Re: T. Rex mechanics

[Randy King <randyk@ims.com>]

At 02:52 PM 3/25/98 -0500, ngear@gvtc.com wrote:
>Martin Baeker wrote:
>While I'm at it--
>
>Randy King wrote:
>>Turning isn't always this simple.  By leaning into a turn, you can
>>take some of the torque off of the foot.
>
>Although I am picking on Mr. King here, I have received several similar
>messages about leaning or banking, so I'd probably better say something
>about this.  There is nothing about the act of banking into a turn per se
>which will help a body rotate in the direction of that turn.  It still comes
>back to torque transmitted through the ground contact(s).  In quadrupeds,
>this generally means the front legs impart more centripetal force going into
>the turn (ie, press out harder against the ground) than the hind legs.
>Humans don't have front and hind legs, but with our vertical bodies, only
>small and barely noticeable quantities of torque are needed to start and
>stop us rotating, so foot torque is more than ample to the task.  Is it
>actually obvious to most people that leaning over in a turn does not have
>the effect of rotating the body into that turn, or should I explain this
>further?
>


Pick away... I pick back sometimes.  :)

Although your argument makes sense from a physical point of view, I don't
think turning is that simple.  If you can can change your momentum, then
pivoting becomes a simpler task.  If you use the ball of your foot, it is
much easier to pivot than using your heel.  When running, people bank a
little and use the balls of their feet.  If you learned to walk on stilts,
turning while moving is difficult without banking.  A stilt doesn't offer
anything to build torque on.  

Admittedly, this area is outside of my expertise, but I have to go with
my gut feeling on this one (so far).  Hows that for scientific?

-Randy