Stop Press! In an uncharacteristic fit of astounding generosity, I have decided to commence this my second year of uniBlogging by offering a small but truly unique prize to an attentive reader. And that could mean you, so hopefully you’ll see that as a good reason to keep reading even if you’re not a student of dart aerodynamics!
But first our customary dip into the barmy, sorry, balmy waters of that topic! There’s recently been some considerable interest in dart nose cones and their possible effect on dart flight, so it seems appropriate to give my perspective on them. Basically, I think they’re quite a good idea – in fact at the end of last year I was even considering a metal nose cone as a possible feature on what were to be the next Sigma darts. Hence, somewhere in the bowels of the Dart Cave, are some prototype nose cone Sigma sets that Q, Unicorn’s engineering wizard, made up before we settled on the 950 design.
So what are the pros and cons of nose cones? Well, the obvious pros are the mitigation of damage to flights during close grouping, combined with a possible reduction in bounce-outs. The main con, as far as metal nose cones on Sigma 950s was concerned, was the difficulty of incorporating them in a barrel design which matched the in-flight characteristics of Sigma 970s, a factor which I felt was important. Apart from anything else, it was key to enabling the same shaft/flights combinations to be used.
We did also briefly consider plastic nose cones, but somehow the idea didn’t quite seem to fit in with the hi-tec Sigma image. But maybe we were wrong! I certainly wouldn’t rule out the prospect of revisiting the concept for future Sigma designs.
But that’s all a bit “beside the point”, I’m supposed to be looking at the aerodynamic effect of nose cones. And, to be honest, they won’t have much. Theoretically, the shoulder on flat-nosed darts will create a tiny low-pressure “separation bubble” which moves the effective centre of pressure of the nose lift very slightly rearwards and hence increases stability by a tiny amount, which is why blunt-fronted shapes are generally more aerodynamically stable than streamlined ones. Drag, on the other hand, will be higher, but with darts this effect will be too small to notice.
However, although a nose cone on a dart might fractionally reduce stability, the improvement in flow separation will result in slightly more “linear” aerodynamics, so what you lose on the roundabouts you gain on the swings and the aerodynamic effects should not outweigh any benefits in terms of flight damage and bounce outs.
And now for something not completely different. On the subject of nose cones I must confess that the reasons for the excessive munificence promised in my first paragraph are not completely altruistic but are partly to make some amends for the fact that I have been labouring under a bit of a misapprehension. After we discarded the nose cone idea for what are now called Sigma 950s, I moved to a straightforward 97% tungsten design which incorporated a slight chamfer on the nose to help reduce flight damage. However, when Q duly produced a set of prototypes it became apparent that the brittle 97% alloy would fracture during mass production far too often for comfort.
As I have previously explained, the decision was hence made to go to a more malleable 95% alloy (which meant an emergency barrel re-design to maintain the aerodynamic properties and hence some dedicated burning of the midnight oil – a bit of a shock as we research scientists aren’t used to deadlines!). And that, as far as I knew, was that - except it wasn’t! Over in the factory the chamfer was still causing problems and was thus omitted from the final product. Unfortunately, due to a slight confusion over the meaning of an “increased taper”, I thought it was still there.
So, in compensation for my error, I am offering that one-off set of 97% Sigma 22g prototypes (sort of 970/950s), complete with their slight chamfer, to the reader with the best memory (and “nose” for a bargain?). If ever three darts can be truly unique, these are and, although they are not quite to Unicorn production standard, they are nonetheless a testament to Q’s engineering skill and ability. Moreover, they have been used by yours truly (although I’m not sure that’s so much of a recommendation!).
To avail yourself of this once-in-a-lifetime opportunity, simply be the first to post a comment to this blog telling me which Unicorn Maestro I said was definitely not a novice. All being well, I plan to announce the winner in my next blog, so Good Luck!
Q&As
Deon and Arif on Sigma 950s v 970s
Perceptive comments on the differences between Sigma 950s and 970s, guys! Deon is correct that the centre of grooving on 950s is behind the maximum diameter whereas that on 970s is more coincident. The 970 pattern was designed to encourage a finger/thumb balance “John Lowe” type grip, which, it can be argued, is theoretically purer from a scientific viewpoint. However, many players use a “thumb push” grip which the 950 accommodates somewhat better. As these players include Phil Taylor, I for one wouldn’t like to say it wasn’t at least as effective! Finally, it’s probably worth saying that the lower tungsten percentage on 950s doesn’t mean they’re intrinsically inferior to the 970s, but it does mean that the top available weight has to be 1g less.
Incidentally, talking of John Lowe, I’ve heard people say that Sigma Pro flights aren’t new but are just copies of ones he once used. Well, they’re half right! As I told Red in the Q&As to my “The Good, the Bad and the Ungainly” blog: “The basic design for Sigma darts was formulated nearly a quarter of a century ago and the flights you saw John Lowe use on TV were indeed prototypes for those now used on the Sigma Pro.”
Bob and Sigma Set-ups
Thanks for all your feedback on Sigmas, Bob! The nose issue I hope I’ve covered enough above and, as for gold finishes, I’ll admit to being rather too dismissive of them just being a colour change as they do have a slightly different feel to plain tungsten. On your other points, Q tells me he is correcting the Sigma 950 cards and also says he’s not keen on supplying o-rings as standard, partly because they can sometimes interfere with a player’s grip. As for changing the Sigma set-up, are you sure the kicked-up tail with the Ones doesn’t just reflect the trajectory impact angle? Finally the longer shaft on the Pro contributes to increasing the moment of inertia and hence lengthening the yaw wavelength - which, as I’ve explained in previous blogs, can help the accuracy for better players (so it could be a good sign that you prefer this set-up!). Finally, thanks to you, Warren and Deon for the birthday wishes!