Well, here is my first post about quad- and other types of copters, I hope you won’t be too strict on me. I’ll try to be consecutive and concise about whatever I know about copters. Being a beginner copterologist myself, I’m here to make the whole thing easier for newbies just like me. We are going to discuss:
1. Choosing parts and components
2. Tuning a completed copter
3. Introducing 'aircraft guys’ vocabulary
Now let me tell you what inspired me to write this post. When I decided to craft my first quaddie, my arsenal included:
1. A toy quadcopter. It really could fly!
2. A burning desire to have a genuine quaddie and film panoramic high-altitude vids.
3. A tiny bit of money that freed me from having to wait until all parts arrived from China.

By the way, financially it was a bit different from what I had expected, and that is just one more thing that made me want to write this post. Well, first things first.

Ironically, I approached copter-building in a much less than first-things-first way, so some paragraphs may leave you asking questions. There will be answers to all questions at the bottom. Also, I have provided a glossary for beginner copterologists, which contains terms that are normally used by RC hobbyists. I can say it is a must-have thing, because this type of language is commonly used in most articles relating to the subject. I should note that most copterologists are former model aircraft constructors who use their own, often highly specific terms. This post focuses on helping a first-time RC aircraft hobbyist (and, definitely, a copterologist) to assemble and launch his/her first quadcopter. Well, so much for the intro, let’s go for it!

Part I. Why a Quadcopter?

Having a quad- or any other type of copter in possession is fair in many aspects. First, it is stunningly intuitive in operation. To me, it is just like moving my limbs whenever I need to. You can send it in any direction. Here is a little picture, which shows the basic directions.



As we can see, copters actually have the same arsenal of movements as humans, plus the up-and-down vector. Just put all these vectors together, and there will be no gaps left. Consequently, buying a copter is an IDEAL option for a beginner aircraft model constructor. It is the only good option for those too busy to go into details about aircrafts’ structure. A quad is for those who want to just fly. Just take off and fly! Quite exciting, isn't it! If you still have doubts, here is a table of the pluses and minuses of currently available RC aircraft. I could not figure out how to build a table, so I made a screenshot instead:



It may look strange to a passive observer, but it’s true.

Part II. What Should We Have?

This has to be an important step toward understanding copters. This part is about whether you want to take the whole thing seriously or all you want to do is just take off and fly. This is not as simple as it sounds, since this is not only about your desires, but also about your opportunities. Because I usually judge by myself, I should confess, I’ll describe my personal viewpoint. So, Number One: it’s simple - you have some money and you want to fly, don’t you? Just go and buy a ready-made copter! You’ll be happy! Although I’m not an advertiser, I can say that DJI is the top RTF (ready to fly) system manufacturer. Just Google it, and your dream will come true.

Number Two: you have little money, but you don't remember yourself doing things in your night dreams other than flying, do you? If that is the case, this post is for you, so read on! Other options are nothing less than crosses between the Number one and the Number two. It’s all up to you!

Part III. A bit of theory, which you cannot do without.

Now that you have decided to assemble a quad on your own, let’s go through the basics:
1. Choose a layout.
2. Choose componers.

I guess, you have viewed scores of quadcopter layouts on the Internet and wondered (yes, you have!) about differences, haven’t you? Let’s begin. Here is a pic showing the most popular ones.



The diversity is fantastic. So what? Let’s see the terms first:
1. Tricopter – three propellers
2. Quadcopter – four propellers
3. Hexacopter – six propellers
4. Octocopter – eight propellers.
It is not only the number of props, but their location as well, that makes a difference. Here is an example:



This one shows a six-prop tricopter. Actually, a copter type gets its name from the number of beams, not props or motors. For instance, a quadcopter can have eight motors and propellers similar to the one pictured above (two motors per beam), but that is not what makes an octocopter.

Now that we know the layout, it is time to make a choice. The choice should depend on our goals and means. Let’s go through each layout and choose the most suitable one. Actually, I have already chosen it for you, but what if you have a different opinion?

1. Tricopter. This one is believed to be the most maneuverable. The downside is its complicated structure. Limited functionality, poor lift and weak reliability compared to other copter types – that’s how I take it. Honest, I’ve never taken this one seriously.

