�@�@Ways of eco-flight

�@�@�@They are to make use of the inertia as much as possible, to beat with the
�@�@natural frequency of the wing system and the irreducible minimum amplitude
�@�@of a demand, and to avoid the occurrence of negative thrust or negative lift
�@�@which might appear on the flapping up run.

�@�@�@They make use of a thermal ascending current, a climbing current along
�@�@a slope, or a current in atmospheric boundary layer. (They acquire a
�@�@potential energy from those currents and exchange to the kinetic energy by
�@�@the gravity in spite of beating or non-beating flight.)

�@�@�@It rides on a fair wind. (It increases the velocity relative to the earth
�@�@(the flight velocity).) For example, if a bird rides on the fair wind of
�@�@velocity 10m/s, the velocity of 36km/h will be supplemented.)

�@�@�@It make use of the surface effect by skimming the surface of the water or
�@�@the ground. (The flow around the bird changes under the influence of the
�@�@surface of the water or the ground, the lift and the thrust should increase.)

�@�@�@Large-size, that keep somewhat of lift in the flapping up run, fly in
�@�@formation, and then the opposte rotating vortices running out from both
�@�@tips of wing are canceled out and as a result the induce drag should be
�@�@reduced.

�@�@�@Small-size birds, that have small weight and powerful muscle, makes use
�@�@of the bounding flight and the inertia in maximum.

�@�@�@The ways of bird's eco-flight are similar to our eco-drive in car and bicycle.
�@�@They should run with the velocity that make maximum the value of the
�@�@distance covered/the spent fuel. The inertia should be utilized maximum.
�@�@The brake uses at irreducible minimum of a demand. A downward slope
�@�@should be utilized maximum.

return
next