by Paul Coco
Since the explosion of multicopters, there has been little mention of how to properly design the frame or account for the aerodynamics. There have been multiple blogs
and articles, which rely on rules of thumb and experience to
determine the proper materials needed to construct the frame
or the length of your rotor arms.
Even when accounting for aerodynamics, most people
only take into perceptive the lift and power of a multicopter.
Optimizing your flight envelope can maximize your lift, flight
duration, and forward speed.
A well-engineered frame can increase the efficiency of any
multicopter and reduce the level of noise or excess signals to
gyros and accelerators, compensating for vibrations. The main
source of vibrations on a multicopter comes from the motors
and the propellers. Based on the material selected for your
frame and rotor arm length, these vibrations could be absorbed
Within the course of graduate study for mechanical
engineering, I related principles of vibrational analysis,
aerodynamics, and fracture mechanics to design the best frame
for a tricopter. Most people can overcome the design of the
frame by adjusting the proportional, integrated, and derivitive
controls (PIDs), or by placing an anti-vibration pad under their
flight controls, but this may not always give you the proper feel
43 Model Aviation DECEMBER 2013