Do Enclosed Trailers get better mpg than open trailers?

[steve-o]

I wish there was somekind of way I could explain a study I saw done at a college I attended a few years back. But I will try to the best of my ablity.

Think of a truck with a trailer in a wind tunnel. As the steam of smoke comes over the hood it travels up to go over the cab, but when it comes over the cab it immeadietly goes doward. Now, if you are using a open trailler this air that comes over the cab will push directly downward on the trailer, causing drag. But, if you had a enclosed trailer the the air will hit the front trailer and go back over the top and sides. This is why you see some trucks with the fin like things on top of the cab (to push the air totally of the trailer.)

Now the experiment the group did was not dealing with trailers, but was dealing with the fact of tailgate down or up gets better mpg. They put a replica truck in a tank of water and pushed water over it with wood chips in the water. The wood chips showed the exact path at witch the air would travel. They proved that tailgate up got better mpg because of the downward force of air on the bed. I would think this would have the same effect on a open trailer.

Sorry if I lost any of you guys. Kinda of hard to explain. Wish I could draw a picture some how.

the air in the bed is called dead air and the air flows smoothly over it with the tailgate up . with the tailgate down the air is very unstable causing the drag . the same with the open trl. and the ramps with the wire mesh. the air is swirling back , up , down , sideways and every which a way creating drag.

steve

[GeorgiaLandscaper]

correct, same thing I am saying

[Bulldog26]

I know with my open trailer that on the high way behind a semi it pushes me around pretty bad. I'm sure that is due to the sail I'm carrying at the back of the trailer. Thanks for all the quality reply to this thread. Great information.
bt

[dave_n_mulberry]

but now is that drag caused by a flat surface or do you get better gas millages by having a bull nose trailer that has a v like a boat cutting water? a flat nose bardge woukld use a lot more fuel to get started but a v would use very little....


however if you had a bull nose v with a lift like a hydro foil does that reduce the drag and increase effifiency (sp)?

only NASCAR knows for sure

[steve-o]

I was waiting for this to happen...

Where's Woody & Transman?

Folks we'll get to the bottom of this soon. No BS either?

I'm all ears!

i would have thought woody and transman would have been all over this one.

steve

[Jimmy&Sons]

I don't need any study to tell me my 20' enclosed gets worse mpg than my 20' open.

It just does. Period.

[Bulldog26]

i would have thought woody and transman would have been all over this one.

steve

I though the same thing. I would really like to get their take on this issue.
bt

[Jimmy&Sons]

Do you not understand that an enclosed weighs close to 3X more than an open ?

Even one of my idiot sons knows the enclosed is going to suck the tank dry faster.

[Bulldog26]

Give the quality of your posts to this thread I would and stated in the org. post that I thought/think the same as yourself, but do you understand the back of an open trailer has this big thing that stick up in the air that could be called a sail catching the wind. Add to that the ztr's you hauling adds up to a lot of flat space to catch wind. If you have driven behind a semi with such trailer you prob. understand what I"m saying. Yes an open trailer is much lighter close to three times the weight, but it's much more aerodynamic.
From your earlyer post about the tail gate, The information given thier is a great reason to have this thread. I have never pulled an enclose trailer and started this post to get the opn. of other that drive one day in, day out and make a disision from that information. You seem to have a problem with that??????
bt

[Bulldog26]

One last reply JIMMY&SONS, I think the mpg could be better with the enclosed if you were hauling each trailer over the road at an average speed of say..... 65mph or more over a long period of time. The aero. advantage would increase the longer you drove without stopping. In town driveing, stop and go I totaly agree hands down an open trailer would do much better.

[GeorgiaLandscaper]

Well the question in that case, what causes a truck to burn more gas, the wieght a trailer or the drag on it? I would think the drag would. Im not very educated on physics, but it seems that the drag of the open trailer's gate and the objects on it (mowers) would make up for the weight of a enclosed trailer. Couldn't it be argued that air drag on a trailer just makes it heavier to pull?

Im sticking to my original opion, the aerodynamics of the enclosed trailer would help it get better gas millage.

[dave_n_mulberry]

but an open trailer made out of steel may actually be heavier than an enclosed trailer made out of aluminum......

[Bulldog26]

I just checked the weight of an enclose Haulmark today, 2200-2500 on a unit with a hauling weight of 7000. That is their basic landscape trailer. I did talk to my buddy and I can get it at cost. Things are looking good for me to get the enclosed.
bt

[Bulldog26]

Sorry Dave, I'm not sure, but I'm guessing that is Steel. I'm not sure if you can get it in Aluminum, but if you could wouldn't that effect the hauling abilities of the trailer?

[steve-o]

Do you not understand that an enclosed weighs close to 3X more than an open ?

Even one of my idiot sons knows the enclosed is going to suck the tank dry faster.

i will play your game now a$$hole for the benefit of the guys who want to get a real answer. as i said earlier my open 16' weighs 1880 lbs. and the 16' enclosed weighs 2588 lbs. maybe one of your daughters can do the math for you.

steve