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With all the solar panels and other appendages on the roof of our EKKO, I thought it might be a good idea to add a fairing to the roof line.  I did this mainly to reduce wind noise from roof items, and *not* to reduce drag (we’ll get into that at the end).  This was actually not too bad of a mod.  Once I finally got cracking on it, the process was maybe four hours, start to finish.  Lots of pictures here so let’s get started.

If you’ve been around here a while, you might remember that I also added a roof-rack-mounted fairing to our Travato, Lance.  I’m going to do much the same thing here, except it turns out to be even a bit easier due to the construction of the roof.  In the Travato, I was dealing with a contoured roof on a metal-bodied van.  But in the EKKO, the roofline where I wanted to add the fairing was perfectly flat!  This meant that I didn’t need to make and fit a template, and then trim the fairing material to it.  That alone saved a couple hours.

 

The first step in adding the fairing was to add a front crossbar to the roof rack.  As shipped from the factory, the EKKO does not come with a front crossbar.  This is partly due to wind noise.  Whatever you do, don’t try adding a front crossbar by itself without a fairing… you’ll go crazy from the noise.  You can purchase an extra crossbar from Winnebago.  Alternatively, you can purchase a front crossbar from Summit Products directly (they make the rack parts for Winnebago).  If you order from Summit Products directly, the part number you’re after is 108037_A.  Adding the front crossbar isn’t too difficult, it just bolts right in with 5/16 carriage bolts.  I slid the front crossbar as far back as it would go – against the front towers on the side rails.

 

Then, it’s time to bend up some brackets.  I made mine out of 1/8″ aluminum bar stock.  I cut it into pieces about 8 inches long (but you could go a bit longer), and filed down all the sharp edges.  You’ll need to get on the roof with a bevel gauge in order to determine the angle to bend the brackets to.  Just clamp down the gauge and use it to transfer the angle – don’t try to measure it, that’s just frustrating.  And even then, you’ll probably get it wrong the first couple of times (I did), so just make up some extra blanks from the get-go and you’ll be less grumpy about it.  I wanted to match the slope of the roof to provide a smooth ride for the airflow – pictures later and you’ll see what I mean.

 

I have this metal bender that I got the last time I made a fairing, and I think that may have been the last time I used it, but it sure was nice to have.  Since I don’t use it that often, it’s always an adventure to bust out the manual and figure it all out again.  If you don’t have a metal bender, and don’t want to purchase one, you should be able to accomplish these bends with an anvil, a vise, and a hammer.  I’ll admit to fine-tuning the bends I got from the metal bender with a plain old hammer.

 

Once the brackets are made (I made 6, plus some extras), you can lay them out on the fairing.

The fairing material itself is 1/4 black acrylic.  I was able to get it from a Utah supplier and have them cut it to 75 inches long by 12 inches high, which was just about perfect.  All I had to do was round over the corners of the piece and it was good to go.  To round over the corners, I just traced around some jars and lids I had laying around.  I put a decent sized roundover on the top corners, and a tighter one on the bottom.  To make the cuts, I just used my (awesome) jigsaw with some fine-toothed blades.  You need to worry both about shattering this stuff, and about melting it, so use the finest blade you can find and take it slow.  But don’t linger too long in one place and get things melting.  Come to think of it, maybe you should practice on a piece of scrap if you’ve never done it before, because I can’t exactly describe the feel.  It’s not hard though.

In addition to cutting the acrylic to shape, you’ll need to layout the brackets on the sheet so you can drill holes.  I mounted the fairing to the bracket with 1/4″ stainless machine screws, washers, and nylon lock nuts.  This meant I needed 1/4″ holes in both the brackets and matching holes in the acrylic.  The holes in the brackets are easy.  You can just use a twist bit, and you should drill these first.  It helps to use a center punch when drilling metal so your drill bit doesn’t wander.  Once you have one, you’ll wonder how you ever drilled holes and kept your sanity without it.  With the holes drilled, lay out your brackets on the fairing, and mark the matching holes in the fairing.  KEEP TRACK OF WHICH BRACKET GOES WHERE!  There will be small deviations in the bracket hole locations, and you’ll find they won’t necessarily all be interchangeable.

