Wind deflector like the big rigs - Montana Owners Club

RADHAZJOE · 10-02-2005, 10:37 AM

I have asked many 5er pullers with the wind deflectors on the cab of the tv. 3 to one they say gas milaeage did not improve but it did keep the front of monty cleaner. I would like a few mopre opinions before I spend the money.

Also, some tell me taking the tailgate off the truck does increase diesel mileage, like substituting a louvered tail gate or a net. Any opinions on that?

CountryGuy · 10-02-2005, 12:23 PM

The front cap of our Montana's was designed to be aerodynamic. Not sure what the affect of one of the wind deflectors would be??????????????

Dave e Victoria · 10-02-2005, 01:17 PM

I can believe that the wind deflectors would help the bug situation a little much the same as one at the front of your hood helps keep some of them off your windshield. As far as improving mileage, the only help is to somehow reduce the airpressure on the front of the trailer. As Al said, the Montanas are already designed to be aerdynamic.

A deflector on top of the truck might actually hurt mileage by directing a laminar flow of air directly at the middle of the front of the coach. A much better approach would be to break up the laminar flow as it crosses over the top of the truck. In the aircraft industry, this is accomplished with "vortex generators". These are little vanes about an inch or so high. They stand vertically and are placed a few inches apart. They are slanted to the right or left in a staggered pattern. They create turbulence that disturbes the laminar flow of air.

I thought about experimenting with such an arrangement but was discouraged because it looks like a trap for depries and would probably get tangled in the car was brush. Moreover, the real effect of these schemes is typically very difficult to evaluate in the real world. You might, for instance, get a 2 or 3 % improvement in overall drag. And, drag is only one of the elements of energy use. Figuring a 10mpg rig, we would be talking about a quarter of a mile per gallon difference at best. Definitely hard to prove

Some might try to dispell this arguement by pointing to the large deflectors on the top of Semi tractors. The devil is in the details, as they say. In the case of eighteen wheelers the deflectors are very, very large and are also relatively close to the trailer. The idea here is to help the laminar slip stream get up over the top and around the trailer. Close observation will also reveal that several companies have streamlined the top of the front of trailer to achieve a result more like Montana has attempted.

azstar · 10-02-2005, 05:14 PM

Dave's right on the money. It's a difficult problem to deal with. A couple of TT's ago, I tried one. We had a cap on the Truck on which I mounted it. It had an adverse affect. It actually created a vaccum between the TT and the TV, which was strong enough to suck the Propane Tank Cover up and over the top of our TT. The last time I saw it, it was bouncing down CA 395.

I decided it was too much trouble to continue to play with.

Happy Camping

sreigle · 10-03-2005, 12:17 PM

I have no firsthand experience but have talked with several with the wing. A couple said they thought mileage improved but were not sure. Some said mileage actually went down. Most said they couldn't tell a difference. I read somewhere it can help if you have exactly the correct angle and that differs for each tv/trailer combination. If you get the wrong angle it makes things worse is what I was told. Again, no firsthand knowledge.

I saw a test somewhere recently where they showed that driving with tailgate down actually decreased mileage. I don't know the effect on mileage of a FW tailgate up compared to a stock gate.

Broome101 · 10-04-2005, 01:42 AM

Would not have one besides it would not fit into my garage with one on anyway. My brother in law has one and swears by it, he pulls 30 foot car hauler said it took some sway out of it when big rigs went by. Who knows but I would not have one of those big things sticky out like sore thumb, but that's just me.

Montana_4391 · 10-05-2005, 11:55 AM

RADHAZJOE,
I asked the same question about the spoiler and the replies I got were basically don't waste your money. A good waxing on the front of the Monty will allow bugs to come off easier and it's a lot less weight than the spoiler. Fuel mileage won't be improved much when you factor in the extra weight of the spoiler and it also sets you up for more crosswind problems.

As for the tailgate issue, you can save fuel by removing the tailgate in two ways - first off the aredynamics of removing the gate improving airflow, plus it's that much less weight to carry...unless you add the spoiler and counteract everything! LOL!

richfaa · 10-05-2005, 03:42 PM

Spoke to a Rv hauler in Elkhart, Ind while on the Factory tour yesterday. He was hauling a Montana and had a deflector on roof of his TV. Asked him if it worked.He said he had over 200,000 miles logged on this TV and said that the defelecto gave him 30% improvement in MPG...It was a turbo Wing cost was @ 900.00. I got the phone number and web site..
www.wingmaster.com.. I figure he should know

tollmann · 10-05-2005, 05:22 PM

We have a large deflector on the roof of our TV. It folds flat to the roof when not in use. The only time that we set it up is when we will be pulling during the summer in a buggy area. I have seen NO difference in MPG either plus or minus. We run a 5th wheel tailgate with the round bars to allow air to flow thru it. The biggest benefit is the reduction of the air turbulance in the bed of the truck. With a stock gate the air whips around back there strong enough to lift a cooler (empty) right out of the truck. I have also seen people loose gas cans from back there. We still tie our coolers down but once I forgot to and there was no harm done. Bottom line is I would buy the tailgate again but I have my doubts about the deflector.

Dave e Victoria · 10-06-2005, 05:35 AM

Rich,
I think I would wear some pretty high boots in the vicinity of that RV Hauler. Even the manufacturer, who has some pretty outrageous claims, doesn't even suggest that kind of improvement. I think his 30% fuel mileage improvement is off by a factor of 10 or more.

richfaa · 10-06-2005, 02:54 PM

Yes //I looked at the site and they say it reduces turbulence by 30% and maybe 10% on fuel...maybe....think he got his numbers mixed up. IF it saved 10% on fuel, if you were averaging 10MPg that would be 1 MPG better and at a cost of $900.00 you would need to drive a lot of miles to break even????

dersequim · 10-26-2005, 01:36 PM

Bill Fallow, RIP, who used to write for Trailerlife did an article on improvements to your TV. He listed 100. The Deflector was the least cost effective IMPROVEMENT?, in his opinion, listed. He felt that most would NEVER pull enough miles to get their moneys worth.

old turbo · 10-29-2005, 01:59 AM

I would not spend all this money on deflectors. Put your money in larger exhaust systems,air intake systems,injectors,and anything else on the engine system that can improve milage. Keep your eye on the mpg part of your trucks computer system and adjust your speed to the best mpg. Keep your tires at the right air pressure for towing. Get a complete alignment done on the truck,both front and rear.Check your rv tires for air pressure.Is your rv pulling straight? Dont take for granted that your rv is pulling like an arrow,remember these things are massed produced,I could put more her but I think I have already spent your $900 with ease.

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