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Open Roads Forum  >  Travel Trailers

 > What is the REAL fuel economy savings with an aero nose TT?

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aftermath

Washington State

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Posted: 11/10/11 01:20pm Link  |  Print  |  Notify Moderator

I had a white box trailer that I sold and purchased an Airstream. Got the same mileage with both but......the box was a 21 ft hybrid that went down the road at about 3900 lbs. The Airstream is 25 ft with a GVW of just over 7000 lbs.

Aerodynamics do make a difference but not as large as many would claim. As someone has already said, the shape of the front and the back will come into play, that and how low it is and whether or not the belly is wrapped. I am sure there are lots of other factors too.

Unless I was planning on doing a lot of driving, I would not waste much time worrying over this. Get what you want at a price you can live with and don't look back.


2008 Toyota Tundra, Double Cab, 5.7L V8
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copeland343

Central Louisiana

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Posted: 11/10/11 04:11pm Link  |  Print  |  Notify Moderator

IMO the front is not the problem it is the vacuum off the square rear of the trailer that is the problem. The front of the towing combo is the truck pulling the trailer, the truck is what deflects air onto or around the trailer that makes a lot of the differences in towing. Get rid of the vacuum at the rear and that is were you can pick up better MPG. That is just my opinion.

chevor

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Posted: 11/10/11 04:44pm Link  |  Print  |  Notify Moderator

Would you raise the tongue of the trailer higher (lowering the roof at the rear to reduce this vacuum?


2010 Gmc 2500 CCSB Duramax,1ton rear springs, 90g box tank, 0ver 585,000 Odometer miles, 20k Curt fifth wheel, 18k Curt rear mount hitch,Bridgestone Duravis R500s Rancho 9000 Shocks, Firestone Airbags, bypass oil filter
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Ron Gratz

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Posted: 11/10/11 04:58pm Link  |  Print  |  Notify Moderator

Here is a good article which talks about Tractor-Trailer Aerodynamics.

Much of it aslo applies to TV/TT aerodynamics.

Ron

LarryJM

NoVa

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Posted: 11/10/11 05:33pm Link  |  Print  |  Notify Moderator

Bucky Badger wrote:

93Cobra2771 wrote:

I currently have the TT in my sig - standard non aero nose, your typical brick making it way through the air.

I've noticed a trend of newer TT with severely rounded noses, for example the Dutchmen 263RLSL



(link if my code doesn't work)
http://cars.adloe.com/Dutchmen-Kodiak-263RLSL-2012_abnkkkenkiadominabia.html

Has anyone noticed real MPG gains when changing from similar weight square nose vs the new style aero nose? Or do we just take it for granted that the new style nose is indeed more aero which leads to true mpg gains?

Have there been any true data on this from manufacturers or other sources?


...if there is it's probably minamal


I agree and I have one of the more DRAMATIC supposed aeordynamic fronts ... see pic below




It's hard to compare, but with the same TV and a more traditional front with both being only 1,000 lbs apart and the older one being almost 12" higher in the back with an open undercarriage vice the enclosed belly with the newer one I have seen zero difference in mpg measure over the exact same route of 800 miles one way.

Older trailer ...



IMO it's about just the height and turbulence of the wheels, etc. and the TV that has more to do with the mpg you see than any fancy front design of the TT.

Below is a full profile pic of our current trailer showing the heights in relation to our van ...



Larry

* This post was edited 11/10/11 05:58pm by LarryJM *


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LarryJM

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Posted: 11/10/11 05:55pm Link  |  Print  |  Notify Moderator

copeland343 wrote:

IMO the front is not the problem it is the vacuum off the square rear of the trailer that is the problem. The front of the towing combo is the truck pulling the trailer, the truck is what deflects air onto or around the trailer that makes a lot of the differences in towing. Get rid of the vacuum at the rear and that is were you can pick up better MPG. That is just my opinion.


That seems logical but is not what I saw with the two trailers I towed over the exact same route with the same vehicle at the same speed as I showed in the pics in my prior post.

