Trailer Aero Device

[pballance]

It looks like I have purchased a 24' enclosed trailer and with the price of diesel skyrocketing I have started looking at ways to get a little better mileage. Don't tell me I have too much vehicle for such a small trailer or I should buy a hybrid

I am wondering if anybody has experience with either a Nose Cone as found here: http://www.nosecone.com/aepull.htm
or airtabs as found here: http://www.airtab.com/ or both?

There are some rv guys who have built their own that claim a 1-2 mpg increase in fuel economy. Those guys have used FRP over a PVC or metal framework to build sort of a "nosecone" style device that doesn't have the elegant curves.

Any thoughts?

Thanks

[supersmile]

I've looked into these in the past, and the break even amount (savings vs. purchase price) was always too many miles to justify. But I haven't checked into them now that gas is over three bucks a gallon, and that could make them more attractive.

Of course, allowing extra driving time and slowing down to 55 would probably save even more gas, and its free, but who wants to do that?

[Greg Amy]

http://www.everytime.cummins.com/every/pdf..._Whitepaper.pdf

Dunno how much difference that would make, but I'd be very surprised if it would make a 2mpg difference (that's 15% or better for your typical truck pulling a small enclosed). I also recall those things are pretty darned expensive...

I tried a cheap ($125) roof wing from JC Whitney on the back of my van. Couldn't quantify any improvement, but it felt like it towed better. Hell, probably didn't, but it sure looked pimpy...

[pballance]

I found one more to look at that claims SAE validated 6% better economy as a full system (side skirts as well as nose device). Not sure if ROI will every catch up unless it is included in the intial purchase.

Link : http://www.freightwing.com/view/www/freigh...ng%20system.htm

This one intrigues me. I can build something pretty similar for not a lot of $$$. The physics of it make sense as well.

edit: Neat article as well from Cummings. I found it interesting that the rolling resistance of different surfaces varies so widely. It makes sense, I just never thought about it.

[MMiskoe]

Seems to me that the faster you go, the more effect it would have - so now you can justify going faster. Sounds like its a win-win.

[lateapex911]

http://www.everytime.cummins.com/every/pdf..._Whitepaper.pdf

. Hell, probably didn't, but it sure looked pimpy...lying by the side of the road.... [/b]

fixed that for you


PR ballance, the airtab things, are, IIRC, designed to sit on the trailing edge of the cab of a semi, and "spoil" the air or "lift" it so that it reattaches better to the trailer. I *think* you need to have a form that is close to, or matches the form of your trailer as your tow vehicle or those to work. I think they are a way of "tricking" the air to think that the gap between the cab and the trailer is smaller than it actually is, but if your tow vehicle isn't the same basic size and perimeter shape as your trailer, i think they aren't going to work.

I looked at the nosecone thing, and was surprised nobody was cranking these out cheap. They can't cost that much to make, and you'd think they'd sell like hotcakes if they were less than the prices I found, which were in the 300 -400 range.

[Greg Amy]

fixed that for you [/b]

Hey now, I got it back, didn't I?? Besides, now it's lookin' pimpy on top of the Excursion...

[pballance]

Hey Jake, If you found them that cheap I want to know where. Not that I am going to buy one, but I may. For the GS Baker types, here is some light reading for you:

http://books.google.com/books?hl=en&lr=&id...G_Yi60#PPA51,M1

FWIW, I sent an email to the nosecone people. a ROM on the cost for a standard tag car hauler is $665 plus shipping. If I was on the west coast, maybe but that seem pretty high for me.

Now, On the other hand, here is a guy who is pretty ingeneous. He built his own. I am considering a hybrid of a nose cone and this design:
http://www.johnbridge.com/travel_tra...rodynamics.htm

Can you tell it is a little slow at work today(thisyear)

Paul

[JoshS]

Now, On the other hand, here is a guy who is pretty ingeneous. He built his own. I am considering a hybrid of a nose cone and this design:
http://www.johnbridge.com/travel_tra...rodynamics.htm
[/b]

I'm not an aerodynamic engineer, but that guy's last paragraph, to me, hits the nail on the head. The vacuum behind the rear of the trailer is likely to be a much greater contributor to the fuel economy problem than the front of the trailer.

[supersmile]

I'm not an aerodynamic engineer, but that guy's last paragraph, to me, hits the nail on the head. The vacuum behind the rear of the trailer is likely to be a much greater contributor to the fuel economy problem than the front of the trailer.
[/b]

That's one reason I never bought a V-nose trailer. Just look at the rear design of a modern Formula Vee - it closes back up to try to allow the air to blend back together. For that matter, think of the draft you get off a semi!

Maybe the hot ticket is a trailer with a Vee at both ends.

[lateapex911]

Well, look at some of the transporters out there, they have parge rounded "bubbles" ..I think it's the BMW transport company..on the back. That would be the way to go, but it's rather impractical for enclosed trailers.

[mlytle]

i had a nose cone on my wells cargo trailer. came with it, so can't give before and after data. no idea if it improved mpg, but it was more stable towing than my flat front hallmark trailer..

[IPRESS]

How about the V nose? Is it better mpg wise or just pulls better or not?
I have used a fiends very old Pace that has a slope nose (fiberglass, and it seems to get better mpg and does pull better.

[MMiskoe]

The back of the trailer is a problem. I read a study that found a 1/2 to 1 mpg improvement on big semi's by altering the rear of the box. It was different than the BMW transports mentioned above, but I am sure that's why they do it. I think most trucks don't have anything back there due to the trouble it causes for unloading the truck.

Look at what some of the late '60s cars were doing to improve top end at the Mulsan (sp?) straigt at Le Mans. There isn't as much gain by tailoring the rear, but there sure is something to be had there.