Whoever wins a bobsleigh race is the one who makes the most of the laws of physics, explains Jean-Michel Courty professor at Sorbonne University, and author of the Youtube channel “Thank you physics!”
Because the only two driving forces of the bobsleigh are thrust and weight. To make a better slide than the others, what counts are, first of all, the 50 meters of thrust at the start to give speed to the machine which weighs between 170kg and 210kg empty. Pushers usually have five seconds to propel the bobsleigh and jump into it. At the end of the push, the bobsleigh already reaches 40km/h. So the pusher must also be a good sprinter to be able to follow.
Once started, the driving force of the bobsleigh (it is its weight that drags it down the slope) intervenes. There, the second secret to winning: limiting friction forces. It is then necessary to limit the frictional forces of the air, on the one hand, thanks to the aerodynamics of the bobsleigh (which is obviously very studied, as in formula 1) thanks also to the position of the crew which retracts the head and who must keep the spacing optimized between the crew members so that the air flows as well as possible. Obviously, it is also necessary to limit the friction forces on the ice by making the skids of the bobsleigh skid as much as possible on the track. And there, it is essentially a question of piloting and trajectory.
The pilot can turn the bobsled’s front runners by pulling handles.
To choose the fastest trajectory, without skidding, you have to control the centrifugal force, go up a little on the sides in the turns… but not too much.
Of course, it’s easier said than done, especially when you’re chaining around twenty turns, over 1.5km at more than 100km/h. The talent of the driver is therefore to anticipate, and it is to always project himself into the next curve. Knowing that with each meter covered, each movement of the crew counts: in the end, victory is generally decided in a few hundredths of a second.