Takin' the Vortekz plunge

[philp100]

LOL, sounds like my trip over the pass last week. Better than 80 miles through the snow going less than 40mph. The worst is when I get down lower elevations and it all turns to 4" of slush. Yuck.
I thought that one of the air tabs claims was it kept the back of your vehicle cleaner (or I may be remembering someone elses claims about them). Does Vortex make any such claims, and if so did you see any cleaner rear glass?

Phil

[SL8Brick]

Originally Posted by philp100

I thought that one of the air tabs claims was it kept the back of your vehicle cleaner (or I may be remembering someone elses claims about them). Does Vortex make any such claims, and if so did you see any cleaner rear glass?

Phil

With my rear spoiler still on, my rear window gets just as dirty. I'm going to remove it as soon as I get a few successive hours to do it properly. Hopefully I can get a tuft test in before then.
My co-worker w/the A6 Avant says that his rear window stays cleaner w/the VGs. Then again, the A6 wagon has a more gradual transition angle(~140deg) than the boxy Volvo(~100deg).
As far as I know, Vortekz makes no claims of it.

On another note...it was smooth sailin' into work this morning. A consistant 60mph on the highway and no red lights on the backroads . I still have lots of driving left this weekend...we'll see how this tank pans out.

[green swift]

I have installed some generators on my swift. These generators are hand made not the generators off the internet. My generators are made out of aluminum and are strong and light. I have seen the plastic ones and don't like them because after a while they will probably be weakened by the sun. I have tried these generators at different distances from the end of my roof line. I think I have found the best location. I (by fluke) found an easy test to see the generators in action without a wind tunnel. I have seen about 3% gain in mpg with them installed. The test I found by fluke really opens your eyes on how they work. I have some generators, I made extras for testing, if anyone wants them drop me a line...

Green Swift.

[GasSavers_RoadWarrior]

To my eyes, the install on that yellow 'vette looks like a mistake. I am fairly sure it should have clean separation at that point without them and that that model has underbody aero, maybe even a diffuser that fills in from underneath. I could see those maybe causing lift at speed.

[Philip1]

I too took the plunge

[charlesB]

those look really good, nice job

[zef95]

I been thinking about this for a while, with a few road trips coming up. The purpose of the Vortekz tabs are to keep the flow attached to the rear window. They were design around sedans. Would sticking them on a boxy wagon really work?

I hope so, but I have my doubts.

Also, any ideas on how to temporarily attach them? I do want to finally try them for myself (I don't mind buying them) but I don't want to rip off paint in case I change my mind.

[GasSavers_RoadWarrior]

The principle has been around for some years, been applied to truck bodies, aircraft, etc, I wouldn't say they were designed around sedans. Maybe that brand isn't quite as agressive as the ones used on large trucks and trailers and hence somewhere in between would suit wagons better.

Heat gun will probably get them off.

[SL8Brick]

I look at it this way...the rear window angle of many wagons is similar to some boxy sedans. The only difference being the altered airflow from VGs obviously will not have a trunk lid to reattach to on the wagon. IMO, there should still be a decrease in low pressure immediately behind the upper half of the rear hatch. Its just an idea.

A brief update on my VG experience: My FE has remained unchanged. However, I have noticed an increased feeling of stability, especially when running in clean air on the highway. My boxy wagon seems less phased by crosswinds and passing tractor-trailers.

[zef95]

http://www.autospeed.com/A_108676/cms/article.html

Here's the section when they tested a MB wagon:

As you would expect from the foregoing, a wagon is always going to have a large wake - it can be interesting comparing the Cd for the wagon and sedan versions of the same car. Here the streamline clearly leaves the car at the rear spoiler - which has been placed there to give this clean separation. (If the attached flow wrapped around onto the rear window a little before leaving the car body, it would create a suction peak, increasing drag despite the slightly smaller wake. Better to flick it off!) From this image you would expect the area behind the car (ie the full width, and up to the lower edge of the rear spoiler) to be all turbulent wake - and you'd be right.

The small amount of smoke being injected into the wake below the wagon's spoiler is insufficient to completely fill the wake - but you can clearly see the low pressure that's holding the smoke behind the car. That its top edge is so clearly demarcated shows that the spoiler is doing its work - the attached flow is separating cleanly at that point. The curved rear glass of the wagon is there for styling purposes only - it doesn't contribute to a smaller wake and so could have been vertical without changing a great deal of the aerodynamics.

The hatch window of the MB is even more slanted than my 9-5, and it doesn't do squat for aero, it seems. There is one term, though, that I'm unfamiliar with; what is meant by "suction peak?"