rollbar = less wind

[Jon Pike <jhpike@domain.elided>]

>This past weekend my wife and I attended a local auto-x in the Spider (115).
>We had about 30 miles of travel in each direction at highway speeds. This was
>the first real mileage put on the car after I installed the Autopower street
>rollbar. We both noticed and commented that there seemed to be a lot less
>~buffeting~ from wind ... which normally requires that I strap my ball cap on
>extra tight. I can't say that the "windy backwash" is totally eliminated but
>it seems to be more than 50% better (I haven't done any wind tunnel testing).
>It all seems a little weird that just a little bit exposed rollbar hoop would
>make that much difference, but there is truly an improvement ... go figure.
>
>Tim Lentz
>Tampa, FL
>1974 Spider
>
Huh..  well I'm picturing the airflow over the windshield.. and you can 
imagine the flow goes up and over the "cockpit" area,  arching back 
down, and curling back some into the vaccum created..   If you stick 
something in the edge of the flow,  even a fairly narrow bar,  it might 
"raise" the place where that arched air meets the body again (i.e. move 
it farther back down the car)  thereby  reducing how much of that flow 
comes back at your head..

( I hope at least one person can follow this description...  Slides! I 
need Audio Visuals!!)  ;-)

I wonder if  a properly placed narrow wing,  might be a design option 
for carmakers to reduce the buffeting in convertibles?

Jon
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