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Inflateable or not inflateable, what is the better choice

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Inflateable or not inflateable, what is the better choice

Postby Guest » Sat Mar 29, 2003 9:02 am

:girl: Hi there,

can anybody give information on non inflatable kites.
How is it to relaunch them from the water? Is it possible for a beginner:

:bye: ellie

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Postby Pump me up » Sat Mar 29, 2003 10:25 am

Inflatables are vastly superior to ram airs.

I've summarised the reasons for the superiority of inflatables:

1: Lift to drag ration (L/D)
- The highest L/D ratio is not always optimal. A high L/D ratio is critical in large kites because they move slowly. Large kites output steady power but generally lose out in ability to turn suddenly and generate sudden upward pull.

- Because large rams (eg Warrior 16.5) have a HUGE "D" coefficient compared to inflatables, they are unable to generate the sudden upward power spikes.

- For this reason, large rams can pull steadily enough, but will ALWAYS lack the jumping ability of a large quality 2003 inflatable.

-Small kites move rapidly and therefore have large power spikes. These kites are INTENTIONALLY designed to move slower by ram and inflatable manufacturers. The lack or presence of a leading edge/ram cells is really irrelevant in the small sizes since SLOWNESS is a virtue in these sizes. The things to look for in these sizes are luff curve, chord, aspect ration for aerodynamic handling.

2: Inertia
- Because large ram airs have a much larger mass of air in them (filling the pockets) their inertia is enormous. It is very difficult cranking this mass of air across the sky to generate sudden power spikes and therefore lift.

3: Rigidity
- Small inflatables are better than small rams because they have a semi-rigid structure. This improves consistency, stability of turning, and precision in handling. Kite makers like Naish and Flexifoil are actually moving to make their kites MORE rigid by joining the struts firmly to the leading edge.

4: Wing tips
- Far from being a hindrance, the tips of the inflatable act as rudders, enabling faster, more controlled turns (and therefore larger more controlled power spikes)

5: Foil shape
- Inflatables have a consistent foil shape because they are semi rigid. Rams deform and change their foil shape which causes an inconsistent aerodynamic profile.

6: Luff curve
- If you want a flat luff curve, choose an X2 or similar
- If you want a deep luff curve, choose a Rhino2 or similar
- If you want in-between, choose a Slingshot or similar
- Because rams sit further back in the window than equivalent inflatables (due to drag) they "feel" a bit like the R2, but without the other benefits of an inflatable.

7: Relaunch
- Ram lovers make a big issue of this. It isn't a big issue. Beginners find relaunching inflatables a cinch after a few sesssions. Just make sure you choose an inflatable that is easy to relaunch (eg Toro). Yes, rams can reverse launch, but so what? Rams can launch directly downwind in the water, but so what? This is dangerous for a beginner, if anything, because it increases the chances of being flung or carted.

8: Safety
- Inflatables are safer than ram airs because
-- Downwind launches are bloody SCARY for a beginner
-- Rams deform, twist, wineglass, explode in the middle of the power zone etc when they are downwind of obstacles, in rotors, and in VERY gusty conditions. This is VERY dangerous. Some of the most frightening kitemares I've seen have involved ram users walking along beaches in slightly offshore conditions - their kites have been virtually uncontrollable and have endangered both the rider and other beach users.
-- Wind dropouts and gear failure
--- You will invariably experience a few catastrophic gear failures (eg broken lines) and complete wind dropouts every year. If you are a fair way offshore, you can use the inflatable as a "sail" to sail back in. Alternatively you can use the inflatable structure to support your weight.
--- All ram airs become hopelessly waterlogged after 45 minutes - unlaunchable and certainly unable to support your body weight.
-- Surf conditions
---While it is always a gamble if your kite gets hammered by a wave, at least you've got a chance if it is an inflato. If it is a ram air, it's curtains.
-- Bridle tangles and failures - Scary (eg see thread: Flysurfer Warrior Exploding)

9 Pre-inflating
- Ram users struggle to pre-inflate their kites in a lot of situations eg slightly offshore conditions.
- Without pre-inflation, ram users find it very difficult to water launch. This skill is often required eg downwind of promontories.

10 Resale
- Contrary to the propaganda of the ram lovers, ram airs and inflatos have similar lifespans. The major determinant of a kites lifespan is obsolescence - in 2-3 years, whatever you're using now won't be worth much and will have been superseded.

You will find it easier and more rewarding to learn on an inflatable. Please do yourself a favour and avoid ram airs - they are dangerous and aerodynamically inferior.

Guest

Postby Guest » Sat Mar 29, 2003 10:34 am

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Postby Pump me up » Sat Mar 29, 2003 11:03 am

Oh, I forgot to mention... the superiority of inflatables over rams is repeatedly confirmed by large, reputable competition results.

eg There were no ram airs in the top 50 of the PKRA last year.