The only difference I saw as with the older trailer with the TV on CC it would drop out of cruise on like three or four places and with the newer trailer with all the supposed areodynamics that did not happen, but that is really a very minor difference over 800 miles.

Larry

Turtle n Peeps

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Posted: 11/10/11 05:58pm Link  |  Print  |  Notify Moderator

t-smith wrote:

The problem / solution isn't in the front of the TT. It is in the back.

The trailers with the biggest MPG improvement are those that have a rounded or tear-drop back.

What we don't see with our bricks in the back, is the turbulent air that is swirling directly behind our TT, causing drag. It's not the pulling the front through the air, it's the dragging a vortex behind our TT.

edit: in the NASA link that the post above mine has - check out the tabs on the rear that they were using to manipulate the air behind the vehicle.

What he said. Nobody thinks about the huge drag in the back.


~ Too many freaks & not enough circuses ~


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jmtandem

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Posted: 11/10/11 06:54pm Link  |  Print  |  Notify Moderator

Quote:


I've always wanted to try AirTabs. They are designed to create controlled vortexes to help reduce drag. Anyone use them? I imagine they could help a little, but I can't see them making my flat backed more aerodynamic to the point of saving 1-2mpg



t-smith,

There was quite a bit of discussion and testing of the air tabs about ten years ago in the Turbo Diesel Register (a publication mostly devoted to Dodge diesel trucks). If I recall the bigger issue with the tabs was how they worked to effectuate the air leaving the square back trailer to keep it both dust free and to reduce sway. The surprising benefit was to reduce sway and according to the author of the articles they worked in a noticable way. I am not sure how much they cost nor how many are needed to see any result but am sure that they need to be placed about every foot or so to work and they were not placed on the back of the trailer but near the rear of the trailers sides and perhaps along the roof at the back.


'05 Dodge Cummins 4x4 dually 3500 white quadcab auto long bed.
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jmtandem

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Posted: 11/10/11 07:03pm Link  |  Print  |  Notify Moderator

Quote:

Minimal at best. Remember that with a V nose you will ONLY get full effect when wind is directly ahead and wind coming from just OFF of the nose will actually hit a flatter front than it would on a standard front trailer. With the traditional trailer the wind would be striking the trailer front at ABOUT the same angle as a V nose with head on winds.



Skip,

You might be correct about V nose trailers. However, the nose in the OP's pic is the traditional front with some aerodynamics that tend to pass the air over the top of the trailer not to the left or right. My opinion of a V nose trailer is that if the wind is blowing at all, there will always be wind hitting a frontal area unless all the wind is from the rear. The trailer is a gimmick and probably not effective especially when considering the lost and awkward inside nose space.

The general rule of thumb that is not totally accurate but probably close enough is that it takes four times the power to double the speeds. Traveling 50 mph requires a certain amount of power and fuel; traveling 100 mph about four times that. However, what is important is that at 100 mph aerodynamics are far more important than at 50 mph. Somebody suggested wind tunnel testing and adding the V nose trailer to that mix would be very interesting. Maybe the V nose should be followed by a V rear to get some advantage from the vacuum that is formed.

Gale Hawkins

Murray, KY

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Posted: 11/10/11 09:03pm Link  |  Print  |  Notify Moderator

Bucky Badger wrote:

93Cobra2771 wrote:

I currently have the TT in my sig - standard non aero nose, your typical brick making it way through the air.

I've noticed a trend of newer TT with severely rounded noses, for example the Dutchmen 263RLSL



(link if my code doesn't work)
http://cars.adloe.com/Dutchmen-Kodiak-263RLSL-2012_abnkkkenkiadominabia.html

Has anyone noticed real MPG gains when changing from similar weight square nose vs the new style aero nose? Or do we just take it for granted that the new style nose is indeed more aero which leads to true mpg gains?

Have there been any true data on this from manufacturers or other sources?


...if there is it's probably minamal


2x but it may help sales. If they helped I would think the companies would develop data to support that. At one time this style was common in Class A motor homes but since it did not work I guess was the reason they dropped the style.

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