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SoutherlyBuster

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SoutherlyBuster last won the day on November 5

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About SoutherlyBuster

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    posting Maniac

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  • Location
    Christchurch, New Zealand
  • Interests
    Kitesurfing, landboarding down hill or with kite, RC gliders, skate boards.
  1. Foil board for next Olympics

    Now this will be interesting to watch, Foil Kites with Foil Boards now accepted as event in 2024 Paris Olympics, see https://www.iksurfmag.com/kitesurfing-news/2018/11/world-sailing-agm-confirms-kiteboarding-for-the-paris-2024-olympic-games/ Sorry LEI fans, no LEI’s permitted Will be an open class.
  2. SOLD Trampa mountainboard

    Looks like MBS Trucks, but the deck looks like a custom, I am thining more like a Trampa rather than MBS board, MBS’s usually come with shinny ripple free decks with a picture on it rather than the raw out of the mould finish.
  3. Hello. newbie Q bout depower kites-

    Jumping with an 8m^2 depower, DON’T, not yet any way. At this size the kites are very responsive and typically the winds needed to boost you off the ground for this size kite are big winds and tend to be gusty — all translates into unpredictable, you go up quick and come down hard. I would probably go for a 10 m^2 depower as the first depower, winds will be lighter right for it, safer for you and boosting will be better. Don’t worry about boosting until you are total comfortable with your kite and landboard. If using handles with your fixed briddle, rig up a strop, ie rope between your handle ends which hooks into your harness, this takes the load off your arms. Bar systems to make fixed briddle systems into “like” depower are ok, my son used the ozone turbo bar, they are nice, but if you are on a budget and really have in mind a true depower kite, then a strop is a better option.
  4. The next big thing?

    Difference between this and and LEI? Small diameter pressurized hosing? Advantages? Not much said about the design in the video. Oh sorry just looked at the web page link provided, ya cool.
  5. Night Buggy

    My son and and and I did some night flights on the clay pan at Kingston, great fun, all the wind gusts had dissapeared, very steady wind and the moon was out. Just had to remember where the nasty obstacles are.
  6. eBay & Gumtree Finds

    Sounds like a buggy engine to me brm brm ... post some pics as you run down the salt pan with them. You’ve got a bit of kiting history there, good buy.
  7. Super Tracks - video

    @RedSky sorry to hear that your GoPro Fusion lens got ruined. I guess I have always taken it for granted that the GoPros have a protective shell protecting the lens. Just googled it for the Fusion and see there is nothing for it due to the 360 degree field of view, argggg! Saw a Chineese made case for it, don’t know if that wrecks the 360 view. Sounds a like a poor design choice for an action cam targeted at extreme sports.
  8. Naish Foil Board

    Depth, ah right the p=density x depth x g. For the mast can be important but I doubt important for whistling. Where is the whistling coming from? Well in my opinion, it is not just from one thing. Think of it like a guitar or violin, the sounds come from the vibrating string (our vortex sheet coming off the foilig trailing edge), the vibrations then get transfered to something which amplifies (the wing to mast to the board) the sound, then eventually to something that creates air pressure waves so we can hear it. If the vibrations were solely confined to the water, I doubt we would hear it. To amplify the vibrations, you need to tune the natural frequency of your strucutre to match the forced vibrations, hence why same foils with different mast/board some sing, some don’t. Ever pick a guitar and notice the sound rings nicely and others just sound dull? It is all about getting that resonnance right in the structure of the body and for guitars and violins the air space since it has it’s own set of natural frequencies.
  9. Naish Foil Board

    Vertical or horizontal makes no difference as gravity makes no difference here on the formation of the vorticies, and it is the vorticy formation alternating between either side of the foil that causes the vibration. Surfaces being further apart, yes agree. I thought about this too, there must be some sizing effect going on. If you zoom in close enough there will always be a blunt end of the trailing edge. I suspect the characteristic length would be the boundary layer thickness. I expect the above article was an A to B comparison, same foil size, just alter the taper angle. So at some point a blunt end would make no noticable difference. Agree some of these sharp edges look nasty for rider safety. Reckon the blunt hard trailing edge plus the relatively soft tape I used is a good solution, just a mater of find tape that lasts long enough. Helicopters use a special tape for the leading edge for abrasion resistence ... hmmm. Yes the tape was double backed onto itself to creat a thinner trailing edge. At the moment I am thinking, don’t mess with the foil, just use tape, main motovation is rider safety against cuts. The tape lasted well for one session, will see how long it lasts. Longer term solutions would be tapes with heat activated glue applied to the resin coating. I suspect if the foil wing and mast were made of a very heavy highly damped material with zero vibration transmision you would not hear the wistling. Apart from the very low frequency vibrations that one would definitely feel through your feet, the high pitched frequnecies may be more noticable depending on the stiffness and mass of the mast and board, if the whistling frequency excites one of the natural frequencies of the mast and board, then it would be clearly audible, like a sounding board of a piano.
  10. Naish Foil Board

