Definition of terms used in equation

It's not clear what the terms in the equation denote.

Am I correct to establish from the Calculations spreadsheet and Burgers & Chiappe (1999) that:

Cl is the lift coefficient (taken as 1)

f the flapping frequency

Amp the amplitude of a flap

U the ground speed of the running animal (?)

S the wing area

It's not clear whether p corresponds to the "average factor that considers lift being generated only during the downstroke (0.5)", or whether it represents air density (ρ); presumably this is given as the constant 1.23 in the spreadsheet.

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1 Answer
Accepted answer

Thank you for your question. "p" (Rho) designates air density, which is 1.23 kg3/m3 at sea level (and is used as a constant in the spreadsheet). To model performance at higher elevations, this value can be adjusted. "U" is the airspeed over the wings. The total airspeed felt by the wings will be a combination of the translational speed (i.e. how fast the animal is going, relative to the air, at the end of a leap, for example) combined with the induced airspeed from flapping the wings.

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