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Author Topic: Kitemaking v. sailmaking.  (Read 2412 times)
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Old Greebo
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« on: October 18, 2010, 03:29 PM »

Now yes, I'm a newbie.  I so far own, and am flying, a HQ Yukon.
Please don't sneer - it's the kite that I bought here in the UK earlier this summer, having been reintroduced to kites and kiting by a not-quite son-in-law (don't ask!) in Western Australia.  That was 6 months ago.
He let me fly both of his kites.  Firstly the Huntsman (a 2.5m span monster that kept dragging me by the heels over the sand of Two Rocks Beach).  Secondly the Redback, which at 1.8 metres was easier to handle but still provided incredible excitement.

Both kites, when assembled, were taut and flat.
No, I don't mean flat - they had shape and style.  BUT they didn't have wrinkles or any looseness in the sail.
When I assemble my Yukon, no matter how careful I am to get the standoffs in the right position, the sail is wrinkly.

In my younger days (heck, I'm talking about the nineteen fifties here!) my dad had a sailing dinghy.  It had a set of sails made by Gowens of West Mersea.  Me, I had a canoe, and I wanted to make a set of sails for it so that I wouldn't have to paddle the thing everywhere I went!  And as Gowens were less than 50 yards from the causeway where I used to launch my canoe, I went to them hoping to get some hints.

Their hints boiled down to one main thing.  Well OK, two.
The second one is that the sail shouldn't be dead flat.  It should have a degree of 'belly'.  And the 'belly' of a sail depended on very precise measurement of the strips of cloth that were sewn together to form the sail.
The first one is that unintended wrinkles in a sail have a seriously bad effect on the sail's efficiency.

And yet ...
My Yukon  -  my little, less-than-1.6-metres across Yukon, is a sail.  And it has more wrinkles than me!  And I'm 74!
Worse!  I've been looking for a Better Kite.  But I've been horrified to see how many of the upper-end kites are proudly advertised, by their manufacturers, with crumpled-up sails.  Take a look at the pictures they post on their web sites.
I'm not only talking about the mass-produced jobs.  Look at some of the boutique sites.  No, I won't name names, but sorry, there seem to be wrinkles on view everywhere!

Is there any cross-fertilisation between the sailmaking and the kitemaking fraternities?  Can any of the boutique kite guys claim to have served an apprenticeship in a proper sailmaker's loft?  If not, what other skills can they tempt me with?  Or do I just have to listen to their acolytes and be converted to The Faith?

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Will Sturdy
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« Reply #1 on: October 18, 2010, 04:23 PM »

Kites and sails have a lot in common, but they are to do two very different things.

All a sail has to do is produce lift/driving the boat. Making lift is just a small portion of what a sport kite sail must do.

Some kites like speed kites do use more 'proper' sail design techniques. If you look at them they generally have very smooth skins with some belly. They only have to exhibit a minimal amount of control though, so they have basically the same goals as a sail.

Trick/competition kites are an entirely different story. I like my trailing edge to buzz. I find that helps slow the kite down and improve control. No decent sail would ever buzz.
My sails have a ton of wrinkles. That disrupts the airflow. I have found that that helps a kite stall a bit more easily. Others may disagree, but that's been my findings.
I personally haven't experimented much with broadseaming. I just don't have the time or resources to do enough experimenting to really optimize anything with that. Some of my kites are framed to add a bit of the same effect to the sail though - like the saber's spine is really pulled back by the upper spreader, which means that the sail has a sharper 'v' in normal flight than it otherwise would, helping tracking immensely. So in my case they are accentuated purposely.

Some folks like Ken at blue moon have done some work with real broadseaming and that's one of the things that lets the mojo fly in so little wind. I don't think any of his newer kites use broadseaming though (am I wrong here?)

I do think that there's lots we could learn from sail design theory that's yet to be explored with kites, but very little of it is directly applicable.

I don't know of any kitemakers who sell their kites and have any actual training in sail aerodynamical theory and construction. I'd trust someone with experience in kite design over someone limited to sail design when it comes to kites though.

And if you really want to try to advance kite designs, you can always design and make your own kites. It's not that hard and you could be on to something.  Smiley
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mikenchico
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« Reply #2 on: October 18, 2010, 04:54 PM »

Also I think most of the pictures you are refering to are ground shots, much of the wrinkling disappears when the kite is flown. Many sails have battens that tension the sail more then our kites, except for the speed kites we've gotten away from battened sails for the most part.

