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Originally Posted by Hersbird
In order to get the king of crosswinds represented in those pictures wouldn't they have to be 40 mph or higher directly to the side? Seems at 60-65mph with a normal 15 mph wind hitting somewhere short of directly to the side would be much less drastic. Also I was looking at an article on train crosswind analysis that shows how a big crosswind is reduced closer to the ground depending on terrain https://www.google.com/url?sa=t&sour...Uk0dCgEYsDwY_w
We will be headed across eastern Montana in a few days to try out our new modded camper but hopefully will just face mild wind conditions. |
A 3/4 crosswind is the worst for fuel economy. As winds aren't ever perfectly steady (let's call the use of cruise control the vehicular version of "perfect" speed control as the computer works from inputs formulaically) a vehicle at a perfectly steady speed on otherwise ideal road surface will have the combined steering inputs and engine fuel burn rate vary in both degree of force, and duration. In other words, it starts to upset itself on top of outside forces.
If a person wants an FE version of why to stop every two hours for a break, this is it. The hardest thing a driver resists is fatigue. Fine motor skill declines throughout the day. It cannot be denied, but it can be delayed.
Second, it is also the reason to use sat images or other for an RV'er to keep any extraneous steering and braking events to a minimum in re breaks and fuel stops. Planning these keeps the acceleration event tenths penalty at a higher minimum in re-entering roadway.
Crosswinds (let's call them unfavorable winds) and fatigue are unavoidable. So are a certain number of stops. With the latter planned, and the day broken into time & distance legs, the driver WILL exert more care over along day within these settings, these two-hour and hundred or so mile distances.
For example, if a group is traveling and has stopped for lunch, even if they use the restroom both at the beginning and the end of a one-hour fuel & food break, they WILL need to stop again within 1.25-hrs, not 2.0. Preferably just under an hour. This stop needs to be planned as well.
All of this is to help offset the effect of winds. They need not be strong. Add to them that with the exception of completely rebuilt Interstate, that the cross-wise undulations (the worst are ruts) of the road surface is part of steering resistance.
It would be helpful to see just how much farther per 1000-miles the vehicle travels on Interstates due to winds above the speed of X. Time lapse overhead would be pretty cool. And this figuring is part of determining road resurface, but is cited along with other factors. It is a known factor to those who advocate about roads and national oil imports. For an RVer it is pronounced in compassion to traveling solo. Closer to what a big truck experiences.
The tow vehicle travels farther, but the trailer travels even farther than it would (and always does). This doesn't seem like much, but change from a pickup with work gear steering on live axle front suspension (and the usual improper hitch lash up) and go to a truck with rack and pinion plus a VPP hitch (which locks the trailer to the tow vehicle) and the wind force plus road surface degradation has to go a lot worse that the driver can't more easily control the rig.
There is no way to offset the sail area of an RV except by initial design. Even the best trailer will travel farther over the day than the tow vehicle due to slowing, steering and winds. Those effects can be controlled, I've argued, better than they are in 99% of cases. Being painstaking and/or upgrading equipment establishes a better baseline.
So, yes, higher crosswinds are dramatic, but one is never quite free of winds. Night time is a basic exception. And one can try to offset them in planning stops, these planned deceleration and acceleration events inside a short daily leg, but they are a fact that those towing have to contend with