Experimental analysis of ice friction in the sport of bobsleigh

We report the first derivation of the coefficient of friction between bobsleigh runners and ice from experimental measurements performed in a controlled environment. In a series of experiments on both horizontal ice and a track sloped at 6.80°, a radar gun was used to sample the speed of a moving sled in the range of (1–10) m/s at a sample rate of 31.25 Hz. The acceleration of the sled, and thus the coefficient of friction, was extracted from these data, with a value of (4.2 ± 0.9) × 10−3 for the coefficient of friction associated with a set of two-man bobsleigh runners. There was no detectable variation in the coefficient of friction with velocity at this range of speeds and experimental accuracy. This result improves our knowledge of this coefficient over currently accepted values determined from indirect measurements, and indicates that the coefficient is lower than the currently accepted range.