Aerodynamic trailer design

[Ecky]

Thinking about grabbing a pair of these for my wheels:




They're a bit expensive, and I'd need to remove the fairings to get the wheels off, but so long as I keep a socket kit with me it shouldn't be too much of a problem,

Also, I had the idea of moving the axle to the top side of the leaf springs to increase the maximum depth (and volume) of my box, at the expense of maximum suspension travel.

[BamZipPow]

Originally Posted by Ecky

Thinking about grabbing a pair of these for my wheels:




They're a bit expensive, and I'd need to remove the fairings to get the wheels off, but so long as I keep a socket kit with me it shouldn't be too much of a problem,

Also, I had the idea of moving the axle to the top side of the leaf springs to increase the maximum depth (and volume) of my box, at the expense of maximum suspension travel.

To think outside of the box per se, instead of trying to attach the wheel pants directly to the wheel axle...you could attach them to a long arm and mount the pivot point forward of the wheels. Secure the back end to the axle with a zip tie or strap so the pant assembly won't keep lifting up as you go over bumps. You will need to allow fer some clearance on the backside of the wheel as the pant assembly will be on a different arc than the wheel assembly.

To git access to the wheel assembly, remove the strap or zip tie and lift it forward. The setup would work similar to the protection on a tire balancing machine you see at the tire stores. Easy access!

[freebeard]

Nice. What source? What size?


http://decorides.com/wheelpants.html

$799 Fiberglass WHEEL PANTS (that steer) for Street Rods
....
Dimensions of the wheel pant when sitting on the floor of the garage upright, by themselves, with no wheel or tire inside it, are 25 3/4 inches tall, 40 3/4 inches long and 7 1/2 inches wide, outside dimensions.

[slowmover]

I'm building a passive oven to cook my tires at highway speeds. Looks exactly like those wheel pants.

Be careful.

The torsion axles mentioned in a couple of posts are worth your investigation. They can sometimes be clocked for ride height. They will certainly allow that trailer to follow the car better. They are more naturally shock absorbing to keep trailer bounce to a minimum. See BZPs ride quality issues. While not the same, keeping distractions to a minimum is good for driver attentiveness.

Trailer roll center height is also better c

[Ecky]

Originally Posted by freebeard

Nice. What source? What size?


http://decorides.com/wheelpants.html

Those particular ones are on eBay for $125, and should fit 13" wheels. I'm not sure if they'll be wide enough, but that's close to the going rate for the size.

[aerohead]

you could do split fairings as well
http://ecomodder.com/forum/showthrea...-t-7839-7.html
#62 (permalink)
They may not perform as well as a fully-enclosed fairing,but they don't add frontal area and tire changing is as easy as it will get.

[freebeard]

$125 sound reasonable. Bandsaw them in half, solid mount the inner half and make the outer half removable with Dzus fasteners. You could adjust the width as needed in that process. Air scoops so slowmover doesn't have to worry.

aerohead --

At 7:45 PM,in Odessa,TX,at 350-miles( 564 km )and at 63-mph ( 100 km/h )and in total darkness,the driver side trailer wheel went it's own way,with the trailer crashing onto I-20.
Four lug bolts were gone,along with the wheel/tire and dust cap from the hub.
The lead and trailing fairing for the wheel were completely destroyed and spring fairing damaged.The bellypan was breached and rear outside corner of steel wheel well displaced inward and poised like a knife-edge over where the tire tread would have been.

I had that happen to me in the early 90s with my Type III Notchback. I made a left turn from a stop sign and within about 150 feet all four lug nuts on the left rear evaporated leaving the wheel and tire stuffed up into the wheelwell. WTF! I walked the road and they were nowhere to be found. ??? Possibly the weirdest thing that ever happened to me.

I took one lug nut off each of the other three wheels and I wasn't even late for work.

[Ecky]

I have some time, I'll see if I can score something for epic cheap. In the mean time, I found some free materials conveniently on the side of the road:




~100 square feet in 33 sheets of 24"x18"

I'm thinking of quilting it together to make the siding. At the very least, I have some more material for a belly pan for it, and for the rear of my car.

[ChazInMT]

Hey, I was looking at this and sort of asking "What If?" regarding the pressures involved here. If I'm not mistaken, there is going to be a high forming along the roof of your trailer due to it being above the curve. And below the trailer there is going to be a fairly deep low. When these 2 meet finally in close proximity, I fear a wiggly vortex (Aerohead has a better term for this, I'm too lazy to find it again) will form and be noisy while robbing you of some efficiency here. Not sure what the solution is. I'm hoping Aerohead looks at this and has some insight...(yeah I went there) as to: A) If my fear is justified. B) Is it significant. C) What can be done to mitigate.



Higher Res Version Here


My only thought on mitigation would be to build down below the rear of the trailer behind the axle. This would serve to have a greater separation between the 2 pressure zones and reduce the strength of the low.

I hope this makes sense, my area of concern is that place 12-18 inches behind the back of the trailer where the red & blue are about to meet. I have always gotten a little worried when 2 areas of differing pressures are close to each other.

I sort of used a more distant shot of an Insight for analysis in my illustration here. It is to scale top to bottom and the trailer gap is the same.

Also I might suggest that you build as far forward as possible on the front of the trailer to reduce the gap some more.

Your project looks great, I hope this helps you a bit. Where you at in FL? I'm guessing panhandle by the trees (no palms) in the background.

[Ecky]

Much appreciated!

I'm already as far forward as I care to go with a fixed structure. If I experience problems on the highway, perhaps a shark-tail fin on top would help?

And yeah, Tallahassee.