Breaking Wind

[rick danger]

Anyone ever experiment with any aerodynamic products? Just curious if anything could make a noticeable improvement in mileage. Is an enclosed underbelly an aerodynamic feature? Or just for cold weather/insulating? I wonder if there is anything available for tt's like what I've seen on the back of tractor-trailers lately.http://www.iowa80.com/DirectionsWEB/...hp?catid=WINGS http://fleetowner.com/site-files/fle...11/01/atd3.jpg

[norty1]

I think it is multi function. I like that the underbelly is protected from road grime. It also provides a baffle to hold heat near the enclosed thanks and lines, even though not air tight it does keep the area from freezing if the furnace is running.

[Panhead]

From the title of your thread I thought this was going to be a whole different conversation.

[Locky66]

I was a little nervous to click on this post.

[kvangil]

Originally Posted by Panhead

From the title of your thread I thought this was going to be a whole different conversation.

LOL. Same here.

[Wrascal]

Back about the late 80's my father in law pulled a 5th and used something similar to what you see on semi's, a large wind deflector. When not needed it folded down - blocking the rear window view. Standing upright it looked good; I don't know if it really did much towards improving the MPG, its advertised purpose.


Now please excuse me, I feel the wind.

[rick danger]

I thought the thread title might get a few more looks....A few laughs and maybe learn something in the bargain....I was actually noticing some trailers with what seemed a more aerodynamic nose than the Octane. A nice rounded fiberglass cap on front. I wish the Octane had that. The one link I put (first one) had a pickup truck wing halfway down the page. Maybe like the one Wrascal was describing. I wonder if the trailer front needs to be a certain distance from it to be effective. An instance where a 6' bed would be better. Mines 8'

[Camper_bob]

I have to wonder if something like this would be worth it to the average RVer. You might see a fraction of a mile difference. This wouldn't mean much to someone who tows 2-5K miles per year. However, on a big rig that goes hundreds of thousands of miles, a little difference translates to big money. The payback period would be truncated significantly.

Then again, I posed the question a while back because of something I saw in an RV park, and the consensus was that it wasn't worth it. I was intrigued by the idea because the front of my trailer is VERY flat and VERY vertical. I was thinking if I could sling the air up over the top of the tall vertical surface, it might make some significant difference...

[milw156]

I would be curious to know those Air Fairings work as well for kicking the air upwards by the time the trailer hits it.

[spoon059]

It seems to me that a truck with a cap on it or an SUV would get better mileage simply because air doesn't go over the cab, then down behind the truck and slam into the front of the camper. It SEEMS that having the air slam into the front of the truck and front of the trailer would result in more resistance... therefore having it only slam into one would create less resistance.


But what do I know...


I'm also the guy that wonders why long haul buses and Class A campers have such a flat front. Seems awful inefficient.

[herewego]

I think Myth busters did a show on this ?
send a email mythbusters@m5industries.com

[Panhead]

I've seen these out there and seems like a much less intrusive system that aparently works. Looks much better than hanging that big boxy trailer tail off the back of the unit.

http://www.airtab.com/

[Seann45]

Air wings.. yes they work HOWEVER if you leave them up when not towing they cost you mpg's. Airtabs.. if those really worked you would see a lot more of them on semi's. Enclosed underbelly yes it does work a little.. it smooth's out the air flow under the rig, now how much it really helps is another question...

[TeamFoxy]

I think the #1 factor is frontal area. Wind resistance increases with the square of the speed so anything you can do to reduce area and speed will decrease resistance. A flat front is has greater resistance than one with an angle to it because the air passes around rather than being pushed.
If you watch auto racing, you will often see cars drafting one another. The pair can go faster than either could go by themselves. It follows then that anything you can do to make the wind see one longer continuous vehicle rather than separate truck and trailer will be better.

If you tow your trailer 1000 miles a year, a 1% increase if fuel efficiency might save you $3 or $4. To commercial trucker driving several hundred thousand miles a year even a 1% increase if fuel efficiency is worth having.

[Camper_bob]

Originally Posted by TeamFoxy

If you tow your trailer 1000 miles a year, a 1% increase if fuel efficiency might save you $3 or $4. To commercial trucker driving several hundred thousand miles a year even a 1% increase if fuel efficiency is worth having.

My thoughts exactly!

[oldmanAZ]

MONTHS ago on another site I stumbled upon a similar topic. Someone there had run computer simulations using a very sophisticated software program to model the air flow and determine the drag etc. The software showed animations of the path of the air and relative air velocities.

They modeled various sizes, angles, and fore and aft positions of flat 'wings' (no 'V' shape wings) to deflect the air up and over a trailer being towed by either a van or a pickup truck with a camper shell. As I recall, they had around 4 to 6 different simulations over a period of several days.

Every time a simulation was posted, there would be requests that said, "Thank you for that, but next time could you try ..." because someone wanted a configuration tested that would be more like the one they had or the one they were thinking about buying. One poster said he KNEW his wing it helped his MPG because he had fewer bugs to clean off his trailer...

Anyway, my take away viewing the simulations... IT DEPENDS. There are so many variables involved that a design that worked very well at 45mph might be little help at 65mph, what might work well on a calm day, might not help in a cross wind, what might help with a very boxy trailer might not help a trailer with a rounded nose, etc., etc., etc.

I have no idea of the software used or the processing power required to run it. The poster abruptly stopped posting the simulations. My guess was that his employer found out about it.

I looked for the bookmark to the link, but couldn't find it. Sorry. I've had some computer problems and recently changed PCs.

[namusmc65]

It is a personal opinion IMHO! Lol. To me, the few cents saved is not worth the hassle of putting something like that on my vehicle. To the commercial hauler, his opinion is going to be totally different. Each to their own.

[rick danger]

I'm toying with an idea. I bought 12' aluminum boat to take camping with me. The plan was to put it in the back of my pickup. I'm thinking of a way to have it to use the bow to "split" the wind before it hits the front of the trailer. To cold out to do much messing with it now though

[Jagiven]

A while back, I ran into a couple with the shorter version of the 23B. We started talking about his cedar strip canoe on his truck (with topper), he said when he has the canoe on top it increases his fuel mileage by 2 to 3 mpgs.

As for the OP the enclosed under carriage will allow the air to slip right by without becoming more turbulent from hitting hoses and cross members. Result a slightly improved fuel economy.

I think about modeling a cab wing, but to much to do and not enough time. Key would be the angle and distance from the tt, you would want a shallow angle (under 45 degrees). I think of it like a motorcycle jump, if it is to steep the front suspension compresses on impact and you loose you speed and momentum.

The general equation for the distance*R*traveled by a bike launched from a height*h*with speed*v*at an angle*θ*is*R=(vcosθ/g)[vsinθ+√(v2sin2θ+2gh)] whereg=32 ft/s2*is the acceleration due to gravity,*h*is measured in ft, and*v*is measured in ft/s. You would probably prefer to have speed in mph, so making the conversion I find an equation you can use which is*R=(0.0672v·cosθ)[v·sinθ+√(v2sin2θ+29.76h)] with*v*in mph. For example, if*θ=300,*v=20 mph, and*h=10 ft, then*R=35 ft. www.askphysicist.com. The basic formula could be tweaked to determine optimal angle and distance from tt to make the wing work as designed.

[Nighthawk 96]

My towing mileage went from an average of 8.5 to a little over 10 mpg when I added a cap to the back of my truck. I think cap causes less air to hit the front of the trailer.
I tow at 65 mph or less.