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46932Re: Peter Lynn Feb Newsletter

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  • dtraub1second
    Feb 1, 2002
      Thank you very much for the Newsletter and helpful information. I
      have the shoulder collapsing problem with my 630 and have some
      questions about the recommendations in the Newsletter and would
      appreciate clarification. I hope a response is posted on the forum
      because others have expressed interest in solutions and I believe
      they would also appreciate more info.

      The Newsletter says, "Sometimes it's difficult to tell from flier
      descriptions whether a particular problem kite has a stretched centre
      or a hooked tip and it's important to correctly identify the cause
      before making corrections." How can we correctly identify the cause?

      I think it would help a lot to know Peter Lynn's definitions
      of "Asymmetrical flying", "Shoulder collapsing", "Tip Luffing",
      and "Centre Luffing". Knowing your definitions of these problems
      would help any of us with problem ARC's to diagnose them and apply
      the best solution.

      One suggestion is to take the whole binding off and re-sew the TE.
      In an email, Lachlan Bead suggested that only the binding at the tips
      should be removed. I think that would be easier but is it better to
      remove the entire binding? He also suggested I try a leach line
      between the silver panels but this was not mentioned in the
      Newsletter. It was not effective enough for me. Is it not advised
      at this point?

      The Newsletter said the spars can cause these problems and one
      recommended solution is stiffer wing tips. Is there a stiffer grade
      of those carbon fiber tubes? Where can we get them? Also, I would
      think the smaller ARC with the shorter tips would be less likely to
      suffer from the flexibility of the carbon tubes because the tubes are
      shorter and the same stiffness as used in the 1120, for example. Is
      this more likely to be a problem with the bigger kites?

      I thank you for the helpful Newsletter and thank you in advance for
      any more advice that will help improved my experience with my beloved
      ARC's. Long live the ARC.


