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Re: Fw: Dinosaurs and birds



I also note that they authors report no statistically significant difference 
between free sprinting and assisted sprinting with regards to average speed or 
any kinematic parameters.  In other words, they cannot reject that the 6.8% 
observed difference is chance variation.  Sadly, this leaves us with a bit of a 
conflicting message.  I have to say that the paper was excellent find by Don, 
nonetheless.  

My hypothesis is that the assisted runners maintain their maximum speed for 
more of the course than in the free sprinting trials.  If so, the differences 
should expand on a longer track (they were only filmed and timed over 10 
meters), so that hypothesis should be testable by comparison with longer runs 
(though they must obviously still fall within sprinting distances).

Cheers,

--Mike H.

> Science is indeed wonderful, but I note in passing
>  1) that these were highly trained athletes
>  2) that they used an elastic towing device to even out pulses (birds 
> would 
>  have a pulsed thrust and lift).
>  3) they were not subjected to pulsed lifting forces while being  
> uniformly 
>  towed.
>  4) if the 6.8% increase in running speed held between species (which 
> I 
>  doubt), then it would lead to a 14% increase in lift and a cocurrent 
> 
>  decrease in thrust.
>  5) wind gusts are typically on the very loose order of 25% of wind 
> speed 
>  (subject to considerable variation).  This would lead to a transient 
> 56% 
>  increase in lift with no consideration for flapping.  Being naturally 
> lazy, 
>  I'd probably wait around for a gust and do it the easy way.
>  6) cursorial birds aren't observed to use wing-assisted straightline 
> 
>  sprinting.
>  JimC