Civic hatchback aerodynamics

[basjoos]

Originally Posted by thisisntjared

i think it could even be more streamlined, the plastic behind the extends from the side windows should be angled in closer. that mid frame should be like a trapezoid instead of being a rectangle. i bet he will get great gains, but its amazing that there is still more!

If I went with a 1 piece boattail and gave up the ability to access the hatch, I would have angled the midframe in more. But I had to keep the midframe broad enough to allow room for the lower mini-tailgate to open out.

I got 68mpg from this tank dispite 120 miles of driving in the rain. Normally at these temps and with this amount of wet road driving, I would have seen mileage in the low 60's. I've noticed the biggest effects of the boattail in high speed coasts. In 35 to 45mph coasts, there is a decent improvement over the pre-boattail performence, but in coasts where my speed peaks at 60 to 70mph there is a large difference in how far I end up coasting and rate at which my speed drops.

[Silveredwings]

Wow, that's a beautiful thing. Tell me, do you get any flutter of the clear vinyl at any particular speed?

Very inspiring.

[ZugyNA]

COOOOOOOOOOOOOOOOOOOOOOL.

The REALLY BIG question?

Could you get the same results from mounting a WING as with the VW?

[basjoos]

So far I have had it up to 75mph without any vinyl flutter.

A wing wouldn't be as good as a boattail. With the boattail, I don't leave any eddy turbulence behind me (its interesting driving down a leaf covered road and seeing very few leaves disturbed). The wing on the Beetle helps to mitigate some of the terrible aerodynamices of the Beetle's design, but it still leaves a big eddy behind it.

[onegammyleg]

Originally Posted by basjoos

but it still leaves a big eddy behind it.

Eddy ?

[theclencher]

No, silly!

[onegammyleg]

ahh ,,the Munsters , ya just gotta luvem !

[Silveredwings]

What an elegant design.

Originally Posted by basjoos

So far I have had it up to 75mph without any vinyl flutter.

A wing wouldn't be as good as a boattail. With the boattail, I don't leave any eddy turbulence behind me (its interesting driving down a leaf covered road and seeing very few leaves disturbed). The wing on the Beetle helps to mitigate some of the terrible aerodynamices of the Beetle's design, but it still leaves a big eddy behind it.

I see, that's great. I agree about the wing; you may be able to redirect the air to minimize separation but at the cost of induced drag on the wing and interference drag at the wing's pillars unless you designed complex fillets.

[MetroMPG]

Originally Posted by basjoos

its interesting driving down a leaf covered road and seeing very few leaves disturbed)

What a neat observation.

[FormulaTwo]

Very nice
I don't think I have had the chance to comment on this yet.
I would love to do this to my car, but I am not that far into it yet.
It really does not look bad at all. I have airtabs on the way.
I feel like it will be forth the money to test htem out, since they are only like $2.50 each.

Maybe eventually as i slowly get more hardcore about FE i will end up with a similar setup to what you have.