In my last uniBlog I looked at the science behind Unicorn Sigma dart barrels and described, amongst other things, how their low MI (moment of inertia) allowed maximum scope for designing aerodynamically optimum shafts and flights for them.
I’m now going to look at this topic in a bit more detail and explain how the Sigma Pro and Sigma One steel tip darts can share the same barrels but be optimised for different standards of player. In doing so, I’ll also be touching on some of the aerodynamic theory which causes uniLab to recommend different darts for different players.
But first I want to answer a question that no-one has yet asked me, although I expect they soon would have done! If Sigma darts were designed using uniLab, why doesn’t it ever recommend them? Well, the answer is simple - Sigma barrels, shafts and flights are deliberately excluded from uniLab’s database, not only because they would tend to dominate its recommendations, but also because they were designed as a co-ordinated unit rather than for use with other components. However, rest assured that, for many players (providing they didn’t express a preference for a different barrel shape or grip), the uniLab Selector would recommend Sigma if it were allowed to do so.
And, if uniLab were so allowed and you used it to look for a steel tip dart and put in your standard as “Pro”, it would duly tend to recommend the Pro version, whereas, if you were not so ambitious with your skill rating, it would tend to recommend the One. The reason it would do that is because the program adjusts the importance of a dart’s various aerodynamic characteristics depending on standard. The better the player, the more important millimetric accuracy compared to, for example, in-flight stability.
This raises the key question of how can a dart be more accurate? After all, it’s not a guided missile; it doesn’t know where you’re aiming. If you throw it at the treble 1 rather than treble 20, the dart can’t decide you made a mistake and divert accordingly!
Well, of course it’s true that no amount of aerodynamics can compensate if a dart is thrown in the wrong direction, but it can make one thrown in the right direction miss the target. And it can do this in two main ways. Firstly, in-flight yaw as well as any asymmetries in the dart itself can cause the very aerodynamic lift which stabilises it to throw it off course. Secondly, remembering that it’s the CG of a dart which follows the trajectory along which it’s thrown but it isn’t the CG which sticks in the board, any inconsistency in a dart’s yawing motion will cause a variation in the relative locations of the CG and point at impact, and that would be a source of inaccuracy.
Unfortunately, these two mechanisms create a slight conflict of interest. The first implies that, to make a dart more accurate, the lift from its flights should be minimised. The second implies that the lift should be maximised to make the dart as stable as possible and minimise any variation in impact angle. To reconcile this conflict as best we can, we need to decide on the relative importance of these two sources of inaccuracy. This is where the standard of the player becomes a factor.
UniLab uses the principle that the throw of a better player will tend to create more consistent (and, generally, lower amplitude) yawing motion than that of their less skilful counterparts. The relative weightings on the sources of inaccuracy I’ve outlined are thus adjusted accordingly.
In addition, the lower the standard of player, the greater the importance that is placed on dart stability in its own right. Irrespective of its accuracy, a dart that flies and hits the board at pronounced angles will have less predictable aerodynamics (exactly what I mean by that I’ll explain another time) and is more likely either to bounce out (especially in soft-tip boards) or block follow-up darts.
The design logic behind the Sigma Pro and Sigma One should now be becoming a bit clearer. The low MI of the barrel means that, for both versions, the different levels of stability required can be achieved with a relatively small, low lift, flight, thereby maximising accuracy. And the required stability of the One, designed for the improving player, is greater than the required stability of the all-out-for-accuracy Pro, which is why the One has a lighter shaft and larger flights (although there’s a lot more to their design differences than just that).
And the topic for next time? Just what those “required stabilities” are and why!