Chapter 3. Anatomy of a Drone

Standard Prop

The same “tractor” propeller used on standard front-engine R/C airplanes. In orange in the diagram above.

“Pusher” Prop

These contra-rotating props exactly cancel out motor torques during stationary level flight. Opposite pitch gives downdraft. In dark grey in the diagram above.

Motor

Usually a brushless electric “outrunner” type, which is more efficient, more reliable, and quieter than a brushed motor (Figure 3-1).

Figure 3-1. Motor

Motor Mount

Sometimes built into combination fittings with landing struts (Figure 3-2).

Figure 3-2. Close-up of motor mount

Landing Gear and Boom

Designs that need high ground clearance may adopt helicopter-style skids mounted directly to the body, while designs with no hanging payload may omit landing gear altogether (Figure 3-3).

Figure 3-3. Landing gear and boom

Boom

Shorter booms increase maneuverability, while longer booms increase stability. Booms must be tough to hold up in a crash while interfering with prop downdraft as little as possible.

Main Body

Central “hub” from which booms radiate like spokes on a wheel. Houses battery, avionics, cameras, and sensors (Figure 3-4).

Figure 3-4. The main body of the drone

Electronic Speed Controller (ESC)

Converts DC battery power into three-phase AC for driving brushless motors (Figure 3-5).

Figure 3-5. Electronic speed controller (H) and radio receiver (K)

Flight Controller

Interprets input from receiver, GPS module, battery monitor, and onboard sensors. Regulates motor speeds, via ESCs, to provide steering, as well as triggering cameras or other payloads. Controls autopilot and other autonomous functions (Figure 3-6).

Figure 3-6. Flight controller computer

GPS Module

Often combines GPS receiver and magnetometer to provide latitude, longitude, elevation, and compass heading from a single device (Figure 3-7).

Figure 3-7. GPS module

Receiver

Often a standard R/C radio receiver unit. The minimum number of channels needed to control a quad is four, but five is usually recommended (as seen in Figure 3-5).

Antenna

Depending on your receiver, may be a loose wire whip or helical “rubber ducky” type (Figure 3-8).

Figure 3-8. Antenna

Battery

Lithium polymer (LiPo) batteries offer the best combination of energy density, power density, and lifetime on the market (Figure 3-9).

Figure 3-9. Battery (M) and battery monitor (N)

Battery Monitor

Provides in-flight power level monitoring to flight controller.

Gimbal

Pivoting mount that rotates about one, two, or three axes to provide stabilization and pointing of cameras or other sensors.

Gimbal Motor

Brushless DC motors can be used for direct-drive angular positioning, too, which requires specially wound coils and dedicated control circuitry that have only recently become commercially available.

Gimbal Controller

Allows control of direct-drive brushless gimbal motors as if they were standard hobby servos (Figure 3-10).

Figure 3-10. Gimbal controller

Camera

GoPro or other compact HD video unit with onboard storage. Real-time streaming is possible with special equipment (Figure 3-11).

Figure 3-11. Camera