Extending Levitation Delta Upper Wind Range

edited June 2011 in General
I have a standard 9 ft Levitation Delta and have it found it to be a reliable flier for my KAP rigs in the 12 - 20 MPH wind range. I have flown it in higher winds but this is outside of it's designed wind range (flies erratically and pulls too hard).

I was out flying a couple of days ago in 20 to 30+ MPH winds. I typically use a 7.5 ft Conyne delta or Trooper delta for these higher winds, but wanted to try something that would provide some additional lift. So, for the fun of it, I substituted the shorter Conyne spreader spar into the Levitation and it flew suprisingly well. The stock spreader that came with my Levitation is 46.75 inches long. The Conyne spreader is 39.5 inches (7.25 inch difference).

I flew the Levitation for about 20 minutes with a single fuzzy tail and captured some of it on video (see below). It flew at a relatively high angle (50+ deg) in winds ranging between 20 and 30 MPH with a measured line pull of 10 to 15 lbs. It provided more pull and was more stable than my Conyne and Trooper deltas.

Levitation (short spreader)

I'm not sure if shortening the spreader this much is a good idea or not. I've only tried this on my Levitation once but the results were surprisingly good. I am wondering if others in the kiting community have tried shortining the spreaders this drastically on deltas and if it is a good approach for obtaining higher wind range or am I asking for trouble?
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Comments

  • Well, it has the effect of decreasing sail area and more importantly, IMO, aspect ratio, and perhaps changing the center of pressure and therefore the balance of the kite. Looks like a worthwhile technique to me -- I can't see why you'd be asking for trouble. I hope some kite design maven like Becot-san will chime in here.
  • Very good idea Mike. Dan Leigh made a page about this way to increase the wind range of a Trooper (mmm, may be not your drastic way ....): http://www.deltas.freeserve.co.uk/custom_trprs.html
    I usually fly a Trooper and un 9ft Levitation and find there is a wind-range gap between these two kites. Shortening the spreader seems to be a good way to reduce this gap. I'll try as soon as possible. This will be very usefull for my travel/hiking kit.
  • edited June 2011
    My fishing pole kite is now all weather vehicle. Main reason is that is has special "Curb Lines", which allows tuning with infinite precision. If you look this video closely, the kite has one line on left on top of the kite (from center pole to wing tip) and one below (from center pole to the end of cross pole). Youtube Video

    Now the curb on the top is adjusted when the wind is hard as hell, it corrects the tendency to veer left. And the otherone is for correcting the tendency to fall sideways when wind totally dies.

    Also it is my unscientific belief that delta wings needs drag, ie flappiness for stability. So it has those flapping wing tails.
  • I accidentally found a photo of DC, made by Mr.Katsutaka Murooka Japan. I did the same with my 7.5 'DC. Kite ceased to turn in strong wind gusts 25 mph. Quickly rises to the top and pulls better. I did the pictures at 20 mph. http://www.flickr.com/photos/bluekiteteam/5779975638/in/photostream
  • Timonoko: Thanks for sharing the video. I really enjoyed it! Lot's of entertaining bits, good scenic shots, and adventure!
  • edited June 2011
    Timonoko - Truly OUTSTANDING video on many levels! Just Excellent.

    Two questions: What is the brand/model of your kite, or did you make it? It is beautiful. (you are obviously very handy - sort of an outdoors Leonardo),

    and can you explain once more what you mean by "curb lines." I looked closely at the video more than once, but cannot really see what you are referring to...even though you explain it above. I am dumb, I guess.

    Mike - 30mph!? Wow! Thanks for doing this experiment -- it really opens some doors.

    Phil
  • edited June 2011
    "Curb" as in "Curb your Enthusiasm". This is far beyond my anglo-linguistical abilities. But look at the picture below. Because the kite is made of cheap 3 euros/meter material, this line in my hand is preventing (ie curbing) the material from stretching too much.
    Curb Line

    The green square keeps the "Curb Line" in place when it is loose.

    And yes the kite is made by myself. It is made of 2 euro 3 meter fishing poles. Just because carbon rods are so expensive here in infinlandia.
  • Ahh, I see. Thank you, Timo. To understand then, if the kite were constructed with a low stretch material, perhaps the curb lines (what I might call restraint lines) may not be necessary? This kite looks a bit different than the one in the video -- did you make both of these?

    You are a man of many, many talents.
  • edited June 2011
    Same kite. Those green strenghtening ribbons are underside, thats why it looks different. At some point the material yields, whatever it costs, and the curb line prevents that.

