Civic Hatchback Aerodynamics part deux

[ajohnmeyer]

So in following the footsteps of the pioneer Basjoos before me, I too am setting out on the road of improving the aerodynamics of a 5th generation Honda Civic hatchback.

Goals are as follows:
1.) Improve aerodynamics from Cd: 0.32 to Cd: 0.26 or better (Honda Insight equivalent)
2.) Materials must be Weather, impact and wear resistant with a (projected) life of 5+ years of normal use.
3.) Overall design of components must be removable, with no permanent changes to the structure of the automobile.
4.) Aesthetic considerations play a role, notably in the S.W.M.B.O. test. (She Who Must Be Obeyed cannot object *too* strenuously to the aesthetics of the modifications).

In pursuit of these goals I plan to implement the following modifications, in roughly this order:
1.) Rear wheel fairings (not the most effective, I know, but the easiest, and most forgiving)
2.)Front wheel fairings
3.)Partial front belly pan
4.)Fiberglas front nose/splitter
5.)Boat-tail

And now for a quickly photochopped picture of phases 1-4
http://i239.photobucket.com/albums/ff289/ajohnmeyer/94Civic2.jpg



Now, to kick-off my little project I acquired a full sheet of 4-5mm (?) thick peice of white one-sided-grained ABS plastic. This actually took about a solid month of trying to track down my local plastics supplier. But today I actually found him and for a mere $75 took home a sheet of awesome white ABS.
http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4869.jpg


ABS seems to me to be the ideal material for making fairings and such because of it's malleability under heat and because it can be "welded" with the right equipment. Luckily my local Harbor Freight store has the welding kit if I ever feel spendy, and they had a heat-gun on sale for $9.99 last week which I fortuitously saw fit to pick up even though I had no ABS at the time.

Stay tuned for the next episode: "Templates Galore!!!"

[TomO]

Your plans are looking good. Might I suggest one difference though, fill in the "valley" where the OEM trim would be.

[cfg83]

ajohnmeyer -

So in following the footsteps of the pioneer Basjoos before me, I too am setting out on the road of improving the aerodynamics of a 5th generation Honda Civic hatchback.

Goals are as follows:
1.) Improve aerodynamics from Cd: 0.32 to Cd: 0.26 or better (Honda Insight equivalent)
2.) Materials must be Weather, impact and wear resistant with a (projected) life of 5+ years of normal use.
3.) Overall design of components must be removable, with no permanent changes to the structure of the automobile.
4.) Aesthetic considerations play a role, notably in the S.W.M.B.O. test. (She Who Must Be Obeyed cannot object *too* strenuously to the aesthetics of the modifications).

...

For the nose, I would do the following :

1 - Remove the bumper cover and set it aside.
2 - Go to a junkyard and find another same-gen Civic bumper cover.
3 - Do anything you want to the junkyard bumper cover. Here's a good thread with an example idea on that :

Have you used dope?
http://www.gassavers.org/showthread.php?t=5584
I was wondering if anyone has tried making an aero mod in the same fashion as an early aeroplane? This is, make a frame, stretch a sheet over it, and then paint it with lacquer or urethane. Hunting down coroplast is surely easier, but I'm curious as to whether this would work?

That way, you could do anything you want to the nose and have it be 100% reversible. I think this would satisfy your S.W.M.B.O. requirements.

That's one of my many many many long term plans, if I ever get the time.

CarloSW2

[basjoos]

I'll be interesting to see your results. I am curious why you decided to go with only a partial belly pan when full coverage would give better FE results? Also wheel spoilers and side skirts are cheap and easy to do, but aren't on your list.

Foamed PVC is considerably lighter and cheaper than ABS and can also be welded (I've done it using PVC welding rod and a heat gun) and can be heated to create permanant bends. I flush-covered the OEM trim groove on the sides of my car.

[DarbyWalters]

I think the ABS Plastic would work great for the underbelly pan pieces...very sturdy! It would also be great for the side skirts mentioned above. Then I would work on the wheel skirts with a lighter material. Sounds like you have some pretty ambitious plans...we won't recognize it by the beginning of next year probably. Seems like spun wheel covers would be a bit easier than skirts for now...

