Hood splitter for my vw

[winkosmosis]

Look at the article. They say that increasing hood angle reduces drag if it prevents separation. Bubble = separation.

[winkosmosis]

Originally Posted by Frank Lee

And don't call this thing a splitter, cuz a splitter divides flow and this ain't doing that.

The OP calls it a splitter, I'm just using his terminology

What should we call it, a lovely lady lump?

[Frank Lee]

Originally Posted by winkosmosis

Look at the article. They say that increasing hood angle reduces drag if it prevents separation. Bubble = separation.

Separation at the FRONT of the hood! NOT where the bubble is.

[Frank Lee]

Originally Posted by winkosmosis

The OP calls it a splitter, I'm just using his terminology

What should we call it, a lovely lady lump?

You can call it that if you wish. I was using "blister".

[winkosmosis]

The "bubble" by definition isn't as good as sheetmetal/glass. It's high pressure and that pressure is acting on the vehicle, applying rearward and downward force.

If you're saying the high pressure bubble isn't a source of drag, you might as well say the low pressure bubble at the back of a vehicle isn't a source of drag. So does that mean boattails are useless??

[winkosmosis]

Originally Posted by Frank Lee

Separation at the FRONT of the hood! NOT where the bubble is.

The inclination of the engine hood also has an effect upon the drag. Fig 5.4, afterCarr, gives an example of this. Once the slope is steep enough to keep the flow attached, further sloping does not reduce drag any further. The ‘optimum’ slope angleF depending upon the leading edge radius and on the windscreen rake.

[Frank Lee]

Originally Posted by winkosmosis

The "bubble" by definition isn't as good as sheetmetal/glass. It's high pressure and that pressure is acting on the vehicle, applying rearward and downward force.

And those same forces aren't acting on "blisters"? Or even the comparable zone on, say, an Aptera?

If you're saying the high pressure bubble isn't a source of drag, you might as well say the low pressure bubble at the back of a vehicle isn't a source of drag. So does that mean boattails are useless??

I think one ought to compare the sizes of those two entities before getting carried away.

[winkosmosis]

Originally Posted by Frank Lee

And those same forces aren't acting on "blisters"? Or even the comparable zone on, say, an Aptera?

The blister can be shaped to optimally, the bubble is shaped according to the airflow and the pressure... like a raindrop, which people think is "teardrop" shaped, but in reality is not aerodynamic at all.

I think one ought to compare the sizes of those two entities before getting carried away.

We know it's enough force to matter because cars designed to be as aerodynamic as possible have a shallow windshield and a steep hood to the point that they're nearly the same, eliminating any bubble.

20° average slope windshield

[winkosmosis]

The Civic looks like it even has a shallower windshield than rear window. Turns out it has a 25° windshield, 23° rear window by my measurements. They wouldn't spend that much on glass without reason, especially since the trend is toward making cars look like RWD sport sedans with long hoods and upright windshields.

[Varn]

Interesting comments.I should do some coast down tests. I imagine that measured top speed might be a good indication.