But take a look at Tim Benson's kites,  I think they have some of the tightest, smoothest sails available right now.
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« Reply #3 on: October 19, 2010, 12:41 AM »

As others have said lots of makers have used broadseamed or 3 dimensional sails, and many of the tricks used in obtaining some billow in the sail without resorting to broadseaming will manifest themselves as wrinkles while the sail is at rest. eg wrinkles around the lower spreader connectors often hint at a sail where the cut or the direction of weave in certain panels will generate some billow a couple of inches inboard of the leading edge. Others have made kites with sails as smooth and tight as drum skins that ping audibly if you flick them. Neither is good or bad, all have different tradeoffs.

A 3 Dimensional sail is good for a sail whose main purpose is to generate lift/pull while in flight or simply fly smoothly e.g. A boat sail, buggy engines and kites designed to fly in the least possible wind. A very tight sail will tend to be fast and responsive, sometimes to the point of being twitchy. However most high end stunt kites these days are designed for tricks; for tricking you want the kite to stall easily and fly slowly. For that you don't need billow in the sail, and you don't need a sail that's super efficient so typically they're fairly flat but not overly taut and often have loose trailing edges to generate drag and slow the kite down.

One technique doesn't work for all types of kite, some kites are taut as a drum such as the Benson Deep Space but some people find them over responsive, others love them. On the other hand some kites have slack sails such as the NSR, which has probably had more competition success than any other kite. Wrinkly sails, tight, 3 dimensional broadseamed all have their applications.

Different strokes or whatever, but if its wrinkly its not necessarily bad.

Have a look at Benson, JoE & Blue Moon Kites for sails that are as good as it gets and for competition inspired design have a look at Carl Robertshaw, Shaun Tinkham and RSky kites
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Old Greebo
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« Reply #4 on: October 19, 2010, 01:42 PM »

Thanks for the replies.
I wasn't trying to be clever (and no, I don't think anyone was accusing me of that).  It just seemed to me that a kite was a sail.  And I think you refer to the fabric part of the kite as a sail, don't you?
So I guessed - assumed - there would be some sort of parallel between the skills of sailmakers for sailing, and sailmakers for kitemaking.  Both types of sail are designed to create energy for driving a heavier-than-air object.  The kite has to be driven through the air.  The boat has to be driven over the surface of the water.  But I would have thought that the principle was the same.
You all make points that (as a newbie) I have to accept as valid.  But ...
Let's return to my rather-less-than boutique Yukon.   If I hold it up in a fair breeze, it billows out a bit but it still shows wrinkles.  And I grudgingly accept that because I know it's a cheap, mass-manufactured-in-China kite.
[Sorry HQ, if you're looking in, but you and I both know that that is how it is!]

But if a kite costs 200, and you hold it up to the wind, shouldn't the sail billow out nicely and show beautiful, totally wrinkle-less curves?  And don't try to kid me that the wrinkles are (to use computer-speak) a feature rather than a problem!
Maybe it's easier to create a wrinkle-free sail when you're working with something that will go up a 10-metre mast, instead of just gracing a couple of 1.5-metre lengths of 5mm carbon fibre?


Anyway ...
I've been selling off my old archery equipment on eBay, with the intention of using the proceeds to purchase a really nice kite.  When I'm finished, I expect to have something like 300 available.
What I'd like to have is a nice, big 2-line delta that tries (without quite succeeding) to pull my arms out of their armpit sockets in a force 5.  I want it to be fast, without being unmanageable.  I want to do manoeuvres, but I'm not desperate to do all the clever, flippy-over-and-look-pretty stuff that I keep seeing on the promotional videos.  If I can ever master the stunts shown in http://www.kite.net.au/manouvres.htm I'll be satisfied.   I particularly like the Bristol!

Suggestions, anyone?
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RonG
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« Reply #5 on: October 19, 2010, 03:12 PM »

Some folks like Ken at blue moon have done some work with real broadseaming and that's one of the things that lets the mojo fly in so little wind. I don't think any of his newer kites use broadseaming though (am I wrong here?)

Paul Shuman of Aerodrone Kites also did quite a bit with broadseaming back in the day.  My old competition Stripes was a wonderful kite that flew in remarkably low wind for its considerable weight, largely owing to the broadseaming.  Once the wind hit 10mph though, the kite became a buggy engine.  Therein lies the Achilles heel of a super-efficient, boat sail-inspired sport kite.

Loved those kites, but these days I'll stick with my loud, relatively aerodynamically-incorrect kite sails.
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tpatter
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« Reply #6 on: October 19, 2010, 03:28 PM »

But if a kite costs 200, and you hold it up to the wind, shouldn't the sail billow out nicely and show beautiful, totally wrinkle-less curves?  And don't try to kid me that the wrinkles are (to use computer-speak) a feature rather than a problem!

