biggest foil/Flysurfer basher on the planet. Why he bashes no one really knows...looks like he believes in his own BS Or is he someone working for a foil brand?
Thanks Toby for the opportunity to discuss the inferiority of ram airs.
Inflatables are vastly superior to ram airs. 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.
Increased drag compromises the L/D ratio, making ram airs less efficient and aerodynamically inferior, compared to inflatables.
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 (one of the reasons ram airs are a poor choice for wakestyle riding). 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 into the water.
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 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 e.g.
It took a long time for the guy in the video to relaunch his Flysurfer and the kite almost became completely un-relaunchable on two occasions through bow-tying. If only ONE wave had landed on it, he would have had to swim in, dragging his waterlogged kite with him.
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 in the water, 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, bridle tangles, or waterlogging. These aren't such big problems with inflatables. Check out these links about ram airs sinking or becoming un-relaunchable: eg viewtopic.php?f=1&t=2346569 eg viewtopic.php?f=1&t=2358958&p=608890#p608890 eg viewtopic.php?t=2359156&p=617396 eg viewtopic.php?t=2358602&p=704984
SAFETY Inflatables are safer than ram airs because: a) Downwind launches are SCARY and can be dangerous. Eg viewtopic.php?f=1&t=2359529 . Because only a small bunch of slightly weird people use ram airs, there is confusion about their correct use, leading to potentially dangerous situations eg viewtopic.php?f=1&t=2360971 b) 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 beach users. c) Surf conditions While it is always a gamble if a kite gets caught by a wave, at it has a fighting chance if it is an inflatable. Ram airs can be EXTREMELY difficult to relaunch in the surf (see above - "Relaunch").
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 seaweed 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 eg cross-offshore conditions and downwind of promontories. I once witnessed a Flysurfer lover trying to launch at a headland in cross-offshore conditions. A friend grabbed one tip while he grabbed the other tip while they ran up and down a narrow strip of beach, trying to pre-inflate, to no avail. He packed up and went home while the inflatable riders drift launched.
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 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 ever made it into the top 20 on the PKRA http://www.prokitetour.com/ or placed 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, waves, height, course-racing) 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) Wind dropouts and gear failure ALL kiters experiences a few gear failures (eg broken lines) and COMPLETE wind dropouts every year. You're usually safe with an inflatable. It can be used to "sail" (self-rescue) or swim to shore. If things go REALLY bad, the inflatable structure can support your weight, eg viewtopic.php?f=1&t=2368004
The following is an example of "diraklib's" experience with ram airs in wind dropouts:
"the SA-19 is huge and can whack you silly if you let it get down wind of you in a low wind launch. It is downright scary - be ready with the QR at all times if not up and riding!!! I can't say I agree with claims that you can ride the SA-19 in anything lower than a steady 8 knots. I made a personal choice to not ride the SA-19 any more. It went down twice in lulls and managed to bow-tie on the way down - there was no way to relaunch. I was not as lucky as others that self rescued. My kite was full of water by the time I dragged my very tired and frustrated a$$ to shore. It sounds simple, "wrap the lines around the bar, fold the kite in half, roll it up on your board and paddle in"... noooo... there are lines everywhere under water that wrap around your feet as you are trying to manipulate the kite. You just pray that a gust won't pop the kite up and slice of an appendage. The kite ... is just too scary when it goes down. My attitude now is - if my LEI won't fly, I shouldn't be on the water. Anyone interested in a slightly used SA2-19m??? Cheap???"
The following is an example of FredBGG's experience with a line failure:
The other day I had a front line fail. Wind was slightly off shore... I really needed a tow to the beach. I had the kite safely on the 5th line folded in half (flysurfer Foil) I waved down two kiters.... both expert judging by their riding. Both refused to help. One even yelled if you can't relaunch it's your problem. Anyway after a difficult ordeal in the surf and current I got back to the beach. I had to rest a bit but my board was still out there.
For the full admission viewtopic.php?f=1&t=2362065 The problem here isn't with the other kiters, it's with Fred's choice of kite. If Fred had an inflatable, he would have been able to "self-rescue" by grabbing the tips and "sailing" to shore. The other kiters refusing to help is understandable: Fred opted for less safe equipment. It's his problem and he shouldn't impose on others to make up for his equipment deficiencies. Also, towing a ram air to shore is like towing a sleeping bag full of water - difficult and dangerous.
f) 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.
This video may prove the 7-8 knot low limit. Both kites - the 21m Flysurfer and the smaller (?17m) inflatable are FAILING TO STAY UPWIND and, by the look of the flag, there's about ? (hard to say) 8 knots of wind.
It's interesting to note that the ram air and the inflatable are both struggling IN SIMILAR CONDITIONS.
My Speed 3 19 DL gives up under 5 knots... - Gunnar Biniasch
Wind moving at <7 knots (13km/h) simply cannot deliver enough power for ANY kite to perform; certainly NO KITE WILL PERFORM AT 5 KNOTS. Gunnar's exaggerations can be found at viewtopic.php?f=1&t=2361421
g) Objective Testing A variety of kites were tested in a "Light Wind Showdown" in San Diego viewtopic.php?f=1&t=2319439&hilit=ram+airs+crash+in+san+diego . Despite the over-hyped claims from the U.S. Flysurfer rep, Ted Bautista, Flysurfer ram airs crashed and burned. The overall consensus was that ram air kites are ok in light wind, but turn VERY SLOWLY. The overall impression was that there are much better inflatables. h ) BIG INFLATABLES are better than BIG FLYSURFERS in Light Winds See this thread about the poor light wind properties of Flysurfer viewtopic.php?f=1&t=2349064 , in particular:
I read all the same reports and reviews that everyone else here probably read and spent the "big bucks" for the S2-19, but to be honest was extremely disappointed and sold it…Flysurfers just plain suck in gusty, light winds…I had a hard time keeping the thing in the air much less getting enough power from it to go on the water… A couple months later I got an 07 Waroo 20m…and it is the best 20m I've ever flown. I am able to fly it in winds I would never have thought possible.
i) Peter Frank's opinion Peter Frank, a well respected commentator on the sport, says 8-9 knots is the bare minimum viewtopic.php?f=1&t=2365531
What is the lowest wind condition I can go kitesurfing and what is the best kite brand and size for it?
It depends a lot on your weight, how low you can go. If you are "average" around 80kg, the lowest you can go will be around 5m/s (10knots) with the right kite and board. If you are REALLY experienced, you will be able to push the lower limit down to about 8-9 knots, but this is the absolute lowest wind possible to kitesurf in (holding ground/going upwind) with average weight IMO. And talking about EXACTLY how "low you can go" is just pure bullshit - as you can not measure the windspeed at the kite, which is the only true value for this. Sometimes you have a huge windgradient, sometimes a small one, and air temperature and height also influences. But around 10knots is the limit for most kitesurfers, and just a small tad lower for the "extreme" ones When you talk about windspeed - where is it measured then ? At headheight, maybe around 2 meter above the water ? Or at 10 meter height, which is our (Denmark) meterological standard height for wind measurements ? There is a difference of typical 2 knots, so VERY important. My point is - always take those claiming "this and that" as their minimum wind speed with a grain of salt Peter
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 tiny minority on the beach, 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, eg http://www.seabreeze.com.au/forums/Kite ... -on-beach/ 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.
Users browsing this forum: Bing [Bot], Google [Bot] and 19 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum