@article {Norberg179,
author = {Norberg, U. M.},
title = {Aerodynamics, kinematics, and energetics of horizontal flapping flight in the long-eared bat Plecotus auritus},
volume = {65},
number = {1},
pages = {179--212},
year = {1976},
publisher = {The Company of Biologists Ltd},
abstract = {The kinematics, aerodynamics, and energetics of Plecotus auritus in slow horizontal flight, 2{\textendash}35 m s-1, are analysed. At this speed the inclination of the stroke path is ca. 58 degrees to the horizontal, the stroke angle ca. 91 degrees, and the stroke frequency ca. 11-9 Hz. A method, based on steady-state aerodynamic and momenthum theories, is derived to calculate the lift and drag coefficients as averaged over the whole wing the whole wing-stroke for horizontal flapping flight. This is a further development of Pennycuick{\textquoteright}s (1968) and Weis-Fogh{\textquoteright}s (1972) expressions for calculating the lift coefficient. The lift coefficient obtained varies between 1-4 and 1-6, the drag coefficient between 0-4 and 1-2, and the lift:drag ratio between 1-2 and 4-0. The corresponding, calculated, total specific mechanical power output of the wing muscles varies between 27-0 and 40-4 W kg-1 body mass. A maximum estimate of mechanical efficiency is 0{\textendash}26. The aerodynamic efficiency varies between 0{\textendash}07 and 0{\textendash}10. The force coefficient, total mechanical power output, and mechanical and aerodynamic efficiencies are all plausible, demonstrating that the slow flapping flight of Plecotus is thus explicable by steady-state aerodynamics. The downstroke is the power stroke for the vertical upward forces and the upstroke for the horizontal forward forces.},
issn = {0022-0949},
URL = {https://jeb.biologists.org/content/65/1/179},
eprint = {https://jeb.biologists.org/content/65/1/179.full.pdf},
journal = {Journal of Experimental Biology}
}