Cargo Trailer Aerodynamics

[ITTOG]

Anyone know anything about the referenced subject? I have a v nose 6 x 12 and was wondering if this is better than a flat front but with it starting about 4 feet high and slowly increasing to 6 feet (similar to tear drops that aren't curved in the front). This height is floor to roof. The overall height is about 7' 9".

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[dreadlocks]

I think that would depend on if the trailer is wider than the tow vehicle.. if not then it would draft alot better behind the TV w/the leading edge lower than the TV roofline.. If the trailer was wider than the tow vehicle, a V-Nose would probably be the better of the two.

Aero is nice, but really only at interstate speeds.. I'd venture that most are like my self and attempt stay off the interstates intentionally, unless I really need to cover alot of ground quickly aero is not that big of a concern, especially as your setup gets heavier/bigger and driving it full out on interstates for long distances gets requires exponentially more fuel/money.

I've towed alot with cars because a little cargo trailer drafting behind the vehicle got significantly better fuel economy than strapping on a roof rocket or something for more cargo room.. but that was almost strictly an interstate setup, I had to cover a few thousand miles in very little time regularly.

 

[Kent Wold]

I'm no expert but if you look at a raindrop you start to see how natural aerodynamics work. Blunt end leads with the sharp end as the tail.
A box fish is considered one of the most aerodynamic natural shapes. You'll have to Google it to see.
The shape you are describing is sort if similar to a tear drop which resembles a raindrop as well and is a very aerodynamic shape long term.
Counterintuitively a pick up truck with an open bed actually has better aerodynamics with the tailgate up than down! What happens is that a bubble of air develops behind the cab in the bed of the truck effectively making the truck bed similar to a fast back coupe, think Bullitt Mustang or Shelby Cobra.
Not sure if this helps but it's a beginning I hope.

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[ITTOG]

Thanks for the comments. Good thought on the width. The attached pictures shows the vertical profiles. The truck is 6' 6" tall and trailer height was previously mentioned. I believe only the tires and fenders on the trailer are wider than the truck. Maybe I need the v and a dropped front.

Since I live in Houston I do a lot of highway miles in order to get to nice places to overland. This the reason for my concern.

I can't do a tear drop or smaller trailer because it must fit my four wheeler which is 50 inches high do to bins on it. I do a lot of all day four wheeler trips with family.

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[Kent Wold]

Looking at the pictures you may actually be getting more drag from the undercarriages than from the bodywork of the two vehicles.

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[Deleted member 9101]

Yeah... the back of the trailer creates a lot if drag. Look at the aerodynamic aids they use in the rear if semi trailers.

 

[dreadlocks]

Could try something like this: http://www.airtab.com/

 

[Teardropper]

The flat back of trailers suck. Literally.

I don't remember ever seeing those air tabs on a semi-trailer except in their adds. If they worked, they'd be on every trailer on the road. Fuel eats profit, obviously.

The subject has been studied: https://truckfreighter.com/improve-semi-tractor-aerodynamics/

I'm a glass-half-full guy but a realist on this subject.

T

 

[JaSAn]

The flat back of trailers suck. Literally.
I don't remember ever seeing those air tabs on a semi-trailer except in their adds. If they worked, they'd be on every trailer on the road. Fuel eats profit, obviously.

One of my neighbors is a manager for a FedEx hub. He has them on all his intercity trucks. He says they save ~ 12% on fuel. I've thought about doing something similar to my camper, just for giggles.

https://slate.com/culture/2013/04/truck-panels-what-do-they-do-explained-photos.html

 

[Louisd75]

One of my neighbors is a manager for a FedEx hub. He has them on all his intercity trucks. He says they save ~ 12% on fuel. I've thought about doing something similar to my camper, just for giggles.

https://slate.com/culture/2013/04/truck-panels-what-do-they-do-explained-photos.html

Trailer tails do work and it probably would not be difficult to make your own. Other things to think about is that it's all cumulative, some things are easier than others.

Trailer height: ideally you can match the trailer roofline to the TV roofline. Easier with an SUV, with a truck you'll likely want a canopy. Along these lines, avoid putting things on the roof if at all possible.
Trailer width: keep it narrow. Ideally no wider than your TV
Trailer length: avoid long tongue lengths if possible. Keeping the trailer body close to the TV minimizes the gap and reduces the the size of the pocket that turbulent air can get stuck in.

 

[Teardropper]

One of my neighbors is a manager for a FedEx hub. He has them on all his intercity trucks. He says they save ~ 12% on fuel. I've thought about doing something similar to my camper, just for giggles.

https://slate.com/culture/2013/04/truck-panels-what-do-they-do-explained-photos.html

I'm sure the trailer tails work because they are commonly seen. I hope your neighbor is right about the 12% savings but it begs the question: Why aren't they popular? Trucking companies would pounce on a 12% fuel burn.

But grab some and let us know.

T

 

[ITTOG]

Thanks everyone for the comments. I have been thinking about modifying my trailer due to all the wind drag but may try these out first. If I do try them out I will let you know how it goes.

Given I will not put any of these on my truck I still have the issue of the wind resistance forward slash drag in the front of the trailer. So maybe I need to modify it there and then just add the tails on the back?

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[BritKLR]

Larger and squarer kills mpg. I went from a 5x8 trailer that tucked nicely behind our Tiger and regularly got 12-13 mpg across the country. Upsized to a 6x10 taller/wider trailer and immediately dropped to 9-11 mpg (same cargo weight). Like dragging a wind sail....

 

[KIRBY]

"Trailer length: avoid long tongue lengths if possible. Keeping the trailer body close to the TV minimizes the gap and reduces the the size of the pocket that turbulent air can get stuck in ."
I'm planing to put an x-Cargo 20 cartop carrier on an Ironton 40x48 trailer. I want the tongue as short as possible while not crunching against the rear of the car in a full lock forward turn. Is there a formula for determining how short the tongue can be?

 

[Brianj5600]

Kirby, you may find that having the trailer too close hurts aero. Think of the X cargo as a tail cone. If the frontal area of the trailer is much smaller than the rear surface of the TV, having the trailer as close as possible may eliminate the "cone effect" of the X cargo. If the vacuum behind the TV is closing at about the biggest cross section of the trailer I believe that would reduce drag the most. All this is speed dependent of course, but could be validated with tufts of yarn and a GoPro.