ESC

Castle Creations 35 Amp Brushless ESC

An Electronic Speed Controller, or “ESC” controls the speed of the motor.  ESCs will have a power limit.  The more power an ESC can handle, the larger, heavier and more expensive the ESC will be.  When choosing an ESC, it needs to match or exceed the motor’s peak amperage.  If the peak amperage of the motor is 13 amps, then an ESC rated at 15 amps will be sufficient.  An ESC with a lower rated amperage will overheat and possibly fail.

Some common features of an ESC are a low voltage cutoff.  The low voltage cutoff will cut the power to the motors when the voltage drops to a specific level.  This is a protection feature for LiPo batteries.  If a LiPo battery’s voltage drops below its minimal voltage, it can permanently damage the battery.  The low voltage cutoff protects the battery from dropping below its minimal voltage.

Some ESCs can be programmed to have different throttle responses, adjust the low voltage cutoff limit, reverse the motor’s direction and change the switch rate.

Connectors

Power connectors come in various of shapes and sizes.   Choosing a power connector is dictated by power requirements and compatibility.   The most common power connectors are XT-60, Deans Ultra Plugs and EC3 and EC5 Bullet Connectors.

I use the Deans Ultra connectors but I found they can lose contact when fully plugged in.  This is an inherent design flaw with the T type connector.  I would choose the XT-60 connector if I was not so invested in the Deans connector.  I favor the XT-60 because they are easier to solder and connect and disconnect with ease.

 

Radio

Futaba 7C 2.4 GHz Radio

The R/C radio controls the throttle and the direction that the quadcopter travels.  When choosing an R/C radio, the most important feature is how many channels the radio supports.  One channel independently controls one servo or ESC.  The more channels, the more devices that can be independently controlled.  The minimum number of channels for a quadcopter is 5.  Four of those channels are for the four motors and the other channel for switching between flight modes.   These flight modes could be switching from stable or acrobat mode or to enable or disable autonomous flying.  A radio with more than 5 channels will allow auxiliary devices to be controlled.  Some devices that could be controlled are lights, robotic cameras or landing gear.

Sensors

ArduPilot Mega IMU board

For Scout to auto-stabilize, it needs sensors to find its orientation in space.  No one sensor can do this on its own.  It takes several different sensors working together to calculate Scout’s orientation.  The sensors used to calculate orientation are gyroscopes and accelerometers.  More recently, magnetometers are being incorporated to calculate direction.

Conveniently, there are boards that incorporate all of these sensors together.  These boards are called inertial measurement unit, or IMU.  An IMU uses accelerometers and gyroscopes to measure and report the aircrafts velocity, orientation and gravitational forces on multiples axis.

Scout uses the ArduPilot Mega IMU shield.  I chose this board because it was developed to work with the ArduPilot Mega board.