land-speed
[Top] [All Lists]

Re: Coke-bottle shapes, etc.

To: Skip Higginbotham <saltrat@pahrump.com>
Subject: Re: Coke-bottle shapes, etc.
From: Wester Potter <wester6935@comcast.net>
Date: Sun, 29 Apr 2007 12:36:25 -0600
Let me toss this out ... from my reading and discussions with some 
streamliner folks.  The question the Coke bottle shape raises for me 
concerns the interruption of the boundary layer around the car.  The 6% 
decrease toward the rear of the vehicle that allows the boundary layer 
to remain attached seems to be a big factor with many wind tunnel 
devotees.  Breaking that flow in any area causes turbulence/drag in 
that area whether it is at the front, around the wheel wells, exhaust 
exits or the canopy over the driver's helmet.  A narrow waist, a la 
Redhead, would seem to create an interruption that counters the gains 
in airflow.  Turbulence off the top of a front wheel is a major factor 
for lakester and roadster folks too ... the direction of the motion at 
the top of the wheel is the opposite of the direction of the vehicle to 
which it is attached creating air turbulence and thus drag.  The air 
coming off the rear of a liner isn't clean.  Nish is making his vortex 
generators (they gave me about a 1 mpg increase on my brick of a truck) 
and really likes what they do to direct the air around the back of his 
car and parachute deployment.

Obviously no conclusions, just pondering some largely unanswered 
questions.

Wes

On Apr 29, 2007, at 12:15 PM, Skip Higginbotham wrote:

> Ed, don't forget that the coke bottle advantages for a car will likely 
> need a top view of the car in order to balance the frontal area as the 
> view proceeds from end to end.
>
> skip




<Prev in Thread] Current Thread [Next in Thread>