High Wind = White Knuckle driving - any suggestions?

bigb

2011 Winnebago Via 25Q on 3500 Sprinter Tucson, AZ
When I looked at Vancompass I could find no Falcons to fit the rear of the NCV 3500, only Fox 2.0
 

ches

Member
When I am planning a trip I always consult Weather Underground to see where the wind blows even for a low roof sprinter, I may even design my trip around the direction. I love a good 30mph tailwind. But then again I am retired and I can afford to take my time. Oh yeah, and I hate to drive over 60mph; too much to see.
Once in Deming, NM I was planning to camp in the area for a few days. Once I fueled up I noticed a nice strong east wind (Deming style) and thought how nice it would be to be in Arizona. I got back on the road heading west. One of the great things about traveling is being flexible- follow the wind.
 

autostaretx

Erratic Member
I had a 6 hour drive through 50 mph crosswinds this week.

I was pondering the physics. Some people say "drive slower". But, I'm trying to sort through the physics of things.

Wouldn't it be (theoretically) better to drive faster? If you sail, you may be familiar with "apparent wind". The faster you drive/sail, the more the wind is on your nose and not a cross wind.

For example, if you are parked and the wind is 50 mph directly from your left, you have 50 mph hitting the side of your van.
If you drive 50 mph with a 50 mph crosswind, the wind is now at 45 degrees forward, and the apparent cross wind is now 25 mph.
The side force does not change.
Although the total vector may differ ("appear to improve") with higher speed, the actual Y (sideways) force component doesn't change.
At 60 mph, if it takes you a second to correct, you've got 88 feet down the road (straight ahead)
At 70 mph, it's 102 feet.

Since you have to steer into the wind to avoid slipping sideways, your wheels are demonstrably *not* "sticking to the road".
It could well be a case of the X component being veered sideways, so the number of feet you're displaced sideways in the lane may also increase with speed.
You'd almost think that the Sprinter would "weathervane" into the wind due to its (relatively) pointy nose and side-of-barn -shaped rear end. But it doesn't, does it?

--dick (who kind'a enjoys vectoring ... and the effects of semi trucks bow wakes adding to the fun)
 

elemental

Wherever you go, there you are.
Wouldn't it be (theoretically) better to drive faster? If you sail, you may be familiar with "apparent wind". The faster you drive/sail, the more the wind is on your nose and not a cross wind.
I look at it another way. A gust of wind acts on the side of the van for a duration of time, during which the van is deflected to one side or the other from its straight ahead course. The faster you are going, the longer distance the force of the gust acts along to deflect the van away from the straight line forward. At an extreme, if you were traveling 10 MPH, a 1 second gust would act over a distance of less than 15 feet (14 2/3 feet per second). If it deflects the van 1 degree, you would end up off course by about 3 inches [I calculated it as sin 1° * 14.666 feet = 0.26 feet]. At the other extreme, if you were traveling 75 MPH, a 1 second gust would act over a distance of 110 feet (110 feet per second). The same 1 degree deflection puts you off course almost 2 feet [I calculated it as sin 1° * 110 feet = 1.9 feet]. Slowing to 60 MPH (88 feet per second) reduces the 1 second 1 degree deflection to about 1 1/2 feet. Slowing to 50 MPH cuts it down to about 1 1/4 feet.

Of course, the actual gust duration varies, and you are actively counteracting it while it gusts, so how much you really deflect varies based on steadiness of the gust and your corrective driving skill. But slowing the van down gives you more time to react and correct before you are in danger of coming out of your lane.

[Edit: And after I posted I saw that dick had already made the same case but with less math :) ]
 
I had my dealer program cross wind assist. Today driving in NM on I10 got it with a big gust and it came on. It worked a few times in CA on my way to Phoenix did not display but I could feel it. I gave a View with Fox shocks, sumo, hellwig sway bar. Driving in cross wind is tough.
 

Aqua Puttana

Poly - Thread Finder
...
Wouldn't it be (theoretically) better to drive faster? If you sail, you may be familiar with "apparent wind". The faster you drive/sail, the more the wind is on your nose and not a cross wind.

