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Electronics

         The next step in building your quadcopter is the electronics.  This is anything on your quadcopter that requires power.  In this section, we'll be looking at the hardware aspect of these components (no coding involved yet).  There are two categories that I'll be splitting this in to:

 

On-Board

1. Motors

2. Electronic Speed Controlles (ESC)

3. Batteries

4. Gimbals

5. Powered Landing Gear

 

Off-Board

6. Transmitter/Reciever

7. Charger - Adapter

 

 

          If you haven't figured it out yet, anything that is physically mounted to the quadcopter is considered 'on-board' and anything that isn't is considered 'off-board'.  Gimbals and Powered Landing Gear are not essential to your quadcopter and require heavy programming, so I would recommend those sections only for advanced builders.  

 

Lets get started!

Preface

Preface

Motors, ESCs, and Propellers

In the following sections, we're going to talk a lot about Motors, ESCs and Propellers.  These three components have particularly intimate relationships with one another so they're difficult to talk about independantly.  You almost have to think of these three parts like pieces of a puzzle.  You have to make sure they all fit together before you buy them.  I'm going to use this preface to explain how these parts interact and why it's important to make sure they're all compatible. 

 

What to choose first

As far as your driving factor goes, you should probably be picking your motors first.  You motors characterize your quadcopter by determining it's speed and power.   After you've picked your type of motor, you can pick an ESC and prop that fit it.  Your ESC, Electronic Speed Controller, will depend on the operating amperage of your motor.   Your props will depend on the rotational speed of your motors (Kv).   Your motor and prop combination will give you the expected thrust of your quad, so they must be chosen together. 

 

This section wasn't meant to explain, but rather to lay the foundations for explanation so it's ok if you don't really understand.  Just keep in mind that these parts all rely on eachother and you'll be fine. 

Motors

Motors

The motors of a quadcopter represent the physical limit of what the quadcopter can accomplish.  Optimizing you motors will influence your payload capacity, top speed, manueveratiblity, flight time, and more.  Here we'll discuss the pros and cons of motor characteristics and find which motors are best for you.  I'll also be talking about propellers in this section, since the two components go hand in hand.  Or shaft in hub.

 

What are motors?

You might think this is a stupid question.  You're probably thinking, "of course I know what a motor is.  A motor takes electricity and turns it into spinning motion.  It spins things."  

Well you're right.  It was a stupid question. I'm glad you know what a motor is. Now we can move on.

What characterizes a motor?

When shopping for a motor, you'll need to look at a few key specs. I'll list them here and explain them in the following sections:

 

Motor Specifications:

  1. Inrunner vs. Outrunner

  2. Brushed vs. Brushless

  3. Weight

  4. Kv (RPM/V)

  5. Max Current

  6. Max Voltage

  7. Shaft Diameter

VoloCopter Prototype

[Volocopter.com]

Inrunner vs. Outrunner

When you're shopping for motors, one term you'll run into a lot is "outrunner".  This means that the shaft and outer housing of the motor spin together.  If you've never seen or heard of an outrunner before, it can be kind of hard to imagine.  Check out the video below to see what I mean.  A normal, or "inrunner", motor will spin only the shaft.  In the case of quadcopters, you want outrunners.  This is because outrunners have more torque and last longer.   The advantage of an inrunner is a very high rpm.  In our case, we don't need very high rpms and we aren't using a gearbox.  We would much rather have the torque. 

 

The verdict:   Outrunner

 

 

Outrunner Video

[Karlis Strelkovs @ Youtube.com]

Brushed vs. Brushless

To understand the arguements between brushed and brushless, you need to understand how a motor works.  A dc motor has two main parts: a coil of wire and some magenets.  By some magic of physics, sending electricity through a coil produces a magnetic field.  This magentic field interacts with the magnets, producing motion.  Now, a brushed motor will have the coils on the inside, and the magnets along the outside of the motor.  The rotation is produced by changing the polarity of the coil twice per cycle (by reversing the current in the coil).  A brushless motor has the magnet on the inside, and multiple coils spin around it.  

 

It's a bit complicated to explain in words.  If you want to know more, thinkrc.com explains it well.  

 

When it comes to quadcopters, you want a brushless motor.  Brushless motors offer more power and efficiency, but require an ESC.  

 

The verdict:   Brushless

 

 

Brushed vs Brushless Motors

[ThinkRC.com]

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