To drill the holes in the acrylic – and this is important – use a 1/4″ spade bit with spurs.  I’ve tried to use regular twist bits on this stuff and it just grabs it and makes a mess and you’ll probably slice your hands open.  This fairing is too large to take to the drill press without an army of helpers, so you’ll wind up drilling it with a hand drill.  Just make sure to back up the cut so you don’t blow out the back side of the hole (which would be the front of your fairing).

 

Once the holes are drilled, mount up your hardware with the stainless machine screws, washers, and lock nuts.  For the bottom of the fairing – where it would ride on the roof of the RV – I added some of this edge trim.  It just snaps right on to the acrylic, and stays there by friction.  I was able to cut it with scissors, and just tap the last bits of it onto the fairing with a mallet.  I’m thinking this should keep the fairing from rubbing through the paint or fiberglass up on the roof.

 

With that on, the last thing I did before mounting it up was to sand the edges of the acrylic.  Nobody is going to be inspecting the edges of the acrylic way up there – I did this mostly to keep from shredding my hands while I was trying to mount it!  If you were really super motivated, you could always flame-polish the edges of the acrylic with a MAP blowtorch.  I’ll admit I almost did this just because I thought it would be fun to play with a blowtorch.  But there was a chance I could damage it, and I only had one piece of the acrylic, so I stuck with just sanding it.

 

After that, it’s time to head up to the roof!

 

The fairing is held to the crossbar with more 5/16″ carriage bolts, washers, and flange nuts – just like the Winnebago installed solar panels.  If you’ve forgotten to drill the crossbar-side holes in your brackets, that will be painfully obvious now.  Also, if you installed your front crossbar before you put 6 carriage bolts into its track, this is when you’ll remember what a good idea that would have been if you had it a few hours ago.

 

You really do want to make sure that the fairing is tight against the roof along the bottom.  What you DON’T want is for the wind to get under the fairing and to lift it up somehow.  That would be noisy and bad.  You may have to do some fine tweaking of your mounting brackets at this point to get the fairing to sit exactly where you want it.  Take your time here (I went up and down off the roof 3 times to get it right).  Resist the urge to bend the brackets while they’re attached to the fairing – that will not end well.

 

Eventually, you’ll get things dialed in where you want them, and the job is done.  Like I said, this only took me about 4 hours, start to finish.  Unless you count all the time it took me to find the acrylic, and then drive to Salt Lake City to pick it up.  (But we were going there anyway.)  The rest of the parts and tools should be available anywhere cool stuff is sold.

 

Now, how is it working?  As far as the noise abatement goes, it’s a fantastic success!  We get very little wind buffeting or noise from around our vent fan anymore.  Absolutely no complaints there.

As far as drag or gas mileage goes, the jury is still out on that one.  I made the fairing so that it covers up the wind’s view of pretty much everything that was on the roof, except for the side towers of the rack.  And I worked to get the profile of the fairing to match the existing roof cap line, as you can see in this picture.  So why am I not sure that I reduced drag?

 

Here’s the deal.  The equation for drag is this:

Borrowed from NASA. (really!)

 

And while this fairing might have reduced Cd, the coefficient of drag, I also increased A, the cross sectional area.  The fairing is 75 inches wide and as angled on the roof presents 9 inches of height to the front.  That’s just over four and a half square feet of surface area I installed.  Now, not all of that was “additional”.  We can deduct the cross sectional area of the things that were already there that I covered up:  the crossbars, the Maxx Fan, the air conditioner, the solar combiner box, the ladder, and even the side-area of the solar panels (which was almost a square foot itself).  So it’s probably somewhere closer to 2 square feet of area that I added.  Did I reduce the Cd enough to make up for that?

Well, the only way I’ll ever know for certain is to take Number One into a low speed wind tunnel…  which I’m totally game to do if I can find a tunnel that will work with us on it.  I’ll keep looking.  In the meantime, I’ll be watching our mileage to see if I can notice any changes.  I’ll be honest though, our mileage varies wildly from 11 to 15 mpg depending on wind, hills, and a host of other factors I have no real way to compensate for.

So for now, we’re just enjoying the quiet and calling it a win.  Hopefully some wind-tunnel-owner will offer to help figure out the drag bit for us.

Cheers!