Bowmen of Skelmersdale

Time and Motion

When are different motions important?

So far, we have identified three main types of motion (displacement, rotation and vibration) and divided the shot into three periods, (before, during and after). Its worth looking at the different types of motion and when they are most important, to get a clear idea of priorities in picking a stabiliser set-up.

Effect on arrow flight

It takes little thought to see that, as we progress through the shot, bow motions have successively less effect on arrow flight. Before the shot, bow motions literally control

where the bow is pointed. During the shot itself, there is very little time to change the arrow direction. Though the full force of the bow hand would move the bow about 5mm during that time, lateral forces are substantially smaller, and the arrow is in any case barely in contact with the riser. So motion during the shot is normally less important than before the string is loosed. Movement after the shot, of course, has no effect on arrow flight. There are, however, a few more things to consider before assuming that we only need consider motion before the shot!

Effects after the shot

Uncontrolled Bow movement after the shot may still be damaging to overall performance. Factors to think about include:

The archer anticipating rapid movement before loosing

Distraction of other competitors (especially indoors)

Wear and tear, or loosening, of parts of the bow (eg a sight working loose)

The table (next page) shows where the different types of movement are most

important.

What bow behaviour needs controlling?

Bow  movement

Timing - When is movement important?

Time and Motion

Controlling bow displacement

Weight, Mass and Inertia

Static and Dynamic properties

The misnamed TFC

Controlling bow balance

Centre of Gravity

Finding the centre of gravity

Changing the balance using weight

Weights and Distances

Rods, weights and risers

Controlling bow vibration

Causes of Bow Vibration

Reducing Vibration - Damping

Bow Resonance

Tuned damping - more on TFC’s