This paper deals with the problem of estimating external disturbances acting upon aerial vehicles. First, a dynamic model based on the linear and spin momentum equations of rigid bodies is presented. This model renders the system linear, which is innovative in the area of disturbance estimation affecting UAV. Next, two estimators following the line of already published external disturbance methods are reviewed and adapted to the new model. Also, two Kalman observers that exploit the linearity of the derived model are presented. Finally, all the methods are compared in simulation using two case studies that consider ideal and realistic scenarios. © 2018 AACC.