    Actually I just remembered that there was some monster winds in February, maybe some 20 meters/second. I had curb lines on both sides, and I found solution for that particular situation, but never anything universal. So I say my kite's maximum wind is about 15 meters/second (ie 30 miles/hour). Those fishing poles are anyway very good for kite making, no problems with them.
  • I was scratching my head quite a bit trying to increase wind range for 9 ft Lev Delta. Had spreader broken 3 times in strong wind conditions (20 MPH+)
    It usually snaps close to ferrule. Because of spreader's flexibility it bends so much that it snaps.
    Finally, I just replaced fiberglass sreader with solid bamboo stick of the same diameter. You can get a pack of those in a dollar store. It is also couple grams lighter than original spreader :)
    It worked beautifully and now I use my Delta for strong winds.
    If Leading edges brake I will replace them with bamboo too :)

    Hope that helps,

    Yury
  • Many thanks Mike to gave me the impuls to try (what I did 30mn ago). It works fine ! No more gap between Levitation and PFK.
    Timo: not sure (at all !) to understand very well what your trick is, but I'll try again and guess it's (one more time) a very clever one. And it was, once again, a great pleasure to watch at your video.

    With a Trooper spreader (93cm instead of 122)


    And with a 7ft Premier Kit (111cm)
  • Outstanding work, Mike and Timo.

    I have been thinking about buying a Levitation for a while now, and this will probably seal the deal. I assume it would be better to go with the beefier Levitation, as opposed to the Levitation Light, for using in higher winds?

    How small does the kite pack down to? Has anyone converted this to a more convenient travel size? I like to put my spars in a 37 inch art tube when traveling. Is there any way to do this with the Levitation and still have it be strong enough for the higher wind range?
  • The longest spar or spine section in the 9 foot Levitation Delta that I have is 29.5 inches. If you leave the forward sections of the two leading edge spars and the forward section of the center spine in the kite, you can just get the kite into a 35 inch space. So your 37 inch travel tube should be OK.

    I was thinking (that's the problem!) that I might like to pack it down smaller than that and was considering using 3 piece spines and spars instead of the 2 piece. Any thoughts on doing that properly? I have some 0.2540 inch (6.5 mm) pultruded graphite tube from Kite Studio (part RLG2540L) and corresponding aluminum ferrels and was going to make each spine/spar with 3 equal size subsections.
  • edited June 2011
    A couple concerns I have with using the shorter spreader are:

    1. A normal length spreader is long enough that usually has to be flexed to get it into the wing pockets. A shorter spreader results in looser wing material and could possibly pop out of the wing pockets in turbulance. It may be good to use a pin on each end of the spreader to make sure the spreader does not accidently pop out....

    2. I'm not sure if there is a yet unknown mode of instability that the kite can get into with the wing material this loose (i.e. when it overflies will it get into an unrecoverable power dive?)

    I don't know if these are real issues or not, but given more flight testing by multiple people, we should know the answers relatively soon. Until then I suggest proceeding with caution before hanging a camera on it...

    Mike
  • Very interesting stuff! Timo, I'll have to try your approach and see how it works on my kite.
  • edited June 2011
    Ormes, Thank you for testing this on your kite. This is encouraging data. I also have hopes that this will fill the gap between my Rok and Trooper/Conyne.

    Michael, I have a standard Levitation and it seems to be very well built and should be able to take the higher winds. I'm not sure about the Levitation Light, but I've heard good things about it's construction as well.

    Mike
  • Mike - I cannot see exactly what could cause the Lev to overfly as in concern #2 above, especially in higher winds like we are referring to. My guess is that it would never go over 70 degrees in 20+ mph. This is an exciting prospect! Thanks again.

    This gives me a good excuse to get a delta, finally.
  • Us delta advocates have always had plenty of excuses to get a delta. They are wonderful KAP kites.
  • edited June 2011
    Any idea if Sky Shark P200 tubing with an internal ferrel would be strong enough for the shortened cross spreader of the 9 foot Levitation?

    The flight angle of the Levitation seems quite high and there is only one loop for attaching the kite line. Do most of you guys fly the Levitation with a tail to reduce the flight angle? Are there attachment points on the kite for a tail?
  • Lev has 3 points for tails. 2 on wings and one in the middle.
    I personally found out that it is way more stable and better for kap to fly with one tail attached. And yeah, it overflies less that way.
    However, if the wind is light it will overfly whatever you attach.

    Hope that helps.
    Yury
  • edited June 2011
    Thanks, Yury! I will try a tail and see how the kite performs.

    Rather than use the Sky Shark tubes with an internal ferrel, I found a spar I had with an external ferrel, very similar to the stock spreader. I cut this down to about 40 inches. It does feel like it is short enough to come out in flight, though my guess is that a strong wind would probably keep the spar in place without a problem.

    While rigging my new Rokkaku, I found one possible safety feature that might be worthwhile when using the shorter spreader on the Levitation. Small loops could be sewn on the inside ends of the Levitation's spreader pockets and a tensioning line could be added which could be secured by a tautline hitch. This would be an extra bit of insurance against the shorter spreader popping out of the pockets.

    I am away from home for a while and don't have the necessary materials with me to try this, but I will make this modification when I return home and report back.
  • Michael, after running into you this morning I had a brain fart: Two safety pins and a short length of light line would be enough to do what you're saying. In a pinch, anyway. I like the idea of the more permanent loops. But this would get you going in the short term.

