2018 - Guide to QuadCopters (Pt 1)

2018 Beginners Guide to Quadcopters (Drones)

Well, as you probably guessed from the title, this is a beginner’s guide to what we in the hobby call Quadcopters or Multirotor. The modern day colloquialism is “Drone” or “UAS” but these have come more recently refer to radio controlled aircraft as whole. So when we say Quadcopter we are specifically talking about the area of the hobby that relates to aircraft that use 4 motors to provide thrust and lift to the craft.

Quadcopters or “Quads” for short are an area of the hobby a lot of people are getting interested in, and it’s not surprising, the ability to take off and land from almost anywhere and the feeling of you being in the pilot seat are pretty attractive. The ability to see from the quad itself is known as FPV or First Person View. Modern Quads are usually equipped with cameras so that the pilot can fly from the quads perspective, rather than TPV or LOS [third person view or line of sight].

FPV Quads have become as popular as of late because of social media, network television shows and of course the fact you can pick up inexpensive “drones” from most malls, stores etc. but what separates the quads here is that these machines really do not have any flight assistance modes at all. This is where the largest learning curve takes place. Also, one thing to note, is that we will be discussing at times some fairly advanced electronic knowledge, and a basic understanding of electronics principals may come in handy. This may be covered in another article, but not in this one.

In this guide, I will walk through my recommendations for someone first getting into the sport, as well as best practices to get off the ground (the right way) and of course provide a solid foundation for someone looking to start diving into the world of Quads.

Anatomy of a Quadcopter:

Probably the best way to understand how these machines work, is to understand what makes them go. If you are new to Flite Test or the hobby in general, let’s start with the basics and work our way through how these things move.

One other thing before we get going; there are ALOT, and I mean, ALOT of acronyms used in this hobby, I will have a glossary of these terms at the bottom of this guide.

1. Electric Motors
   • This is the part of the Quad that actually makes it go. This is also one of the parts of the quad that came from electric radio controlled airplanes, before they began to be used on quads. Usually these motors are 3 stage electric motors, comprised of an outer bell with magnets, and an inner fixed component called the Stator. The electric motor receives its power and signals from the electronic speed controllers to allow the craft the fly. [we will go through the powertrain shortly]
2. Video Transmitter (VTX)
   • The Video transmitter is part of the video system on board the quad that allows the pilot to see what the quad is doing in flight. [we will go through video systems shortly]
3. Video Antenna
   • This is the part that emits a signal to the pilot to allow the pilot to see the video from onboard the craft. The antennas on most quads are tuned to emit/receive on the 5.8GHz range. [we will discuss some of the differences between control and video link shortly]
4. Camera or Video System
   • This of this as the eyes of the quad, allowing pilots to see what is in front of them. Back in the old days of FPV (only 6-7 years ago) pilots used mini security cameras to feed video. Now, dedicated camera systems, some of which even have built in recording capabilities.
5. Electronic Speed Controllers
   • Electronic Speed Controllers or ESC’s as they are known by in the hobby take battery power and provide a signal to individual motors that the ESC is soldered too. Each craft has 4 motors (thus a quad) and 4 ESC’s that provide power to each one. (we will discuss how these signals are interpreted by the motors in later guides)
6. Power Distribution Board
   • Power Distribution Board or PDB as they are known are printed circuit boards that provide power from the flight battery through the rest of the quad. Modern PDB’s have built in circuits to provide clean power to almost all the systems on board a quad.
7. Flight Control Board
   • Flight Control Board or FC is the brains of the quad. This is what turns the inputs from the sticks into actual movements on the craft. We will go into more specifics in later guides, but for now, just know the basics… it makes things do what they are supposed to.
8. Propellers
   • Propellers or Props are highly engineered plastic components that provide the lift the craft needs to leave mother earth. They are probably the most inexpensive part of any quad and are usually the first thing that will break when you fly. Having enough of these on hand will keep you in the air.
9. Receiver
   • The Receiver or RX takes the signal from the transmitter sticks and converts the signal to a language that the Flight Controller can understand. This is usually sent over the 2.4GHz band on a digital signal. (we will go into radio options later in this guide)
10. Battery
    • Flight Battery’s used by quads are known as LiPo Battery Packs. LiPo or Lithium Polymer is the chemical composition of the batteries most commonly used in the hobby. These are high discharge batteries that can deliver a lot of Amps to the power system of the quad, up to 120 Amps at some points! LiPo safety is certainly something we will cover as it is one aspect of the hobby that EVERYONE should be cautious of.

How do They fly?:

Answering the question of how these craft fly is not quite as simple as explaining the components on board. Quadcopters, unlike other RC vehicles (Cars and Boats) moves in 3D space, so not only do these craft fly forward and backwards (Y Axis), left and right (X Axis), they have the ability to go up and down (Z Axis). 

