Back in 2008, I added a roof-mounted air deflector toward the rear of the roof on our Excursion to, hopefully, decrease aerodynamic drag and "bug splatter" on the front of our AF 32D. I purchased the "Aeroshield Wind Deflector" from Camping World:

http://www.campingworld.com/shopping...eflector/34579

Pros:

1) It seems to work as advertised. Based on thousands of miles of towing at about 68 - 70 mph, I would say that the airfoil increased our gas mileage by about 10%. So, instead of getting around 9.5 mpg, I appear to be consistently getting around 10.5 mpg. Financially, this means the air deflector will eventually pay off the $350 investment. Our recent 3600 mile trip was $90 cheaper due to the air deflector alone.

2) The truck seems to be able to hold speed better in a headwind towing condition as well.

3) The bug splatter population is definitely reduced. This is a big deal in the south central U.S.--we have a lot of big flying bugs!

4) It is adjustable. I set mine at about 60 degrees above horizontal when towing, and back down onto the roof when not.

Cons:

1) You have to come up with a good way to mount the air deflector, and this can be a challenge. I designed some alumimum brackets to fit into my existing roof rack rails. This eliminated using straps or other contraptions, but it was quite a bit of effort. It is also a pretty big deal to mount prior to a trip. For shorter vacation trips, I just leave the air deflector at home.

2) Because the air deflector reduces the pressure acting on the front of the trailer, it actually creates a turbulent bubble with a negative force acting on the window guard that our trailer has. The window guard will "hop" a little bit, working against the latches. On our trip to DisneyWorld last spring, one of the 2 latches came unscrewed, the window guard twisted, and then pulled the other latch out. The entire fiberglass window guard then flipped backwards to the roof top. The hinge was damaged, as well as most of the underlying aluminum frame. I was able to repair it satisfactorily, but I'm sure the air deflector contributed to this mishap.

3) Even with the air deflector all the way "down", it increases the height of the Excursion by another 6". This could be really bad if you forget and drive into a parking garage.

At the end of the day, I would probably buy this air deflector again. I like how it improves our mpg and performance. If you add a deflector, however, I recommend you double-check security of your window cover latches--if you have a front window on your travel trailer.

 

Good info, thanks Forest. Could you update the link?

 

Done. Did it...

 

Thanks for the info Forest. Yours is the only Ex I've ever seen with a deflector and it's great getting your feedback from using it. I'm looking into it, either one like yours or maybe fabricating a slightly longer/taller one in aluminum.

 

It's an interesting idea that I had not considered before seeing your installation. I have an Airstream which has all rounded corners and front. Everyone I talk with says that contributes to fuel economy as well so I'm not sure I could get as much as 10% increase (advertising says that the Airstream already gives up to 20% more efficient towing).

Airsteam use rubber toggles on the fornt window cover so they would have to be looked at carefully given your experience.

Thanks for sharing!

D

 

I too have used an air deflector wing for the last 2 years on my 7.3 '02 Excursion. I echo Forest's analysis and agree with his excellent assessment. I pull a 32 foot Outback travel trailer and it pulls like a dream. I have a 6 inch all spring Skyjacker lift, with Air Lift air bags in the rear, 37 inch Nitto tires, a weight distributing and sway control hitch, with a 120 hp DP Tuner. The wing provides stability, keeps the bugs off the front, and helps with milage. Thanks Forest.

 

What type/style/make/ air deflector do you use? Any pics of it? I'm trying to dig up as much info about these as possible before either buying/building one. By the way, that's a very wicked lookin ride you have there! Love the snorkle, if the truck ever actually gets too deep for it I think YOU might need your own snorkle too!

 

Would these wind deflectors add additional weight to your axles and tires? The faster you go, the more weight it generates.

Probably the amount is insignificant...?

 

I had gotten mine when I had my 'Burb. It definitely helped in stability. But yeah, it caused a negative airflow that sucked my LP tank cover right off on I-83. I didnt realize it until I got to the campground.
I did also have trouble rigging it up to the Ex. I need to figure out something better. I used mine on the Ex on our trip to Williamsburg and got about 9 mpg. Coming home with out it, was about 8 mpg.
Also agree on the parking garage thing...I encountered that one and had to quick jump out and take it off. Fortunately no one was waiting behind me.

 

The air deflector I purchased is rounded on the corners. I think you need to do that to minimize aero noise on whatever you build. A longer/taller one would be more effective as well. I can tell from the bug splat pattern that mine could be bigger. I'd say mine is about 18" tall if you stand it up straight. You could be very effective if you made one 36" tall and had it in a gentle arc (or at least a wide "V") about the vertical center. Keep in mind that you are trying to guide the air around the trailer and the Excursion roof-top is only about 60" wide--compared with 96" for most trailers. It is a 3 dimensional problem and you can only do so much without joining the trailer directly to the back of the truck with some sort of faring.

I estimate that there may be another 1 mpg (from aero effects) to wring out of my lash-up when towing at 70 mph. Before I try a bigger wing, I am going to look at the front bumper air dam on the Excursion. I think the bigger front air dams from 2008-2010 F-250s may fit on my front bumper. They extend about 6" below the bumper (instead of the 3" on mine). Blocking some of the air going underneath the Excursion would help as well. Pretty ugly under there from an aerodynamic drag perspective.

 

You may be right. It might not give much of a bump in fuel economy as you already have a pretty aerodynamic trailer. You can tell from looking at my rig, that it was not made to be low drag.

On the Airstream, I would think you could gain a little bit by considering some improvements on the awning arms (rounded fronts) and faring the a/c, if possible. You may gain much more by reducing air flow under the truck. As I mentioned, I think a bigger air dam on the Excursion would help.

 

Thank you, very helpful information. My trailer has no front window so that is not an issue.

Can you please give me some pictures and info on the Brackets you made. I am interested in putting one of these on my Excursion, but like you the only way I will do it is attached to the roof rack rails toward the rear of the truck.

Thanks so much.

 

Good info, can you please give me some Pictures and help regarding the brackets you made to attach it to the luggage rack frame rails please. I want to put one on my Excursion, but like you the only way I will do it is attached to the luggage rack rails near the rear of the truck.

thanks so much

 

Thanks for the good info.

Yikes sucking the Propane tank cover off, is scary, I would not have thought off that. What did you do? strap it down after that?

thanks

 

Great review! A fellow Sunline owner bought a wing about four years ago and I saw it in action at a Meet & Greet. He stuck a Sunline decal on his. He had gotten it for Christmas the year before, and this was June, so he didn't have much experience with it yet, but the concept was interesting. I really appreciate the real world data here. I don't tow mine enough to justify one, but I like the concept.