Nearly everyone has seen the bobsled races in the Olympics. Teams of 2 and 4 launch themselves in a sled, down an icy track at over 100 km/hr. The tracks are made of concrete, which are coated with ice in the winter. The combination of ice and the aerodynamics of the sled mean that competitors can travel down the track at extreme speeds while pulling 5 g’s. And I can certainly appreciate the mental and physical resilience of these athletes based on my experience down the track.
Teams are composed of the pilot, a brakeman, and then two extra pushers if a 4-man team is racing. The pilots must steer a light-weight sled on steel runners, while the others push the sled off to a fast start at the top of the track. The athletes wear spike shoes to gain traction while trying to push the sled on ice from a complete stop. Most tracks have at least one straight section and then sequences of turns known as the ‘labyrinth’.
The bobsleds are composed of the frame, the runners, the aerodynamic shell, a steering system, and the brake system. The steering is a pulley-system that controls the front runners. The pilot pulls on rings that are attached to the rope and pulley system to control direction. Crew members can also use their weight to help with steering.
It’s evident that to win a race requires strong and resilient athletes. But there’s more physics to it as well. To win a race, sleds must be fast. And a fast sled maximizes aerodynamics to increase acceleration and minimizes drag.
Designing an aerodynamically efficient shell can decrease drag created by the air passing around the sled. This prevents the sled from slowing down as much. Designs also try to minimize the amount of friction between the metal runners and the ice. Even though this is not much to begin with, every advantage counts. After the pushers overcome static friction to get the sled moving, the athletes want to maximize momentum to accelerate the sled as fast as possible down the track.
From then on it’s the pilot’s job to maintain the path of least resistance using all external variables to his advantage, including centrifugal force to keep the bobsled stable on turns. Oh and don’t forget to have fun.