Before we begin to pair these movements up with the sticks and how the quad moves through space, we will go through each maneuver and then pair them later.

Now let’s talk about maneuvers that allow the quad to move through space. These are the same as an aircraft’s except for the way the craft moves through the Z axis.The simplest axis to explain first is the Z Axis. The up and down is controlled through the power delivered to the motors, the faster the motor turns the propellers the more lift that is generated, thus raising the craft up. More power, more lift, makes it go higher. We call this gaining altitude.

The next are best explained in this diagram:

Understanding the vocabulary of directions of the quad will allow you to understand what the individual motors are doing, as well as troubleshooting later on. Moving through 3D space, directional moves follow the same naming convention as that of aircraft. Starting with Pitching, dipping the nose up and down, this changes the trust line making the quad move forwards and backward. On the Z axis, accelerating the motors changes the altitude of the quad making it go up and down. Lastly, X axis moves this is probably the most challenging to put into words, but simply put, there are 2 methods of moving the craft in the way, Rolling, which tilts the craft about its Y axis. This causes the quad to slide left or right. The other way to have the quad move about the X axis is to Yaw by moving the nose about the Z axis. The reason for these maneuvers relates back to the way airplanes fly. Flying forward, the aircraft banks to the left by tilting its left wing down, this increases lift on the right wing, pushing the aircraft left, however the nose is still pointing forward, the plane requires rudder input, or yaw input, to push the nose around into the turn. These two moves keep the nose pointed around a turn.

Now understanding these moves, let's explore the way the motors make these moves happen. After you get a sense of how the quad flies we can begin to talk about how you control the quad, and how the onboard flight control board helps the quad stay stable in the air.

Unlike airplanes or helicopters, Quads do not have any other control surface other than the speed of the motors. In order to keep the quad stable, and not spinning out of control, 2 motors spin clockwise, and 2 spin counter clockwise:

In order to control the moves of a quad in flight, increasing particular pairs of motors will place a force on the quad to initiate the move.

To roll the quad, in this case to the right, two motors on the left side increase speed, thus forcing the quad to the right. For left turns the opposite is true. 

Pitch is the same as roll except the pairs are at the front and back of the Quad. In this example the front motors spin up to lift the nose up, thus pitching the craft backward.

Yaw on the other hand is a very interesting control. The yaw control relies on gyroscopic effect to rotate around the center of the quad. Unlike the other controls, this one is much more sensitive, and in the early days of quadcopters, this was the most challenging control to tune. The two corner motors acceleration forces the quad to turn about the center. The yaw control becomes important mostly with roll turns, to coordinate and point the camera into the turns to allow the pilot to see.

How do you control this thing?!

If you're familiar with other radio-controlled flying a quadcopter is very similar. The control system in a quadcopter is the same as it is in a regular radio control aircraft. The radio system on a quadcopter is usually a controller with 2 gimbal sticks and a variety of switches that allow the pilot to change modes on the quadcopter while it is flying. Radio controller’s styles vary from a standard game style controller to a more traditional looking radio controller, those are usually a square or rectangular form with the 2 gimbal sticks in the middle.

In the United States most pilots fly using flying in Mode 2. Throttle and Elevator are on the stick on the left hand side and elevator and aileron control are on the right. By mixing the controls on both sticks the pilot is able to operate the quadcopter and fly however they would like to.  Unlike GPS style quadcopters, like DJI, the stick on the left hand side, on the up and down, is not on a spring. The pilot has full control of the movement from bottom of the gimbal to the top giving the pilot full control of the throttle low end to high.

What is incredible about the radio systems that we use now is that they can be customized at adjusted for the Pilot's preference so that the quadcopter react the way that the pilot intended to. This means that every pilot has the Precision in the ability to fly in areas that many other types of flying machine simply cannot complete. Putting a camera onboard makes the experience incredibly easy and allows the pilot to really express themselves through their flying.

In the next all article we will discuss how the electronics connect to the quadcopter, and how the flight controller operate as well as how the control system connects to the flight control system as well.  since this is a very technical I felt the need to write the first one so that everyone has a very good foundation to set the precedent of the technical aspects that are required for building one of these machines.  Once learned it is very to work on quads and also troubleshoot the different systems in case something isn't working.

Thank you so much for reading this first article and I look forward to releasing the second one soon. Stay tuned on a Facebook page QuadCourses as well as Instagram @QuadCorses_FPV.  Do you have any questions feel free to write them in the comment section I will try and I'll see them as quickly as I can otherwise you're welcome to leave any comments on the Facebook page.

(the below will grow as we progress through parts 2 and 3.

Glossary of Terms: