Shapes, design, pulleys, of wave kites

[zarb]

Hi all, I posted this on the Oz forums but hopefully some more tech minded people can get a bit more of a discussion going on this:

I am curious about the shapes of some of these wave kites being released for 2014 and what affect they have on performance and choice in riding style.
The differences are sometimes enormous (and some more subtle) and although they might be visually noticeable to me, I am unsure about how they change riding characteristics.


On one hand we have the Reo and RRD Religion: They appear to be the most "open" in design.



Then half way towards being more typical "C", there is the Airush Wave:


All the way towards being the most "C" in shape are the upcoming North Dice:


Firstly a question about general shape. The reviews done on the Reo/Airush yield more similar results in power delivery than the RRD compared to the Reo, despite the Reo being more similar shaped to the RRD. Reviews of the RRD say that it generates far more power through turns than the Reo and Airush. Why is this? Are powerful turns more to do with a different build characteristic?

Next a question about the pulleys. The Reo seems to be the only one in the lineup without pulleys. I understand that this is supposed to offer a more direct feel with the kite. But one of the major strengths that reviewers have noted with the RRD is that it offers excellent direct feel, despite having pulleys. Another contradiction with the pulley issue lies in the speed and responsiveness that people have noticed in the Airush Wave. 6 pulleys (?), yet it was noted to be the most responsive and fast kite in the lineup in reviews and not at all "spongey".

If it's true that RRD and Airush have found a way to overcome these once despised pulley characteristics, does this then simplify the argument of pulleys vs no pulleys to a question of "Absorbtion of gusts and better depower" vs "No failure points" respectively? When surfing down the line, strapless, what would be a more desirable characteristic in a wave kite - absorbing gusts and smoothing out a ride with pulleys, or having no complicated pulleys on a bridle to f**k up your kite when you eat sh#t?

As for the North Dice, to me it just looks like a C kite with slightly different wing tips. How is this going to compare to the other kites when it is released?

[zarb]

I was also curious about the claim that pulleys on well designed bridles will smooth out the ride and absorb gusts, as well as give better steering when depowered. To me, this seems just as important riding strapless in the surf, as a direct feeling in the kite given without pulleys (or so it seemed until the Airush and RRD kites).

Here is the claim from the Airush website:

Actually some truth in the design? Or just a load of marketing crap?

Has pulley design reached a point where it's no longer seen as a negative for a kite to have pulleys?

[L0KI]

I believe that pulleys on well designed bridles contribute to smoothing out the ride / absorbing gusts.
And allowing for more back line tension when depowered so steering is more effective while depowered.

[Westozzy]

Told ya zarb first reply already has a lot more than our ignorant fellow Aussies on our local forum.

I suggested zarb post this as I thought it is worth discussion.

Don't let me down international crew, what ya think?

[zarb]

I believe that pulleys on well designed bridles contribute to smoothing out the ride / absorbing gusts.
And allowing for more back line tension when depowered so steering is more effective while depowered.

Along the same vein of pulley design now overcoming that spongey feel to come up with a fast responsive kite, do you think non pulley kites have also overcome the backline tension issues when depowered? The Reo reviews say it has good steering when depowered, which by all accounts shouldnt be true in a non pulley kite right?

[L0KI]

These are my opinions and they are based on my experience.
I've been on many types of kites for a number of years.
I'm an average kiter with limited talent and lay no claim to know shite from shinola about kite design.
I'm in no way interested in arguing with anybody that disagrees with whatever I say.
Not aiming that disclaimer at you Zarb, just covering my ass before a random shark smells blood.

I think you can make great kites without bridles, great kites with bridles and no pulleys, and great kites with bridles and pulleys.
There are many factors and they all matter.

I have only one kite designed for waves (Epic Renegade) and it is bridled with pulleys.

My last experience with a non bridled kite was with the Epic Judge C kite.
Love the kite sheeted in, but when sheeted out the steering suffers a bit.
The Judge works more like C kites used to, where the sheeting range is short and the kite doesn't depower much before the steering is affected.
The Judge has significantly more sheeting range than old school C kites because of wingtip width and shape, but less than bridled kites do.
As we all know, bridled sle/bow/delta kites have massive bar sheeting range and fly/steer well sheeted out.
Kite shape, bridles and pulleys all contribute to this huge range obviously.

I've been on the Ozone C4 kite that is bridled with no pulleys, but it is not a wave specific kite obviously.
The C4 back lines go more slack with less sheeting than the bridled SLE's do but far better than C kites of old.
I've been on Blade Prime C kites that have a bridle with a pulley, the back lines keep better tension when depowered and sheet out more than the C4 does.
The C4 gets it done without a pulley, and does it very well, as all the Ozone kites do.
But the pulley on the Prime helps the sheeting range grow, and I like the Prime better.

I owned Flexifoil Strike four line C kites, I had a Fuel, I had a quiver of Slingshot Octane C kites with 5 lines, I owned a Rebel sle with no bridle but a loaded fifth line, and I've owned bridled sle's, deltas, bows and now bridled C kites.
I think kites feel the way they do based first on all the aspects that go into a kites specific canopy shape, then bridle or not, then the bridle layout and connection points, pulleys or not, then lots of small details.
Just my opinions, and they are free, so we all know what they are worth.

[Westozzy]

Hey I'm gonna argue with you oldnbroken, what you said was sooooo wrong....

Ha ha only joking. I will say the the slack afforded on the C4 is exactly what the freestylers are looking for when getting that bar around.

From an experienced guy in oz...

Wave kites are a little different to some other areas of kiteboarding in that the designer will try to build a kite in the form of what makes sense to them in terms of what they want in a wave kite. Rider input is also sought but some of this depends on the testing conditions and more. Kites like the BWS Noise work best in side to side off conditions. RRD, North and Ozone tend to do much better in the cross-on as well as cross off.

Kite feel is very personal as everyone rides in different conditions so any review is going to be subjective and bias to the riders personal style and body weight. Some kites like Ozone tend to work better for lighter riders on surfboards whereas North have much more power per given size and so suit heavier riders or twin tip riders. Most agree that the best wave kites are the ones that deliver the smoothest uninterrupted power, so in this writers opinion open span kites tend to be too on/off with their power as the kites pivot turn and stall in the turn thus disrupting power during a bottom or top turn then "spiking" the power as the kite re-accelerates across the wind window.

The more vertical larger wingtips force the kites into radius turns which give very consistent power making it easier for the rider to anticipate board trim and body balance during maneuvers on the wave. This equates to a more smooth and less jerky method of riding a wave. The problem is that a kites shape can only offer you about 1/4 of the characteristics of the kite. Wing tip shape, span, pulleys and bridles, canopy profile, and aspect ration all have significant bearings on the "feel" and performance of a kite. When riding in cross off conditions a less responsive kite with good depower is more important than a ballistically fast kite with excellent drift capability.

Drag and power have a huge impact on the demands of a rider on his or her kite. Assuming we are talking about 20 knot winds, a heavier (100kg) rider on a twin tip will not get enough power out of a Reo 10m, compared to a 100 kilo rider on a twin tip on a North kite. This situation is reversed when a light rider is using Norths in strong winds, they simply have too much power when a Reo will be much easier to deal with.

There is no such thing as the one single kite being perfect for everyone in all conditions. All wave riders should remove their blinkers and shut out the opinions of others and should independently evaluate the kites for themselves with a demo in the conditions they will most likely be riding in. If a rider can objectively try several different kites, they will find one works better than the other for them. I am not dissing and brand or model here, there is a kite that is perfect for every rider but you won't find out what is perfect for you unless you try for yourself. "Don't believe the hype" - Public Enemy. There are lots of great kites on the market, and some not so great. Enjoy the search for what works for you.



Ps (from me) the reos turn unpowered really well in my experience. No pulleys.

[L0KI]

Agree with all of that,...well said.
And I would like to try a Reo and Neo, heard they were both very good.

[ChristoffM]

Lots of good comments! I agree that people tend to only evaluate kites based on things they can see (pulleys, C shape or bow shape) whereas other factors might have more influence sometimes.