Competitions indirectly assess
- Jumping
- Hangtime
- Control
- Upwind ability
- Stability
- Turning speed

Contrary to the assertions of the ram brigade, there will be no ram airs in the top 20 PKRA this year.

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Postby rufus » Sat Mar 29, 2003 11:10 am

Oh goodie! Another game.

I'll say 50 replies on April 20th.

:wink: Rufus

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Postby Kitedemon » Sat Mar 29, 2003 11:13 am

THis Post Screams Out......... "DELETE ME"

Or atleast take several peoples opinions before you listen to one person who is over opinionated and is determined to force his views down ur throat.

Id cough them back up first and take a look at what he's telling you


BORING

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Postby edmis » Sat Mar 29, 2003 11:53 am

there is NO answer to your question

YOU HAVE TO TRY BOTH


edmis

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Postby kjorn » Sat Mar 29, 2003 12:16 pm

Pump me up wrote:6: Luff curve
- If you want a flat luff curve, choose an X2 or similar
- If you want a deep luff curve, choose a Rhino2 or similar
- If you want in-between, choose a Slingshot or similar
- Because rams sit further back in the window than equivalent inflatables (due to drag) they "feel" a bit like the R2, but without the other benefits of an inflatable.
What the hell is luff curve? I checked on google and it seems to be something to do with windsurf sails, or boat sails.

Please elaborate.

And rams can sit anywhere in the window - it is mostly determined by the angle of attack, which is set using the bridle.

john.e.boy

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Postby KiteGlider » Sat Mar 29, 2003 2:30 pm

Having limited sailboat experience, I was interested in learning more about "luff curve". This what I found on a web search.

Relating to sails, boat and windsurfer, luff curve is the depth or belly of the sail. The sail cloth/material is cut to allow excess to give profile or "depth".

So PMU is saying that the LEI is a fat belly sail anchored with 2 or 4 lines.

I had some of the best times in my life flying my fat belly sail anchored to a control bar with 4 lines.
mast deformations possible : luff curve, rotation, rake and inclination. -
So the amount of luff curve being one of the mast deformation factors that introduces dept or foil profile into the sail.

If related to the LEI, then we're talking about a 180 deg luff curve?
The curve is also on a different axis than used in sail design.

Taken out of context from: http://www.lo0.com/fireball/readings/firezone-a10.html
To understand mast tuning one must know a little about how a sail is designed and what gives it its shape. Seam taper and luff curve are the two main components to sailshape and depth. Seam taper (also known as broadseaming) is the depth built into the sail. Seam taper has a percentage depth (percentage of chord length), a maximum draft position source of the shape you see in your main when you are sailing. When you put a positive luff curve on a straight mast the extra cloth (beyond the straight luff) is cloth added to the depth of the main. Most of added shape appears in the luff. How much luff curve is the question most often asked by sailmakers.
Luff curve seems specific to sail design. When talking LEI profile shape IMO we're considering geometry in terms of air-foil design.

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Postby Mr Jo Macdonald » Sat Mar 29, 2003 4:10 pm

Hi Ellie, I fly both Leis and foils and love them both. There are a lot of posts about whether one is better than the other on the forum that you can find if you use the search function and then try to read through the posts disregarding the biased opinions/windups/flame wars/whatever. Personally I use middle/high AR leis and a high AR foil so the leis are easier but flying the foil made me a much better pilot and I've had hours of satisfaction out of it in wind that my leis wouldn't get me going in, I use it on land in winter and in very light wind too, 3/4 knots. I'm just in the process of souping it up, something I like to do with all my stuff.
Anyway there are more technical leis out there and easier foils so there is definately a lot to choose from.
I would agree that the best thing is to try flying both types of kites with someone who has valid experience, take a few leasons with an instructor if you haven't already. A school is also a good place to try kites out.
About relaunching from the water, nearly all kitesurfing foils are closed cell foils so very little water will get into them and they relaunch from the centre of the window by simply depowering the kite if it's sitting on its trailing edge. If the kite's on its leading edge you either let go of the bar so the kite goes to the leash or pull on the brake lines and the kite will turn over onto its trailing edge so you can launch it by depowering. In lightwind personally I think it's way faster than relaunching an lei. In strong wind relaunching it from the centre of the window can be a bit of a power trip and leis launch fast in strong wind anyway. In really light wind (below 7 knots) it will be hard or even imposible to relaunch any kind of kite. Practicing in the shallows is best and anyway if you're learning you'll get loads of crashing/relaunching practice. If you're at this stage a used 2002 kite for about half the price of a new one is probably best so you won't bust up a new one.
Some people say a foil is better if you kite alone for launching/landing but I do this with both kinds, I'd say it's easier to damage an lei this way but if you're starting you shouldn't be on your own anyway.
Until this year foils were definately better for lightwind and leis for jumping but now there are good big leis for lightwind and powerfull jumping foils so like I said above you should try both and see which you like the most.
Ask anything you want and have fun.
Jo


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