The Story of the Javelin- Bringing it Back Down to Earth

Talking about the sport of javelin throwing brings back memories of school sports days and the ‘safety’ javelins we would throw, made from what I can only describe as the grey pipe insulation you would normally find under your kitchen sink! I was lucky if I was able to project the length of grey tubing over a metre! I don’t put this down to my inability to throw, more to the poor aerodynamic properties of this particular javelin.

Thankfully the javelins used in competition are distinctly better in design than the ones I used as a child. However, in their competitive life, javelins have undergone significant design changes to alter their performance. Specifically, to make them harder to throw. This may seem counterintuitive, but the change was with good reason… let’s look a little further.

The History of the Javelin

The javelin has a strong historic record, going back around 3000 years, to the times of the Mycenaean’s and the Romans. The Javelin was originally designed as an offensive weapon and used in favour of the spear as it was lighter and could be thrown rather than thrust, allowing long distance attacks against an enemy.

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An Agrianian Peltast holding three javelins

The javelin saw its introduction to the sporting world in the games of the ancient Greek’s in around 500 BC, with a much lighter design than their military counterparts, the objective was to achieve the greatest distance.

The design of the javelin differed greatly from the design most people have now become accustom to, with the athlete holding onto a thin leather cord wrapped around the middle of the javelin, rather than the javelin itself. When the javelin was thrown the leather cord would unwind and the javelin would follow a spiralled flight, very similar to the way a toy spinning top is made to rotate by pulling a string. The javelins, made from thin pieces of wood were by their nature, very unbalanced. The rotation stabilised the javelin in flight.

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Matti Jarvinen at the 1932 Summer Olympics

Javelin throwing as an Olympic event

The sport of javelin throwing was first introduced to the Olympics in 1906 as a freestyle event with very few rules and regulations over design. The 1912 Olympics saw the formation of the IAAF, setting strict rules and regulations on the design of the javelin and with it, the first world record. In the following years the world record and Olympic gold distances continued to increase, culminating in a world record distance of 104.8m, set by Uwe Hohn in 1984. Distances such as these posed significant safety risks as there was the possibility of overshooting the stadium and the javelin landing in the crowd. Furthermore, there was an increasing amount of times when the javelin would land flat on the ground, resulting in heated protests when these throws were declared invalid by the competition officials. Listen to the commentary on the video below, it’s made clear why the javelin had to be changed.

In an effort to solve these problems the IAAF redesigned the men’s javelin, with effect from the 1st April 1986. The redesign saw the centre of mass moved 40mm forward from the centre of pressure- the point where aerodynamic lift and drag forces act (we’ll talk about this more later). The tip of the javelin was also modified to be blunter and less aerodynamic. These changes mean the javelin travels a shorter distance and descends at a steeper angle, helping the javelin stick into the ground rather than simply laying down. The women’s javelin saw no change until 1999 when the records similarly increased to a potentially dangerous distance and the javelin saw the same redesign.

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Bregje Crolla at the 2007 Eurocup Championship

Unsurprisingly, the redesign had a significant effect on performance, as can be seen in the graph below. The graph shows world record and Olympic gold distances for the men’s javelin throw across the modern Olympics from 1912 to the present date.

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From the graph, you notice the distance records continue to increase, up until the world record in 1984. With the introduction of the re-designed javelin at the 1988 Olympics you then notice a significant drop in performance. After the redesign the records start to gradually increase again as manufacturers fight back and add design improvements to the javelin.

Designers and manufacturers of javelins started to fight back by adding dimples, holes and rough coverings to increase tail drag and hence increase the distance travelled. Such modifications were banned at the end of 1991, with Seppo Raty’s record of 96.96m using such a javelin being removed from the record books. The javelin currently used at the Olympic Games saw its debut at the 1992 Olympics in Barcelona, Spain.

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Current men’s and women’s javelins (Men’s shown in blue and women’s shown in white)

The re-design in more detail

Before we can start to fully understand why the javelins design changes altered its flight properties, let’s look at the original javelin design and try to understand how it flies. The original javelin design had the centre of mass at the centre of pressure. The centre of pressure is the point where aerodynamic lift and drag forces act. Just like the wing of an aircraft, a javelin can be ‘lifted’ by the air if angled appropriately. What this means in practice is that when lift forces act the javelin falls more slowly and travels further.  As the centre of mass and centre of pressure coincided the pitching moment (how the javelin rotated during flight) completely depended on the way it was thrown.clip_image012

The original Olympic javelin, as used by Uwe Hohn up until 1984.