[McPatrick]

It's awsome someone else is starting to transform a Civic hatchback now. If my money situation ever allows it this is something I am going to do as well. What garage tinkering could be more fun? And she-who-needs-answered-to can be told that this is a hobby that saves money instead of buring it :)

I'll follow this thread for sure and please keep those photos coming!

[cfg83]

DarbyWalters -

I think the ABS Plastic would work great for the underbelly pan pieces...very sturdy! It would also be great for the side skirts mentioned above. Then I would work on the wheel skirts with a lighter material. Sounds like you have some pretty ambitious plans...we won't recognize it by the beginning of next year probably. Seems like spun wheel covers would be a bit easier than skirts for now...

I think CO ZX2 got 1/16" thick 8'*4' sheet of ABS plastic from Home Depot in the "wall stuff" department. Less than $30, I think.

CarloSW2

[ajohnmeyer]

I am curious why you decided to go with only a partial belly pan when full coverage would give better FE results? Also wheel spoilers and side skirts are cheap and easy to do, but aren't on your list.

I am wanting to do a full belly pan, though I am planning an EV conversion. If I do a belly pan now I may well have to make another one after I take replace the gas tank with a battery box during the EV conversion process. Wheel spoilers (especially on the front) are hopefully going to be incorporated into the belly pan.

As for the nosepeice, my plans right now are to make the lowest front extension out of a U-shaped piece of aluminum. Then, stretch out a few yards of white "sweatshirt" fabric from the aluminum bar to the top seam of the bumper. Once the sweatshirt fabric is thoroughly covered with fiberglass resin the "real" bumper can be removed. The sweatshirt fabric thing is a trick from my car-audio days, it's a lot better to work with over a stretch-mold than regular fiberglass mat. It cures a lot thicker, stretches better, and ends up needing a lot less bondo if you paint it.

[ajohnmeyer]

So I got the first of my aluminum supports for the rear wheel fairings attached to the car tonight. It got dark before I could get the second side on though. Oh well, I have a little time tomorrow. So here's some lovely crappy pics.

Here's the horizontal support brace installed; it's pretty sturdy.
http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4870.jpg



On the back side I've attached it with an "extruded U-clip" to the rear bumper.
In the front I basically attached it with a larger, stainless-steel version of your standard drywall anchor. I unknowingly chose to drill into the body where I can't get behind the sheet metal to get a nut on the bolt. So that's where the big drywall anchors come in.
After having it on the car, I've decided that I'm going to try to find a hinge to put on the front part of it tomorrow. A hinge will greatly facilitate tire removal if (when) I get a flat.
http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4871.jpg



The only other thing I need is a much smaller bracket above the tire to hold up the top of the fairing.

So far, I have spent about $8 on the 1"x 1/8" aluminum bar stock and about $15 on various stainless steel hardware, that seems like a lot for hardware, but it is stainless steel, and I have changed my mind about fasteners about 3-4 times now...:rolleyes:

[ajohnmeyer]

ok, I got all the brackets for the rear fairings installed. There is one horizontal bar running the length of the wheel well opening on the bottom and a small tab on the top of the wheel well opening approximately between the 11o'clock and 12 o'clock position (from the drivers side)
http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4877.jpg


Now I just have some template-finessing to do. The initial templates I made for the rear fairings are a little off. I made them before I had the aluminum brackets made or installed, so they're a bit off.
http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4878.jpg

[XFi]

Wow, NICE! I wonder who is going to carry Team OPEC Busters numbers this round of the competition? ;)

[ajohnmeyer]

So I got the rear fairings finished up and installed. They need a little bit more coaxing with the heat gun in places. That and the heads of the bolts and the washers need a good coat of white paint.

http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4879.jpg



http://i239.photobucket.com/albums/ff289/ajohnmeyer/IMG_4882.jpg


For all those interested in using ABS in the future please note that it will discolor if you heat it up too much with the heat gun, so heat up the back side of the piece so you wont see the discoloration when it is installed.

