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The common perception of engineering and sport is that of shiny new bikes, aerodynamic helmets and sleek bobsleds. I often get asked, “isn’t it just the best equipment that wins now, rather than the athlete?” The answer – as far as I’m concerned – is obviously “no” and I’ve spent my working life in the field of sports engineering. I’ll explain why.
Skeleton bobsleigh simulation using ANSYS (formerly Fluent) CFD, and Ensight software. Skeleton and slider model of Kristan Bromley created from 3D laser scanning and surfacing with Geomagic Studio.
Figure 1. The new roof on Wimbledon's Centre Court has been claimed to slow the ball down, make the ball heavier and make the air more humid, none of which quite adds up (picture from the Guardian, 2009).
The comments made about the new roof over Wimbledon’s Centre Court have puzzled me. The Wall Street Journal and the Times had the headline “Wimbledon Roof Slows Balls Down” while the Daily Mail had “How Centre Court’s new roof puts a dampener on Andy Murray’s serve” (I admit that I’m quoted in this one). One comment suggested that “due to the increase in humidity when the roof is closed, balls are heavier and travel slightly slower through the air“.
Well, I’ve done a lot of work for the International Tennis Federation (ITF) on ball impacts, aerodynamics and surfaces and the comments above are physically contradictory (although not necessarily obvious). I want to explain the contradictions and in the process figure out what happens when the roof closes to make the players complain that the ball is slowing down. Hawkeye data has shown the ball to be travelling up to 5 mph slower when it reaches the reciever if the roof is shut.
What do physicists think about when they’re running? I’m currently training for my first marathon (gulp) which gives me a lot of time to think. Running around Sheffield, most of the time I think about how unfair it is that there is another hill and wonder why it is that the wind is always against me no matter which direction I’m going in. Generally, when I’m running all the blood seems to flee my brain so mental calculations take an awful long time: here are just a couple that keep me occupied on my long training runs.
The velodrome which will host the track cycling events at the 2012 Olympics in London is now open. The facility is the first to open in the Olympic village and has been given the title of the ‘best in the World’. When a country hosts a major sports event, such as the Olympics, they want to show off their facilities to the world and create a lasting legacy. This usually means impressive architecture, such as the Bird’s Nest stadium in Beijing, or state-of-the-art transport links and infrastructure. The engineers behind the new velodrome have gone a step further by designing the facility specifically to allow the cyclists to ride faster and hopefully break world records. In addition to a specially designed track, the air temperature in the velodrome will be higher than usual to reduce aerodynamic drag acting on the cyclists. For those of you worried about breaking a sweat whilst you watch, don’t worry the spectator area will be nice and cool!
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.
It may seem like I have balls on the brain if my last couple of posts are any indication. Balls are such a big part of sport and Sports Engineers are fascinated by the way they behave as they bounce on the ground and fly through the air.
I’ve seen two amazing videos recently which exhibit the way in which balls can still baffle us.
Rugby, the penalty of wind
The video below shows a Rugby player taking a penalty in what the Irish tourist board might describe as ‘a slight breeze’. Be sure to watch from all angles to get a good idea of what’s going on.
Ok, I admit it – I’m a stats nerd. I love nothing better than perusing the league tables in the back pages of the Sunday papers, so imagine my delight when Prozone offered me the chance to analyse their data from the 48 games of the Group Stages of the 2010 World Cup.
In a previous article in the New Scientist prior to the start of the World Cup (Haake and Choppin (2010), June 5, 35-37) and on this site (“Does altitude affect football tactics“) we suggested that altitude might have an effect on tactics, and in particular on shots from inside and outside the box. The only data available at that time however was for the 8 World Cup qualifying games for Mexico – including those at Mexico City at 2,200 m.
The results showed that the number of shots from outside the box increased with altitude at the expense of those from inside the box. The question is, has the same happened at the World Cup?
It seems that everyone has something to say about the Jabulani. As the official ball for the 2010 World Cup, it has a lot to live up to, but seems to be attracting more criticism than jubilation.
It is now a World Cup tradition that the new ball should be roundly slated before the tournament begins but the bad press for the Jabulani failed to cease once the matches got underway. This was no doubt assisted by a slew of lacklustre performances as players and coaches looked for something to blame. But with the ball being described as ‘horrible‘, ‘supernatural’ and even ‘impossible‘, might there may be a little more at work than mere sour grapes?
.jpg "The Adidas Jabulani Ball")
- The Jabulani ball hasn’t been well received
On 4th December 2009 the new ball for the World Cup in South Africa was unveiled. The product of years of research and development, the ‘Jabulani‘ was the most highly engineered football the world had ever seen. Prior to the launch adidas had even gone to the extent of testing the ball in the Bundesliga, to highlight any potential problems. Yet despite extensive laboratory and field testing the ball has faced heavy criticism from a number of the world’s top players, such as Brazilian goalkeeper Julio Cesar and Italian striker Giampaolo Pazzini. England goalkeeper David James has even been quoted as describing the ball as ‘dreadful’ and ‘horrible’.
So, what has gone wrong, why is the most advanced football to date still facing criticsm from the top players?
It might be possible to partly answer to this question by delving into the history of World Cup footballs.
Last November, I proposed that for this Summer’s world Cup Altitude will be key, the thinner air in Johannesburg will cause the ball to behave significantly differently than at sea level. Less air resistance means faster shots and straighter trajectories. As part of a feature for the New Scientist (p35-37, June 5th 2010) we created a shot simulator to show how the same shot behaves at different altitudes. I also studied matches played by Mexico in the FIFA World Cup preliminary rounds leading to the current Finals, including home games at Mexico City at an altitude of 2,200 m.
- Fig 1. Maradona lifts the World Cup in Mexico’s Azteca Stadium in 1986.
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