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 Post subject: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 3:27 am 
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LAND & SNOW
Inflatables are superior on snow and land. More and more riders are recognising this:
https://www.kiteforum.com/viewtopic.php ... 3&p=735337
viewtopic.php?f=1&t=2355153
viewtopic.php?f=1&t=2367967&start=40

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


LIFT TO DRAG RATIO (L/D)
Rams have HUGE drag ("D") compared to inflatables for 3 reasons:
a) Increased friction at the "boundary layer"; ie interface between air & kite, because of minute ripples in ram air kites.
b) Bridle drag.
c) Thickness. Ram lovers describe the diameter of inflatable leading edges as a liability. However, the thickness of ram airs is typically two to three times as great. Worse, much of the thickness is near the trailing edge, causing gross aerodynamic inefficiency. An inflatable trailing edge, in contrast, is thin and aerodynamically efficient.

MASS & INERTIA
Ram airs contain a huge mass of entrapped air; consequently inertia is HUGE. Large ram airs (eg Flysurfer 19m & 21m) contain >11kg of air in their cells vs 2-3 kg in the tube structure of inflatables. The huge inertia of ram air kites causes a multitude of problems including poor lift, slow turning, difficulty kitelooping, and diminishes the "sweet spot" for unhooking. Poor turning and acceleration results in inferior dynamic power (the power generated with sinusoidal kite movement).

RIGIDITY, STABILITY, & FOIL SHAPE
The semi-rigidity of inflatables improves consistency, stability, turning, handling, and aerodynamic profile. Ram airs are soft and floppy.

Birds, wasps, stunt kites, and planes are rigid. ALL high performance aircraft (eg hang-gliders vs paragliders) have rigid structures. Rigid hang gliders out-perform soft paragliders on all measures. Interestingly, the trend in paragliders is towards increased rigidity, e.g. stiff mylar reinforcements, plastic stiffeners in the leading edges and carbon fibre rods sewn into the ribs. These stiffening innovations have resulted in paragliders that are so successful in competition that old-style soft gliders are no longer competitive. Similarly, kite manufacturers are always looking for ways to make kites more internally rigid, eg by joining the struts firmly to the leading edge, adding fifth lines, and mini-bridles.

Semi rigidity enables inflatables to withstand gusty conditions better than ram airs. Ram airs deform, fold, collapse, and twist in gusty conditions. For stability problems in ram airs stemming from lack of internal rigidity, see: http://www.foilzone.com/phpbb3/viewtopi ... sc&start=0

Check-out this ram air kite loop http://vimeo.com/10799435 You'll notice the kite partially collapsing during the loop, leading to the rider being slammed.

Another weakness of the soft structure of ram airs is a lack of tactile feedback. The kites are soft so the feedback is soft, sloppy, and imprecise. Rigid inflatables, in contrast, provide a wealth of nuanced feedback to the rider, eg kite position, speed of turn, and gradations of power delivery.

TURNING & SLED EFFECT
The tips of inflatables act as rudders, enabling faster, more controlled turns. Also, they enable a "sled effect", leading to better stability and predictability. This "sled effect" is pronounced in C-kites and is noticeably poorer in bow kites and ram airs.

LUFF CURVE/DEPTH PROFILE
Luff curves vary extensively. Inflatables with flat luff curves sit forward in the window whereas inflatables with deeper luff curves sit further back in the window. It is the same principle as land sailing: If you want more "bottom" end with a sail, you deepen the luff curve (eg releasing the outhaul). If you want more "high" end, you make the luff curve shallower (eg tighten the outhaul). Inflatable kites are deliberately engineered with different luff curves and this determines many performance differences, eg deeper luff curve kites are better for "wakestyle" because of more constant pull whereas shallower luff curve kites go upwind better.

The excessive drag and inertia of ram airs causes them to sit further back in the window compared to inflatables. Also, when ram airs move too close to the side of the window, they start collapsing and deforming. Hence, there is less scope for ram designers to modify the luff curve.

