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 Post subject: Re: Strutlessssss
PostPosted: Fri Jan 28, 2011 7:03 pm 
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Location: Paia, HI
It all depends on what you want. Lift for jumping is not the most important factor in a wave riding kite. In fact you have to build an extra strong surfboard capable of withstanding impact to be able to jump it. So the most important factor for me in wave riding performance is how well the kite floats downwind and how well you can turn the power off to stay in the best part of the wave. Yes the LE is fat on the One. But... don't judge it till you've tried it. I think the Lithium is the other kite in the Airush lineup that has the smaller LE and two extra struts. Similar profile to the One. In a 12m and 15m kite, weight makes a difference.

Strutless is one of several next evolution steps in kite design. I'm sure it has it's downsides. But, weight savings without sacrificing durability and simplicity are important variables in my opinion. If it needs battens forget it in my opinion. If it only does one thing well so be it. If it doesn't easily relaunch when wet in light winds then that is also and issue. The variable are endless.

Prototype kites are the only way to make incremental improvements in a new experimental kite design. I wish I could ride more of the strutless prototypes I've seen. Wish I could say more and was better informed about the work being done. I hope the research continues and a superlight good performing production kite comes to market.



grantman54 wrote:
Quote:
What you save on 2 small bladders you pay on an oversize leading edge.


The Airush One leading edge is huge! Maybe thats a good thing for slowing down the kite if you want a park and ride kite but to me it seems like you will be creating a dead space on the canopy right behind the LE, especially when the kite is at the top of the wind window. Thus losing lift.
I haven't tried it, so maybe the One would actually blow my mind but looking at it from a distance gave me a bad impression.


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 Post subject: Re: Strutlessssss
PostPosted: Fri Jan 28, 2011 8:16 pm 
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Location: shallow sea
Starsky wrote:
...High strut count with tons of bridling can make for loads of stability in high winds, but that just encourages riding with too much kite. We have enough of that already. Idiot proof stability is great for idiots. The rest of us want performance and will gladly rig the right size kite for the conditions to get it...
aren't the cabrinha kites for speed record with 7 struts called high-performance kites? and some low AR hybrid kites with 4 or 3 struts advertised as stable?
i know what you want to say, but if it would be in my power i'd prohibit to use terms performance and stability referring to kites. i mean these terms are complex and largely subjective. there are no simple measuring units to characterize these terms.



i think it is not possible to make a usable and commercially viable single skin kite without a single support of the canopy. even more, i think one central strut kite has pretty much same qualities as the three strut kite.
it is even number of the struts what is senseless.
there have to be a central strut to divide canopy to a different AoA areas producing turning momentum when rider is pulling one side of the bar.
some french brands started with even number of struts, then others followed. but the ones who started it learned the right way to do it - the span between two struts closer to the center of the kite shouldn't exceed 1/3 or may be even 1/4 of the projected wingspan of the kite. otherwise kite will loose its profile, hence lift, air speed and speed of turning.

here is the latest RandD blunder - genetrix origin, expecteted release march 2011. look at the canopy folding on to the leading edge and the correct profile of the LE where the strut is:

http://www.hanglos.net/news/259208/kitesurfnews-genetrix-origin-2011.html


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 Post subject: Re: Strutlessssss
PostPosted: Fri Jan 28, 2011 10:05 pm 
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first, i want to remind about another strutless, single skin kite design:

the naiboo morphine
http://www.niaboo.com/
Image

(those inflated double skin sections are just to make it float on the water, because it has a aluminium rod for the leading edge)

and this leads directly to the second idea:

why not make the struts self-inflating with no bladders but just airtight ripstop and air valves? ram air inflated struts :-)

should be much lighter than those heavy dacron + bladder struts ...

in fact, those leading edge and those struts is what makes a kite heavy !!!
do the math: assuming 40g per squaremeter ripstop, makes

17 sqm * 40 gramm per sqm / 1000 = 0.68 kg for the skin. the rest is for those heavy bladders and dacron and stuff !!


