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Dual line development 
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Joined: Mon Sep 29, 2003 7:43 pm
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Post Dual line development
We are flying very similar kites in 2010 that we were 20 years ago which is when I started messing about with these things. Whilst they are generally similar they differ greatly in detail. For those who haven't watched this evolution first hand I thought I'd try to point out some ways in which things have changed.

In order to illustrate this I've used three kites - a California Wasp from 1992 (although designed earlier), an Area 51 from 2000 and a Cosmic TC from 2007 - to act as representatives for roughly a decade each.

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All of these kites attach the bridle at the same points; LLE, ULE and T. The Wasp gets an extra, loose line midway between the LLE and ULE that is really there only when the frame gets under heavy strain. The Area 51 sports one of the many variations on the theme of active bridles with lines all over the place making a mobile tow point. The Cosmic uses the recently widespread reverse turbo arrangement.

Also note that the sail of the Wasp is "ripstop nylon" whereas the others are Icarex, with areas of mylar on the Area 51. All use dacron tunnels in the leading edge to hide the spars. The framing layout is identical.

The Area 51 has trick lines to avoid tip wraps and reduce wear on the TE which the Wasp lacks. The Cosmic discards these lines in favour of wear resistant reinforcements and neater wingtips to achieve the same effect.

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Here is one of the areas where development has taken place. The Wasp has a homemade centre-T with vinyl tubes and aluminium tubing cobbled together to do the job. Both of the other kites makes use of specifically designed and manufactured parts.

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Compare the sparring - the Wasp uses arrow shafts, the Area 51 has generic carbon tubes (could be Exel, could be FibreForce, could be almost anything), the Cosmic gets made-for-kiting spars.

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Again the changes in how kites are built is shown; the Wasp has fittings fashioned from whatever bits were deemed suitable, the Area 51 and Cosmic get specific parts. Note the covering that the Cosmic has sprouted, hiding away snag points.

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The area of the standoffs. Once again, the move from homebuilt to manufactured.

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The build of the nose area remains the same from the early '90s, albeit getting cleaner and tidier over the years. The Cosmic is the only kite to sport yoyo stoppers.

What else can we see in terms of design ? Well the Wasp has standoffs that measure 19cm. A Fury .85 has an almost identical wingspan but has standoffs of 28cm. The Wasp is all straight lines, notably in the unspeakably noisy trailing edge, whilst the others make use of gentle curves in both the LEs and TEs.

So.... in reality these kites, separated by nearly 20 years, are remarkably similar in how they are put together. But that's not what we fly them for. We fly them for what they can do and make no mistake the more modern the kite, the more it can do. You might think that the Cosmic doesn't FlicFlac especially well but the Wasp will give you a whole new perspective. The Area 51 might come from the golden age of "trick kites" but just see how well it yoyos. The major progression in these kites is in their performance through finessing details, not revolutionary changes. There's still fun to be had flying an older kite but if you're any kind of enthusiast you'll soon miss the things that the newer kites have made possible.

I'm almost certain I had a point when I started writing this 8-[

Mike.


Fri Apr 09, 2010 10:56 pm
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Post Re: Dual line development
Thanks Mike, a very informative and enjoyable little retrospective. Are you defining the CTC as the paradigm of modern kites? I find it difficult to disagree with that sentiment :cool:

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Fri Apr 09, 2010 11:21 pm
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Post Re: Dual line development
Nice post Mike =D>


Fri Apr 09, 2010 11:23 pm
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Post Re: Dual line development
Thanks for some informative pics. I've always fancied trying a wasp but the construction certainly isn't pretty :shock:


Fri Apr 09, 2010 11:30 pm
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Post Re: Dual line development
Infinitive wrote:
Are you defining the CTC as the paradigm of modern kites?

I'm not suggesting that they are anything more than typical of their respective eras. Certain aspects of each kite are particular to that time.

Mike.


Sat Apr 10, 2010 1:03 am
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Post Re: Dual line development
Ian Newham wrote:
I've always fancied trying a wasp but the construction certainly isn't pretty :shock:

The construction is "of its time" :wink: as is the overall design and flying. Back in '92 you needed to be something of a DIY man to come up with ways to hold your kite together, not just pick up some fittings off the shelf.

Mike.


