This study focuses on aerodynamic modeling of a quadrotor helicopter and the estimation of the model parameters in wind tunnel tests for hover, vertical climb, and forward flight conditions. The motion of a quadrotor is mainly affected by the aerodynamic forces and moments generated by rotors. Accurate calculation of rotor loads is essential for high fidelity simulation of a quadrotor. Momentum and blade element theories are used to obtain expressions for rotor forces and moments for a traveling vehicle. The parameters of the models are then identified through wind tunnel tests where the forces and moments created under various wind conditions and rotor speeds are measured with a six axes balance system.
Nomenclature= angular speed of the rotor = density of air = inflow angle = inflow ratio = rotor advanced ratio = solidity ratio , , = Euler angles = overall residual propeller angular speed ̅̅̅̅ = average drag coefficient ̅ = average of observed values ̂ = fitted value = induced velocity = side force coefficient = hub force coefficient = pitching moment coefficient = drag moment (rotor torque) coefficient = rolling moment coefficient = thrust force coefficient = aerodynamic body coefficient of the quadrotor in x, y, and z body axes, respectively = lift coefficient = moments of inertia = products of inertia = resultant inertia moment in the z direction = aerodynamic body moments in x, y,and z body axes, respectively = Error Sums of Squares = Regression Sum of Squares = Total Sum of Squares = vertical force of blade = horizontal force of blade = climb velocity = aerodynamic body forces in x, y, and z body axes, respectively ̇ ̇ ̇ = velocity of the rotor in x, y, and z body axes, respectively = angle of attack (a.o.a.) of the rotor 1 Research Assistant at CPC, Department of Aerospace Engineering, dekaya@metu.edu.tr, Student Member of AIAA 2 Assistant Prof., Department of Aerospace Engineering, kutay@metu.edu.tr, Senior Member of AIAA Downloaded by CORNELL UNIVERSITY on July 31, 2015 | http://arc.aiaa.org | 2 = twist angle = distance between rotor center and Center of Gravity (C.o.G.) n = number of test cases/observations = radius of the rotor R= rolling moment = free stream velocity = observed/measured value = side force = area captured by rotor = hub force = resultant aerodynamic moments acting on the quadrotor in x, y, z body axes, respectively = number of blades = pitching moment = drag moment (rotor torque) = surface area of the quadrotor = thrust force = resultant aerodynamic forces acting on the quadrotor in x, y, z body axes, respectively = lift curve slope = thrust force coefficient for hover = drag moment coefficient for hover = drag acting on the blade = lift acting on the blade = error term = gravitational acceleration = distance between rotor axis and Center of Gravity (C.o.G) = mass of the quadrotor = angular speeds of the quadrotor in x, y, and z body axes, respectively = linear speeds of the quadrotor in x, y, and z body axes, respectively = sideslip angle y = pitch angle = total vertical forces actin...
