Manned OctocopterUpdated November 2020
The Manned Octocopter was a multirotor aircraft that I helped design and build in high school with my friends. I was introduced to multirotors and aircraft design by aerospace engineer, Sahevaan Taneja, who lead our team through the 15-month undertaking. I learned a lot over the course of this project. It was the first time I had actually built something and it was also the first time work didn’t feel like work. I spent a lot of 11th and 12th grade dreaming of the day we would finally take to the sky with man on board.
Multirotors are traditionally designed for unmanned applications but our goal was to fly with a passenger on board. We liked the redundancy of having 8 rotors since the ability to safely land even after a motor failure was a non-negotiable feature for us. Our octocopter had 4 motors running clockwise and 4 running counterclockwise.
At a stable hover, the oppositely rotating motors can cancel out each other’s torques keeping the multirotor in position. Unlike planes and helicopters, multirotors usually don’t have control surfaces or flaps to redirect airflow. The only way to maneuver is by changing the relative speed of the motors to redirect thrust in the desired direction. When adjustment along any axis is required to turn—or maintain stability in windy conditions—a difference in the speeds of the motors can induce the necessary tilt or torque. For example, when the RPM of the four motors in the back increases the aircraft tilts forward and some thrust is directed backward, moving the aircraft forward while maintaining lift.
The lithium polymer batteries, brushless DC motors, and wooden propellers we used gave us about 200 kilograms of thrust for 6-8 minutes. We also used the Naza-M V2 flight controller from DJI for our piloting system. After many rewarding months spent designing, sourcing components, soldering, and testing, we logged our first successful manned flight on July 22nd, 2017.