Development and Experimental Validation of a Lifting Line-Based Model for a Robotic Falcon

The Robird is a bird-like drone classified as an ornithopter that flies by flapping the wings. Its unique design features make it resemble a Peregrine falcon in size and weight, in addition to the flapping flight performance. This paper proposes the application of Prandtl’s unsteady Lifting-line method combined with a dipole sheet wake model to predict the circulation and the unsteady lift and thrust of the wing. For the cases considered, the numerical method predicts that both the lift and the thrust of the wing vary with time, but both are positive during the flapping flight. Finally, the numerical prediction is compared to experiments performed with 2D3C PIV for a wind-tunnel model of the port-side half of a Robird. The measurements and the results of the numerical simulation show topological similarities. For the downstroke, the near-wake of the flapping wing takes the shape of a free shear layer, which has the same orientation as predicted by the numerical method.