Re: [[OT] Rear Wing Aerodynamics - trivial...NOT!!

["Brian Haygood" <Scirious@hotmail.com>]

Alright, I can no longer resist.  I have to chime in.

The big rocco rear wing reduces drag (to what degree??), and reduces rear
end lift by 30%.  That's according to our very own website, by the way.

Neal Wrote:
>>Thus, ADDING parts almost never reduces drag (though it can in some cases,
as Cathy pointed out). Think about it: how can you stick something in the
wind, where there was nothing there before, and have it actually reduce
drag??

Actually, you can.  Look at the fairings on a motorcycle (and vortex
generators on wings).  Fairings aren't trimmed to keep the frontal area to a
minimum exclusively, but also have the goal of providing smooth flow
transitions and encouraging flow separation where appropriate.  Certainly
there are exceptions, such as windscreens, which are there to keep the
driver comfy, not for the wind's sake.

To reduce drag at the rear of an object, you have two options.  One is to
taper it (SR71 style) at something in the neighborhood of 7° (subsonic,
etc.etc.etc.) or preferably less.  The next best option is not, as many
would expect, to taper it as best you can (like a football), but to keep
that slight taper as long as you can, then end as abruptly as possible.  A
few examples:  Chrysler 300M and others, Honda Insight, Toyota Maxim/Pontiac
Vibe, BMW 3 series, numerous motorcycles (other than suzuki), ...

That's probably how the big wing earns its keep in the drag department.  It
forces the airflow over the hatch to level out earlier and separate from the
vehicle earlier than the smaller wing.

Does it really live up to the claimed figures above?  I don't know, but it
sounds reasonable to me.

Interesting stuff about the TT and NB sunroof closing.  Didn't know that.  I
really like TT's, but I sure wish they had a more stable shape.  Hmmm.  Most
guys like top heavy women, too, so maybe appeal and function are truly
separated.

There is a local contingent of VW owners that have big, exteremely low chin
spoilers.  Looks kinda, well, I guess I never made up my mind on that.
Probably pretty darn stable at speed, though, I suppose.  A bit much on a
Jetta GL, me thinks.

I'll ramble no longer.  It seems to be carrying me downhill.

Sincerely;
Brian Haygood

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