This month's AE presenter: David
Date of presentation: 10 Apr 2017
Subject: Quadcopter Aerodynamics
Description: I discussed how the multi-fixed-rotor design is an alternative to conventional collective-pitch rotors. Everything is a trade-off in engineering. Long, high-aspect-ration rotors are more efficient that propellers. However, large rotors have a lot of rotating mass, so thrust changes must be made using a complex swashplate to change the rotor pitch. Quadcopters with small propellers are less efficient, but simple because thrust changes can be made by changing the speed of the fixed propeller. We discussed the aerodynamics of quad copters including handling torque, yaw pitch, roll, and lift. A key enabling technology for quadcopters is the electric motor. Although flight times are usually short to keep lightweight batteries, electric motors can have up to a 5x increase in power vs. weight when compared to internal combustion motors. The discussion concluded with a brief history of multi-rotor aircraft. The first successful helicopter in 1923 was actually a quadcopter. In the near future, we will continue to see a proliferation of small UAVs based on the quadcopter design, and perhaps personal air taxis.
