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Old 10-15-2017, 06:19 AM   #1 (permalink)
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Question Belly pan and front air dam

Hi sorry if this has been asked before. If i fit a belly pan do i attach it to bottom of air dam or just lowest point of orginal bumper. Many thanks dave

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Old 10-15-2017, 02:40 PM   #2 (permalink)
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Dave,
All of the ones I have seen so far are at the lowest part of the front bumper. The air dam extends below the belly pan.
This is how I plan on doing mine as well.
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Old 10-17-2017, 12:38 AM   #3 (permalink)
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I'd remove the air dam. The belly pan is more effective at doing what the air dam is currently being used for. The air dam is getting in the way of the belly pan taking over that job.

There is a reason that boats don't have chin spoilers
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Old 10-17-2017, 08:58 AM   #4 (permalink)
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Panther 140 the car feels so much more stable in strong crosswinds which we get alot of living in windest part of europe. Would rather sacifice mpg for safety.
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Old 10-17-2017, 07:12 PM   #5 (permalink)
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Quote:
Hi sorry if this has been asked before.... Many thanks dave
Like always, no information to inform the response. My Superbeetle and my Dasher have completely different architectures under the nose.

In general, you would need to establish the stagnation point and decide [if] to move it up or down. This establishes whether the air goes around or over the car. Then decide how much downforce you can afford or need. This will establish the profile of the bumper/airdam. A protruding lip aka splitter will gain downforce without adding drag
AFAIK.

If the airdam protrudes below the bellypan it will form a vena contracta that constricts the flow.* aerohead reports that the guy at Darko wind tunnel suggests a softer, rounded lip. This would form a converging duct, a much better situation.

*[citation needed]
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Old 10-18-2017, 08:17 PM   #6 (permalink)
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Hi freebeard suggling to follow what you are saying. My air dam is right at front of car and curved bulge at bottom. So is that good or bad. If good do i fit belly pan to bottom of airdam. It would slope slighty upwards towards engine block. Many thanks dave.
[IMG]pug 406 air dam[/IMG]
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Old 10-18-2017, 08:41 PM   #7 (permalink)
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406 air dam

99389e88024e1f90bad3d86bb95f0f1f1

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Old 10-18-2017, 08:42 PM   #8 (permalink)
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406 air dam

99389e88024e1f90bad3d86bb95f0f1f1. Hopefully you can see photo of air dam.
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Old 10-19-2017, 04:20 AM   #9 (permalink)
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1st paragraph answered by your picture.

2nd paragraph, trying to condense 5 years (yikes!) of lurking in the Aerodynamics forum. Specific questions?

3rd paragraph — The part about vena contracta is probably wrong. That describes what happens with a square edge, such as if the bellypan attaches to the edge of the airdam or bumper. If the bellypan attaches to the bumper and the airdam protrudes below that it's not vena contracta just a straightforward obstruction as Panter140 points out.

It comes down to the relative height of the bumper/airdam and the engine and suspension. The bellypan should be flat, with a rolled up front edge if possible. That obtains the converging duct. The area in front of the tires is a different matter. You want spats or sponsons there.
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Old 10-19-2017, 11:38 AM   #10 (permalink)
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Quote:
Originally Posted by Panther140 View Post
There is a reason that boats don't have chin spoilers
Boats aren't moving against a ground plane; the road complicates things. Hucho explains it as having two bodies moving relative to each other, with interactions between the boundary layers of each.

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