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Scientists Discover How To Stop Luggage From Toppling On the Race Through the Airport (theguardian.com)
An anonymous reader quotes a report from The Guardian: Scientists have worked out why suitcases tend to to rock violently from one wheel to the other until they overturn on the race through the airport. This most pressing of modern mysteries was taken on by physicists in Paris, who devised a scale model of a two-wheeled suitcase rolling on a treadmill and backed up their observations with a pile of equations and references to holonomic restraints, finite perturbations and the morphing of bifurcation diagrams. Fortunately for non-physicists, the findings can be reduced to simpler terms. For the suitcase to rock it had to hit a bump or be struck in some other manner; the faster the suitcase was being pulled, the more minor the bump needed to set it off. So far, so obvious. But Sylvain Courrech du Pont wanted to know more. Why did a rocking suitcase swerve and make such violent movements that it might eventually topple over? After more treadmill tests and more equations, the answer popped up: because a suitcase's handle pulls from the middle and the wheels are at its sides, the suitcase swerves inwards whenever it tilts up on one wheel. If the rocking overcomes the dampening effect that happens when each wheel touches the ground again, the suitcase will keep on rocking or eventually flip over. In conclusion, the researchers discovered that "when a suitcase starts to rock out of control, the correct response is not to slow down but to pull it faster." The scientists have published their findings in the journal Proceedings of the Royal Society.
The handle is also on the same side as the wheels, so when you're pulling it along the weight is above the pivot point between the wheel still on the ground and your hand.
If the handle was on the opposite side from the wheels the weight wouldn't be as high (it would be more in line with your hand and the wheel), so the suitcase would be more stable.
actually I prefer two-wheeled suitcases, but they are nearly impossible to buy new.
stores nowadays just sell four-wheeled.
unfortunately four-wheeled suitcases suck over rough ground, especially over cobble stone sidewalks common in Europe, with their tiny plastic wheels that easily break.
As I just posted below - before seeing your comment - those idiots need to hit the accelerator when the trailer starts swerving! Any other maneuver is bound to lead to a bad day.
Speeding up does work.
A second technique that works is to put the car in neutral, effectively decoupling the travel-direction forces transmitted through the hitch. With no more tugging it along, the trailer will settle down (this stops any more energy from being put into the trailer's motion, letting roll-resistance quench out the speed and oscillations). I have done this. Just decouple and coast.
You are correct that hitting the brakes is the absolute worst thing that the driver can do.
I was about 10.... We were on the way home from a camping trip, and my mom was driving.
Some asshole cut her off, and she instinctively hit the brake. My dad was yelling at her to hit the gas... to no avail. We jacknifed and flipped. That's stuck with me ever since. If your trailer is out of control, speed up.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.