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An experimental investigation of the dynamic performance of two new rotor blade airfoils was undertaken in a transonic wind tunnel. The EDI-M109 and EDI-M112 airfoils were tested at 0.3 ≤ M ≤ 0.5 for pitching motions with amplitude 0.5 • ≤ α ± ≤ 8 • and frequencies 3.3 Hz ≤ f ≤ 45 Hz. The results show the dynamic stall performance of both new airfoils, and the effect of frequency, amplitude, and higher order pitching motion on these results is described. The pitching moment peak size was found to have an approximately linear correlation to the normalized mean angular velocity, and thus test cases with the same maximum angle of attack and oscillation frequency had similar dynamic stall qualities. The correlation between low aerodynamic damping for high-frequency, low-amplitude pitching motion, and poor dynamic stall performance is shown to be low. The pitching moment peak of the EDI-M112 airfoil is shown to be smaller for M = 0.3 and 0.4, and peak for the EDI-M109 airfoil is lower at M = 0.5. The dynamic performance of the airfoils is compared to the OA209.