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Concept'air 12m Pulsion kite

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kitexpert
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Re: Concept'air 12m Pulsion kite

Postby kitexpert » Mon Feb 04, 2019 11:01 pm

Well done if you were able to ride and others not.

Last snow kite season on a very light wind day a young local kiter (at least 20lbs lighter than me) came to spot and rigged his 14m LEI. He was suspicious for the wind but he wanted to try anyway. After some time it was obvious he couldn't get his kite properly in the air, it just back stalled down before he was ready to go or at best dropped after couple of seconds when he was moving. He cursed another missed opportunity out loudly, there had been a couple of weeks of light wind only.

I was finishing my session (17m LEI) and after packing my kite and watching his attempts I asked if I could try. My intention wasn't to embarrass him but to show him how to pull kite up and immediately loop it to create power and get going. I did a short trip out and back, it wasn't good kiting but I wasn't yet struggling too much. He was a bit amazed, but there wasn't much reason to. Actually it was far from my real fights with low wind, once it took couple of hours constant looping to get some miles done back to my car. One mistake and kite would have dropped leading to difficult or impossible relaunch.

Reasons why this young guy couldn't do it: he didn't have enough strength for long steady pull, he didn't know how to loop it correctly and to use generated power, he didn't know which is correct direction to go after start and he let kite too far to the edge of the WW.

Low wind kiting needs precision, it punishes from mistakes. How well it finally goes depends on many things, kiter skill is one of the most important factor.

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jakemoore
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Re: Concept'air 12m Pulsion kite

Postby jakemoore » Tue Feb 05, 2019 6:30 am

kitexpert wrote: This must be called pilot incapability, lack of try or BS. Problem is not to get kite in the air but to develop enough power to get going without losing ground. Looping kite constantly and dragging yourself slowly downwind is possible in lightest of winds but it doesn't make much sense.
No doubt a kite that weighs less helps quite a lot. One strut LEI flies sooner than a many strut LEI. No struts are lighter still. Foil kites have a better efficiency than the no struts but wider and slower turn.

An ultralight foil or single skin that flies sooner than any tube kite is really no surprise. My normal cloth foils weigh less than my one struts by a kilogram. It does not take an expert to to guess how hanging an extra kilo on a kite would affect it in light winds. Maybe a CAD would help?

It fascinates me that the Pulsion is staying in the air better than the single-skins. That is the surprising result.

Regis, what weight cloth did you choose? And how much does the kite weight?

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Re: Concept'air 12m Pulsion kite

Postby Regis-de-giens » Tue Feb 05, 2019 11:33 am

Of course a beginner who does not combine loop and adapted bar stroke on the kite will get limited low-end ; it is obvious, no need to repeat this side argument every time. It would not have been fair if I had compared different pilots skills without mentioning it. It was not the case.

Your are right Jakemoore, kite weight is (obvious I agree with you, but unfortunately not for some people) one leading parameter. Indeed it can be surprising that Pulsion flies with less wind than a single skin, but weight are almost the same actually, since single skin use heavier cloth; if I had to detail my feeling, I would say that wind is similar for the kite at the zenith, but Pulsion is more stable and efficient when working it in the very lower end (and restarts better at the next "gust" thanks to the entraped air that keeps its shape). This better low wind flight has also been reported by a friend some month ago.

Today I have my 3rd model of Pulsion, that I had in several cloths previously with the following weights (on the same calibrated chemical balance):
1- 27gr intra+extrados /40 gr intercells: 1750 gr
2- "new" 32 gr everywhere : 1750 gr (others have measured it at 1600 gr, scale tolerance IMO)
3- my current one : 27 gr everywhere : 1618 gr (1900 gr for the 15m)

Now if you want my personal analysis / estimation on weight impact :

- zenith : for the fly limit in the air at the zenith, lift shall be proportional to weight ; moreover lift is proportional to (wind speed)^2 ; so as a consequence, if you save 25 % of weight, you should save 13% of minimum wind. Low arch is a good point , limited ratio will be in favor of zenith stability at very low wind (I experienced this with my ex Pulsion 18m , same cloth higher Aspect ratio and and a bit less stable).

