Minimizing Aerodynamic Effect for Trailer Towing

[freebeard]

unheardofinstruments -- To quote the Beatles — We'd all love to see the plan.

bluebunny --

( I want to post a "poor man's canard" which mimics a blown-slot airfoil high lift device for maybe some of you folks to test? a cheap and easy and robust design to build for a few dollars around a bluff body...)

Do you want to pursue it here , or there?

[bluebunny]

Originally Posted by freebeard

unheardofinstruments -- To quote the Beatles — We'd all love to see the plan.

bluebunny --



Do you want to pursue it here , or there?

There! Thank you! I do not wish to highjack any threads...not sure of protocol...OK?

[Dave's Civic Duty]

Originally Posted by bluebunny

Hi Dave,
These are rather small, so if you have a large trailer that really extends out in the air stream, Larger may be better. In any case, they will be subject to high loads; much higher than say a trunk wing. They must be sturdily constructed and securely mounted.

What are you towing behind what sized vehicle?

6x12 enclosed trailer, 14' 16' 18' Campers & a 24 ft pontoon boat w a 28' trailer.

Dave

[freebeard]

...not sure of protocol...OK?

Just click the blue button.

[ByDesign]

I really appreciate all that everyone has posted here. Great thoughts and education!

Here's a wrap-up for the year. I'm done with the expos for a few months, so thought I'd post a synopsis.

The truck usually gets something between 14.7 and 15.1 MPG on the highway. Stinks, but gets me there -- and for that matter -- anywhere I've ever wanted to go in sun, rain, deep snow, mud, ice, wind, sand, back hills, high-clearance washouts, high mountains, 4-wheel-drive trails, etc..

That being said I've used 14.8 MPG as the baseline for the truck, and 12.6 MPG as the baseline for comparison with the trailer (pulling the trailer without modification -- Trip #1). 12.6 MPG (or minus 2.2 MPG) is a 15% hit for pulling the trailer. With the gap filler, 13.3 MPG, or minus 1.5 MPG is a 9% drop from normal. That means, having the gap filled yields a 5% improvement (roughly, for these simple one-off tests).

Slowing down 10 or so mph yielded about the same savings as adding the gap filler. Again, keep in mind that these are one-off tests with uncontrolled variables (like wind), so don't take this too deep. A good portion of the slower test improvement could just be staying out of the enrichment scheduling on the engine map. Interesting, none the less.

In dollars and cents, that means, for one of my expo trips (~200 miles give or take), the savings with the gap filler or the slower speed is less than 1 gallon of gas. 3 or 4 times a month that doesn't pay for much time or material in mods -- it doesn't even pay for my time to go a little slower! -- which is actually a pretty depressing thought.

More trips with variations like hitch height and speed have yielded basically the same results as above. The best econ achieved was 13.8 MPG for a 210 mile trip on snow and ice so the speeds were low, but rolling resistance higher. So many factors, most of which are not controllable.

It might seem a little silly, but I love the learning, even if the results are hard to distinguish sometimes. Thanks for all the comments and thoughts. I've got some time now and loads of ideas (thanks to you), so we'll see what comes in the spring.

[rumdog]

Quote
In dollars and cents, that means, for one of my expo trips (~200 miles give or take), the savings with the gap filler or the slower speed is less than 1 gallon of gas.*

Cheap gas seems good, but as prices go up so will returns from aero mods.
i commend you on your gap filler, and it showed positive results. Just imagine an optimised setup, with other mods helping.
I have a similar truck and trailer setup - old gmc sierra pulling 6x12 single axle. Check it out http://ecomodder.com/forum/showthrea...p-30843-3.html
aerostealth has done some pretty cool work on aeromods for pulling trailers