...
I'm not smart enough to give calculations, but intuitively a box driving down the road doesn't seem to be the same as a sailboat, but I don't know that. I think slowing down a vehicle has much to do with steering on wheels and reaction times.

Anyway, your comment got me thinking about sail design and square riggers and apparent wind. A search took me here.


That resulted in much more time reading than I expected. Not really related to your question, but I found it interesting.

vic
 

borabora

Well-known member
One thing to keep in mind is that wind force is essentially due to kinetic energy of air molecules. Kinetic energy increases with the square of velocity. This means a doubling in wind speed increases the force by a factor of 4. If you are driving with a sustained side wind speed of 20 mph and a 30 mph gust hits you the sideways force is not 50% higher but is more than doubled.
 

az7000'

Active member
and generally keep weight low.
IMO weight helps, we have a 10,000# motor home on a 3500. Its taller and has more on the roof, I was in horrible winds last week between Page and Flagstaff, annoying but manageable. A light build that is tall seems like it would act like a sail, a light boat with a size "X" sail seems like it would be faster then a heavy boat with the same size sail.

We do have Agile fox's and Koni Reds at highest damping setting, great overall, biggest change was rocking in and out of driveways. Good Michelin E rated tires, no fancy driver aids on our old girl though.

Good Luck!
 

tDot

Active member
IMO weight helps, we have a 10,000# motor home on a 3500. Its taller and has more on the roof, I was in horrible winds last week between Page and Flagstaff, annoying but manageable. A light build that is tall seems like it would act like a sail, a light boat with a size "X" sail seems like it would be faster then a heavy boat with the same size sail.

We do have Agile fox's and Koni Reds at highest damping setting, great overall, biggest change was rocking in and out of driveways. Good Michelin E rated tires, no fancy driver aids on our old girl though.

Good Luck!
You're correct. My response was poorly worded. I meant, keep weight 'low in the van'. A heavier van overall is less responsive to wind gusts.
 

autostaretx

Erratic Member
Then there's the other half... you feel you're being blown across the road, so you steer into the wind...
Then the gust stops (or "relents") ... now you're in a windless condition, with your wheels pointed somewhat sideways.
NOW that 88 (or 102 or 110) feet per second are doing nothing but trying to drag you into the parallel traffic! :eek:


--dick (with a very lightly loaded Sprinter)
((the 60 mph = 88 feet per second is something i figured out as a kiddie, and the number has stuck in my head forever since))
 

Docpaulo

Active member
Then there's the other half... you feel you're being blown across the road, so you steer into the wind...
Then the gust stops (or "relents") ... now you're in a windless condition, with your wheels pointed somewhat sideways.
NOW that 88 (or 102 or 110) feet per second are doing nothing but trying to drag you into the parallel traffic! :eek:


--dick (with a very lightly loaded Sprinter)
((the 60 mph = 88 feet per second is something i figured out as a kiddie, and the number has stuck in my head forever since))
That was me.. steering wheel was 15 degrees to the left just to stay on a straight road... good explanation...
 

Albush1

Member
I bought a high roof 2016 170 extended with 28k miles with original shocks and it didn’t feel confident in the wind and passing big rigs until I installed front Sumo Springs and Bilstein shocks/struts. It was a completely transformational, better-in-every-way experience now. In fact, I passed a guy in a similar Sprinter on a gusty day and I could see his vehicle being man-handled by the wind and I had a much more comfortable experience in the same conditions.
 

autostaretx

Erratic Member
No mention of Sprinters steering control?
Perhaps it was my imagination that I felt some automatic correction helping to keep me straight on a windy day years ago.
It depends upon your Sprinter's vintage ... the T1N gradually gained "ESP" in 2005/6, the NCV3 has it in spades.
MB did a country-wide "dog and pony" on it (there's a thread with recent postings of the video of their demo track ).

--dick (ESP= "electronic stability program" ... effectuated by applying brakes and slowing down the engine)
 

elemental

Wherever you go, there you are.
No mention of Sprinters steering control?

Perhaps it was my imagination that I felt some automatic correction helping to keep me straight on a windy day years ago.
Sprinter vans don't have any actuator that moves the steering shaft; they use braking forces to force a directional change (I assume that they are one-sided brake applications, but I don't know that they are).
 

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