Flapping-wing vehicles produce aerodynamic lift and thrust through the flapping motion of their wings. The performance of a flexible-membrane flapping wing is experimentally investigated here. A new scheme for finding flight envelopes for a particular flapping vehicle is introduced as well. A flapping-wing system and an experimental setup are designed to measure the lift, thrust, and power usage of the flapping-wing motion for different flapping frequencies, angles of incidence, and various wind tunnel velocities up to 12 m/s . The obtained results are used in the performance analysis of this flapping wing. For each given weight (or payload), one may find the best cruise speed for maximum range, corresponding to a minimum ratio of power to cruise speed (i.e., energy usage for unit distance), or for maximum endurance corresponding to minimum power (i.e., minimum flapping frequency).