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Super XL Pro ballistics - notfortheatrocious?

Posted by UniBoffin at 16:52 on 12th August 2010 in UniBlog

The story so far – in the last exciting episode “Secret of the Unicorn”, Tintintanium, our lightweight but durable metal hero, formed screw-in dart nose cones which didn’t add much MI (Moment of Inertia). This cunning ruse allowed the new, longer, Sigma XL darts, when fitted with the same flights and magnesium alloy versions of the same shafts, to have the balance and flight characteristics of the existing 950 and 970 Sigma Pros (although not the Ones). It also meant they could have easily replaceable points.

And for me, as far as Sigma XL was concerned, that might well have been MI Mission Impossible accomplished. Then Phil Taylor switched to his smaller DXM flights, which persuaded me to re-examine the potential of similar (just how similar I showed last time) prototype Sigma flights from the 1980s. So now the tale continues….

I’ve explained before just how Sigma Pro darts use their impact angle to improve their accuracy - see, for example, “The Adventure of the Three-Quarter” posted in March 2008 (you can find it, along with all my other past blogs, via the “UniBoffin” link half-way up the right-hand side of the Unicorn Home Page). But for this trick to work properly requires the darts not to stall and stay close to the realms of “linear aerodynamics”, which basically means they mustn’t wobble about too much.

Which explains why this configuration of Sigmas was called “Pro”, because it can help the accuracy of better players who launch their darts reasonably straight, but is less suited to those whose throw induces a lot of that dreaded “wobble”. For such players, high stability is the most obvious aerodynamic trait required, which is where that Sigma One set-up comes into its own.

But one thing which surprised me somewhat when Sigmas started to become more widely used was that the Pro set-up seemed to be proving suitable for a higher percentage of players than I had anticipated - after a bit of practice, even I could use it!

This, combined with The Power’s success with his DXM flights, convinced me that there could be scope for a yet smaller-flighted Sigma dart which used the same accuracy-improving trick as the Pro but was less stable. On the minus side, this would mean it would be more unforgiving in that it would require a cleaner throw to keep it within the realms of linear aerodynamics and hence maintain its carefully crafted inherent accuracy. On the plus side, though, the smaller flights would reduce target obstruction as well as some potentially undesirable second-order aerodynamic effects.

With that in mind, I started to look at set-ups which could turn Sigma barrels, not only the new XLs but also the existing 950s and 970s, into “Super Pro” versions – hard to use properly, maybe, but potentially awesome if you did. And the first thing my calculations indicated was that, for the same set-up to work for both new and old Sigmas, the point protrusion on the XL version should ideally be 3mm less than the XL Pro’s 28mm. The next finding was that, due to mass distribution considerations, an end-loading shaft would be needed instead of a side-loader. However, because the Super Pro, amongst other things, would have a greater requirement for precise and positive flight location than a Sigma One, I didn’t really want to use a plastic shaft.

Fortunately, though, although my sums also revealed that aluminium would be too heavy, they showed that the magnesium alloy used in the Sigma XL Pro side-loading shaft would do the trick. The Sigma XL Super Pro end-loading shaft was thus born.

And so to the Super Pro flight design, which is based on my 1980s prototype flight, with the same delta planform to maximise stall angle. However, the matching shaft having to be an end-loader meant I could – indeed should - reduce the length of the flight a little. This increased its aspect ratio (basically width divided by length), raising lift efficiency, reducing flow interference from the barrel/shaft wake, and improving flight location. This last factor is particularly relevant as it was one reason I specified the side-loading Pro and XL Pro shafts for use with standard Sigma Pro flights.

Of course, the reduced length means the Super Pro flight won’t fit properly in side-loading shafts, but then I didn’t intend it to be used with them, so I must admit I perversely almost see this as something of an advantage – although it still causes worried looks in the Unicorn design and marketing departments!

So now to the punch line – the final joke on me which proves that, even after all these years, I still don’t know everything about dart ballistics. After Q handed over the first Sigma XL Super Pros for me to test, something happened that, even bearing in mind my surprisingly adequate results with Sigma Pros, I really, really, didn’t expect. They were fantastic, OK, but not just fantastic for the intended Maestros of the Oche, fantastic for a 26-merchant like myself. I was suddenly hitting 140s – me!

