Tuft Testing Smooth Wheel Covers

[fusion210]

You can watch them side by side with the youtube doubler.

http://www.youtubedoubler.com/?video...uthorName=Qman

[ConnClark]

I do think that the tufts jump around more with the smooth wheel covers. I might have an explanation. It might be possible that the smooth wheel covers allow the turbulence to retain more energy.

Also note this is not a true ABA experiment. The first test was titled Test "A" . The second test was titled Test "2" . So technically you have done A2 testing

[NeilBlanchard]

The other uncontrollable factor (that would also be an issue with the one side smooth suggestion) and that is cross winds may have been different speed or different directions during the tests?

[tasdrouille]

I will concede that this tuft test was deceptive; there was definitely a lot more movement on the second video with the covers on. However, uncontrolled environments are, as their name imply, unpredictable. No force was ever measured here, only tufts movements resulting from vectors that might or might not have been the same between runs. Every controlled test I've ever seen tells me wheel covers reduce drag, so I'll stick to SAE papers results to tell me what works and what does not for the time being.

The results were were quite entertaining to look at. Keep on the good work. You might want to give a couple coast down test a try.

[kstruve]

Yeah, more tuft movement with the discs, I think. Especially further down the car from the front wheel - in the area near the end of the front door.

[d0sitmatr]

2 things I noticed

• 1. as mentioned, it looks like your getting more disturbance from the wheel well back with the discs installed, but it also looks to me like (from the direction of that disturbance) its coming from inside the wheel well.
• 2. the affect of the car doing the videoing, when they pulled forward a little, you could see the disturbance it had on the airflow of the vibe. I think to get a better idea of this would be to use a motorcycle as to have as little effect on airflow around the vibe as possible

.

from the looks of the shadows and such, I dont think there was much time between the two tests, and while I do understand that 15 mins is all that is needed for changing weather patterns, I dont think that happened here. but, we cant tell if there is any other vehicles on the road ahead, which would greatly affect the airflow.
lastly, you need to run the tufts all the way to the rear to garner correct wind patterns, as the rear most tufts seemed to me to have less movement in the 2nd vid than in the first.

[California98Civic]

Originally Posted by Tango Charlie

tufts around the perimeter of the wheel well in the nine o'clock to two o'clock positions, were more stable.

To me it looks like this might be true, but in a more narrow range: 10 or 11 o'clock to maybe 1 o'clock. In the fan-blade wheel design is sucking air into the wheel, might that airflow then be forced under the car and out the top of the wheel well? Isn't the movement of air through the wheel itself a source of rolling resistance? Have you tested the effect on MPG? Sorry for so many questions. Thanks for posting the surprising result even though it frustrated you a little. Very interesting.

[orange4boy]

I'm with Daox here. A slight change in wind direction could have done that.

Just because the tufts moved more does not mean the smooth covers would create more overall drag. There are times when increasing frontal area lowers the Cd. Any change in the airflow pattern will change everything around it including in front of the car so perhaps that's what you are seeing there.

I kind of doubt those rims could blow air inwards. RPM is too low and outward pressure too great.

Still a good test and interesting to see.

Have you thought of rounding the trailing edge of your wheel well? I'd love to see how that smoothed things out.

[Tango Charlie]

Originally Posted by ConnClark

...this is not a true ABA experiment. The first test was titled Test "A" . The second test was titled Test "2" . So technically you have done A2 testing

Ha ha! Thanks for noticing my Paul Reiser-inspired attempt at humor. I wasn't sure if anyone would notice.

Neil, yes, there was a crosswind that day. I'm thinking this may very well have buggered my test. I only did one run north with the disc on, and one run south with the disc off. Then we went home. Since she doesn't read this forum, I'll blame it on the wife. I was trying not to inconvenience her too much. Lesson learned.

There were no cars ahead of us, I was careful of that. I tried to hug the side of the road to provide as much space between the two cars. dOsitmatr, which clip and at what time do you think you see the disturbance from the camera car?

Orange, great minds think alike. I've been contemplating a wheel well insert with a nice radius-ed edge; something to emulate the first gen Insight. If painted black, it would be visually inconspicuous, too.

California, I have not calculated any gains/losses. My tank to tanks are just too varied to show this small of a change. I think the next thing I need to do is do some legitimate ABA tests. You know I'll post it when I do.

[d0sitmatr]

Originally Posted by Tango Charlie

There were no cars ahead of us, I was careful of that. I tried to hug the side of the road to provide as much space between the two cars. dOsitmatr, which clip and at what time do you think you see the disturbance from the camera car?

I def saw some disturbance in the first vid (more so than the 2nd) when the cam car pulled even/ahead a hair. I did notice you were trying your hardest to hug the edge of the lane