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May 11, 2006

After seeing Dan's (krousdb) handy work with Coroplast on his Del Sol, I started playing around with a sheet of it. I added a aero belly cover to the rear of the Insight and added a engine pan to the Acura TL. That worked well.

I still have a 4 X 8 sheet of black Coroplast left, so I started brainstorming about where to use it.


2005 Honda Insight


Goal :
1.)See if Coroplast will work as a front wheel skirt
2.)Is the aerodynamic gain measureable in FE?


Concerns :
1.) Coroplast rubbing on tire and melting
2.) Retraction system failure and wheel skirt gets ripped off in the airstream
To address concern #1, I glued thin sheets of white Teflon to the rub areas.



http://www.cleanmpg.com/photos/data/500/medium/Insight_FrntWheelCoversBack.jpg

The retraction system is simply a latex glove cut into strips and doubled up to give some tension.
Also installed a small block at the front of the wheel well to prevent the skirt from being pulled in too far. Acts like a stop.

http://www.cleanmpg.com/photos/data/500/medium/Insight_Wheel_Skirts_Straight.jpg



Tomorrow's commute to work will be the first test run. Speeds of 45-55 MPH, lots of turns, some high speed. It's a known course, with a years worth of fuel economy info. I'll see if it's measurable. I'm guessing it won't amount to much.
I'm bringing a few tools just in case they fail during the drive and have to be removed.

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May12, 2006
The drive to work this morning was the first chance to test the wheel skirts.

If this works, I may take the Insight to Bonneville and show those guys a thing or two!;)


At first I could hear the skirt flapping and slapping the wheel well stop. Speed was 38-40 MPH.
Then it got quiet after I picked up the speed to 48MPH. That was strange...humm?


Arrived in the parking lot at work, got out to see how it looked.
Oops! No front wheel skirts. They sheared off at top folded hinge.

A single sheet of Coroplast won't hold up to the forces and the retraction bands need to be much tighter.


Lesson learned. Back to the drawing board (cafeteria napkin).

hm what a tough project, i saw this and thought wow as you increased speed it got quieter but sadly the skirts fall off.

Hm so I guess back to the drawing board good luck!

Hi HawkGT647:

___I am so glad you posted a how to and the actual results even if they were unacceptable on the first go around. I remember talking to somebody here about the experimental Ford Probe II w/ a .19 Cd (I think that is what it was) and it too had a flexible front spat - aero covers. With some Internet sleuthing, you might be able to pick up some tips and tricks from that setup that might help with your own?

___Good Luck

___Wayne

I would try some bumper cover extinsions. use about half the matrial or less. Try fourming it with steam from a really hot and fired up tea kettle. Use small tabs you have cut into the extinsion bent into the leading edge of the fender well. Then use some cheap shooter screws to fasin to inner fender well.

Wan't there a big old citroen that had wheel covers over the back wheels? I think it was the one that the headlights steered with the wheels. The airflow is quite turbulent down the sides of a car, just open the rear door windows at speed and you usually get deafened with the subwoofer like turbulence. From that i suspect fairly big savings in fuel.

Hi Vtec-e:

___The most famous rear wheel covered vehicle amongst the hypermilers here in the states is the Honda Insight as Don was modifying above.

___Here is one of the best examples (Billy’s beautiful 05 ;)) for showing the Insight’s included rear wheel spats (rear wheel opening covers) that help to reduce its aerodynamic Cd.

http://www.cleanmpg.com/photos/data/501/Billy_s_2005_Modded_Insight.jpg

___Good Luck

___Wayne

Wan't there a big old citroen that had wheel covers over the back wheels? I think it was the one that the headlights steered with the wheels. The airflow is quite turbulent down the sides of a car, just open the rear door windows at speed and you usually get deafened with the subwoofer like turbulence. From that i suspect fairly big savings in fuel.

Citroen did that to an extent on a bunch of their vehicles, including the 2CV, DS (which had those turning headlamps), and CX. It looks like they stopped that practice in the 1990s, though. Peugeot and Renault also lowered the rear wheel arches a bit during the same era, but I don't think they ever covered the wheels to the same extent.

Consider running the corrugations in the other direction (vertically).
And maybe consider gluing two pieces together so you can have corrugations going in both directions.

In addition to Bruce's suggestion, you also might consider using long springs to return to position. In addition, if you could create a vertical "hinge" by scoring the coroplast, it might help. If you go with the hinge, then make the metal tire plates cover the entire area of back, up to the hinge. That way, the spat will be encouraged to bend at the scored hinge.

It occurs to me that the spats could be tested on an interstate, with little turning, by simply taping them temporarily in place. Get a baseline run of perhaps 20 miles, then go back and repeat with the spats in place. You could install them on the ramp, leading to virtually no turning, and taking the turning issue out of the experiment.

If it appears worthwhile, THEN work on the final design. There's a reason that most aero fans only consider the rear. Just thinking out loud.

Wan't there a big old citroen that had wheel covers over the back wheels? I think it was the one that the headlights steered with the wheels. The airflow is quite turbulent down the sides of a car, just open the rear door windows at speed and you usually get deafened with the subwoofer like turbulence. From that i suspect fairly big savings in fuel.

2CV from the 50s. (The ugly duck.)
DS from the 60s.
SM from the 70s with the leveling and steerable headlights and variable height suspension.
CX from the 80s.

The CX was the last "real" Citroen, they went bankrupt, Peugeot picked up the pieces but kept the brand.

-mr. bill