The ‘Clap and Fling’ hypothesis, which describes augmentation of lift during the wingbeat of certain insects and birds, was evaluated experimentally in model form. Using induced velocity output as a lift index, and testing at a Reynolds number of roughly 83000, it was learned that:

  1. 1.

    The main ‘Clap and Fling’ aerodynamic effect consists of raising the lift output realized at the beginning of the stroke. After one chord of travel, ‘Clap and Fling’ effects are minor.

  2. 2.

    Considered over a complete stroke, ‘Clap and Fling’ lift output is limited to 1.15 times the lift output of an identical fixed incidence wing undergoing the same jump start trajectory.

  3. 3.

    ‘Clap and Fling’ output is limited by considerations of maximum circulation and circulation persistence. These limitations are not envisioned in current analyses.

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