Remote-Controlled Quadcopter
July 2020 - August 2020
The goal of this independent project was to build a remote-controlled (RC) quadcopter. The motivation behind this project was twofold: to design and fabricate a structurally stable frame and to get hands-on experience building an electro-mechanical device from the ground up.
Quadcopter Components
Electronic Components
All of the quadcopter components were purchased, save for the frame. This encompassed all of the electrical components of the aircraft. Once I determined the types of electrical components needed, I researched the compatibility of different products before settling on my final part list. The list of purchased parts is as follows:
4 brushless motors
4-in-1 ESC board
Lithium Polymer Battery
Flight Controller
Radio Transmitter
Radio Receiver
Frame Design
I wanted to design the frame of the quadcopter to provide structural stability and withstand the forces and moments exerted on the aircraft. I also wanted the final design to be as elegant and simple as possible.
As with most design projects, the quadcopter frame saw multiple prototypes and testing before its design was finalized. This iterative process gave me a chance to develop and hone skills in rapid prototyping.
​
​
Testing and Iteration
First Test Flight
The first test flight saw the electronics able to power on and spin the motors.
Issues:
Structural failure in the motor arms, due to the significant bending moment exerted by the motor thrust
Electronics housing placed such that it interfered with propeller motion, causing the aircraft to be unable to take off from the ground
​
Solutions:
Redesign of the quadcopter frame that placed the electronics housing beneath the top of the structure that held the motors
Reinforced motor arms
Motor structure thickened
Preliminary Design
 |  |  |
|---|
Second Test Flight
The aircraft was unable to take off from the ground, due to the uneven landing surface provided by the battery.
​
As a result, the next iteration of the design was to include a landing leg that would be mounted below the electronics housing, and would double as a battery enclosure.
Third Test Flight
The structure of the quadcopter seemed to be stronger than the previous iterations. However, the aircraft remained unable to achieve liftoff.
Issues:
Roll control was acting the wrong way (i.e. when the quadcopter tilted to the right, the left-side motors would speed up instead of the right-side motors)
Quadcopter would tip over before it could achieve flight
​
Solutions:
Washers that were located between the motors and the propellors were replaced by more symmetric 3D-printed rings
Flight controller was re-configured and the motors were mapped correctly
Roll PID values were re-tuned to make roll control more sensitive (the P value was increased)
​
Before conducting a fourth test flight, I performed roll, pitch, and yaw control tests keeping the quadcopter in my hand and exerting the appropriate torques on it manually to elicit the correcting responses from the motors.
Design for Third Test Flight
 |  |  |  |
|---|
Third Test Flight
Fourth Test Flight
The quadcopter was able to achieve liftoff on this flight, along with good roll, pitch, and yaw error correction.
Issues:
User controls were a bit too sensitive for controlled flight
​
Solutions:
RC response rates were altered to make the user controls less sensitive
Fourth Test Flight
Fifth Test Flight
The aircraft was controllable and easier to fly than the previous iteration.
​
Issues:
Significant deflection of the motors from their upright position
Excessive motor heating and a possible structural problem on the frame itself
The issue of motor overheating was thought to be caused by the motor bolts being inserted into the motor windings
Attachment of the electronics housing and the landing leg was weak and susceptible to significant damage
Takeoff and landing of the quadcopter were a bit unstable due to the narrow landing leg
​
Solutions:​
Thicken the structure, especially around the deflected area
Separate motor mount designed to be placed upon the frame and for the motors to be mounted to
I redesigned the connection points between the electronics housing, the body, and the landing leg to be friction fit joints
Enlarged landing leg
Deflection of Motors Caused by Overheating
 |  |  |
|---|
Fifth Test Flight
Sixth (and Final) Test Flight
The new fiction-fit frame design proved to be structurally stable and strong, without the use of any adhesive.
The wider landing leg provided a more stable base from which take-offs and landings could proceed without need for immediate roll correction.
Each of the motors and the neighboring frame mounts were not excessively hot, even after a lengthy flight.
And, the quadcopter was easier to control and manage while flying.
Final Frame Design and Physical Final Product
 |  |  |  |  |
|---|---|---|---|---|
 |  |  |
Final Test Flight
Future Development
After the final test flight, I determined all of the project objectives to be met to my satisfaction. And, I was ready to proceed with the next level of quadcopter development.
This RC quadcopter was meant to be a starting point in a longer quadcopter project, later phases of which would involve learning the intricacies of quadcopter control systems and writing a flight computer that would make the quadcopter fly autonomously.