Although I have a heavy box-shaped car, I was thinking about the Mercedes G63 specifically. That is a powerful engine on a non-aerodynamic car, what happens if you take it over 100mph and get hit by a gust of 60mph wind? My car gets literally pushed around lanes during heavy winds at highway speeds, has anyone ever even gotten a G63 past 150mph?
In: Physics
A lot of wrong answers or partial answers here.
Aerodynamic lift is what is happening. Nearly all vehicles develop some amount of lift at highway speeds, and certainly at 100+ MPH. Essentially this lift is making the vehicle appear lighter than it is, and makes it easier to push the car around with a similar force. Sometimes this lift can be several hundred pounds at each axle causing a significant change in vehicle dynamics. Combine the lighter wait with a large boxy shape that acts as a sail on a boat and you can get not-so-confidence-inspiring handling at high speeds.
When a force is applied sideways, things are flexing. The car wants to move sideways from the wind but the tires are keeping it in place.
When moving, the contact patch between the tire and the ground is constantly changing. As it rolls, a different part of the tire is on the road. If the tire is deflected slightly, the next patch of tire to hit the road could want to be just a little wee bit further to one side.
You’re saying you should be able to hear it, but whenever you take a corner the inside of the wheel is moving slower than the outside of the wheel. You don’t hear screeching from that either, because it isn’t a lot.
So wind comes, say, left to right. Not a tornado, so it doesn’t just blow the car off the road.
That causes the car to lean, takes some of the weight off the left side and onto the right side. This deforms the tire more and gives it more grip at the same time. As it rotates down the outer edge wants to be a wee bit more to the right, so it grips and pull the car over.
In a stationary car, the wheels aren’t turning. Everything will deflect and go right back to where it was.
Disclaimer: I mostly made this up and then went and looked and found a scholarly article that stated that stiffer tires reduce the effect of crosswinds significantly so I’m probably on to something.
You ever try walking in a gale force wind, same concept. If you are stopped you are stable, when in motion it’s easy to be re directed by a gentle push.
I have a G63 and you definitely feel the wind. It’s shaped like a damn filing cabinet. I’ve definitely taken it up to a 100 or so, but I put K02 all terrains on mine so they aren’t rated to handle the top speed of a G63. Not that anybody has any business going that fast to begin with.
Try doing it on a motorbike!
I left my bike for at the airport for one night overseas trip. When i came back the weather was torrential with winds gusting in all directions.
It was an interesting motorway trip home that night.
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