[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Fw: Dinosaurs and birds
To sum: in theory, a biped that can sprint at a given velocity can exceed
that velocity, w/out falling down, by applying appropriate thrust to the
upper body. This is because the stride frequency at maximum unassisted
running speed is NOT the maximum stride frequency attainable by the hind
Try it yourself: lie down on your back and make running motions. You'll soon
find the speed at which you can move your legs is limited even in the
absence of any resistance (other than drag in air).
In other words, when the wings produce too much thrust, the legs can't keep
up, and the animal either flies or trips over its own feet, inevitably. Make
a thought experiment: if you were tied to a car on a highway, could you stay
The maximum speed a biped can generate through unassisted use of the hind
limbs does NOT constitute some magical theoretical barrier that cannot be
I'd bet money it's very close to that barrier, which is not magic at all but
depends on length and mass of the hindlimbs in total and the arrangement and
size of the muscles that move them.
2). Total power relative to forward motion is not coming from the hind
limbs in this situation, yet evidently there is a term in your equation
that "...requires higher hind limb power (that we've already limited)".
[???] Why is that? In fact, relative to the theoretical situation as
posited, NO forward thrust is required from the hind limbs... nor is any
aerodynamic lift required, as the legs serve to counteract gravity. Note,
that can be done mechanically, w/out thrust generation other than that
required to pull a given leg forward into the front of the stride cycle...
...fast enough, wherein the rub lies.