Nothing is mentioned here about roll cages stuck up into the airstream:
...I have always felt that big ugly full hoops with generous amounts of
padding create more drag than a nicely shaped coupe configuration.
When I look at my rather tall roll bar and all of it's appendages, I shudder
to think about all of the turbulence it creates.
> Keep in mind that is with a windshield. They had a similar discussion on
> the SCCA production car forum. This is what was said
>
> "1.) An open car with no windscreen and a fairing and/or tonneau to smooth
> the air across the cockpit is the fastest of the bunch.
> 2.) a closed car with a well-designed rear window area (like a fastback or a
> little lip wing) is second fastest.
> 3.) an open car with a full-height windscreen and an open cockpit is at a
> disadvantage as is a closed car with a poorly designed rear window (think of
>a
> 510)
>
> The reasons are that the back side of the windscreen in an open car becomes
> a low pressure area. Air rushing over the car is sucked down into the cockpit
> creating turbulence and drag. The same is true of the poorly designed closed
> car - it's just that the drag is above the trunk. A Fastback helps close the
> airstream over the car and creates less turbulence. The open car with no
> windshield (just a fairing or tonneau) has the least frontal area and no
>place
> for turbulence or drag to slow the car except behind the rear bumper. I hope
> that helps. If I were driving a Spec Miata, I'd want the top on. but if I
>were
> driving an EP/FP Miata with no upright windshield, It would be a roadster.
> -Basil"
>
> I hope that helps.
>
> -Bob Adams
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