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.