For all the "Flat Nosers"

[flboy]

So you went from 19MPG with no towing and shot to 24Mpg while towing? If I am understanding this right, I find it hard to believe regardless of the height? I'd expect breakeven at best understanding your trailer is very small and likewise very light.

Assuming true, must be more than your shifting involved to get 5 mpg gain, else they'd just program that in and sell alot more trucks and I'd drive it like that every day. If it was all drag, you would think all vehicles would have vortex generators built in to help meet the CAFE standards?

Not saying I do not believe you.. but has to be more to the story. I'd like to understand that and bottle it. Maybe recently fix somerhing on your truck and it was always suppose to get 24mpg? Running no ethanol gas now?


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[McDave]

In two years of owning my Tacoma, the best MPGs I ever recorded (and I record 100% of my tanks) was 19 MPG, and that was a highway trip from Colorado to Albuquerque, NM.

Since hitching up my CTC and hauling it on a couple road trips, my highest recorded MPG, which was while hauling, has shot up to 24 MPG.

So, I don't get what you fellas are going on about. I saw a huge improvement while towing mine and all I did was cut 8" out of the height of the roof on the trailer.

(as a disclaimer, I'm fairly certain my improvements are because my truck doesn't have tow/haul mode to keep it out of overdrive so I manually shift my automatic while towing).

I'm not sure the Harley will fit if I take 8" off the height. My wife will, but I'd have to crawl in there. But that is interesting info. Gotta be drag related somehow.

McDave

[aggie79]

I guess one could arch the top and add these flow devices to decrease the rear "suction" drag:

[McDave]

Yes, yes! This is exactly the kind of stuff we can learn from and copy, imitate, steal etc. I'd take 10% to start with.
Thanks! You wouldn't have a link by chance?

McDave

PS. That is one biga** teardrop!

[aggie79]

Those were pictures from their website that I "captured" several years ago. Here is a current link: http://www.donbur.co.uk/gb-en/products/aerodynamic-teardrop-trailer.php.

[rebar]

I bet if you ran a V nose backwards, you would see a improvement. But how to get the ramp door to clear the tongue?

[bdosborn]

In two years of owning my Tacoma, the best MPGs I ever recorded (and I record 100% of my tanks) was 19 MPG, and that was a highway trip from Colorado to Albuquerque, NM.

Since hitching up my CTC and hauling it on a couple road trips, my highest recorded MPG, which was while hauling, has shot up to 24 MPG.

<snip>

I have a Tacoma and I've tracked the mileage for almost 50K, basically from when it was brand new. My best mileage was 22mpg and my average according to Fuelly is this:



My TTT is fairly short, and narrow compared to a a lot cargo trailers and my mileage goes *DOWN* to 14 mpg when I tow, not exceeding 65mph.



I need to know what kind of magic trailer you have that increases mileage as I'm going to buy one.

Bruce

[fourbtgait]

So I don't have a ton of experience towing and haven't started my CTC build yet, but I am the kind of person that researches for literal days, and as a result bought a flat nose trailer after reading many forum posts and other internet commentary from old curmudgeons with decades of road experience.

So heres what I found, summarized (hopefully) with simple explanations.

- Those air tabs DO make a difference, but the worth is more in preventing trailer sway and feeling more stable by breaking the suction at the back. Don't expect more than 1 MPG difference, do expect to stop feeling the sway when a semi passes.

- V-noses don't actually help aerodynamics, though many swear they do. If your vehicle was pushing the V-nose, it would help, but the air is already broken by the front of your vehicle. What happens instead is that there's more surface area on a V-nose for wind to hit both those sides, and add to sway. However, this is a difference you could see in a wind tunnel. The average person could pull both and probably not notice. If there is a MPG difference between the two it couldn't be more than 1-1.5 MPG.

- Those nose cones DO help, but you're probably better off with a DIY solution. 1-2 MPG difference but commercially they're around $700, so the math doesn't work out well.

Other things to consider doing:
- Insulate the underside of your trailer to the bottom of the supports. Air moves down there too, so the less pockets for air the better.

- Get the top of your vehicle level with the trailer. Personally, I'm going to add a rooftop carrier to my SUV because right now the trailer sits a good foot higher, and thats a big sail.

- Distribute the weight inside evenly. Thats just trailer 101.

So if you do all the things I wouldn't expect more than a 3-4 MPG increase, and that will vary per driver and vehicle. Doing all those WILL do a lot for trailer sway and safety, which arguable is worth way more than an extra stop at the pump.

Hope this helps, but take it all with a grain of salt because its just research.