- looping : the story becomes more articulated if you consider you are actively working the kite, because then it will depend on both its L/D ratio when crossing the window (flat arch + high aspect ratio is better like for running-360 Degree exercizes for example) and its ability to keep its fly quality and speed during a turn (flat arch + high aspect ratio is now worse). So even if the light weight has a great impact on both phases, a balance has to be found between antinomic design parameters, which is extremely hard to modelize correctly in numerical simulations (transient states, low wind pressure, air filets local detachments, potentially several Reynolds numbers spread along the kite ...) hence designers skills.

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Re: Concept'air 12m Pulsion kite

Postby kitexpert » Tue Feb 05, 2019 6:39 pm

jakemoore wrote:
Tue Feb 05, 2019 6:30 am
No doubt a kite that weighs less helps quite a lot.
Low weight does not make kite any bigger or make it pull more. For design point of view making kite from lighter material is trivial, no amount of CAD can help that. If 12m kite weights 132g more or less isn't very interesting.

But when FS makes very complex Soul such a light weight kite, that is interesting and admirable.

Last winter I had a session with 12m Nitro2, it was quite light wind perhaps 8-10kn. I had good time with it and it is not a light weight kite but heavy.

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Re: Concept'air 12m Pulsion kite

Postby jakemoore » Tue Feb 05, 2019 7:10 pm

kitexpert wrote:
Tue Feb 05, 2019 6:39 pm
Low weight does not make kite any bigger or make it pull more. For design point of view making kite from lighter material is trivial,
10 knots is force 3. 6 knots is force 2. I start to consider flying tube kites at 12 knots. I can go lower but is less fun.

Yes a kite that pulls harder can lift in lighter wind.

At minimum, lighter wing loading makes a bigger kite practical. My experience is there is a difference, in pull especially at the light air. Less force from gravity allows the kite to rise to zenith faster and a better loop for power. Less kite weight and line tension required to keep the kite in the air allows deeper downwind angles.

Then there are the lulls and moments when line tension is lost bobbing up and down in shore break while dragging deep enough to waterstart. Yes I have done kite 360 running in a circle in zero wind with Flysurfer Psycho 1 12.5m. It’s exhausting but was a functioning alternative to the 24M C kites of its era. Good luck running upwind in ankle deep snow.

Indoor kites are above all light. No doubt the Soul is a marvel of engineering and design. Soul in 15m is 840g or 30% heavier than the lightest Pulsion. How much would a cyclist pay to shave 840g off a 9 kg bike. I wish the problem of weight was trivial enough to have more contenders in Force 2.

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Re: Concept'air 12m Pulsion kite

Postby jakemoore » Tue Feb 05, 2019 11:52 pm

Regis, it looks like you have had a couple of 12m Pulsions now. Why the changes? How are they holding up?

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Re: Concept'air 12m Pulsion kite

Postby kitexpert » Wed Feb 06, 2019 1:34 am

jakemoore wrote:
Tue Feb 05, 2019 7:10 pm
kitexpert wrote:
Tue Feb 05, 2019 6:39 pm
Low weight does not make kite any bigger or make it pull more. For design point of view making kite from lighter material is trivial,
10 knots is force 3. 6 knots is force 2. I start to consider flying tube kites at 12 knots. I can go lower but is less fun.

Yes a kite that pulls harder can lift in lighter wind.

At minimum, lighter wing loading makes a bigger kite practical. My experience is there is a difference, in pull especially at the light air. Less force from gravity allows the kite to rise to zenith faster and a better loop for power. Less kite weight and line tension required to keep the kite in the air allows deeper downwind angles.

