Project: ECOfamily Civic and its Aero Hitch Box / Boat Tail

[aerohead]

I'm hearing rumblings from local oilmen!

[christofoo]

I have a pretty long list of mods this car still needs... here are the rear wheel skirts I did last month:

The first edition was designed with clearance to spare on the moon disks, so it has way too much dish:

This is still on the driver's side, I might just rebuild it... someday.

I'll describe the build of the second skirt, I designed this to fit tighter with pizza pan covers. Less dish, no tuck shrinking on this one.

I had some clear plastic sheets I found in the trash from the Kammback windows, held the sheet on the car with magnets, traced the wheel well, then clamped it on the aluminum and cut.

Next, add some ribs for stiffness:


Add magnet gasket sheet. Riveting doesn't seem the ideal way to attach. It's time-consuming and I wonder if some of my rivets end up scratching the car. Also using construction adhesive, but I don't think I'd trust it alone.


Some clips for the wheel well - these work as long as the magnet gasket overlaps the body, otherwise there would be nothing stopping them from falling into the well.


Here's what the clip looks like in situ:

This one has been on here a while, you can see the winter salt caked on here.

Here's the final product:

(Try to ignore the salt and the dent some fool made in the car.)

[christofoo]

Two of my half-moon 'racing' disks went missing this year, before I took the other two off and put them in the trunk. The reason is that I got some snow tires on some new rims in November, and the steel rims in question were a loose fit. I didn't notice when I put the racing disks. Are pizza pans more aero than half-moons anyway? It seems like the extra dish in the half-moons is undesirable to my 'aero eye,' but it's easy to be wrong.

It took a while to source some pizza pans that were cheap enough for me. Walmart had 16" pans for $3.8 ea, but I want 15-15.5" for the R14 rims. Eventually found 15" on ebay, $20 for 4 w shipping, i.e. $5 ea.

I also got some hub caps from Walmart. I got the ones with the least dish, but the pizza pan dish was a much better match to the OEM hub caps.

Put jack nuts into the OEM caps:


The reason I initially didn't want to use the OEM caps, the winter rims don't have the same dish as the OEM rims, such that the OEM lug nut retaining rings don't fit the hub cap on the winter rims. In the end, the answer was zip ties:


Finished product (I have 2 of these done, need to make 2 more eventually):


For now I have to remove the 6-32 phillips screws and the pizza pans to get at the air valves, but I'm thinking I might cut a hole for the valves and apply some cover, or just tape.

[christofoo]

Did some tufting with the driver's side wheel skirt in place - just wanting to see where I'm at again.



Probably boat-tailing the wheels is the biggest thing I see here. Also I think I see turbulence on the wheel skirt, perhaps because of the dish and I didn't put the half-moon hub cap on here for some reason. Also seeing a bit of turbulence at the c-pillar transition onto my Kammback. Perhaps a similar bit of turbulence going from the tail light to the coroplast gap filler.

Anyways, room for improvement.

(Video will be uploaded in a minute, for the curious
Boat tail tufting with wheel skirt, with and without gap smoother - YouTube

[aerohead]

The magnet gasket is clever.I like it a lot.
The skirts should improve the performance of the tail,providing a cleaner 'source.' Fun!

[christofoo]

By the way, the tail is off for the winter.



The AHB gets in my wife's way (she's shorter). The Kammback is trouble in snowy icy weather, I still don't have a decent provision for clearing it.

It'll go back on the car when travel weather returns. By then I should have the anchor magnets beefed up. But the car won't really see that much air drag between now and then.

The custom cart shown under the AHB actually allows me to do removal and installation by myself.

[christofoo]

Originally Posted by aerohead

The magnet gasket is clever.I like it a lot.
The skirts should improve the performance of the tail,providing a cleaner 'source.' Fun!

Just remember you can't trust the magnet gasket for security. Gotta have some clips in there for sidewind forces, as well as bumpy roads. But it does work really well to get a clean leading edge. I'm using McMaster 1834K1. I tried McMaster 5756K36 since I thought the specs were similar, but it just is not the same stuff. Quite a bit to pay, ~$8 per sqft, so gotta be judicious with this stuff. (Can't remember if I'm repeating myself, this is the same as the leading edge on the Kammback.)

[aerohead]

Originally Posted by christofoo

Did some tufting with the driver's side wheel skirt in place - just wanting to see where I'm at again.



Probably boat-tailing the wheels is the biggest thing I see here. Also I think I see turbulence on the wheel skirt, perhaps because of the dish and I didn't put the half-mod hub caps on for some reason. Also seeing a bit of turbulence at the c-pillar transition onto my Kammback. Perhaps a similar bit of turbulence going from the tail light to the coroplast gap filler.

Anyways, room for improvement.

(Video will be uploaded in a minute, for the curious
Boat tail tufting with wheel skirt, with and without gap smoother - YouTube

I'm seeing a little dancing at the junctions and corners between section panels but even Kamm had some of that. The flow is recovering everywhere.Maybe a tiny bit of vorticity,but with the gradual contour you've created I don't suspect that they'd have any real energy-robbing potential.
I like it all.
Going after the wheels will be a good thing,as,as the drag of the body comes down,the proportion of the wheel drag to overall drag is going up.
Great project,really fun to see it fall together.

[Jyden]

Great work. keep it coming!

[California98Civic]

The wheel well skirt clips can be made to hold tightly if you design them to allow for a bolt that can be used to tighten them only the wheel well lip. That's what I did, following I think a design by metro. I also was not satisfied with how far the poked out, and have since adjusted them with aditional clamps to pull them into a position more flush with the vehicle side. Thanks for all the write-up deets and the pics.