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 Post subject: Re: Strutlessssss
PostPosted: Fri Jan 28, 2011 10:20 pm 
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why not?
i like this design. i guess there will be no problem with the canopy cloth in the near future.

only problem is how to fold the aluminium rod in the back pack compact enough?


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 Post subject: Re: Strutlessssss
PostPosted: Fri Jan 28, 2011 10:25 pm 
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@eree: look at the videos on the homepage. the aluminium rod is foldable like those carbon rods for tents.


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 Post subject: Re: Strutlessssss
PostPosted: Sat Jan 29, 2011 1:19 am 
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Location: Ontario
Windwing seem to make a decent argument for wanting a little luff ability in the centre of the canopy. No centre strut is used in the Hadlow Pro and the Ocean Rodeo Razor. Doesn't appear to hurt them any. Both turn very fast with great power.

Cabrinha's 7 strut kites are exactly what I mean about kites engineered for the kook who insists on taking kites out way overpowered.

Plenty of 3 strut kites that are killer stable, but none are much fun when ridiculously overpowered. Thats why they make em in 5 and 6m sizes.


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 Post subject: Re: Strutlessssss
PostPosted: Sat Jan 29, 2011 3:09 am 
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Location: Wolfe Island Canada
Ya but those 7 strut xbows do rock even for kooks.....;)


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 Post subject: Re: Strutlessssss
PostPosted: Sat Jan 29, 2011 9:16 am 
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herculon wrote:
why not make the struts self-inflating with no bladders but just airtight ripstop and air valves? ram air inflated struts


like one of las year niaboo prototype ... it works...here a classic 5 fith line kite without bladder nor dacron...lighter kitesurf kite ever ;) ! but it's not perfect, it's not finished :

Image

or this last niaboo prototype, with a aluminium tube...it works very well :

Image

sorry I can't put better picture, it's slightly secret...bye


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 Post subject: Re: Strutlessssss
PostPosted: Sat Jan 29, 2011 2:30 pm 
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@funalex: really interesting! i hope we will see some videos soon! a real lightwind single skin kite with minimal bridle - that would be awesome !


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 Post subject: Re: Strutlessssss
PostPosted: Sat Jan 29, 2011 9:26 pm 
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Location: drtuba.eu, kite-stuff.org, eXtremist.si, kajtar.si
@Kamikuza: that might be true in LW. Also I don't thing strutless is good over, say, 13m... IMO in more than 10kts you wont see canopy sticking to the water anymore (like you can see it in say under 8kts at virtually all LW kites). You may also notice that fairly wide tips still raises the canopy so the canopy can still catch wind below and "unstick" the center canopy

@DrLightWind: I don't like battens, even the small ones on the TE's, I'm giving to this a lot of tunning on my designs. Please find some short clip of land testing of one of my latest design below (nothing special for most of the guys here... but can tell a lot). Concave is the one of the keys for sure ;). Also I have few things to work on overall canopy stability in my hands ;)

@2cents worth: the problem of lighter fabric (conventional in kiteboarding) is thickness and strength with that... it is normally more prone to the abrasion, tears, etc... I have some thoughts of using lighter fabrics in my extreme LW projects in future but I'm still "weighting" the decision... I see next step in kite fabric "evolution" in so called nano-fabrics (read way too expensive stuff for now to see it on the market soon I think).

@Bill: there is the truth in your saying, but Booster had at least one initial design problem - its a pure C. One wise man once told me - you won't know until you try it... ;)

@funalex: love your work on your strutless designs, latest do look great! :thumb: Are you still using LE rods on latest?

@eree: we, hobby builders did no center struts ages ago than any commercial company did. The days of ZP and similar were THE days (altho these days are no different :D ) Check the vid below and if you'll notice any profile "breakings" of any kind in the center of the kite (except extreme depowering) I'll buy you a beer! ;) The thing of that Genetrix kite is that they used too thick profile too far forward, but that might also happen when there is not enough wind. Many kites have this issue but if it's small there is no bit problem. Turning momentum has virtually no involvements with center, but with tip area.



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