Then there are the lulls and moments when line tension is lost bobbing up and down in shore break while dragging deep enough to waterstart. Yes I have done kite 360 running in a circle in zero wind with Flysurfer Psycho 1 12.5m. It’s exhausting but was a functioning alternative to the 24M C kites of its era. Good luck running upwind in ankle deep snow.

Indoor kites are above all light. No doubt the Soul is a marvel of engineering and design. Soul in 15m is 840g or 30% heavier than the lightest Pulsion. How much would a cyclist pay to shave 840g off a 9 kg bike. I wish the problem of weight was trivial enough to have more contenders in Force 2.
Yes lighter is better, no one denies that but question is how significant differences are. At least some 132g for 12m kite is not worth mentioning. For dynamic benefit you must calculate weight differencies for complete weight of kite, including weight of the air inside. And is lighter with lower L/D better?

In 6kn there is only a fraction of kinetic energy available compared to 10kn, precisely 36%. This is the energy what kiter uses for traction. For similar kites to achieve same pull it would mean to have almost three times as big kite. Many don't want to accept this and they continue to give unrealistic low end wind speeds for their kiting. In reality explanation is measurement error or wind gradient or both.

There won't be much competition in 6kn wind speed category. To order kite from light weight material is trivial but it will be costly and kite will be fragile. Then you can struggle with risk for self rescue and do lame kiting perhaps in 1kn lower wind than before :roll:

Soul is more efficient kite than Pulsion because it has less drag and very probably also more lift. This means higher L/D which means more pull, more jump height, more hang time, higher speed through the WW and more powerful loop and better upwind ability. If kiter knows how to fly his kite high L/D is also very beneficial for lightest winds, then it is possible to fly actively and to get more apparent wind which is of course essential.

How much would a cyclist pay for a bike which is 30% more efficient?

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Re: Concept'air 12m Pulsion kite

Postby jakemoore » Wed Feb 06, 2019 5:24 am

kitexpert wrote:
Wed Feb 06, 2019 1:34 am
Yes lighter is better, no one denies that but question is how significant differences are. At least some 132g for 12m kite is not worth mentioning. For dynamic benefit you must calculate weight differencies for complete weight of kite, including weight of the air inside. And is lighter with lower L/D better?
Maybe the improved L/D from single-skin to Pulsion is what allows the kite to stay in the air just a fraction sooner. Just for the purpose of having numerical discipline, the difference between Soul 12 (FS reported 2340 g) and Pulsion 12 27g (Regis reported 1618 g) is 722g. Thats slightly more than a pair of size 44 Birkenstock Milanos. I suspect hanging my sandals off your heavy Nitro2 or stuffing them into the vents of Soul or Pulsion will have a noticeable effect on how the kite flies in force 2 and 3 winds.
kitexpert wrote:
Wed Feb 06, 2019 1:34 am
In 6kn there is only a fraction of kinetic energy available compared to 10kn, precisely 36%. This is the energy what kiter uses for traction. For similar kites to achieve same pull it would mean to have almost three times as big kite. Many don't want to accept this and they continue to give unrealistic low end wind speeds for their kiting. In reality explanation is measurement error or wind gradient or both.

