Help w/Side Wind Deflectors

[Flyfisher]

Hi Folks - I have been working on side wind deflectors for my Hawk for a while now. I built a mockup of them in cardboard (see pictures). The biggest problem has been what to build them out of. I looked at having it built out of aluminum, fiberglass or plastic but the quotes were in the $500 range. Seems like I am going to have to do it myself to make it affordable. I think that leaves me with constructing it out of either wood or sheet metal. I am a little more handy with wood than sheet metal, but I am still kind of guessing my way through it if I did it in wood and a little more lost if I tried to do it in sheet metal.
Then I realized that I have this wonderful resource of creative people on this forum. Duh! I bet that someone out there has some good ideas for ways to construct these side wind deflectors. I am open to any ideas or perhaps other materials that I haven't considered. Easiest least expensive way to build something that will last is preferred.
Thank you, Gregg

 

[KILR0Y]

Flyfisher, you pose some great questions, but personally I was wondering what your desired outcome of these deflectors would be? It would help me better decide how I'd proceed while keeping any return on investment in mind...

Initial thoughts are that the minimal gains would not justify either the building expense or time installing them to the camper. I could be wrong however because I have no numbers/facts to back this up.

Have you considered using a top deflector like what's used on Thule racks and trays? I've seen a few posts on WTW from people who have installed them over their cab's.

 

[Alley-Kat]

Do a test (or have you already done this?).

Lets make some "telltales", we use them on sails on sailboats to see how the wind is flowing over the sails.

Get some yarn (or something like yarn - lightweight and bulky) and some scotch tape. Cut the yarn into pieces of about 6 inches long. Tape an end of the yarn onto the flat front edge of the camper in the place that you are thinking of making these side wind deflectors. Put several of them on each side in various places... high, low, near the cab, towards the outside. Then have someone drive your truck with the camper on it while you observe the behavior of the telltales from inside the cab.

If the teletales are plastered tight to the front of the camper, then that area is getting direct wind and your idea of side wind deflectors is a good one.

If the telltales float around a bit, then that area is NOT getting direct wind and is probably in the "wind shadow" of the cab and you don't really need the side wind deflectors.

Report your results, I'd be interested to know what you experience with this telltale test.

 

[jha6av8r]

Flyfisher, you pose some great questions, but personally I was wondering what your desired outcome of these deflectors would be? It would help me better decide how I'd proceed while keeping any return on investment in mind...

Initial thoughts are that the minimal gains would not justify either the building expense or time installing them to the camper. I could be wrong however because I have no numbers/facts to back this up.

Have you considered using a top deflector like what's used on Thule racks and trays? I've seen a few posts on WTW from people who have installed them over their cab's.

I wonder if the wings will create a dam effect and not let air escape around the sides. The biggest aerodynamic effect would come from deflecting the air up and over the cab before it has a chance to get trapped under it IMO.

 

[BFH4N]

Hi Flyfisher,

How about cutting them out of big pieces of foam (closed cell) and coating the outside (windward) surface with fiberglass or thin white plastic sheet, glued on? Should be light-weight.

- Bernard

 

[camper101]

Perhaps some ABS plastic out of the scrap bin at your local plastic shop. Could build it from scratch (although the curve would be tough) or just use a thin sheet to do the outside surface of Bernard's suggestion above.

 

[chnlisle]

http://www.wanderthewest.com/forum/topic/7763-wind-deflector/page-3

 

[Flyfisher]

Wow! Thank you for all the feedback. chnlisle - that post is my post of the front wind deflector I built. The purpose of these would be to increase mileage and because it is an interesting challenge. It is entirely possible that it may not pay off, but I can't find any info on anybody that has done it. If I can get 1 to 2 mpg savings without too much time and materials invested, I will be happy over the long term. My inspiration comes from sticking my hand a few inches out the window at highway speeds and noticing the high wind speed. If that is hitting the front sides of the camper that stick out beyond the cab, then it could be producing some small but significant drag. My thought is that it could be number two on the list of drags that I can do something about (number one being the front of the camper). Alley-Kat - I love the idea of telltales. I will do this as soon as I get the camper back on the truck. bfh4n - any idea where I might get large pieces of closed cell foam at and how I might attach it to the camper? camper101 - is ABS kind of like Lexan or other TAP plastic material? Kilroy - you are probably right, but we won't know until somebody tries it.

 

[jcfly]

Flyfisher: I once did a job in a mfr. of Plexiglas furniture and saw how Plexi can be bent to the angle you want. They cut the Plexi to size, then attach a flat heating element to where they want the bend to be. Electricity is applied and the element heats up slowly to the proper temp., and Voila ! the plexi bends.
If you find a shop that works with Plexi in this manner, all you would need to do is give them the size and angle you want them bent to, and you wouild be good to go.

Good luck !

 

[Alley-Kat]

Bending plastic is not that hard, IMO, as a first time "bender".

The heating element is called Ni-Chrome wire (like in bathroom wall heaters), I got mine off Ebay for about $3, which included shipping.

I placed the ni-chrome wire in a metal "U" tray (I already had this) that was filled with Plaster of Paris to electrically and thermally isolate the ni-chrome wire.

As seen in the photo below, I created an air channel on either side of the ni-chrome wire
I used a rheostat (which I already had) to control the amount of electricity which controlled the amount of heat produced.
Once the plastic showed signs of "plasticity" in the area being heated, as evidenced of a different "sheen" to the top surface, opposite the side of the applied heating, I removed the plastic and placed it in my form to cool,
Lots of YouTube videos out there on how to bend plastic to learn from.

The Heater. I just like building things.

The Form

For gentle curves (larger arcs), instead of a 90 degree bend, a thin plywood could be made into a form, and then a high temp air gun (like a hair dryer, but, more powerful, more heat) can be used to heat the plastic. Or get a plastic shop to do the job. In my area that would have cost me over a $100.

Looking forward to your telltale test results.

 

[camper101]

? camper101 - is ABS kind of like Lexan or other TAP plastic material?

It is similar to lex an but I'd call it more durable and less shatter-y. It's also not clear. Not sure if it'd get dinged up by road gravel though.

 

[Captm]

http://www.kingstarboard.com/ would work well for you project.
Cheers

 

[ntsqd]

"Plexiglas" is Acrylic and does tend to fracture or shatter when cold bent past it's yield point. In my mind ABS isn't much different. TAP Plastics has a range of different polymers including the King Starboard, not sure which will bend the best overall. Some can not be bonded or cemented, they must be mechanically fastened. One project in my employment past used Acrylic shapes cut from sheet, heated in an oven (what SWMBO didn't know won't hurt her) and then laid to cool in large radius wooden forms.
http://www.tapplastics.com/product/plastics/plastic_sheets_rolls

 

[Flyfisher]

Alley Kat - What kind of "plastic" are you using?

 

[Alley-Kat]

Ah, the $64 question.
Pretty sure it was NOT acrylic, it was (and is still) pretty supple and flexible.
I'm still making other things from the pieces I've still got.
However, I really don't know, as it was sign plastic from my wife's store, when she closed it in 2007, before the downturn in the economy. White 1/4" thick, with a blue vinyl overlay, that I pealed off. Never showed any discoloration after 11 years with afternoon sun on it every day.