Because of the semi-rigid structure inherent to inflatables the luff curve and overall aerodynamic profile is much easier to standardise and maintain.

RELAUNCH
Ram airs can be VERY difficult to relaunch.
Beginners find relaunching inflatables easy after a few sessions. Yes, some rams can reverse launch, but so what... a lot of inflatables can reverse launch. Rams can launch directly downwind, but so what... so can a lot of inflatables. For intermediates and above, relaunching should not even be considered in the equation because a) they won't be dropping the kite much anyway and b) Relaunching inflatables is EASY. Commonly, ram airs will not relaunch properly because of twisting or bridle tangles. These aren't such big problems with inflatables.

SAFETY
Inflatables are safer than ram airs because they lack rigidity, rams deform, twist, wineglass, and jellyfish in the middle of the power zone etc when they are downwind of obstacles and in gusty conditions. This is VERY dangerous. Ram airs can become uncontrollable in gusty conditions, endangering the rider and other users.

BRIDLE TANGLES & FAILURES
Bridle tangles and breakages are disturbingly common with ram airs. Check this thread viewtopic.php?f=1&t=2354115&start=30
In particular:
schmoe wrote:
A bridle tangle on flysurfer can mean that you do not go out... For me I had many lost hours where the wind is cranking because of the bridles. I rather inflate 5 tubes and know that the setup time is exactly 10 minutes, no more no less, than have setup time that is 70% 5 minutes and 30% an hour. And now with one pump, the setup time of a tube is less, so it is not an advantage of the foil anymore.
Ram air bridle tangles can be very dangerous. A lot of riders have reported how their ram airs caught debris in their bridles, causing their kites to wineglass and spin out of control. Breakages can be expensive (US $500 plus). eg "Flysurfer Warrior Exploding" viewtopic.php?t=4612

PRE-INFLATING
Ram users struggle to pre-inflate in a lot of situations e.g. downwind of obstacles or elevations. I once witnessed a Flysurfer lover trying to launch downwind of an obstacle. A friend grabbed one tip while he grabbed the other tip while they ran back and forth, trying to pre-inflate, to no avail. He packed up and went home while the inflatable riders had a ball.

RESALE
Contrary to the propaganda of ram lovers, ram airs and inflatos have similar lifespans. The major determinant of lifespan is obsolescence. In 2-3 years, today's kites will be superseded and won't be worth much.

REPAIRS & COMPLEXITY
Ram airs are shockingly complex. They have over 1000 parts, many of which require regular tweaking e.g. viewtopic.php?f=1&t=2374470 Ram air repairs are a LOT more expensive eg viewtopic.php?t=4612 Trained PARACHUTE repairers are often needed. Bills >$1000 are common, eg viewtopic.php?f=1&t=2348790 Ram air companies sometimes refuse to honour warranties, e.g. the case above where the kite was <1 year old.

COMPETITION
Ram lovers are all talk and no action when it comes to competitions. NO ram riders have made it into the top 10 recently in a SIGNIFICANT well-patronised event. The top pro riders ALL choose inflatables because of superior aerodynamics. ALL world records and titles (hang-time, speed, freestyle, height) are held by inflatables.

LIGHT WINDS
Ram airs are inferior light wind kites for the following reasons:
a) Excessive drag
(bridles, lack of internal rigidity, excessive friction at the "boundary layer", and trailing edge thickness), compromising the Lift/Drag ratio
b) VERY slow turning
c) Inertia. Large ram airs (e.g. Flysurfer Speed) contain >11kg of entrapped air, cf <3kg in the largest inflatables.
d) Bridle failures and tangling
e) 8 knot limit
Despite the lies of ram lovers, you won't really get going on any kite (ram air OR inflatable) unless the wind is over ~ 7-8 knots and won't really have fun until ~ 10 knots.