2. Quadcopter. Four beams, four propellers. With a layout as simple as this one and the huge number of options, I’ve decided for you again. See this:
Layout +



Layout X


Layout H

Dead Cat Layout


As you can see, even four motors provide a host of options, from which we are to choose the most optimal one, so we go for the X layout. Wonder why? I’ll tell you about all these layouts, just take your time:



Now that we have chosen Layout X, it’s time to get the components.
Frame. A 330/450 size frame will be great for your first copter. The numbers stand for the diagonal distance between the motors. These are standard size options for copters. My first copter's frame was marked X465. I bought it upon the shop assistant’s advice, and it has not let me down once so far. When my copter took a 50-meter tumble I found it with two beams broken, and the replacement costed me only 400 rubles - not quite expensive.

Next thing we look for are motors. There are high quality DJI motors from a top manufacturer. Motors are marked standardly with numbers (for example 2212/920kV), where the first two-digit number (22) stands for the stator’s (sometime’s the rotor’s) diameter, and the second two-digit number (12) stands for the magnet’s length. At the initial stage, you can dismiss these figures. The slash is followed by a more important indicator - RPM per volt. We’ll discuss voltage a bit later. Well, to guarantee a smooth takeoff, we'd better use 720-950 kV motors. Physical size is not important.

We should use electronic speed controllers (ESC) to control the motor’s operation. 3-phase brushless motors are driven by an alternate current. A 4 in 1 speed controller will be ok for our quadcopter, since it is reliable and time-proven, and it takes but a little while to mount and tune it.

A flight controller. Same as control board. The wetware of any radio-guided aircraft. This is the component that should prevent a copter from crashing. So, why isthe choice of the right flight controller type is so important? This is what I think is the most exciting part of the copter assembly process. When I opened a webpage with a long list of flight controllers to choose from, I was infinitely surprised. Prices for controllers with similar characteristics ranging from 1000 to 50,000 rubles was a stunning sight. It proved very simple later. Why do we use a flight controller?

● To keep the quadcopter in a horizontal position.
● To learn cardinal directions (I’ll tell you why later).
● To know the altitude (later).
● To know GPS coordinates (to guarantee a safe return to the takeoff point and its keeping to the route).

Most commonly, a flight controller is a board featuring sensors and a chip, which processes data coming in from the sensors, and commands the motors to operate as directed by the selected program. The higher the price, the better the performance. I wanted to check other similar devices as well, but I could not find a decent match. To sum it up, the more expensive your flight controller is, the easier it is for you to operate your copter. It should be noted that some flight controllers operate a limited number of motors; for instance, Naza-M Light won’t activate more than six motors. However, we can disregard that, because we are assembling a quadcopter, and there are no controllers that activate fewer than 4 motors. If you do not have a knack for programming or circuit designing or are a poor electronic engineer, do not buy cheap controllers, or you'll plain waste your money.

Now we have the frame with motors, a flight controller and wetware mounted on it. Next thing we do is operate it. To do so, we must use a receiver and a transmitter. The receiver is a tiny box with an antenna, which receives the signal emitted by the transmitter. Personally, I call the transmitter a ‘remote control’, because you use it to actually fly your copter. Let’s take a closer look at the transmitter-receiver pair. This is what a typical transmitter looks like:



Things to remember when choosing a transmitter:
● Mode 1 or Mode 2. They differ in the location of the throttle stick. Mode 2 with the throttle stick on the left is more commonly used in Russia; Mode 1 is more popular in Asia.
● Frequency (2,4 GHz). At this point it is of zero importance.
● Number of channels. To fly a quadcopter, you should use at least four channels. However, there must be backup channels as well. Most likely, you are going to choose Turnigy 9x or its clone, which features 9 digital and 8 analog channels, which is quite enough. Now that we have examined it in detail, let's put it all together. Here’s the layout:



Now a bit of detail:
X465 Quadcopter Frame
AX2212/920KV Multicopter Motor
CW/CCW Propeller with 10х3,8 Century Adapters
20А ESC Speed Controller 3A/5В, 4 in 1
Choose the best flight controller you can afford. I have checked both cheap and expensive controllers, and I recommend DJI Naza-M Lite Multicopter Flight Controller.If you have a bit of money, you can buy DJI Naza-M Lite Multicopter Flight Controller with GPS.
Transmitter and receiver. First, Turnigy9x or any of its clones will be ok. It is branded in different ways, but the under-the-hood is the same. The Turnigy 9X Mode2 featuring a left throttle stick and 9 channels, comes with a module and an 8-channel receiver.
RC hobbyists use lithium polymer batteries. Turnigy nano-tech 3300 mah 3S 25-50C Lipo Pack will be the best for your first quadcopter.This is how it works:

1. 3S stands for the number of 3,7V cells. Consequently, 3S stands for 3,7V multiplied by the number of cells (3) = 11,1V, which is quite enough.

2. 3300 mAh denotes battery capacity. Higher the capacity means a longer flight. Many first-timers buy 2200 mAh, which is not bad either and guarantees a 10-minute hover.

3. 25-50С stands for discharge rate; 25 – constant, 50 - burst. Do not concentrate on these parameters at this point, because you will learn to read them later anyway.

Also, you should have a lithium polymer battery charger. I use IMAX-B6 18В 5А (original version), but it is possible to use other charges featuring balancing connectors. Balancing is a must for multibattery chargers.

Part IV. Let’s really build it.

Let’s start with the frame. It is fantastically easy, so there won’t be any issues. Next thing we do is mount the motors using 4 screws per motor – not a big challenge either. I used lock nuts, because I had found out the harm’s way that vibration could cause the screws to go loose during flight and put your quaddie to danger. Do not fix propellers before you finish assembling and tuning your copter!

Mount the ESC speed controller. If you have a 4-in-1 controller, put it in the middle of the upper board. If you are using separate controllers for each motor, nylon-tie them to the beams. As to mounting a 4-in-1 controller, use bi-adhesive. I used it myself, and I can say it holds on tight. Indeed, Velcro is the best option. It is available at specialized stores. Connect the speed controller to the motor. Do not be in a hurry to fix the wires, because you may need to reverse rotation in one or more motors. To reverse rotation, all you need to do is swap two of the three wires. Initially, the connection between the controller and the motor is not strict. At this point, let’s do it randomly to figure it out later.

Next we mount the flight controller. This is a crucial moment, because incorrect mounting can cause your copter to wallow or get out of hand. The flight controller features several sensors, which should be protected against adverse external influences. To ensure stable functioning of the gyroscope and the accelerometer, fix the controller on anti-vibration mounts. Expensive controllers feature anti-vibration mounts. If you have a cheaper model, build an anti-vibration platform – that is easy and not expensive at all. To ensure stable work of the magnetometer (compass), do your best to prevent crosstalk from power wires. Make sure the controller’s needle points toward the copter’s ‘nose’.

Now we want to connect the speed controller(s) to the control board. This has to be easy. Usually, outputs on flight controllers are marked Motor 1, Motor 2, etc. The motor layout depends on the type of the flight controller, so please, read the manual very carefully.

Important! If you are using separate speed controllers, only one of them can be powered. Each speed controller has three wires - positive, negative and signal, which connect it to the flight controller. It is that positive and negative should be used by only one of the speed controllers. If not, you'll burn them. Besides, they may conflict and cause the motors to rotate randomly.

Now we’re going to connect the receiver to the flight controller. It is here that we get obliterated by terms used by RC hobbyists. The receiver’s manual describes the functions of the first four channels. Usually, they are arranged in the following way:

Channel 1 – aileron; this channel is responsible for the left and right vector.
Channel 2 – elevator; this one is responsible for the back-forward vector.
Channel 3 – throttle; provides for takeoff, landing and altitude change.
Channel 4 – rudder; this channel puts the copter on a spin.


This is the most common sequential order, in which channels on the receiver and flight controller are arranged. However, there are exceptions, so take your time.

Next thing we do is connect power. If you are using a 4-in-1 ESC controller, it is ok. All you need to do is solder a connector that fits your battery to respective wires and insert the battery. Make sure there are no short circuits! This can cause severe damage, fire and health damage.

