Abstract: The new bird inspired wing sweep was introduced and compared with straight and conventional swept wings in gliding flight by an experimental test setup. Due to the similarity with the birds’ wing, all test models have S1223 airfoil. Swept models inspired from the bird consist of two parts: the straight part near the root and the swept part near the tip. Aerodynamic forces on each wing were measured from 0? to 24? angles of attack and Reynolds numbers of 4.3×104, 8.6×104, 1.3×105, and 1.7×105. Wind tunnel test results show that wings with an innovative sweep at α > 0 have more lift for Reynolds numbers between 4.3×104 and 8.6×104. Also, innovative sweep increases the stall angle, and the wing did not stall until α = 24? for Reynolds between 1.3×105 and 1.7×105. An increase in lift and having sufficient aero-dynamic performance in low Reynolds numbers for birds’ inspired wing sweep in gliding flight may be the answer to why the wing sweep of birds is not like conventional sweeps.

Key words: bio-inspired wing, wing sweep, wing aerodynamics, bird wing, low Reynolds number