Fractured Axel

WEIGHTS RAWK, DUDE!!

I've noticed that after flying alot my center of gravity changed and I tip over less.

Sorry....

Hmmm sounds like you've had some brass rod inserted in your spine tube near your tail !

My guess on this weights thread is that as Zippy8 said, the kite does not rotate about its CoG, hardly likely really since the input from the lines and subsequent restraining/ hindering forces are outside its body, so I agree here. second although the weights with respect to the kite are fairly small when the kite is in a fade or turtle the airloads( in particular lift) are balancing(give or take) the weight of kite and lines so they are significant. Their input to the whole equation depends on their relationship to the centre of pressure/lift when the kite is in the fade/turtle. So aweight at the "T" may be better than at the spine end. as for the size of the weight, it is really a subsitute for a trimming/ controlling input to hold the kite in the desired position. this can be done by a control service (an aerodynamic input) or by a weight the equates to the magnitude of force required. So a weight at the "T" could have the correct relationship to the centre of lift but because of its position needs to be bigger to have the same effect asa control surface exerting a forec at the trailing edge. My guess anyway.

Zippy8 wrote:

Juha wrote:

WEIGHTS RAWK, DUDE!!

Well quite. Thank you Mr. Double VF Winner for that insight.

your kite’s Center of Gravity. This is the spot that marks the axis around which the kite will pitch when doing all those flippy-floppy moves.

You know what ? This really isn't true. Take a look at your favourite video shot from the side of the kite and the centre of rotation is frequently nowhere near the kite, let alone at the static CoG.

Agree with me dammit !!!

Mike.

I agree Mike

I believe the Centre of Gravity (CoG) and described inte Kitelife article is not valid (in terms of where and why you put weights on a kite).

When we talk about a moving body we should be talking about something called the Instantaneous Axis of Rotation.

When the kite flips, rolls, etc., its motion is described as its rotation and translation about and axis. The kite does not do its things about a fixed point as the article implies !!
It does them about an axis (which not always can be determined and which most of the time is well outside the kite itself). The location of the instantaneous axis of rotation is constantly changing as motion takes place, and with it, a whole set of effects of different rotational inertias in different moments of the motion.

In trying to visualize the concept, the Instantaneous axis of rotation has a lot to do with how the kite tricks, and how those tricks look !!!

(This is well studied in physics, kinematics, and biomechanics -my area of interest. A Google search on the IAR will produce a few interesting articles. Most with lots of numbers and formulas).

Tony