Flight Characteristics of AAM/UAM-Scaled Quadcopters Under Atmospheric Turbulence

The flight responses of quadcopters of various scales (50-1200 lb) are evaluated in the presence of a 20 kt turbulent headwind. Nominal flight controllers are tuned for each aircraft to meet HQ specifications, where the controllers will reject disturbances to the aircraft groundspeed, attempting to maintain zero groundspeed. Froude-scaling is performed to scale the handling qualities specifications of the smaller aircraft, utilizing the additional agility. The nominal and scaled controllers are then compared in rejecting disturbance due to the turbulent headwind. Non-linear dynamic simulations are performed to evaluate the rigid body response of each aircraft, finding that scaling the flight controllers (on aircraft less than 1200 lb) reduces the pitch and roll attitude response so that all aicraft have similar peak-to-peak values. Following scaling, the peak-to-peak roll and pitch attitudes for all four aircraft are within 0.5 and 0.4 of each other, respectively. The improvement in disturbance rejection capabilities from scaling comes at the cost of 24% increase in the RMS current, and 2% additional current margin for the 50 lb aircraft (which is the largest increase). Overall, the increase in actuator activity due to scaling the controllers is less than the current margin required for maneuvering, resulting in the motors not needing to increase in size.

Reference

Bahr, M., Ferede, E., and Gandhi, F., " Flight Characteristics of AAM/UAM-Scaled Quadcopters Under Atmospheric Turbulence ,"

Proceedings of the Vertical Flight Society 78th Annual Forum, Fort Worth, Texas, USA, May 10-12, 2022.