Sat Apr 10, 2010 1:06 am
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Post Re: Dual line development
More of that FA quality versus quantity here. Thanks for the fine post.

obi

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Sat Apr 10, 2010 7:54 am
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Post Re: Dual line development
Good stuff Mike - thanks =D>

Question - where's the next big development? Surely the fram, sail, fittings and bridle are pretty much optimised, as far as a traingle of sticks and fabric on the end of some string goes anyway. Perhaps a fully rigid, moulded carbonfibre framesail*?

*Just off to patent that as we speak...


Sat Apr 10, 2010 9:03 am
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Post Re: Dual line development
Nice post Mike, thanks.

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Sat Apr 10, 2010 9:11 am
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Post Re: Dual line development
Nice work Mike.

I also like the way style developes in accordance with what's en-vogue at the time as well.

Bryan


Sat Apr 10, 2010 12:42 pm
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Post Re: Dual line development
It occurs to me that I let one fairly important thing slip... the Cosmic is the only one to employ tail weighting. Imagine forgetting that #-o

It is sometimes a surprise what you can make the older kites do. The Cali. Wasp pre-dates the Axel but was one of the kites that it was first explored on. You can make it do some pretty advanced stuff but the real issue comes in getting it into position to execute and getting it cleanly out again. I suppose one of the aims of design development is to increase the possibility and reliability of the moves that get dreamt up. In this respect the changes in build details really pays off - I imagine that the Area 51 would do quite well in a modern setting if the LEs were covered, yoyo stoppers added, etc. etc.

Mike.


Sat Apr 10, 2010 10:21 pm
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Post Re: Dual line development
benjai wrote:
Perhaps a fully rigid, moulded carbonfibre framesail[

A bit of a bugger to carry about the place though :wink: I do think that there is room for experimentation with the framing layout for one thing and in making the whole structure more rigid by making the connections less flexible. A lot of overall stiffness is simply given up with the rubbery LE connectors.

The main disincentive to any radical change is, I suspect, that what we already have and what we've had from before 1992 works for us. The Gemini (and before that the Cyborg) represented an original approach but it didn't really develop any further as the delta-shape does what we ask of it and offers huge scope for variation still.

Mike.


Sat Apr 10, 2010 10:28 pm
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Post Re: Dual line development
Nice work =D> I have often thought where the future of kite design might lead, the final point you make about the accepted shape of kites against more innovative designs is prescient. Though its certainly true that we have what we are accustomed to and like, its hard to imagine any other aerodynamic shape, other than the Rogallo Cone (the established shape of a sport kite), that would tick all the boxes with regards to trick kiting. After all we want quite a list:

1. Consistent low speed flight but over a large range of angle of attack (airflow relative to the kite's axis).
2. The ability to easily stall the sail and equally easily re-establish lift generating airflow.
3. The ability to be stable in a number of orientations; fade, backfloat, pancake and conventional kite flight to name a few.
4. Controllable and rapid maneuverability with equally rapid recovery to controllable stability.

If this is beginning to sound like a lexicon of paradoxes then its a fair, if far from complete summation of the kind of qualities we are looking for. All aerodynamic qualities are trade-offs and the trick the sport kite pulls off is a remarkable one though not least of all because it is restrained by the bridle and the lines. This allows it to be fundamentally unstable and incapable of self recovery as a free flying body making all that maneuverability possible . In this sense its close to "fly by wire", where the wire is Shanti line and the computer is you! The other really clever thing going on is aeroelasticity of the sail (or the deformation of the kite's shape under load) which in itself changes the aerodynamic properties of the kite. When this can be made to occur in a fortuitous manner there are huge improvements to be made.

I suspect that the familiar shape we all associate with sport kites, which started life as Irwin Rogallo's design for a space vehicle return system but saw use in early hang gliders, will be with us a while yet. As Mike intimated with the Gemini, I suspect it will be the finessing of the Rogallo Cone shape and the aeroelastic refinements we can make to it that will squeeze further improvements from the formula.

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Sun Apr 11, 2010 11:51 am
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Post Re: Dual line development
A little tidbit of info about weights. They are not a modern development. People used weights especialy in the tail way back in the early 90s as well. Mostly for improved precision to counter oversteer.


Thu Apr 22, 2010 5:32 am
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Post Re: Dual line development
Nice post... Nice reading !! Thank you mike

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Thu Apr 22, 2010 8:09 am
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