      > Newsletter, February 2002.
      > That's it , holidays over.
      > Having knocked a few of the rust flakes off at the Nelson kite
      festival 2
      > weeks ago, now it's right back into overseas festival-ing with
      Kites on Ice
      > in Wisconsin this weekend, Pasir Gudang in Malaysia the next and a
      > dance card for the rest of the year.
      > Actually I've used the last month or two of the no-travel break to
      check out
      > a few half decent Australian reds, fly some kites and do more kite
      > development (the never ending story but more about this later),-
      and also to
      > play with a few old stationary engines of course.
      > In a final holiday diversion, last weekend a couple of vintage car
      > enthusiasts arrived with a very interesting challenge. They had
      secured the
      > rights to make an official replica of the first motor car; Carl
      > single cylinder three wheeler of 1886- from 7kgm's of plans duly
      > from Mercedes Benz. It took 14 months to build and is booked for
      it's first
      > outing in early February. Unfortunately, it wouldn't run.
      > This fits the profile of a perfect Sunday problem- that is; has
      moving bits,
      > makes noises, involves being dirty, is challenging enough to be
      > and is definitely solvable.
      > Just a sudden thought, that I'm too old to have, but no, girls don't
      > qualify- they fail by the final criteria.
      > The Benz' engine has a slide type inlet valve but a conventional
      > sort of half way between steam engine and internal combustion engine
      > technology. It should produce 0.6kw at 250rpm on full throttle from
      > one litre open crank single cylinder engine. Forget fuel injection,
      > engine doesn't even have a carburetor-the air intake passes through
      a sort
      > of half size fuel tank, picking up some fuel vapour fuel as it does.
      > At the start of the day there were only two or three of us but by
      > afternoon rather a crowd had gathered,-many "helpful" suggestions.
      > hours, occasional chuffs were all, we could get but by 4pm it
      settled down
      > to regular running and the proud builder pop popped off down the
      track at
      > the
      > e specification 12 km/hr- albeit with some push assist through the
      > pot holes. Directional control is so rudimentary that at the end of
      each run
      > it was easier to jump off and lift the front wheel around rather
      than to try
      > steering.
      > In just 118 years this motor tricycle has morphed into
      > 150kw/200km/hr/climate controlled/automatic everything/autobahn
      > that cost proportionally less of an average person's discretionary
      > than the barely drive-able original.- doesn't seem possible, but it
      > happened.
      > I wish that kite sailing would parallel this.
      > Today we sailed our latest 4m single person kitesailing catamaran
      for the
      > first time.
      > Because I'd sworn at it extensively during the final stages of
      > (it was behaving very annoyingly), I thought it would bite me back
      as soon
      > as we were on the water. It didn't, or at least it hasn't yet-
      maybe it's
      > waiting for an opportunity with more potential for violence. Maybe
      I better
      > apologise now.
      > At last, an almost perfect boat, with all the best ideas we've
      discovered in
      > 15 years of kite sailing development: four rudder steering,
      swinging seat,
      > pull from leeward, displacement/planing hulls.
      > It also has a few new convenience features like an excellent hook
      in system,
      > no gaps between the hulls and rudders so that lines never get
      caught there
      > and an electric outboard for when you get caught kilometres
      offshore in a
      > dying breeze.
      > It's useable by any yachting standards- easy to sail, very good
      wind range,
      > high top speed (an earlier version has done over 50km/hr),
      excellent upwind,
      > surf stable, 250mm draft, 40kgm, car roof-able.
      > Since 1987, I've dreamt a lot about making kitesailing happen; have
      > many many silly things and some half sensible ones- the buggy boats
      > later monohulls were far from disasters.
      > Can kitesailing ever catch on? This new boat works well enough for
      sure- it
      > 's generations ahead of our earlier commercial offerings in every
      > But will people want to do it in sufficient numbers?- Bored or
      > kitesurfers maybe? Can it develop into a competition sailing class?
      > just as toys for mega yacht owners would be a start.
      > Not that we are planning for production just yet but a problem is
      that as
      > the design has become more sophisticated, it has also become more
      > to make- US $4000 is probably an achievable retail- but not less
      > allowing for transport, taxes and margins.
      > Dreaming on!
      > Peter Lynn, Ashburton Jan. 30'2002.
      > Photos coming soon!
      > Arc Housekeeping.
      > We are hearing of some asymmetrical flying/shoulder collapse
      problems from
      > users of 630 Arcs, so it's timely to re-publish our understanding
      of the
      > causes and the (generally simple) solutions.
      > The incidence of this problem last year was definitely less than 1%
      of kites
      > sold, and as the design construction and materials of this model
      > changed since then any higher incidence now is therefore likely to
      be the
      > result of more older kites in use and users loading their kites
      more heavily
      > as they gain experience and progress to smaller boards.
      > Firstly, asymmetrical flying and shoulder collapsing usually have
      the same
      > cause, one is a pre-cursor of the other. The cause is that the
      fabric in
      > the tip trailing edge area either stretches less than or shrinks
      relative to
      > the more heavily loaded fabric nearer to the leading edge.
      > Stretching is caused by sustained loading. Higher loads and loads
      > for long periods will cause more stretching as will any load
      applied to a
      > wet kite.
      > Shrinking is caused by repeated wet/hot/dry cycles.
      > Because the fabric in smaller kites is proportionally more heavily
      > they are inherently more susceptible to stretch/shrink effects than
      > kites.
      > So far we have always found that a solution is to re-stretch the
      > trailing edge.
      > In minor cases just making the fabric thoroughly wet, stretching
      out the
      > trailing edge (don't pull so hard as to risk ripping it though) and
      > it as stretched while it dries will be sufficient.
      > In more serious cases we have taken off the trailing edge binding
      and then
      > re-sewn the trailing edge without it, taking care to use minimum
      > thread tension. Binding shrinks when it dries out in hot conditions-
      > this is usually only noticeable after repeated cycles.
      > In the most extreme cases we also unstitch the reinforcing Dyneema
      > along the trailing edge and resew it taking lots of care not to
      pull in the
      > fabric edge while doing so.
      > If we ever come across an Arc with stretch problems which don't
      > sufficiently to the above, there are more extensive alterations
      that can be
      > made. The principle is basically to identify where the stretch has
      > and to fold and sew small tapered pleats so as to take out that
      > For appearance and aerodynamic smoothness, these pleats are best
      done from
      > the inside by first opening the adjacent trailing edge seam. For
      stretch in
      > the middle top section of Arcs- which will cause centre luffing not
      > collapsing, this pleat can be done through the zip or velcro flap-no
      > unpicking is required. Sometimes it's difficult to tell from flier
      > descriptions whether a particular problem kite has a stretched
      centre or a
      > hooked tip- and it's important to correctly identify the cause
      before making
      > corrections.
      > Until fabric that is non- shrinking and non- stretching as well as
      > impermeable, tear-resistant, super light, and UV resistant becomes
      > available, some stretch and shrinkage as kites get older is
      unavoidable but
      > fortunately only a small percentage of kites will be effected to
      the extent
      > that their flying becomes unacceptable- and larger sizes are fairly
      > immune. Stretch and shrinkage are not consistent so it isn't
      possible to
      > change the panel shapes of the kites as made so that later
      > is already compensated for- or at least not without causing their
      flying to
      > be unacceptable from the opposite sense in the beginning. So far we
      > always been able to fix any kite that has come back to us- although
      some of
      > them have been so old faded and used out that the cost of doing so
      > probably unwarranted.
      > Tip collapsing and asymmetrical flying can also be caused by broken
      or weak
      > tip sticks- because this will allow the wing tip to form a curve
      when the
      > kite is heavily loaded. Any bending in the tip will change the tip's
      > profile from it's original highly reflexive form to a shape that is
      > susceptible to tip luffing- although when everything else is in
      > condition there is a fair margin designed in before any such
      bending causes
      > a noticeable problem. If weak tip sticks are suspected, try
      swapping the
      > sticks to see if the problem swaps also, or try stiffer sticks. A
      > solution for this is to move the brake attachment point forward to
      the 75%
      > position as this loads the stick more evenly. This does however
      > that the leash be attached to one front line rather than a brake
      > Front line leashes tend to reduce spinning of the kite when the
      leash is
      > engaged anyway.
      > Another but unrelated cause of collapsing is the use of long bars
      on small
      > kites- basically it is possible to oversteer any kite to the point
      > collapse by using a bar that is too long, but this is usually only
      > noticeable on smaller kites.
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