Decided to build a quadcopter? Is it greek for you? Don't know what to start with? This article is right for you. It's based on my own experience.

How it flies?
Two propellers rotates clockwise and two other counterclockwise.


If you decided to build a quadcopter first of all you need to come up with the budget. The size of the vehicle depends on the budget you are ready to spend. Most popular sizes (in mm) are 250, 330, 450, 550 and larger.
  • 250 size copters are small and lightweight. They are mostly being used for FPV flights.
  • 330 and 450 are optimal sizes for budget quadcopter. Such copters have reasonable weight and affordable build cost.
  • 550 and larger size copters are professional ones. They are heavy and expensive. They need powerful motors but they can carry heavy payload. SLR cameras weighing few kilograms for example.
I would suggest to consider 330, 450 size frames. There are a lot of them available at RC stores. You can choose any based on your preferences. But I would like to turn your attention to DJI 330, 450 and TBS Discovery frames. Originals are quite expensive but cheaper clones are available:
F330 Glass Fiber Mini Quadcopter Frame 330mm
Product http://www.rcfair.com/en/product/517343/

Q450 V3 Glass Fiber Quadcopter Frame 450mm - Integrated PCB Version
Product http://www.rcfair.com/en/product/1179587/


Now it's time to figure out what parts quadcopter is consist of:

1. Frame
2. Receiver/Transmitter
3. Flight controller
a) AIOP
b) NAZA
c) MuliWii
d) HKPilot
e) and other...
4. Propulsion system
a) Motors
b) ESC
c) Propellers5. Battery
6. Additional equipment
a) FPV system
• Flight camera
• Transmitter
• OSD
b) On-board camera mount
c) LED lights

Let's review each item in details:

Frame
We've already decided with the frame.

Receiver/Transmitter
Transmitter choice is very important. You need to decide upon how far are you goint go fly.
Most popular options:
  • 2.4 GHz max distance 1.5-2 km
  • 433 MHz max distance 5-10 km (depends on transmitter power. You can fly even up to 20 km on some of them)
Quadcopter needs at least 5 channel transmitter. I have chosen Upgraded FlySky FS-TH9X 2.4G 9CH Transmitter With FS-R9B RM002 Mode 2 . It is not expensive and easy to configure. I chosen this equipment because of its popularity and long presense on the market. It has many clones: Turnigy 9, Avionics etc. You can find a lot of configuration options and other information about it on the internet. Stock JR module can be replaced with FrSky with telemetry support.

Flight controller
There are plenty of flight controllers available on the market. I've chosen Naza Lite with GPS. It has reasonable price and quite simple to setup. AIOP, Crius and MultiWii require more complex configuration so I don't recommend them for beginners. Why I chose controller with GPS? It is needed for position holding and return to home functions. I found it very useful.

Propulsion system
It raises many question among newbies. Brushless motors are being used. They are three-phase (has three wires) and have 90% efficiency. This type of motors needs electronic speed controllers (ESC) to control rotation speed. ESC receives commands from the flight controller and ajust motor rotation speed accordingly.

Probably you should ask how to connect motor to ESC? The answer is simple. Just connect all three wires any to any. To change motor rotation direction simply swap any 2 of three wires.

Now you need to estimate your copter's flight weight. Average weight is 1-1.5 kg (considering 330, 450mm frames). Trust/weight ratio shold be 2-2.5. So summary trust of all 4 motors should be 2-3kg. Accordingly single motor trust should be 500-700g. What motor to choose? Look at your frame specs for what motor sizes are supported. Check for first two digints. They are 22 or 28 in most cases. In the motor name you'll see value called "kv" and looks like 1100kv. It means number of rotations per one volt. High kv motors has fewer turns in their stator winding than less revving motors. It follows thence that less kv motors has greater max current and torque. Such motors could be used with bigger propellers. 820kv and 1400kv motors are like 1st and 3rd car gears.
820kv is for slow steady flights.
1400kv for fast maneuvering flight.

