Although not an avid follower of winter sports, I noticed that the world record for the ski-jump was broken on the 11th of February. Johan Remen Evensen of Norway jumped 246.5 m at the Nordic Vikersundbakken ski jumping hill. The video below shows the jump itself.
What I’ve always found fascinating when watching ski-jumps is the ability of the jumper to apparently defy gravity, which of course is exactly what they’re doing. The long, wide skis used in the sport combined with the characteristic V shape the skier forms on the descent generates lift in a similar fashion to the wing of a plane.
A great chapter in the book ‘Biomechanics in Sport: performance enhancement and injury prevention’ outlines the effect of various parameters on ski-jump performance. (The chapter was available in a google books preview if anyone wants to have a look). In summary, the position, shape and size of the skis, the velocity of take off and the gliding position of the skier all effect on the lift force and hence jump-length.
Through further reading I learnt that the rules of the ski-jump have been changed in order to deter ski jumpers shedding dangerous amount of weight. Apparently, because low weight is such a great advantage in ski-jumping, the race to lower weight has put jumpers at risk of physical and mental damage. As a result, the rules now dictate that if a skier is below a particular BMI they must use shorter skis. The penalty is such that launch velocity is reduced due to lower mass, and the lift forces during the jump are reduced due to the stunted skis. I think this is a great example of a sport changing the rules in order to modify the incentives, as has been discussed in a previous post.
When looking at the progression of the ski-jump world record I noticed that it has been broken ten times in the last two months. More specifically nine of these ten records were made at the Vikersundbakken! Further reading revealed that the ski jumping hill has recently been revamped making it the largest in the world, so it’s little wonder. It’s an intriguing great response to the problem of record stagnation. To go further you need to go faster, therefore simply build higher!