CRV Cross Country Trip Aero - Temporary Aero Just for the Trip

[walteraxe]

Ok, I've been lurking around this site for the past week or so, and just figured I've gotta join to share and get some help. I have a cross country trip, NC to CA. I've been imagining an aero trailer to tow my motorcycle and I've been wanting to build an air dam for my V for the longest time. Fortunately I stumbled upon ECOMODDER!!!

I have less than a week to do it, and a modest wishlist. Also, the V mods have to be temporary b/c the lil' woman won't stand to drive around in a fugly modded car...

Here's what I'm planning to do:
Aero Enclosure for trailer
Airdam
Sideskirts
Kammback

Materials:
1" PVC schedule 40 pipe
FRP (Fiber Reinforced Wall Panels, used in commercial bathrooms)
Vinyl Cove base
Aluminum backing/framing

So, I'm new here, but I've been thinking about this for a long time (engineer), and I'm in construction... so FRP is used on commercial bathroom walls. It's cheap! And readily available at Lowes/HD. The vinyl cove base is also cheap, and should be more resistant to scuffing/scraping the ground.

Here's the car/bike/trailer (trailer in progress):

[88CRX]

This sounds like an interesting project... can you post pictures of your project.

[Xringer]

On the V, you might want to delete the side-tubes (and rear tube?).

Here's what I did to my mud-flaps and grill.

http://ecomodder.com/forum/showthrea...ps-2839-2.html
http://ecomodder.com/forum/showthrea...-crv-2563.html

On the nose job, I'm only using the lower half of the center intake. Since you are going to be pulling a load, I would start off with the upper section open as well.

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I have an idea for installing a quickie air dam. There are 2 tie-downs on the nose with a large hole in each.
If you had a long pipe that would fit into those holes, it could act as a support for your air dam.
By taping holes into the pipe, you could screw in bolts or rods to keep it from rotating (from the wind load) and sliding out one side or the other.
Once it was locked into place, you could drill screw holes for mounting brackets or steel rods to support the air dam.

If I was doing it, I would bend 1"x1/8" aluminum bar stock (hardware store)
around the pipe (shaped like a 'J' hook) and fasten it with a couple of sheet metal screws. Then, I would mount a coroplas (or FRP) air dam across the vertical bars. (After making a template from cardboard).

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Sideskirts:
You could also mount 'L' brackets along the sides and use coroplas (or FRP) there too. Save those metric bolts from the side-tubes.
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Rear wheel skirts??
If you used some bent aluminum bar, bowed out to avoid tire rubbing and mounted some coroplas to it (pop rivets & big washers), then the skirt could be taped down with 100 MPH duct tape. No screws into the car.

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Kammback?
I've been looking at that, but I think my goal of 35 MPG can be reached without doing it.. I'm too dang lazy!

Cheers,
Rich

[walteraxe]

You da man! thanks for the info, Rich.

[Xringer]

If the V is 4WD and If you have the time and not a lot of rust under the rear end, you can pull out the main drive shaft(propeller shaft), rear differential & the two rear drive shafts.
http://www.hondasuv.com/members/showthread.php?t=31745

I've not weighed the parts, but I'm guessing between 100 & 150 pounds.
More importantly, you get rid of the dual pump load on the engine. (Added MPG).

Some people (like myself) don't actually use the RT4WD that much.
Since mine seemed to be going sour and the repair/replacement cost was so high,
I decided that we didn't need it anymore.

I'm not going to be trading mine in to a dealer, so I'm not worried about trade it value etc..

If I was going to re-install it, I would just take out the 3 shafts and leave
the rear diff in place. (drain oil & tape over the side axle holes) Those 3 shafts will only take less than 1/2 hour each to remove. The rear diff would take longer.

Or, take it to a shop.. With a lift and air tools, they could pull everything out in well under an hour. That's not much labor cost..

[walteraxe]

Wait... so you mean I can just make my AWD into a 2WD by removing a few parts? Wow, what MPG savings did you get out of that?

Ok, small update. I made a scale model of the trailer enclosure I'm going to build. I also went to Lowes and bought the FRP. Wow, it's super flexible. At first I thought I was going to have to make a pointed or blunt nose. Now I'm going to make a sort of tear drop out of it.

The images suck b/c I used my macbook camera, but I can at least count the number of joints, and better approximate the amount of PVC I'll need.


I also have to give credit where it's due. I got the FRP idea from finding this write up of a nose cone on a RV: http://www.johnbridge.com/travel_tra...rodynamics.htm

[Xringer]

The V is rated for 25/31 but don't think I ever did that well.
With mixed driving, I've seen a few 26-27 MPG tanks. Mostly highway was never better than 28 MPG.

But w/o the RT4WD, I seem to be getting 30 in town and 33-34 out on the highway. I'm basing this on what I'm seeing on my SG2. I'm not sure, but I think it's pretty close. It's going to take a few tanks to know for sure.

My goal is 35 highway and after I get a good tank calibration, I'll see what some hypermiling can do. I may even hit 36!! Won't know, until I try..

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Regarding the trailer. I think you might want to get some input from the resident experts here, before you get too far into the design..

I think, you might be able to design the nose of the trailer so that it isn't a stand-alone module, but will work with the shape of your CRV in a way that will enhance the overall (CRV+Trailer) cd.
I'm not real sure, but the nose of the trailer might be shaped so that it adds a boat-tail effect to the rear end of the CRV..

I found this pic in my pile of stuff. Maybe can help give you some ideas.

[Xringer]

http://books.google.com/books?id=UzJqTX4LPOsC

Press Preview this book and check out some of the trailer stuff.
Might be helpful.


Wow, some of these bike trailers are neat looking..
http://www.toyboxcarrier.com/motorcycletrailers.html

[walteraxe]

Rich,

Thanks for the guidance, and references. I'm going to see if I can change my design based on those enclosed motorcycle trailers, but have already started some stuff (see pic). It's all in the early stages so I've got some time, to work with it and make any necessary changes. Seems like it's just you and me on this thread, and I don't have a load of time... so I'll just go with what seems best.

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My hope/goal is to get normal highway mileage out of the CRV+trailer combo. That being 25 mpg. Pretty modest for just some aero mods... not sure if I can get the RTAWD -> FWD past the Mrs.

[Xringer]

My guess is, you don't want to make the top any higher than your CRV.. (or wider). That would load down the trailer like crazy..

I think it should be the same height & width as the CRV or smaller.
And, the nose should be as close to the CRV as possible (and still allow turning).

It seems like you would want the trailer to 'draft' on the CRV.
And not stick anything out into the wind streaming by.

The tail end of the trailer should be a boat tail.
It doesn't have come to a point, but can be a truncated boat tail..




I'm just shooting in the dark here.. The more trailers I look at on the web, the more I like the old Airstream design.. They were pretty easy to pull..