If you use a separate speed controller for each motor, solder all the positive wires that come in from the speed controllers together and all negative ones separately. Apply voltage to the resulting harnesses via the respective connector. Built!

Part V. Tuning.

Most important, you should know how to launch motors. All flight controllers feature an accidental activation prevention system, which prevents unintentional launch when throttle is activated. The props will not start rotating if you accidentally move the throttle stick. Therefore, it takes a procedure to arm the motors. You can read about it in the flight controller’s manual. To arm a Naza controller, hold the sticks for 3 seconds as shown in the following picture:


To deactivate the motors, carry out a disarming procedure. Almost all controllers feature a disarm function, which is activated should there be no signal from the transmitter for longer than 3-5 seconds. As a rule, the arming procedure results in a blinking LED indicator (or a transition from blinking to steady burning). Once again: do not fix propellers until you finish building and tuning your copter!

Well, now the activation is complete. Push on the throttle to check the motors. They should rotate in the direction specified in the manual. If you see one rotating in reverse direction, swap two wires that connect it to the flight controller. Normally, quadcopters have two motors rotating in one direction and the other two rotating in the opposite direction. Now that you have set your motors to rotate properly, go over to the final stage of building your copter.

Motors may rotate at a different speed. If that is the case, calibrate the speed controllers. Some controllers feature software, which calibrates them automatically. In any event, it is better to calibrate them manually, all the more so because it is quick and simple. This can be done in two different ways:

Option Number 1. 4 in 1 ESC speed controller.
● Power-off the speed controller and the transmitter.
● Connect Channel 3 of the transmitter (throttle) to Channel 3 of the speed controller (three wires) bypassing the flight controller board.
● Switch on the transmitter. Push the throttle stick all the way up to the full throttle position.
● Power-up the speed controller.
● Wait until it beeps.
● Pull the throttle stick all the way down to the zero position within the first three seconds following the beep. If you do it later, the programming mode will be launched automatically, and you’re going to have to restart the whole procedure.
● Wait until you hear the confirmation signal.
● Power-off the speed controller.
● Calibration finished!
Option Number 2 – each motor has its own speed controller.
● Power-off the ESC and the transmitter.
● Connect Channel 3 of the transmitter (throttle) to the speed controller. Please, remember that the receiver is powered from the speed controller. Therefore, if you have previously disconnected the positive wire from the speed controller, reconnect it (+) and keep it this way until you finish calibration.
● Switch on the transmitter. Push the throttle stick all the way up to the full position.
● Power-up the speed controller.
● Wait until you hear beeps.
● Pull the throttle stick all the way down to the zero position within the first three seconds following the beep. If you do it later, the programming mode will be launched automatically, and you’re going to have to restart the whole calibration procedure.
● Wait until you hear the confirmation signal.
● Power off the speed controller.
● Calibration finished!
● Do the same procedure for each speed controller.
Now that calibration is finished, all motors should rotate at the same speed. Important! Calibrate the controllers with motors connected. Now you can fix the propellers (note the rotation direction of each motor!) All propellers must be fixed in the thrust-up fashion. To avoid damage to furniture and health damage, do not launch your copter indoors!


Part VI. Launch!

Now it’s time to take off! If your copter takes a wrong position right after launch, check the rotation direction and make sure the propellers are fixed properly.

Here is the promised glossary and important information:



FAQ
Question: My transmitter features Acro, Sport, Land, Drift, etc. modes, but there is no Copter mode! How do I use it?
Answer: Take it easy. Use Acro. No transmitter features the Copter mode.

Question: I can’t arm the motors. Am I doing something wrong?
Answer: There are two possible solutions. Number one: check the control system parameters. Make sure the Stick Set option is set to Mode 2. Number two: connect receiver channels properly.

Question: Every time I switch on my Turnigy 9x transmitter the switch error message pops up. How do I fix that?
Answer: It’s ok. Make sure that all the switches are in the ‘up’ position.

In my next post I’m going to focus on three flight modes. See you later!



This is the translated version. You can read the original Russian article here.