Fig. 1. Comparison of translational force coefficients at Re=120 and Re=1400. (A) We rapidly accelerated the wing from rest to a constant tip velocity of 0.26 m s^–1. The angle of attack (AOA) was increased between trials in 10° increments. Labels to the right of the forces in the first panel indicate angles of attack. At both Re, an initial transient peak was followed by stable force generation. (B) Coefficients of lift (C_L) and drag (C_D) averaged between the broken lines in A. The polars form two concentric arcs with values measured at high Re around the outermost arc. (C) Net force coefficients increase with angle of attack, with greater increases at high Re. (D) The angle of the net force vector quickly reaches 90°, indicating pressure forces dominate at both low and high Re.