"Make: Getting Started with Drones" by Terry & Belinda Kilby

• The flight controller is the brain of the drone.
• Lift is the aerodynamic force that keeps an aircraft in the air.
• The four forces acting on an aircraft are weight, lift, thrust and drag.
• US radio controlled aircraft typically operate in “mode 2” controller operation.
• Multirotor craft maneuver using vector thrusting, which is a method of adjusting the relative speed of the rotors to achieve maneuvers.
• The airframe is the main body of an aircraft. All other components are mounted to the airframe.
• Multirotor craft alternate motors and props so each on spins in the opposite direction of the one next to it. This allows the motors to counteract each other and maintain stable flight. This is why most drones have an even number of motors.
• The quadcopter is the simplest mechanical design with the lowest part count of all common multirotor designs.
• The octocopter has eight props, can carry a larger payload, and can maintain level flight if any single prop malfunctions.
• It’s always very important to keep weight balanced front to back and side to side in your drone.
• The QAV250 is one of the most common airframes on the market. It’s extremely lightweight due to it’s simple two-plate design.
• The powertrain is the group of components that generates power and transfer it in a fashion that creates movement.
• There are three main specifications for props: direction, size, and pitch.
• Pusher-props, sometimes called left-handed, generate lift when spun in a counterclockwise direction. Tractor-props, sometimes called right-handed, generate lift when spun in a clockwise direction.
• Pusher props are so called because they were originally used on planes with rear mounted engines and would push the plane through the air.
• Prop size is measured in inches from tip to tip across the hub.
• Pitch is a measurement of how far the propeller would move forward if it were passing through a solid matter with one revolution.
• A higher-pitched prop would propel the craft further with a single revolution.
• Slip is the difference between the geometric pitch and the effective pitch of the prop.
• The higher the pitch, the more air will pass through the propeller with each revolution. Passing more air through the prop results in a higher level of thrust.
• Typically, the higher the pitch and/or the larger the prop, the more lift that is generated.
• Increased lift comes at the price of efficiency (i.e. flight time).
• Props need to be balanced to spin smoothly at high speeds.
• Most modern brushless motors in the hobby industry are identified by the width and height of the motor housing.
• Motors use a kV rating which tells us the RPM of the motor for each volt of electricity fed into it.
• Total lift is the amount of upward thrust generated by a motor and prop combo.
• Payload capacity is the difference between the aircraft’s total lift and it’s All Up Weight (AUW). All Up Weight is the total weight of the aircraft in flight conditions.
• Electronic speed controllers (ESCs) are small electronic circuits that are used to independently control the speed and direction of each motor on the quad. THey work by converting power from the battery into a sequence of electrical signals that are sent across three different wires to the brushless motor. This sequence controls the speed, rotation, and even braking ability of the motor. The required speed for each motor is communicated to each ESC from the flight controller.
• The voltage rating of an ESC determines what size battery you can use with that ESC.
• The current draw of the motors is what determines what size ESCs are required for your quad.
• One of the most important technological developments that has enabled the civilian drone rise is the lithium-polymer (Li-Po) battery.
• A single Lipo cell is rated for 3.7 volts. A battery pack is just a series connection of several cells.
• Use fireproof bags when charging Li-Po batteries and replace them at the first sign of damage.
• Discharging your battery below 3.2 volts per cell can irreversibly damage it. You also shouldn’t store batteries with a full-charge.
• Bullet connectors allow you to connect/disconnect wires without soldering.
• If using bullet connectors, the end supplying power should be the female connector, so as to shield the contacts from shorting.
• ESCs are usually either mounted on the subframe or out on the booms. Placing them on the booms permits additional cooling from the downdraft of the props.
• The motor shaft that spins the prop is threaded. A prop nut is used to hold the prop in place. These threads run in both directions, so be sure to tighten the prop nut in the opposite direction that the motor spins.
• There is no wrong way to connect a brushless motor to a speed controller, only the direction of spin will change. You won’t damage the motor.
• The flight controller is the brain of your drone. It measures the performance of your aircraft through an array of various sensors, hundreds of times per second, and then manages all the micro adjustments that are needed on each motor to keep your aircraft stable in the air.
• Flight controller software is split between open-source and closed source solutions.
• The heart of the flight controller is the inertial measurement unit (IMU). This unit contains a suite of sensors to help the flight controller monitor the activity of the aircraft. The most typical sensors include an accelerometer, gyroscope, and barometer. These measure the acceleration and rate of rotation of the aircraft, and the air pressure (which can often be converted to altitude). These three sensors provide all the date that the autopilot needs to keep the aircraft stable in the air.
• All modern flight controllers have some type of software interface.
• When installing the flight controller, make sure that the forward arrow is pointing in the forward direction of the airframe.
• The flight controller is nothing more than a microcontroller that takes an array of inputs, runs calculations on them, and then sends out the appropriate signals to keep you airborne.
• The three-wire standard that you see on ESCs is sometimes called a servo wire. This always contains a power, signal, and a ground wire. As a rule of thumb the power wire will always be red.
• One feature clearly draws the line between a drone and a model aircraft: the ability to operate using GPS.
• GPS enables several flight modes:
• Loiter: It holds the aircraft at (approximately) a specific position and altitude.
• Return to Home: This allows the aircraft to set a home location and return to it under certain circumstances.
• Waypoint Navigation: Autonomous navigation via pre-programmed routes.
• Follow Me: Use a stream of position data from a base station to maintain a specific distance from the station.
• The battery monitor is an important component of your drone.
• The transmitter is the remote control for your aircraft.
• If you want to use video your transmitter and video signal need to operate in different bands.
• There are two different communication protocols between the transmitter and the aircraft: PWM (pulse-width modulation) and PPM (pulse-position modulation). The main difference is that PWM is analog and PPM is digital.
• SInce PPM is digital it can use digital-serial communication to send up to 9 channels of data across a single wire. This cleans up your installation dramatically, since PWM requires a single wire for each channel.
• Use PPM if possible.
• Transmitters only send control data one-way to the aircraft. To get any data back you have to use a special two-way radio known as a telemetry link.
• The telemetry link takes a series of measurements from your aircraft and sends them back down to the ground where they can be displayed in ground control software.
• Your telemetry radio set will actually come with two different radios. One goes on the aircraft and the other connects to your ground control software.
• Use velcro to mount the telemetry radio to the back of a table or base station.
• As with every other component in the drone world, weight is always one of the first qualities to consider.
• It is always more desirable to have a lighter component.
• Geo fence sets a designated fly-zone perimeter.
• Always fly below 400 ft.
• Fly within line of sight.
• If you want to increase the speed of your quad, try different props.
• The general rule of thumb for increasing flight time is to go with a longer prop that has a lower pitch.