    Tom
  • edited August 2011
    I recently added a tensioning line, featuring a tautline hitch, to hold the shortened (40 inch) spreader securely in the Levitation's stick pockets. I feel much more confident about the setup with the shortened spreader being held in securely. I tested the kite in a wind of approximately 25mph and it flew exceedingly well. I'm very pleased that the Levitation, which collapses into a very small package for traveling, performs so well in these higher winds.
  • edited May 2012
    I must agree with Michael on performance, and thank Mike for the awesome idea! In the remaining winds of Irene today, the 40 inch bamboo spreader allowed the Levitation to fly SUPER well, higher than expected and with strong, steady pull in the 20+ mph wind. It was very stable and did NOT need a tail at all. I'm going to continue using a tail ONLY in lower wind speed while using the 48 inch regular (albeit, now bamboo as well) spreader.

    This shorter spar method gives the kite wonderful range and power. Wow! It's like having a whole new kite in the collection (A Porsche hidden inside a KIA)!

    By the way, a 39-inch line including a permanent loop at both ends, placed over the slightly projecting spar pockets works great to 100% prevent the short spar from coming out.

    Phil
  • edited June 2013
    I've made some refinements to the Levitation shortened spreader concept which make it self-adjust to different lengths based on the wind speed. I've had significantly good results with this and now use my Levitation exclusively for winds between approximately 15 MPH and 30 MPH. Note that I have not flown it in winds much above 30 MPH, so I would suggest getting a fair amount of flight time with it in winds over 30 MPH if you plan to fly in these conditions. I also always use 2 lengths of fuzzy tail to make sure the kite stays stable while the dynamic spreader adjusts to the varying wind conditions.


    Here's a link to more information for building one: http://www.flickr.com/photos/iowakaper/sets/72157629944465156/

    Dynamic Spreader Spar


    Edited 6/6/13: Here's a link to a related thread:

    http://arch.ced.berkeley.edu/kap/discuss/index.php?p=/discussion/3967/dynamic-spreader-spar-for-variable-wind-conditions#Item_5

    Mike
  • Love it Mike! Well done. Increasing the wind range of a kite while in flight is one of kiting's holy grails.

    Like the pocket locks and the line limiter to protect against extreme compression. The Levitation flex stop is a key part of this kite design and helps maintain the center of gravity and kite shape during gust and thus makes this a very good KAP kite. Your design will expand this capability further (a key requirements and advantage when the wind speed drops or picks up with a KAP rig on the line)!

    PFK has a similar concept built into their "Super Delta Kite ". Flew one of these for years till I lost it in a storm....From the flickr feed it looks like you experimented with a few designs (wood blocks with holes and the nylon spacers (epoxied together?)). Which works best?

    Since you are blazing this trail.....I was thinking of a similar experiment...perhaps you could give it a try (I am too busy working....and flying ;-). Basic idea:

    - taking the standard two or three piece spreader spar made out of Sky Shark P-400 wrapped carbon tubes.
    - add one or two internal springs inside the carbon tubes with stops at either end

    Just a rough idea...if you or others have time...run with it.

    See drawing below.

    WW

    Dynamic Internal Spring Spreader Spar for delta kites.
  • edited May 2013
    Wow, that dynamic spreader looks great Mike! I happen to have some P200s lying around after a botched shipment from my supplier - I think I just figured out what I've going to do with them! Your photo plans are fantastic and very easy to follow.
  • edited May 2013
    Jim, I did not find any significant performance difference between the wood block and nylon spacer implementations. The key is to place the blocks or spacers far enough apart from each other to insure that the spar is always able to compress smoothly and does not bind when under pressure. The spar must ALWAYS be able to compress smoothly in higher winds. If it binds and does not compress freely, then it will flex and possibly break. I like your sketch of a more integrated solution with internal compression and think that a design like this with a single spar profile (vs. two overlapping spars) would be better if you could figure out a way to make it light weight and operate smoothly. It's worth pursuing this approach further. Integrating the compression function into the kite spar pocket would also be a good approach. I'm interested to hear ideas that other people have on this.

    nasion, go for it! Let me know if you do make one and how it works for you.

    Mike
  • Well done, Mike! :O)
  • edited June 2013
    Thinking on this while my ITW order crosses the Atlantic. Back in the day a spring steel strip was the secret of the extrodinary wind range of the legendary Powell Stunter in c1975:

    Powell 1975

    Powell 1975 end view

    I never flew mine on a single line but it would fly in pretty much anything except sea water!

    It might be possible to fit an anhederal spreader like this:

    Powell 1975 inverted spreader

    A limiter would be needed to stop the spreader rolling over and losing tension:

    Powell 1975 inverted spreader 2

    ..and finally this might be a better idea:

    Powell 1975 inverted spreader 3

    Might be another approach to achieving the same/similar effect on the Levitation?

    B
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