Tag Archives: Javelin

The physics and mathematics of javelin throwing

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New version 28/Jan/2007

A long-overdue overhaul. The physics has been redone and some typos corrected. It has also been re-calibrated and the paper explains the concepts involved in more detail. The paper also refers to Mont Hubbard’s work in relevant locations.

New version 09/Aug/2005

An analysis of the physics and mathematics of javelin flight. The resulting model is implemented in the software referenced below. As far as I know, this is the only publicly available model which handles all the significant factors including the effective attack angle. It contains a few surprises for javelin throwers and debunks some popular myths.

When I wrote this I was ignorant of the extensive and important contributions of Professor Mont Hubbard of the University of California at Davis. When I contacted him, Mont kindly gave me copies of a number of his papers. His work is full of important insights and should be studied by all interested in this field.

jav2007a_paper.pdf (292KB)

reference

Submitted for publication

 

World Championships javelin, 2005: (BBC discovers we have no athletes either)

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I wrote this after watching the BBC’s attempts to cover the javelin final,(its the pointy thing guys), and then wonder why there were so few UK athletes competing. (There were more BBC athletics commentators at the world championships than there were grade A qualifying UK athletes.)

Anybody who coaches athletes in the middle of an English winter, unpaid, with absolutely sod-all resources (I have to use my own), a bureaucracy which forces people to study for qualifications (good) but also wants them to do it all for nothing around busy lives and pay for the privilege (not so good), will understand how vomit-inducing it is to have the BBC agonise over why we have so few athletes, tennis players and so on in any event. What we can do though is talk about it. Boy are we good at that. But I’m not bitter :-)

BBC_08-05.pdf (76KB)

reference

http://www.javelinclinic.org.uk/

 

Aerodynamic modelling of the trajectory of a javelin

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NEW VERSION 28-Jan-2007, 1.2e. Physics redone and biomechanics handled better as described in accompanying paper in the links.

NEW VERSION 23-Aug-2005, 1.2d. Calibrated on two major championships and including biomechanical data.

This freely downloadable Windows software models the trajectory of a javelin. Its a self-installing executable so when you have downloaded it, just double-click on it and answer the questions, (which you can usually just default).

The Javelin Flight Analyser (JFA) is pretty sophisticated and solves a coupled non-linear set of ordinary differential equations including terms for drag, lift, rotation and allows for the difference between the centre of pressure where the aerodynamic forces act and the centre of mass. It has only been partially calibrated but already produces good results in a wide variety of environments. It also allows the user to specify the type of javelin, the wind direction and strength and various user parameters. It will shortly be able to search for the best combination given various wind combinations.

Version 1.2 has been upgraded from calibration information gained from publications in this area. They are referenced in the accompanying paper.

This is one of a series of projects I am undertaking to improve IT use in track and field, one of my significant interests. I hope you find it useful and will be pleased to receive any feedback.