    I applied some tape to the trailing edge starting on the top side level out extending beyond the trailing edge by about 2mm fold over and stick to the bottom surface of the foil. Humming gone (which I could hear and feel). The tape is very sticky, I use it for reinforcing my foam gliders, sticks like sh@#$/ $# on a blanket. Did not come off during the light wind session 6.6 to 9 knot wind with 18m FlySurfer Lotus.
  11. Naish Foil Board

    Some googling, reading and applying some engineering common sense .... There appears to be a lot of “wive’s tales” and snake oil surrounding the source of the humming, but also a lot of good information out there. From my reading it appears the shape of the trailing edge is the most important aspect to reduce or eliminate the humming. As the two flow streams from the top and bottom sides of the wing come together at the trailing edge, where the vorticies peel off is the important bit. If they peel off consistently on either the top, middle or bottom then no vibraton; if they peel off alternatively between the top and bottom surfaces, this causes a vibration and this is what the hum is. From a Yatching design book, there are some guideliness to reduce or even eliminate this vibration, see below for extracts and source of the book: What I have is a rounded squared off trailing edge — not a favourable shape. So what I need is some thing like option 5 or 8. The fibre glass is wrapped around a shape like option 1, so as not to expose the wood underneath the fibre glass protective layer, I need to add some fairing to the trailing edge to make it one of the more favourable shapes, but also ensure I don’t make it too sharp to avoid cutting myself. Thanks @Kamikuza for the suggestion, it lead me to find the above information. By the way your name appeared in some of the searches . Looks like a lot of other foilers experience the same problem. Also one suggestion was to apply some tape to one side of the trailing edge to stop the fluctuatin of where the vortices peel off, might be a quick way to see if this is where the vibration problems come from.
  12. Super Tracks - video

    Great video, lots of contrasting camera angles. Though would have been nice for the camera wobbles to be synchronised with the music beat . Those rows of pilons on the sand must be annoying.
  13. Hello. newbie Q bout depower kites-

    @alison melia I landboard and kite surf, age 55 years. Landboards are a lot more compact and cheaper to buy compared to a buggy. Just throw it in the back of your car and away you go. Landboards do require good balance skills, all part of the learning curve. If you have any inclination to kite surf in the future, then landboarding is a good move as it provides cross training, oh and not to forget snow boarding with the kites since your are in Tasi. Landboarding on the beach at low tide is geat fun, I would go for Matrix Trucks on an MBS Board, much more stable. Landboarding can also be done on down hill runs on fire tracks without the kite when there is no wind, so versatile. Balancing on a landboard with the smaller fixed briddle kites is harder compared to the larger depower kites in that there is not much to lean on. I only use depower kites these days, use them for: landboarding, dirt surfer, kiteboarding, water hydro foil boarding and snow boarding. So if you want land and water action, ensure any depower you get covers land and water, is more cost effective. Oh and welcome to the forum.
  14. What's everyone's go to kite in patchy light wind.

    Light wind kiting has it’s own joys, the challenge of being able to do it is part of the joy. It often needs more skill to do it, the rewards of being able to do it, the joy. Besides, a nice cruisy run on the beach just can’t beat it — what would you rather do, kite or sulk at home wishing you could? Sorry do not ride a buggy, just thought I would weigh in on the light wind aspect.
  15. Naish Foil Board

    Sea trials are complete, took the board out into the surf with the home made rear wing today. Took some shims along just in case the zero angle of incidence needed adjusting. The lower angle worked to my favour, lifting later but at speed needing to be less forward on the board, so was more managable to control pitch at higher speeds. Gave a nice stable flight. There was a hum though, will need to investgate possible causes. And the rear wing did not break, ya hoo. After the sea trials: (No fairing added between wing and fuselage, might be the cause the the hum. Counterbores applied to the wood were a neat flush fit, but when the glass was applied, the precision was lost, so this might also be the cause of the hum by way of turbulence. All final brush strokes of paint applied in the stream wise direction, to avoid roughness in the wrong direction. Highly approximate, but I remembered the frequency of the hum, then when I came back to my car, by memory I sang the same hum and used the stroboscope on my mobile phone to measure the frequency. 146 Hz, rather low frequency. Foil thickness distribution was "eye" balled, so maybe there are some parts of it causing too negative a pressure, leading to cavitation which also might be the reason for the hum. The wing feels reasonably stiff so would not have thought the hum was due to the wing being too flexible. Oh and pumping the board works better now, used this once standing with kite to get the board quicker up to speed.
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