Flat Bonneville-type spoiler

[brucepick]

Good move. (sorry, I'm an incurable punster)

I'll see you over there next time I drop in here. I need to get some lunch then back to work.

Originally Posted by California98Civic

High Brucepick. I agree. I started a new thread on it because I felt odd talking over a trunk lid project under the heading "Bonneville flat spoiler" anymore. Maybe it was a mistake, but there you go. Here's the thread: http://ecomodder.com/forum/showthrea...ect-17708.html I can see under the lid, through the interior mirrors.

I'm working on tuft testing and fine tuning the prototype after a frustratingly poorly designed test.

[ChazInMT]

Sorry to be so late in the game here. Seemed to me like the thing to build would be something like this if you have a notch back.



Unless you wanna go drag racing, but that's hell on fuel mileage, unless you pulse & glide....which is hell on your win loss record.

[Frank Lee]

I'm I'm seeing double double.

[ChazInMT]

Quit drinking so dam much BEER!

[Frank Lee]

It's HOT- I should be drinking even more beer beer!

[Blue Angel]

I've been thinking about Pro Stock wings and wondering what sort of aerodynamic contribution they would offer to a normal car at highway speeds. Something like this:

http://www.dragracingonline.com/agen...-2010-test.jpg

They obviously have a positive effect on Pro Stock race cars or they wouldn't be used, but I think they are used for added downforce as well as aero, and I'm not sure how much of each.

Then I got wondering what would happen if you tilted it downward to approximate the angle of a boat tail? Would air pile up beneath it and cause lift/drag?

I was thinking about this as an easy to build alternative to a full boat tail, since the boat tail is ambitious enough that most regular people wouldn't attempt it. Thoughts?

[California98Civic]

Originally Posted by Blue Angel

I've been thinking about Pro Stock wings and wondering what sort of aerodynamic contribution they would offer to a normal car at highway speeds. Something like this:

http://www.dragracingonline.com/agen...-2010-test.jpg

The Prius has a diminutive version of the same idea, though not angled downward. I'm sure it works, but one study of box-voids posted here suggested that the specific design form of these things matters a lot. The little spoiler will interact with flow from the sides and such, so you want to keep that in mind. I have been lazily planning to imitate the Prius design for a long time. Also, I believe it is not legal to extend the spoiler beyond the rear bumper.

[Flying_Pie]

Hey guys. I've lurked these forums for some time, and now I'm posting because I recently bought a 2006 Jetta TDI and I'm really interested in this type of spoiler. I put together a couple of images of what I envision and I'd like to know what you guys think.

This design is similar to California98Civic's, but it will be a bit longer and with larger vertical fins. I feel the fins are important for two big reasons: one, I want to isolate the "bubble" behind the car as much as possible, which should create some sort of virtual boat tail and promote cleaner separation. Two, and probably the most important: this spoiler separates two very different air masses - fast moving air on top, and stagnant air on the bottom. That stagnant air will want to push its way around the spoiler toward the low-pressure stream on top (which, I'd like to note, makes me think this spoiler actually creates lift), and these fins should prevent that from happening. I don't claim to be an expert, so I'm open to suggestions if anyone disagrees with my logic.

Now, here's my idea. Rough math puts the spoiler at being around 30 inches long at a constant 13.8 degree slope. I'm sure I'll have to do some tuft testing to ensure that the boundary layer stays attached, but I think it seems plausible. I'd like the trunk to be functional with this thing on it, so the vertical fins will conform to the back of the trunk; the rear-view picture should give you an idea of what I mean.

In these pictures, the spoiler is red and the vertical fins are blue. What do you guys think?

P.S. Laws in my state dictate that I can have extensions as long as 6 feet on the rear of my car, so I'm good on that end

[Blue Angel]

I like the vertical fins following the angle of the trunk opening from a cosmetic point of view. As far as functionality goes, no idea.

[California98Civic]

Look at the box cavity study that drew a lot of attention here at EM last year. Vekke, paulu, and I and other posted links: http://ecomodder.com/forum/showthrea...tml#post296613

If any of the links are dead, I think I have the pdfs and will send them to you.