Although I realise that may just sound like a hyperbolic sales pitch, I promise it’s not. In all truth my scoring didn’t stay exceptional for that long, but it did stay at a level well above my norm. And what I found very interesting was the darts’ impact angles – in the horizontal plane particularly certainly somewhat higher than I was used with more stable set-ups, but with an apparent tendency to make the point swerve into the target bed. The Sigma Pro accuracy trick seemingly made observable.

Of course, most players would find such impact angles disconcerting, to say the least, and that fact alone may mean these darts will indeed, as I had always anticipated, only be suitable for those of a very high level of ability. But I shall always remember that testing session when, just for a while, Super XL Pro ballistics were for the atrocious!

Ethan and Cool Sigmas
Thanks, Ethan – I personally think the new XLs are also pretty hot!

Freddie and Latinum Phase 5s
In the words of The Big Boss, Freddie, Latinum is “a bit Marmite” – love it or hate it!. Nonetheless I’ll pass on your suggestion to him.

Haden, Sigma Pro 950s and Storm Points
The first thing I’d say here, Haden, is that to achieve improved accuracy all Sigma Pros were very precisely designed. Although it would, in theory, be possible for a player to tune a dart set-up to achieve the same trick by trial and error, in practice it’s very difficult to do anything other than find a set-up which minimises impact angle. Which is fine as far as it goes but - as I’ve explained before – obviously prevents that impact angle being used to negate lift-induced inaccuracy.

And that precise Sigma design encompasses the points, whose length, weight, and aerodynamic effect were taken into account in my calculations - as illustrated by the difference in length of Sigma XL Pro and Super Pro points. So using Storm points will affect those calculations (I’ll describe exactly how in a minute). But the good news is that I don’t think the effect would be so significant that it should put you off if you really prefer playing with them. I’ve said before that confidence in their equipment can be more important to a player than advanced aerodynamics, so, if you feel happier playing with Storm points in your Sigmas, then by all means use them.

That said, on to the technical stuff for real keenies! The conical shape of a Storm point will move the centres of both lift and gravity of the dart fractionally forward, which will have opposite, but tiny, effects on aerodynamic stability. Slightly more noticeable may be the increase in MI, which, depending on a player’s release, may cause marginally higher in-flight yaw. However, the effect of any increase in impact yaw on the accuracy mechanism of Sigma 950s and 970s would be in turn partly compensated by the small reduction in point length. Finally, although such points may appear more “streamlined”, any effect on drag will actually be minimal!

There are 3 comments to this post

Posted by Warren at 01:08 on 23rd August 2010

Hi UniBoffin

I am now going to throw a spanner in the works of your full on explaination of the sigma.
I want to throw out a possible challenge as the is something that has me interested.. a SOFTIP Sigma!

18grams with a soft tip point.. I personlly beleive from what I looked at here at home and with a soft tip barrel very similar that it is quite a possibility, so what do you say UniBoffin? Will you accept the challenge and state your theories? As the John lowe barrel is as you know, avaliable in Soft Tip.

Regards from Downunder (Australia)


Posted by Simon at 14:30 on 24th August 2010

hi Uniboffin.

I was fortunate enough to be bought a set of Sigma 970 goldens. Happy days, or so I thought.....

Now i'm not a bad player but obviously have flaws in my throw so straight out of the box I had little control over my scores, ok, I did hit a 140 on the second throw, but trust me, that was a fluke. To cut a long, intricate and potentially technical and boring story short. I have messed around with the aerodynamics (sorry) and i have come up with what I feel to be the best set up for my throw.

Sigma pro 970 golden 25g
Slik Stik Aluminium short (in black which makes no difference to performance but asthetics mean a lot and put pressure on my opposition so please produce some gold ones)
Sigma One flights

So as you can see, things are different to the optomised Unilab original. Could Uniboffin tell me what it is I do in my throw that makes this set up work?

Posted by Ed H at 18:42 on 8th September 2010


What are the barrel dimensions (length, diameter) of the three different weights of the Sigma XL?


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