GEEKS, WEIRDOES, & SOCIAL MISFITS
Inflatable riders tend to hang out and help each other; there's a high level of collegiality. Ram lovers tend to be regarded as outsiders and slightly weird. This is because ram lovers are a shrinking minority on land/snow, inflatable riders are unfamiliar with the special requirements of ram airs, and partly because, as a group, ram lovers DO tend to be weirdoes. One of the simple practical problems with being part of a weird minority is that it can be difficult to find people to help launch and land your kite. I'm not sure why so many ram lovers are strange weirdoes… maybe their weirdness is self selecting, i.e. There must be some sort of psychological problem in the first place to deliberately choose inferior kites in the face of overwhelming evidence of the superiority of inflatables.


Ignore the ram air lies.
And constant propaganda.
Of the lesser kites.


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 5:01 am 
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One word for you Pumpie ol' lad - Elf.
Your argument is invalid; QED.


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 5:22 am 
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Location: jackson WY
I would like to see you land your inflatable overpowered at the top of a mountain. I almost always fly tubes but when hill climbing I sure do like my foils. Ozone kites!


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 5:27 am 
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Joined: Sat Jan 24, 2009 10:42 pm
Posts: 28
Location: Silverton, Co
Park and Play: sure, Backcountry: no way!


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 7:43 am 
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:-? I guess everybody has an opinion. But the weird thing, come on. That's weird. JR


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 10:39 am 
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Joined: Sat Aug 29, 2009 11:25 pm
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Location: The Naki
i hate my foils. i hate the fact that i can walk onto the bench unrole my kite and launch it no pumping required.
i hate the paraglider like glide and float.
i hate the stupid light winds i can fly it in.
i hate the fact that i can kite most days if the year.
i really hate the fast set up and pack up.
i hate how stable the foils are. i specially hate flying no hands...
damn these foils. how dear they have s usefully purpose.


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 2:22 pm 
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Joined: Thu Oct 20, 2005 12:54 am
Posts: 117
Location: Backwoods
Why post stupid shit like this. Everyone has a preferred kite for certain things. Plus it's not a competition its a sport that everyone can be out enjoying. Frankly if you've wasted your time posting this lengthy of a message you're not out kiting so youde best get back to pumping yourself as you're not doing any good here.


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 4:10 pm 
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Posts: 2568
Instead of contest Tubes vs Foils and prize money
Let's instead give prize money to the person who can unmask PMU's identity
Someone out there knows who he is ,where he lives and what he rides
Now that would be SUPERIOR entertainment :thumb:


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 4:52 pm 
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Joined: Tue Feb 06, 2007 5:50 pm
Posts: 353
plummet, I hate watching my son, sitting on the beach, while I'm having a blast out on the river, when the wind is light, and no one else out on the river to have to worry about. It just tears at the ole heartstrings, ya know?

I don't know how many times last year, when I said to myself, "man, self, I wish I only flew LEI's so I could be sitting on the beach with the cool guys. Man, I feel like a complete geek/nice person kiting out here all by my lonesome. I must look like an idiot to all the cool dudes watching me from the shore."

It's a dadburn shame those inferior kites are so much fun, isn't it? :wink:

Hey, maybe I'll wear a sweater vest, with a bowtie, and some big black frame spectacles, next time I'm out there!

Have a cool one, Pump and Shoot!


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 Post subject: Re: Inflatables are Superior to Ram Airs on Snow/Land
PostPosted: Wed Feb 29, 2012 6:19 pm 
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Posts: 383
Quote:
I would like to see you land your inflatable overpowered at the top of a mountain.

Anytime - just come to Norway and se us ;) But i get your point if you kite up, just to pack it down and then ski down.

But seeing people having trouble holding the 19m FS in the air in light wind when I rode past them on a 13m C on the mountain recently, made me think that they are a bit over pimped as well...
To me it seems more like the rider and how much experience you have in light wind on snow rather than what you ride...

For me I prefer tubes on snow!


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