This means the javelin can follow a very uncontrolled flight path with the nose pointing up or pointing down throughout the course of the flight. As observed in many Olympic events up until 1984 this resulted in many occasions when the javelin had lots of positive pitching moment towards the end of its flight, literally meaning the javelin would fall out of the sky and land flat on the ground, resulting in a ‘no throw’.

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The flight pattern of the original Javelin , as used by Uwe Hohn up until 1984. The javelin is acting like a wing for most of its flight.

The redesigned javelin, introduced from 1986 saw the centre of mass moved 40mm forward from its previous position at the centre of pressure. The tip of the javelin was also resigned to be a blunter and less aerodynamic shape.

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The redesigned javelin, introduced from 1986

These changes mean that during flight the javelin has an increased downward pitching moment. No matter how you throw the javelin it always tends to pitch forward. This reduces the lift on the javelin, bringing down the nose of the javelin and meaning that it will stop climbing and start to descend. The point in flight when the nose starts to point down occurs much earlier than with the previous javelin design, meaning it will start to descend earlier and hence travel a shorter distance. The blunter tip introduced as part of the redesign means the shape of the javelin is much less aerodynamic. This creates increased drag forces which slow the javelin down, further reducing its flight distance. The negative pitching motion also means the javelin follows a much more controlled flight path than with the previous design. During the descent phase its nose points down, meaning the javelin sticks in the ground rather than simply falling out of the sky as before- bringing an end to the previous disputes between competitors and officials.

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The flight pattern of the current javelin, introduced from 1986

Accidents and safety concerns

Despite the IAAF’s changes to the design of the javelin and the efforts to reduce their flight distance there has however been some unavoidable accidents.

At the 2007 Rome Golden league meeting, Salim Sdiri, a 28 year old French long jumper was speared by a javelin launched by Finland’s Tero Pitkamaki from the other side of the arena at the Olympic stadium. The accident, caused by Pitkamaki losing his footing was not the first time such an incident had occurred. Thankfully the 28 year old survived the accident with no lasting injuries.

More prominently, in 2012, a German athletics official was killed at a German athletics event when he went to measure a javelin throw but was hit by a javelin before it reached the ground. Accidents do occasionally occur, but deaths are thankfully extremely rare.

Conclusions

Changes to the design of sports equipment such as the javelin poses a number of interesting questions and ethical debates. Is it wrong to restrict the performance of athletes by technological change or should we be allowed to push the boundaries of sporting performance with the use of technological enhancements? This, an article in itself has been previously discussed on our blog by my colleagues, Prof Steve Haake and Dr David James

With the performance of athletes gradually improving it appears the IAAF’s changes to the design of the javelin are having a much less noticeable effect than at the time of their original introduction. Gold medal distances are starting to again near that set by Uwe Hohn and with the severity of recent accidents it would appear there will be a need for the IAAF to make another change to the sport of javelin throwing in the very near future. Whether this will be another change to the javelins centre of mass and aerodynamic properties or a significant change to the sport itself we’ll have to wait and see.

Sean Clarkson

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About yachtingnut

Sean started his engineering career at the tender age of 4, continually ‘wiring’ up his parents’ house with string, wool and plastic socket protectors designed to stop him from being interested in electrics! The fact that he never managed to decapitate his mum and dad remains a mystery, but with this early interest Sean’s future career was sealed. Also apparent from an early age was Sean’s addiction to water, whether it be on top of it, under it or floating on it. After pursuing many water related sports including kayaking, scuba diving and sailing it was Sean’s first water sport he settled on- Sailing, something which he also started at a very young age. Sean competes regularly in many local and national yacht racing championships throughout England are Ireland with varying degrees of success, always attributed to the poor weather…..or so he says! Sean also has interests in other sports including; cycling, badminton, archery and golf. After graduating from Sheffield Hallam University with a BEng (Hons) degree in Electronic Engineering Sean then went onto complete an MSc in Electronics & IT also at Sheffield Hallam University. With such a strong interest in engineering and sport his next move of joining the Centre for Sports Engineering Research as a PhD researcher was only a natural progression. Sean’s main research area is developing 3D camera systems to analyse the way in which the body moves during motion (producing pretty pictures). From his electronics background Sean is also interested in developing instrumentation and feedback systems to measure the movement of athletes and the equipment they use. Sean has a strong interest in the application of consumer hardware such as the Xbox Kinect and Nintendo Wii remote to sports and has developed lots of fancy pieces of software to show off what they can do.

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