Flight Plan: How to Produce Professional Aerial Video, Part 1

Electronic Speed Control (ESC)

The ESC is a tiny microprocessor that regulates the amount of power sent to the motor. Your aircraft will have an ESC for each motor it has. These devices are controlled in unison from the throttle channel of your radio and will allow you to operate your motor from low power to full power and anywhere in between.

The ESC will generally have 3 sets of wiring. On one side you will have 2 wires, black and red, that will go to the battery through some sort of distribution device. On the same side of the red and black wires, you’ll find your servo or receiver wire that goes into the flight controller in its respective motor position. The remaining 3 wires you see will connect to the 3 motor wires . Your motor will need to rotate either clockwise or counter clockwise, as noted by the manufacturer. If you need to reverse the direction of a motor, you can simply swap 2 of the 3 wires and your motor will rotate in the opposite direction.

Your ESCs will be rated for the amount of electrical current they can handle in amps. (30amp ESC). The important thing to keep in mind is that each ESC has a value of amperage it can handle continuously, and a value it can handle for short “bursts” periods of time—say, 15-30 seconds. The continuous value is typically referenced on the ESC and the burst value is approx 20% more, depending on the manufacturer.

Additionally, your ESC will be designed to work with specific battery voltages, such as 2s, 3s, 4s, and so on. Unless you’re assembling a DIY flight system, your manufacturer will have already matched your ESCs to your power and engine combinations. Regardless, it’s still advantageous to understand the details of your aircraft. The more power you ask for, the hotter your ESCs will get.

The heat factor has proven challenging when lifting heavier payloads. Airflow over the top of the ESC has typically been the preferred method of cooling; however, when you’re in a hover, there can be little airflow over these electrical components, thus contributing to an overheat condition and possibly a subsequent motor failure.

ESC technology is improving quickly and there are some fairly robust units available, but be prepared to drop well over $100 per unit. It’s interesting to note that some of the more advanced flight controllers will compensate for a single motor failure. This gives you added safety when flying Octo (8-motor) and Hex (6-motor) aircraft.

Brushless Motors

The brushless motor is the workhorse of your multi-rotor copter. The motor has to support the full weight of the copter continuously while turning at high speeds. Keep in mind that the cheapest motor is never a wise choice for something that is literally hanging in the air from its motors.

Brushless motors receive power inputs from the ESC, providing a rapid response to commanded power changes from the pilot/flight controller. Brushless motors do not use brushes for energy distribution to the rotor, but rather have a group of magnets rotating around the stationary coil, thus resulting in the outer case of the motor spinning around the center. These motors offer higher efficiency and performance with less risk of interference from brushes and gears as in traditional brushed motors.

Brushless technology offers us many choices of motors with different power output and RPMs per volt. There is a relationship between the motor and propeller that is important to understand. Typically, you will not go wrong by following the manufacturer recommendations, but as a general rule of thumb, larger-diameter, slower-turning propellers are normally a lot more efficient than smaller, faster-turning propellers.

There are some limits and drawbacks worth noting, however. Trying to spin too large a prop on a given motor can cause it to overheat. It’s for this reason that motors will usually have a given maximum prop size.

Propellers

Propellers and the materials they are made from can affect flight performance. Good-quality props can improve aircraft control-ability, increase battery life, and improve your video quality, to name just a few advantages. If you’re a beginner, then I would recommend sticking with a plastic propeller (or prop), as you’re sure to damage one or more as you learn. In most cases, the carbon fiber (CF) props will be considerably more expensive.

Once you’ve mastered your flying skills and are ready to start capturing video, you may wish to try the CF props, as they are known to have less vibration, and therefore potentially less “jello effect.” They’re also likely to be quieter, and usually come pre-balanced and perform better under higher RPMs than plastic props. Out-of-balance propellers are one of the most common reasons for unstable video results. Invest in a prop balancer from your local hobby store and be sure to have all of your props in balance.

There are many ways to balance a prop. I like to apply a small amount of clear tape to the underside of the prop that is too light until I’ve achieved the desired results. Anytime you nick a prop or bend a plastic one, you may have to revisit the balancing process.

Global Positioning System (GPS)

GPS navigation capability is not generally required to be able to fly your multi-rotor copter; however, it adds very sophisticated capabilities that were once limited to large, very expensive commercial and military aircraft just a few years ago. GPS offers you dynamic position hold, a come-home feature, waypoint navigation, and the ability to have your copter return to a “home” launch point should there be a communication failure.

Some manufactures provide the ability to pre-program your flight path on your tablet device using touch-sensitive software. You simply touch a spot on the electronic map, set this as a waypoint, and hit “GO.” Assuming you have enough battery, your copter will take off, climb to a pre-programmed altitude, fly to the determined waypoint(s), and return back to the launch point and land, all automatically.

DJI is pioneering what they refer to as “Fly Safe,” a technology whereby the copter is prohibited from flight near airports listed in a database. GPS flight modes are nothing short of magical to the average user. But you don’t get something for nothing, and GPS reliability in our hobby copters can be easily compromised by many variables. For instance, solar flare activity can play havoc with the earth’s magnetic field and could disrupt GPS navigation.

Command and Control: Radio Transmitter and Receiver

Technology is providing us with many different types of control devices from which to issue commands to your copter. Smart phones, tablet devices, laptops, and so on are among some of the more recent advances. Currently, the most popular control device is the time-tested Radio Control transmitter. This device operates in most cases on the 2.4gHz band and has a companion receiver that is mounted to your copter and connected to your flight controller. It allows you to send commands to your copter such as climb, descend, bank, and yaw (left and right), as well as fly forward and backwards.

Once again, skimping on quality (price) will compromise the integrity of your operation. Buying brand-name transmitters and receivers from companies such as Futaba, Spektrum, Graupner, and JR will give you much higher reliability. Additionally, these radios offer more advanced capabilities, allowing you to fine-tune your transmitter feel and sensitivity, adjust camera position, perform start-stop recording, and so on.

These RC transmitters are often referred to as “computer radios,” and can have a rather steep programming learning curve. It’s best to find someone with experience that can help you program or change programs.

The “companion receiver” receives the input commands from the pilot and sends them along a communication bus to the flight controller where the commands are then processed and sent out to the individual ESCs to affect the desired flight path. Both the transmitter and receiver are battery-powered and require monitoring--either before the flight or during--to ensure that your communications will not be compromised. I always suggest a fresh charge the night before flying. Reference your transmitter operator’s manual for your manufacturer recommendations with regard to minimum safe battery levels, and recharge in the field if you need to.

In Our Next Installment…

As we come to the close of part one of our three-part series on aerial cinema and photography, I hope you have developed a healthy respect for safety and flight proficiency, and an understanding of the basics of your aircraft and its components and how they all relate to one another. In part two of this series, we’ll dive into what you need to know about camera gimbals and cameras to maximize your success. We will introduce some techniques that will help you with developing your flight proficiency both with and without the camera attached, and take a closer look at several of the more popular copters.

Additionally, we’ll touch on airspace issues and the ongoing integration of commercial sUAS within the national airspace and the role of the FAA. Lastly, we’ll check in on Carl and Steve to see how they are progressing with their different approaches to honing their aerial cinematography and photography craft.

Until next time… fly safe!