[/quote]


Pretty much sums it up.
The nose cone needs to be a sphere like the commercially produced. Build a mold, make one out of fibergrass, attach to trailer.
Put the angle flaps on the rear of the trailer like tractor trailers use.
Soften the wheel wells and include covers over the wheels to enhance air flow.
I gained 1 mpg by putting kayaks on roof of tv changing the air flow.

Go to the ecomodder forum. Lots of discussions about trailer design, air coefficients, etc. https://ecomodder.com/forum
It was interesting to learn that the flat back of a cargo trailer is more efficient than the teardrop trailer. But can still be improved.

[ris]

We use the Reese Steadi-Flex Weight Distribution System w/Sway Control. 6K GTW, 600TW model
Trailer weighs close to 5900 lb loaded and tongue weight is 590 lbs
At 70 mph we do not notice suction passing or being passed by large trucks. If there is any pushing or suction it is hardly noticeable. We do have a heavy duty aluminum topper on the truck and our trailer inside height is 6 ft. 6 inches. This might help with the sway problem. But if Don notices a big improvement in handling with the vortex generators we will put them on.
Richard

[flboy]

We use the Reese Steadi-Flex Weight Distribution System w/Sway Control. 6K GTW, 600TW model
Trailer weighs close to 5900 lb loaded and tongue weight is 590 lbs
At 70 mph we do not notice suction passing or being passed by large trucks. If there is any pushing or suction it is hardly noticeable. We do have a heavy duty aluminum topper on the truck and our trailer inside height is 6 ft. 6 inches. This might help with the sway problem. But if Don notices a big improvement in handling with the vortex generators we will put them on.
Richard

I will let you know how it goes. My WD Hitch and Sway bars did help with the sway created by the suction since it typically comes from one side first as they pass... but I still feel the suction and draw. The difference now is that I do not have to white knuckle it and have the sway to overcome as they pass. I am expecting the Vortex Generators to eliminate the suction part and likewise help with cross winds .

Between the WD Hitch, Sway Bars, Air Lift suspension and Vortex generators... I am expecting one smooth tow in most all conditions. It does eliminate a lot of the stress and fatigue associated with pulling a trailer all day at highway speeds. If you have done that alot... you know what I mean.

Now if it eliminates the suction, improves stability, and saves me some gas... I will be very happy camper... literally!

[rebar]

What about the trailing edge gizmo you sometimes see on semi trailers? If built right, could serve as a awning roof when the ramp is leveled to be a deck..

[McDave]

So, it would seem that the "gap" between the TV and Trailer is responsible for about 25% of the drag of the combo. No surprise really. with both high and low pressure, trailing and leading faces and different body width/height. This being the case, possibly this is the area that would yield the most mileage gain. Also no surprise, this would be the most complicated because of the articulation and vehicle differences. Here is an ingenious solution for big rigs that could be possibly scaled to our trailers.

http://www.donbur.co.uk/gb-en/docs/1503 ... ochure.pdf

Put on your thinking caps and have some cold barley thinking fluid and lets see how do-able this could be. For pickups lets assume there is a topper, or a van as the tow vehicle.

McDave

[tony.latham]

So, it would seem that the "gap" between the TV and Trailer is responsible for about 25% of the drag of the combo.

If you look at this photo, I think there should be dust boiling out between my Tacoma and the tear if that were the case.



But it may be the fact I've got a camper on the truck's bed.



Tony

[McDave]

Yes Tony, the topper is helpful to pickup aerodynamics all around, but also in your case the tow vehicle is taller than the trailer roof and wider as well. There is still drag as a result of the gap but the dust is kicked up primarily by the tires. The real effects of aerodynamic drag are mostly generated at highway speeds. At lower speed you are still contending with weight and contact friction more than wind resistance and low pressure suction on the flat vertical surfaces. The teardrop shape was designed defeat that from the get go. Cargo trailers are big square parachutes being pulled by shoe boxes.

McDave

[tony.latham]

Yes Tony, the topper is helpful to pickup aerodynamics all around, but also in your case the tow vehicle is taller than the trailer roof and wider as well. There is still drag as a result of the gap but the dust is kicked up primarily by the tires. The real effects of aerodynamic drag are mostly generated at highway speeds. At lower speed you are still contending with weight and contact friction more than wind resistance and low pressure suction on the flat vertical surfaces. The teardrop shape was designed defeat that from the get go. Cargo trailers are big square parachutes being pulled by shoe boxes.

McDave

I noticed a significant difference when I went from a four-wide to a five.

If I had any brains, my next build would be a raindrop.

T


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