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Wednesday, February 17, 2010
Adjusting the curve radius
How do you know how much to adjust your curve radius to correct for under-rotation about the bar?
Enots Nelg
Watch (or better yet video) the jumper from a point directly in line with the bar. Observe how far short of horizontal the jumper is when his/her center of mass is directly above the bar. For every degree the jumper is short of horizontal at this point, decrease the radius of the curve by 1%. So, if the jumper is 18 degrees short of horizontal, decrease the radius by 18 percent.
All other things being equal, increasing the speed with the same radius would result in a greater lean angle and a greater rate of spin.
Thus, if you increase your speed to either improve your impulse off the ground, or because you have a bit more adrenalin during a meet, you can expect to spin a bit faster about the bar as a side effect.
I call this added spin a side effect because it is not generally the desired effect. The desired effect of changing the running speed is generally to optimize the impulse off the ground. Everybody has an optimum approach speed which depends on many factors: anatomical, psychological, environmental, and etc.
If your approach is already producing the correct rotation and you find it necessary to adjust the approach speed to improve impulse off the ground, you will then need to re-evaluate your curve radius. That's not a tough task though. Simply estimate how much off horizontal you are at the peak of your flight and reduce the radius by 1% for each degree you are short of horizontal. If you are over rotating, then increase the radius 1% for each degree of over-rotation.
Watch (or better yet video) the jumper from a point directly in line with the bar. Observe how far short of horizontal the jumper is when his/her center of mass is directly above the bar. For every degree the jumper is short of horizontal at this point, decrease the radius of the curve by 1%. So, if the jumper is 18 degrees short of horizontal, decrease the radius by 18 percent.
ReplyDeleteWhat would be the result of keeping the radius the same but increasing speed?
ReplyDeleteAll other things being equal, increasing the speed with the same radius would result in a greater lean angle and a greater rate of spin.
ReplyDeleteThus, if you increase your speed to either improve your impulse off the ground, or because you have a bit more adrenalin during a meet, you can expect to spin a bit faster about the bar as a side effect.
I call this added spin a side effect because it is not generally the desired effect. The desired effect of changing the running speed is generally to optimize the impulse off the ground. Everybody has an optimum approach speed which depends on many factors: anatomical, psychological, environmental, and etc.
If your approach is already producing the correct rotation and you find it necessary to adjust the approach speed to improve impulse off the ground, you will then need to re-evaluate your curve radius. That's not a tough task though. Simply estimate how much off horizontal you are at the peak of your flight and reduce the radius by 1% for each degree you are short of horizontal. If you are over rotating, then increase the radius 1% for each degree of over-rotation.
You're scientific approach to the curve radius is wonderful. It is helping me with athletes of all ages. Thank you!
ReplyDeleteTravis
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