[cfg83]

ajohnmeyer, aka "Surly" -

Verrrrrrrrry Nice.

CarloSW2

[ajohnmeyer]

So today was my first day driving with the rear fairings installed. I'd guesstimate that I'm seeing a 7-10% improvement in coast-down. My passenger side fairing is a little rattly, the plastic is occasionally rattling against the aluminum support, nothing a little bending or velcro can't handle.

And all of this has got me thinking about what to do next. I think I'll have enough ABS to do the front fairings, grill block and a front undertray (bumper to front suspension arms.) I'm not so worried about saving enough ABS for the undertray because I can get tons of coroplast from my work for free if I need it. We have tons and tons of big outdoor Pepsi sinage that's all printed on white coroplast, and it all gets thrown away within about 6 months of being put up.

I've been thinking a lot about how to do the front fairings, my very first idea was to make something based on those snap-on "spinner" hubcaps. If the fairing could be attached to the outer "spinner" portion of the hubcap, then it could in theory pivot with the wheel when it is turned. This idea got shot all to hell when I made a template of the front wheel and discovered that the wheel well is slightly assymetrical, I think that would make for some problems.

Other options as I see them are conveyor rollers as per basjoos's fairings or using some teflon sheet, I think someone mentioned that in COZX2's fairing thread. So far finding the small rollers seems to be a problem and I wonder how they will hold up to rain/snow/salt/etc.

Opinions anyone?

[cfg83]

ajohnmeyer -

...

I've been thinking a lot about how to do the front fairings, my very first idea was to make something based on those snap-on "spinner" hubcaps. If the fairing could be attached to the outer "spinner" portion of the hubcap, then it could in theory pivot with the wheel when it is turned. This idea got shot all to hell when I made a template of the front wheel and discovered that the wheel well is slightly assymetrical, I think that would make for some problems.

...

Opinions anyone?

On Taxis, there are "add caps" that maintain their orientation.

They not spinnin': ads on taxi cab hubcaps
http://www.engadget.com/2004/09/13/they-not-spinnin-ads-on-taxi-cab-hubcaps/

Taxi Advertising
http://www.nationaltransitmedia.com/TaxiAdvertising/ppc.php

TrafficAds
http://www.weekendtoys.com/catagories/store/trafficads.html

HubAds – The Wheels of Advertising
http://www.adsoncars.com/hubads.asp

NOT SPINS - NOT ROTATING - STAY STILL
http://www.autopure.com/NotSpins.htm
1087
1088

They are not static, they "rock" back and forth when the car changes speed because a weight to keep the add oriented.

You wouldn't be able to make a perfect closure because of the asymmetry you mention, but it would be close.

CarloSW2

[basjoos]

Other options as I see them are conveyor rollers as per basjoos's fairings or using some teflon sheet, I think someone mentioned that in COZX2's fairing thread. So far finding the small rollers seems to be a problem and I wonder how they will hold up to rain/snow/salt/etc.

Opinions anyone?

I got my conveyer rollers from McMaster Carr (Part # 2278T11)
3/4" Diameter X 4-7/8" long, $8.71 each. I've been using them since last summer (put about 40,000 miles of them so far) and haven't had any problems with snow or salt during my usual commute into the Asheville NC area. The only maintenance I do on them is to add a drop of oil to the end bearing every couple of months. Since I exhaust my hot radiator air out through my front wheel wells, the wells stay warm, and dry out quickly once I park or reach dry road surfaces.

[ajohnmeyer]

After thinking a lot about the "spinner"-based front fairing design, I've decided that it's more trouble than it's worth. The primary problem with that design is allowing for the up-and-down suspension movement.

Sometime this week I'm going to fit up some cardboard templates for the front fairings just to see what kind of clearances that I have to work around.

So far I'm liking the teflon (PTFE) idea because of the potentially lower profile and overall KISS factor.