Lets take the aero profile for instance: From what I know, the profile could affect a number of things:
- how powerful it is when sheeted in
- how powerful it is when sheeted out
- how much bar pressure it has when sheeted in (due to it pitch stability)
- how much bar pressure it has when sheeted out (again due to pitch stability at a lower angle of attack)
- how much drag it has sheeted in
- how much drag it has sheeted out

The above factors could change how much affect the depower will be for a given range- more depower for smaller range might require no pulleys like on the ozones.

The above factors will influence how it turns when depowered, again, maybe influencing whether it needs pulleys or not

It could influence bottom end grunt

Influence upwind ability obviously

influence max depowerability

influence drift ability (if it has too low drag when depowered it will overfly)

influence flying speed

influence how close to the window it normally flies at


and probably a host of other features, which then required the shape of the klite, the bridling, pulleys etc to work together with the chosen aero profile to make a good kite for a certain application. I think it gets too complex to just a kite by its colours (as they say) but the obvious things will give a clue as to what might be expected. I think it is always just best to be able to demo a kite and know what it does, but it is fun for us engineering minds to try and figure out what does what. It just gets a bit too complicated to really know.

Interesting topic. Lets think of some more non-obvious things and how it could affect which parts.

I suspect that maybe aero-profile is not too critical, since all inflatable kites have a big fat round leading edge and single surface canopy, making the aero profile changes not as sensitive as my post might come across. So judging a kite by the obvious factors (pulleys, shape) will always be a good starting point to compare kites, but only a starting point. It is always interesting to meet a kite that outperforms your perceptions of what the kite should be able to do.

[lobodomar]

Firstly a question about general shape. The reviews done on the Reo/Airush yield more similar results in power delivery than the RRD compared to the Reo, despite the Reo being more similar shaped to the RRD. Reviews of the RRD say that it generates far more power through turns than the Reo and Airush. Why is this? Are powerful turns more to do with a different build characteristic?

My guess is the RRD has deeper profiles along the span. If this is the case, it generates not only more power through turns, but more power parked as well.

Next a question about the pulleys. The Reo seems to be the only one in the lineup without pulleys. I understand that this is supposed to offer a more direct feel with the kite. But one of the major strengths that reviewers have noted with the RRD is that it offers excellent direct feel, despite having pulleys. Another contradiction with the pulley issue lies in the speed and responsiveness that people have noticed in the Airush Wave. 6 pulleys (?), yet it was noted to be the most responsive and fast kite in the lineup in reviews and not at all "spongey".

All of these kites are low aspect , have a pretty curved platform spanwise and wide wingtips. That should be enough to provide a direct feel, regardless of having pulleys on the front line bridles.

Direct feel and responsiveness to input also has a lot to do with the rigidity of the wing, which can be highly influenced by:
- panels distribution and "tightness" (in how many segments the canopy is divided and how they are sewn together)
- struts location
- canopy material

If it's true that RRD and Airush have found a way to overcome these once despised pulley characteristics, does this then simplify the argument of pulleys vs no pulleys to a question of "Absorbtion of gusts and better depower" vs "No failure points" respectively? When surfing down the line, strapless, what would be a more desirable characteristic in a wave kite - absorbing gusts and smoothing out a ride with pulleys, or having no complicated pulleys on a bridle to f**k up your kite when you eat sh#t?

I think that for this sort of kite, in which responsiveness is already there, the main downside (but it may not be a downside, if the kite is designed well) of pulleys is a less gradual power delivery through sheeting. Since with pulleys you decrease the angle of attack more for a given bar push, there could be an on-off feel through sheeting if the kite is not designed well. On the other hand, having a lot of depower on tap is extremely desirable on a surf kite, specially strapless.
I have never ridden a reo, but my guess is that it has a more gradual sheeting power delivery, and yet is able to reach about the same level of depower as the Airush and RRD, probably because it uses shalower profiles anlong the span. That would explain why low-end is not its forte, at least from what I've read.

As for the North Dice, to me it just looks like a C kite with slightly different wing tips. How is this going to compare to the other kites when it is released?

I have no idea!