Re: Drafting in Bicycle Races

[brian whatcott <inet@INTELLISYS.NET>]

At 11:03 9/15/99 -0500, Joe Bellina wrote:
> ... the water resistance of a ship decreases with length.

It might be more cautious to say that if you plot
resistance(=drag)/(boat displacement) ratio on the ordinate
and speed/sqrt(length) ratio on the abscissa for
various hulls, the heavy displacement hulls show a steep rise
of drag between values of speed/sqrt(length) of 1 and 1.4
and the extremely light planing hull forms show a more
gradual increase beween 1.5 and three.
 The length in question is the water line length, not overall.

This finding is sometimes capsulated as follows:
limiting hull speed =1.34 x sqrt(hull length lwl)

 You could think of this as the point at which the hull begins to
sail 'uphill' due to wave action at the bow and stern.


> if the cars could be considered to be one object, then you
> might expect the resistance to decrease....
> joe

This is a not unreasonable model. It was found very early on that
dirigibles etc. flew with less drag as the length to breadth ratio
(the 'fineness') increased to about 4.



> On Wed, 15 Sep 1999, Richard Tarara wrote:
>
> > ...watching NASCAR racing ..., it would seem that
> > drafting helps BOTH cars....

> > Richard W. Tarara

> > From: Ed Schweber
> > ... one rider will ride closely on the tail of the rider in
> > > front of him so that he will be riding in the "air resistance
> > > shadow" of the front rider....
> > > Ed Schweber
> ********************************************************************
brian whatcott <inet@intellisys.net>
Altus OK