Cars and wind

[nancylebov]

suecochran was doing a road trip yesterday in fairly high winds, and mentioned that it helps to open the windows (a clever idea I haven't seen mentioned elsewhere) and to go more slowly.

The latter seems intuitively plausible, but why would it work that way? Cars making less contact with the road (micro-bounces) as they go faster is my first guess. Anyone have a more solid theory?

Comments

[madfilkentist]

The faster the car is moving, the higher its airspeed is when it's going across or with the wind.

Another effect may be that when you're moving faster, you encounter wind shifts more abruptly.

[madfilkentist]

I should add, that applies only when the car's ground speed is faster than the wind speed. But if you're driving 60 and the wind speed is 70, you should stop driving anyway rather than try to keep up with the wind!

[zenlizard]

Oh, opening windows in high wind speeds is an old trick my family used to do: provided the weather was ammenable to such.

Hey, even the prototypical barn door has a glide ratio of not quite 1:1, meaning that for every (unit length) it falls, it travels nearly (unit length) forward. Lousy shape for an airfoil, and vehicles typically are even worse, (from the piont of view of trying to produce lift), but some lift is produced nevertheless, and is proportional to relative air speed.
It's one of the reasons drag cars have a huge spoiler on the back of the vehicle-an attempt to produce negative lift, and thereby maintain greater contact between the tires and the road. Ultimately, this allows the cars to travel faster measured in groundspeed.

[regalpewter.livejournal.com]

Now here's an interesting thing, when I am driving my 18 wheeler, I actually increase my speed to make it easier to drive with a cross wind. What I am doing is increasing my forward vector to overcome the side force. This is why I never run up against the governor.
BTW this same technique will help you keep control when you have a tire blow out.
YIS,
WRI