We have been considering adding a camper shell to our 07 Tundra. Would anyone know if the addition of the shell will help with the air-flow characteristics against the TT? Would a Classic Wedge style push the air-flow up over the top of the TT and thus reduce drag?
From all I have read or heard the empty bed with tailgate up is the best way to travel in a pickup for best mileage. It seems in air tunnel tests the air flows over/above the empty bed because of the up tailgate. When the tailgate was removed there was more air turbulence and friction. The 5th Wheel tailgate all of us 5er owners use with the V and louvers is not as good as the stock tailgate for good mileage.. However, after you hit the stock tailgate with a King Pin once or twice you use the V tailgate.
However, to answer your question, I don't know about the dynamics of the air flow with a trailer tagging along behind. The shell may divert the air up and over the TT or it might direct it right into it. I do know that most of the owners of the wings on top of the pickup cab that supposedly direct air over the 5th Wheel or TT, claim that it doesn't make much difference as far as mileage goes with it (wing) or with out it.
Bottom Line: I guess my ramblings didn't add much as far as your question goes. :clown:
Thanks for the comments anyway DL, hope that others may be able to add some information for us. We feel that for our needs a shell is important but I don't want the style to be counter-productive; we do need all the mileage help we can get.
The bottom line is this: You're not going to change you mileage by much. Get used to it. A lot of "mileage increasing" gadgets only CLAIM to help by 3%. For every 10 MPG, that's 0.3 MPG. If you normally get 300 miles out of a tank, then you will increase your range to 309 miles.
Hey, wait a minute! That's enough to go to town and back!
The first time they started jacking up gas prices, I put a 'rolling' toneau cover on my Chevy 1500 before a cross country trip. They claimed it would increase mileage by some percentage (I want to say 10% but can't remember for sure), and it did provide almost exactly what they claimed over the same trip a year earlier. So I think that something which provides a smooth surface over the whole bed area (like a toneau cover or cap) will be of noticable benefit if you only have the truck.
Will it help with a trailer? That I can't say. It would depend on what happens turbulance wise in the space between the cap and the trailer. I'm thinking it would vary greatly between setups. About all you could do is make a trip without a cap, and then make the same trip with the cap. That is really the only way to know.
But if you really want savings, slow down. Pulling my trailer, I got 8.2 MPG at the speed limit and 10.2 MPG at 55. That's a 25% improvement!
It would take a heck of a lot of miles to make up for the cost and weight penalty of a shell IF they added any increase in milage! That is not a very good reason to purchase one in my opinion. I use one for the security of the stuff I carry in the bed, it also keeps the stuff out of the weather, and I think it looks good.