This is one of my most favorite sites to see! Nothing quite like watching a powered up kite fly across the window with the sail bulging, sail buzzing, and lower LEs slightly angled due to the pressure. 

Its the kites "war face".
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« Reply #7 on: October 19, 2010, 03:42 PM »

What I'd like to have is a nice, big 2-line delta that tries (without quite succeeding) to pull my arms out of their armpit sockets in a force 5.  I want it to be fast, without being unmanageable.  I want to do manoeuvres, but I'm not desperate to do all the clever, flippy-over-and-look-pretty stuff that I keep seeing on the promotional videos.  If I can ever master the stunts shown in http://www.kite.net.au/manouvres.htm I'll be satisfied.   I particularly like the Bristol!

Suggestions, anyone?


Since you're in the UK I'd suggest a Carl Robertshaw Fury: big, very well made, pulls like a truck in a stiff breeze and excels at precision figures like those in your link. You can enjoy the pull and the figures now but if you want to expand your horizons later they're pretty good at the flippy stuff too (with some practice).
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« Reply #8 on: October 19, 2010, 03:59 PM »

Or just go with a power kite.  Something like the Ozone Flow or Prism Tensor.  Once those sails get filled there are no wrinkles, they do loops and will yank you out of your socks if the wind is strong enough.
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mikenchico
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« Reply #9 on: October 19, 2010, 06:29 PM »

Or a Flexifoil 8 or 10, fast, smooth, hard pulling kites that will draw a crowd.
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JimB
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« Reply #10 on: October 19, 2010, 09:38 PM »

This.

What I'd like to have is a nice, big 2-line delta that tries (without quite succeeding) to pull my arms out of their armpit sockets in a force 5.  I want it to be fast, without being unmanageable.  I want to do manoeuvres, but I'm not desperate to do all the clever, flippy-over-and-look-pretty stuff that I keep seeing on the promotional videos.  If I can ever master the stunts shown in http://www.kite.net.au/manouvres.htm I'll be satisfied.   I particularly like the Bristol!

Suggestions, anyone?


Since you're in the UK I'd suggest a Carl Robertshaw Fury: big, very well made, pulls like a truck in a stiff breeze and excels at precision figures like those in your link. You can enjoy the pull and the figures now but if you want to expand your horizons later they're pretty good at the flippy stuff too (with some practice).
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Old Greebo
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« Reply #11 on: October 20, 2010, 03:03 PM »

Thanks IN and JB.
I've been looking at the Fury.  There's a little drool of lust appearing at the corner of my mouth, but it's rapidly being mopped up by the blotting-paper of the price tag!  I was hoping 300 would get me two decent kites!
And I suppose strings and a natty little kite bag would be extra!
Having briefly flown, and enjoyed, the Aussie Huntsman (which would cost me $aus369, or about 230 in local, rapidly-declining UK money), I'll confess I'm more tempted by that one than the Fury.  See XXXXXXXXXXXXXXXXXXXXXXXXXX for details.
But I'm a learner.   What do I know?
Do we have any experienced members from Down Under who have encountered the Huntsman, and who could post a (brief or otherwise) review?
Come to think of it, am I posting this enquiry in a completely wrong thread?   Apologies if so.

Please. No direct links to other kitestores. Il Duce
« Last Edit: October 20, 2010, 04:41 PM by chilese » Logged
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« Reply #12 on: October 20, 2010, 04:13 PM »

According to the KRD price list, the Fury Standard in Skyshark is 190.  Even the Aerostuff version is 255.  Even allowing for P+P this is signiificantly cheaper than 300 price tag you appear to have quoted.

I'm not going to pretend I know anything about the Huntsman, but the Fury is a World Championship winning kite and I can't believe that the Huntsman has the same pedigree.

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Old Greebo
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« Reply #13 on: October 20, 2010, 05:16 PM »

I have to admit you're right, Jaydub.  I think I must have been blinded by the sight of price tags on other, more specialist kites on the KRD website.
But I'd still like to know if anyone here can report on the Huntsman ...
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chilese
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« Reply #14 on: October 20, 2010, 06:22 PM »

Strictly from the panel layout....

My guess is the Huntsman is a much older design.

I have a Fury. It is an excellent, large, slow moving precision kite which will do modern tricks and lengthen your arms in a strong wind.

Here is a photo showing two similar 8 foot excellent kites.
The kite on the ground is by Paul Shuman (mentioned by the taut skinned RonG)

« Last Edit: October 20, 2010, 06:23 PM by chilese » Logged

John Chilese: Las Vegas, NV
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