One of the most confusing things in initial trials of Bird2 was the huge difference in preferred and also perceived speed. Trialling was initially done with county standard or feather club players and the speed was set to their preference. When we started to test in larger numbers with nylon clubs the early production was thought to be too fast. Measuring ‘medium’ speed Yonex 370s and 300s and others they averaged slow to very slow in speed tests. The assumption is that nylon club players like a good rally and the slower shuttle gives a bit more control around the net where the standard nylon design is less controllable off the racket face. Feather users expect to be able to clear from back to back without straining every sinew to do so, so feathers shuttles are very carefully measured and are offered in a bigger range of speeds but on the whole faster than nylons in terms of distance travelled.
However there are many different aspects to speed. Speed is a function of shape, structure, spin and weight. The standard nylon design is inherently slower so they tend to be heavier than feathers as they move slower through the air. But, in reverse, when playing a tight net shot they travel faster, as they bleed air more readily and therefore travel further upwards before turning over. This leads to a higher bounce (less control) and slower ‘righting’. It also explains the odd description of ‘heavy’ from players who have not used feathers before. Feathers form an almost complete baffle and cup more air when in reverse and, along with some other unique characteristics of feathers, this means a slight hysteresis on contact and an increase in perceived weight. This means that they travel slower, bounce lower and right more quickly. Even with Bird2 shuttles of the same actual weight as standard nylons they were sometimes referred to as feeling heavy as they cup more air similar to feather shuttle. The new production tools will produce a slightly lighter shuttle but with the same ability to cup more air.
Spin rate and spin characteristics are significant for most sports projectiles. The infamous Adidas Jabulani 2010 World Cup ball has been replaced by the Brazuca ball for Brazil. Although the Jabulani ball was felt to be too light, the main problem was the unpredictability of its flight. Although goalkeepers were confused, mostly it affected accuracy on long shots. No word from Adidas but I expect the pattern on the eight panel construction adversely affected the laminar flow across the surface and hence the spin rate, and/or there was less grip on the boot. Whatever it will be replaced by the Brazuca ball with a new crazily patterned six panel design which Adidas says has a more consistent flight.
The performance of a golf ball is affected by spin more than any other projectile. The first golf balls were made of various materials with a rough surface and when they started to mould them with a smooth surface they didn't fly so far. A golf ball climbs up in the air and therefore carries further due the back spin imparted by the slight downward path of the club and the angle of the clubface. The rough surface helped reduce the drag on the ball so the first moulded balls were made with small raised squares which evolved into the familiar dimples as they were more durable and easier to clean.
The spin of a cricket ball affects the flight but more important for swing is the seam. The trick is to deliver the ball without spin such that the seam causes much greater drag on one side of the ball compared with the other. One is allowed to clean the ball which means one side can be polished although it is illegal to rough up the other side, although this is common practice. I was taught that the smooth side should go through the air more quickly; I suspect the opposite is true, anyone tested this?
Picking at the seam of a cricket ball is illegal as is tampering with the feathers on a shuttlecock. However, in both cases cleaning or smoothing is allowed and this makes it difficult to be sure what is going on. Consistency of performance such that people know that a particular action will have a predictable result is all important as skill levels increase. Consistency in the flight of a shuttle is paramount at a high level where centimetres can be crucial and, as good as feathers feel, people do get frustrated when their perfectly weighted clear drifts out for the umpteenth time.
Badminton is the only sport that uses a handed projectile. The anticlockwise rotation of a feather shuttlecock causes it to veer to the right. This means that a high clear will be drifting slightly out on the left side (when you are the receiver) and vice versa. In match play analysis we see twice as many errors on leaves made on the right side because of this. I have not spoken to any coaches who take account of this.
This off-set feature of feather shuttles makes the game slightly more difficult for left-handers. A right handed out-to-in slice shot is hit in the same direction as the lay of the feathers. This increases the spin in the normal direction, opening up the feathers which improves the drop shot and helps accuracy. Left-handers hit into the lay of the feathers (often causing damage) and puts reverse spin on the shuttle which fights the natural direction of spin, thus losing a degree of control.
Tests have shown that Bird2 has a good spin rate and gets more grip on the strings than conventional nylons without opening up or getting damaged like feathers.
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