Because of their potential for application in both civil and military sectors aswellas the challenge in designingatiny flying vehicle, micro aerial vehicles have attracted enormous attention. Several configurationsof micro aerial vehicles are under development, namely fixed wing, rotary wing, and flapping wing. Under rotary-wing micro aerial vehicles, coaxial contrarotating configurations with a stabilizer bar seem to provide excellent stability behavior in pitch and roll degrees of freedom. This paper presents the results of an experimental study performed on a coaxial-contrarotor helicopter modeltoevaluate the performanceofthe rotor system using different rotor blades. The thrust and power of the rotors in independent and coaxial configurations were observed. The percentage thrust loss in the coaxial configuration was seen tobedependentonthe ratioof the upper- and lower-rotor revolutions per minuteas wellasthe spacing between the rotors. A theoretical analysis using a nonuniform inflow model was developed, which corroborated very well with the experimental data. Using low-Reynolds-number drag coefficients for the airfoil, the estimated power consumption of the rotors was found to match very well with the experimental data. A closed-form solution using a uniform inflow model to estimate the thrust performance of a coaxial rotor is proposed, which also matches with the experimental observations. © 2013 by Puneet Singh and C. Venkatesan. Published bythe American Institute of Aeronautics and Astronautics, Inc.