To choose proper ESC you need to know motor max current. Get it from motor technical specs or test bench data available on the internet. Suppose you motor max current is 20A. You need ESC with 20-25% reserve 25-30A. Now look at motor test bench data. Suppose it says 11х4.7 –3S-12A – 830g. What does it mean?
11х4.7 - propeller specs
3S - nuber of LiPo battery cells
12A - current
830g - trust

Therefore max trust is 830x4=3300g, max current 12x4=48A. You need to know max current to choose proper battery and wires.

Do not buy carbon propellers in the begining. It's unnecessary expense. Learn to fly on cheap ones.
Propeller mount depends on motor. Most of props have an adapter for motor shaft. Collet and thread mounts are possible. DJI offers self-tightening props that will never unscrew during the flight. For threaded shaft mount I highly recommend to use thread lock.

Wiring diagram
Control cable - black, power cable (+/-) - red



Battery
You need to select battery with proper C-rate (measure of the rate at which a battery is being discharged) (25C,35C). As you remember our system max current is 48A. Consider 3300mAh 3S 35C LiPo Pack batter.
3300mah - battery capacity
3S - number of LiPo cells (one cell is 3.7v)
35C - C-rate. In other words 3300mah x 35C = 115A
It covers our needs with significant reserve. Batteries with higher C-rate are heavier and more expensive. Let's check if 25C battery with same capacity will meet our needs 3300mah x 25C = 82A.
The answer is yes. This battery is lighter and cheaper. The bigger battery not always means the better.

I recommend to buy lipoly battery low voltage alarm it is very useful.

You'll need a charger to charge your battery. Imax B6 is probably the best choice but be careful there are a lot of low quality clones on the market. I highly recommend you to buy original.
Cheaper chargers are also available:
HobbyKing ECO6 50W 5A Balancer/Charger w/ accessories
Product http://www.rcfair.com/en/product/100621/

IMAX B6 Charger/Discharger 1-6 Cells (COPY)
Product http://www.rcfair.com/en/product/102457/

HobbyKing® B3AC Compact Charger
Product http://www.rcfair.com/en/product/411257/


Handle LiPo very careful. I suggest to buy at least 2 batteries.

Additional equipment
Well, you have decided upon the flight distance and chosen the transmitter. Now time to select FPV system. FPV means First Person View. FPV transmitter must not conflict with control transmitter so proper frequency should be chosen.
• 2.4GHz is compatible with 5.8GHz
• 433MHz compatible with 1.2 GHz
Otherwise there can be interference.

I have chosen 5.8GHz 200mw FPV transmitter and receiver for my 2.4GHz control transmitter.

FPV system consist of
1.) Flight camera
2.) Transmitter on board of the copter
3.) Receiver on ground

To increase communication range standard antenna can be replaced with "Clover".
Most transmitters consumes 9-12v. Small 3S lipo battery will be enough for transmitter and camera that should be chosen according to battery voltage.

What does 200mw means? It is transmitter capacity. Communication range directly depends on it. This transmitter's range is 1.5-2km on open space with clover antenna. Since my control transmitter's range is near the same it fits my needs perfectly.

Now things are clear with receiver and transmitter but how to choose the camera?
The choice depends on your budget. Some cameras can transmit and record data simulataneously but they considerably more expensive. Mobius is very popular camera.
Mobius ActionCam A/V Out Cable Set
Product http://www.rcfair.com/en/product/1199750/


You can use cheap caseless flight camera (it costs $15-25) and record video by separate on-board camera. Another important parameter of the camera is TVL. It is defined as the maximum number of alternating light and dark vertical lines that can be resolved per picture height. The higher this number is, the better the picture. For FPV camera TVL 500-700 is enough. Minimum illuminance is important. 0.01 lux is enough even for flights in the evening. Observation angle should be 100-120 degrees. Auto white balance and flat field correction functions are useful.

You can energize monitor and receiver from single 3S battery. Monitor can be mounted on control transmitter with the special frame or setup ground FPV station on tripod.

• You can buy 2x or 3x axis on-board camera mount. It is rather expensive thing but it allows camera rotation and more stable picture.
• On-board camera itself.
• LED lights, beeper, GPS-tracker
This is the translated version. You can read the original Russian article here.