SEWER LINE AND WIND RESISTENCE
I am new at this, I have researched here and can not find the answers. My two questions are: 1. Sewer line connected at camp ground. I have read here not to keep open the valve to the black tank. ...
Forum Discussion
Unless you're driving many many thousands of miles, the aerodynamic improvements from cleaning up the roof of a typical RV probably won't net any savings over the cost of doing so. The AC in particular does need to have a certain amount of air flowing through it when its in operation (which generally it does using a fan, of course). It's not quite a solid wall to the incoming air. Vent covers over regular vents probably cause more drag overall.
I suspect making the underside of most class C's smoother would have a larger effect; I know mine is pretty horrid in this sense.
Reshaping the back would have a far greater effect, as well. Having a pointy front may look more aerodynamic, but in reality having a pointy back is rather more important. An RV typically has neither, and predictably suffers. There's a reason why a great many new cars are shaped more or less like a Prius, with a long slanty back; it makes a real difference in air resistance. Likewise, it's why the fold-out flap thingies have started appearing on the backs of some truck trailers.
As others have said, there isn't a need to close the gray water valve to avoid having sewer smells in the RV. If you do get sewer smells, not from outside, you have some plumbing problems to sort out--either a trap that has lost its water (possibly due to bouncing around and/or evaporation), or an air admittance valve that is not shutting properly, or something else.
Gray water in the tank that has been sitting for a few days can get a bit stinky, too, so the drain system needs to prevent odors from entering regardless of how you manage the tank valves.
I suspect making the underside of most class C's smoother would have a larger effect; I know mine is pretty horrid in this sense.
Reshaping the back would have a far greater effect, as well. Having a pointy front may look more aerodynamic, but in reality having a pointy back is rather more important. An RV typically has neither, and predictably suffers. There's a reason why a great many new cars are shaped more or less like a Prius, with a long slanty back; it makes a real difference in air resistance. Likewise, it's why the fold-out flap thingies have started appearing on the backs of some truck trailers.
As others have said, there isn't a need to close the gray water valve to avoid having sewer smells in the RV. If you do get sewer smells, not from outside, you have some plumbing problems to sort out--either a trap that has lost its water (possibly due to bouncing around and/or evaporation), or an air admittance valve that is not shutting properly, or something else.
Gray water in the tank that has been sitting for a few days can get a bit stinky, too, so the drain system needs to prevent odors from entering regardless of how you manage the tank valves.