There won't be much competition in 6kn wind speed category. To order kite from light weight material is trivial but it will be costly and kite will be fragile. Then you can struggle with risk for self rescue and do lame kiting perhaps in 1kn lower wind than before :roll:
I have some experiences in Force 2 winds with hydrofoil and premium brand normal cloth medium-high aspect foil kites. This is Force 2 at kite level, based on riding next to a limp flag on a pole attached to a pier at kite level. The flag is only 75 meters downwind of the flying kite and a enjoys few mile fetch of clean wind over the bay. I don't think I can go below 6 knots and usually I want to see 7-8 knots on our iKite sensors to drive to the launch. But at this low end, I am not limited by the impulse of the looped kite on long lines to bring me up on to the board and then up onto foil. The limiting factor is keeping the kite in the air while I access deep water that is upwind of me. Actively flying the kite while trying to body drag or even swim upwind would serve only to drag me back to the shallows.
kitexpert wrote:
Wed Feb 06, 2019 1:34 am
Soul is more efficient kite than Pulsion because it has less drag and very probably also more lift. This means higher L/D which means more pull, more jump height, more hang time, higher speed through the WW and more powerful loop and better upwind ability. If kiter knows how to fly his kite high L/D is also very beneficial for lightest winds, then it is possible to fly actively and to get more apparent wind which is of course essential.
Alas our local Soul riders don't come to the launch in wind I consider to be light. Yes the Soul is a jumper. There is good video evidence of Soul performing in light wind but our local Soul riders are more interested in boosting. Those guys fly quite high in 12-15 knots on shorter lines and its amazing to see. I usually have my 7m in the air when they are out. I would like to fly the Soul in light wind.

kitexpert wrote:
Wed Feb 06, 2019 1:34 am
How much would a cyclist pay for a bike which is 30% more efficient?
VMG is 50% more expensive than Soul. Soul costs a little more than Pulsion. And they all cost a lot more than Pansh. ;)

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Re: Concept'air 12m Pulsion kite

Postby Regis-de-giens » Wed Feb 06, 2019 8:47 am

I had 3 pulsion sequentially, sold the preceeding one to buy the new. Reason for change was the curiosity of cloth impact ; 27/40 was the first pulsion 12 ever, then I asked Conceptair if they could try a cloth similar to FS lotus for its deperlancy and long watertightness for a friend loving lightwind but practicing on a lake with looooong lulls of 0 wind. He was so happy that i wanted to try the 32gr, and a bit too far away for a test. Then I order a 15m 27/27 to push the low end further and was so happy with the good impact of this extrem light cloth that i also changed the Pu12 into 27/27 this summer. I can indeed feel the difference even if 32gr is already a winner in marginal vs other existing kites .

Just a carification : I repeat that i paid all my kites (which is the reason why I had to wait to find a second hand pulsion 3.69). I just negociated a small discount (less than FS opinion leaders...) on the first Pulsion (only) since I took a personal enormous risk by buying the first one in the world with all the reselling risk it implies. Then I started speaking of this kite on my own initiative, since there was almost no other user while it was the best kite I ever had. No reward again , except Benoit good words and some Pulsion buyers thanking me for having presented this kite.

Kitexpert : archimede will tell you that the mass of entrapped air does not impact the weight in the air and zenith in low wind, neither its speed when going up or down (but only impact the inertia for kite reaction time to direction change request, which is another topic).

If LD ratio was such a leading parameter in extreme low end, VMG would have better low end than Sonic 2 and sonic fr which would be better than Soul. That is not the case . I am arguing for years to explain that a race kite is not the optiumum for light winds limits seakers (stability , weight and loop power are more important, no doubt , which are better on medium ratio ).

Actually Soul is clearly below the pulsion under 6-7 knots for its weight and loop power (not a general judgment like for good soul jumps as you said), but any back-to-back TESTER up to now (hence not you) has confirmed this comparison and I can notice it regularly on spots (water or snow).

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Re: Concept'air 12m Pulsion kite

Postby TomW » Wed Feb 06, 2019 7:26 pm

Regis,
Thanks for all the input you give us. It's really valuable and one of key factors that convinced me to make jump to foil kites for Hydrofoiling. I am using Hyperlink UL 9m 85% of my last 90 sessions. As I mentioned, I am using Sonic 2 13m for 6-10 knots. Used it 10% of my sessions.
Looking at replacing it with simpler, lower aspect kite.
Do you think 12m Pulsion is good replacement and give me same low end?
Does it require same type of flying technique as Sonic 2?
I am comfortable using 20m lines. I find longer lines have too much lag and don't help me a lot. So I would like to stay with 20m lines.


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