge lithium polymer batteries. These chargers can often charge more than just LiPo batteries, such as NiMH, Lead Acid, etc.
Some available options when charging a battery with a computerized charger are:
1. LiPo Charge - Charges the battery 2. LiPo Balance Charge - Charges the battery making sure each cell has the same voltage (recommended every few charges) 3. LiPo Storage - Charges or discharges the battery to optimal storage voltage
There are a few settings you have to set on your own when charging the battery (see picture above):
1. How many amps will the charger charge at 2. How many cells does the battery have
The first is determined by the mAh rating of the battery. Simply divide the mAh rating of the battery by 1000 to determine how many amps to charge at.
A 4000 mAh battery will charge at 4.0 amps A 3200 mAh battery will charge at 3.2 amps A 900 mAh battery will charge at 0.9 amps
Most chargers are DC only, meaning you will need to buy a separate power supply. Similar to how a laptop has a power brick. Your power supply should be rated for just as much, if not more wattage than the charger.
Chargers will be rated for different maximum wattages. To determine how many watts your charger should be to effectively charge your battery:
1. Take the fully charges voltage of the battery. 2. Multiply the fully charged voltage by the amps you will be charging at. This will give you the wattage. Example: 4000 mAh 3S battery. 4 amps x 12.6V = 50.4 Watts. A 50 Watt charger will work.
- Note - If a battery is too big for a charger, the charger will take longer and not effectively charge the battery.
Recommended Tutorial Video: Youtube Link
Charger used in my build: Charger
Power Supply used in my build: Power Supply
Step 9: Flight Controllers
Without a flight controller, piloting the quadcopter would be extremely difficult, if not impossible. Flight controllers have gyroscopes and accelerators to keep the quadcopter from oscillating out of control. Some additional sensors that might be included are barometers and magnetometers.
Flight controllers are usually configured with computer software. The flight controller used in my build, the Naze32, uses opensource software called Cleanflight (Cleanflight website). Cleanflight supports many different flight controllers, not just the Naze32. Many YouTube tutorials can be found on how to configure your quadcopter with Cleanflight.
Flight controller used in my build: Flight controller
Step 10: Radios and Receivers
The radio for your quadcopter is what you will use to control altitude, speed, orientation, etc. Radios will usually come paired with a compatible receiver. Radios can range from $30 all the way to $600+. It is the authors recommendation that you start with a cheaper radio. Cheaper radios are less complicated and some might find it hard to spend $200 on their first radio.
Radios are labeled as "Modes":
Mode 1 - Throttle is on the right stick Mode 2 - Throttle is on the left stick (Most common in the United States)
Recommended video on buying radios: YouTube
Radio and Receiver used in my build: Radio and Receiver
Step 11: Conclusion
I hope this guide helped you better understand quadcopters and the components they are made of. The next step is to build your quadcopter! There are many great online resources on building quadcopters. Below are some YouTube channels with step by step videos on how to build and configure a quadcopter. Although the videos use different components than what you might have, remember that different brands of parts all function nearly identical.
When building your quadcopter you will definitely run into problems and make mistakes, everyone does. Searching the internet for your problem will more than likely result in a solution. Remember to have fun!