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Author Topic: New Project 2013, Lilith  (Read 2649 times)
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KiteChemist
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« on: February 20, 2013, 03:11 PM »

This is a small video prewiev of an early version for Lilith, a freestyle kite i'm designing.

This kite has 235cm wingspan, 94 cm height, huge windrange and interesting trick performance.
The version of the video actually is a bit different (faster yoyo's, better and stupid easy taz machines, better jacob's ladders and better backspins)

Lilith second test.


Enjoy!
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Ca Ike
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« Reply #1 on: February 20, 2013, 03:54 PM »

Looks promising.  I see a bit of imbalance in the backflip and a few other quirks but it can be the low wind causing some of it or too much wing in the kite set up.  Hard to tell from the vid partly due to the sun but keep it up and keep us updated.
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KiteChemist
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« Reply #2 on: February 21, 2013, 01:09 AM »

Actually I moved a bit the standoffs to change the trailing edge shape, moved the center t upwards and increased the tail weight to 22g. This solved pretty much the small defects it had in the early version. Anyway the wind in the video was very unconstant (both in direction and speed) so the backflip was a bit problematic during the wind pauses. More videos to come, I hope that the weather will be better in the next days.
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Ca Ike
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« Reply #3 on: February 21, 2013, 04:20 PM »

OUch that a lot of tail weight IMO.  If you have to go over 15g tail weight on a std then I suggest you take a new look at the framing.  Whenever I work on tuning a kite I don't add any tail weight at all.  Most things tail weight does can be done by bridle settings, standoff positions and frame specs. ONce you get the kite flying and tricking well without weight then you can add weight to enhance some tricks.  The way your kite lays over in the backflip suggests an issue in the upper half of the kite either in the bridle or frame specs. If you can send me some good pics of the kite I might be able to make some suggestions to help but first off I'd take out all tail weight and just fly it around and see how stable flight is.

IF it doesn't backslide smoothly, downwind glide without rolling up, have good drive when you pump it or has oscilation (shuddering) when you go through the middle of the window then you have some dynamic instability issues to work out and no amount of tail weight will fix those.  One easy one to look for is where the nose goes when  you axel.  Even with all the tail weight it looks like your kite likes to go tail high in any flat spin trick and hang a bit nose low in a fade. Just using too heavy of an upper spreader can cause all that.

BUilding the kite is the easy part.  Fine tuning is where the real work and learning comes in.  YOu'd be amazed at how much of a difference something as seemingly insignificant as 3mm difference in standoff length can make. 
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KaoS
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« Reply #4 on: February 21, 2013, 04:48 PM »

OUch that a lot of tail weight IMO.  If you have to go over 15g tail weight on a std then I suggest you take a new look at the framing. 

I totally disagree.  There are plenty of excellent modern kites with that amount of tail weight or more.  R-Sky NSE has 18 grams, the smallest Q-Pro weight is 20 grams (okay, so nobody uses the 40 or 60 gram ones), Will Sturdy's Sabre II has 34 grams.

Tail weights aren't there to mask frame weight distribution, they are there to tune it.  Sure you could spend weeks and heaps of dollars trying out frame sets, but you can achieve exactly the same MUCH quicker, MUCH cheaper and just as effectively by putting a bit of weight here and there.

The one thing I would suggest, don't limit yourself to just throwing weight at the tail.  Wingtip weight and weight closer to the T-piece can produce good results in some kites
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Kevin Sanders

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« Reply #5 on: February 21, 2013, 04:56 PM »

Actually the tail weight was increased to speed up the yoyo's and make backspins better (the kite tends to lower drop much the nose in fade after the backspin), not to fix the backflip. I actually fixed some minor flaws moving the standoff positions and it was already possible to cynique it with the initial 18g. The wind in the video was a bit bumpy and unconstant so it wasn't so reliable in the backflip.

Anyway the kite is actually framed this way:
Leading Edge: 3pt-P3X (upper-lower)
Spine: 5pt
Upper spreader: 6mm
Lower Spreader: Black Diamond Nitro

The kite doesn't tend to drop the tail in flatspins (that are very flat) but it is also easy to taz (even if the tail doesn't go spontaneously down). The mayor problems were in the radius of curvature of the yoyo roll up (a bit too wide) that i solved trying different standoff configurations so now the rollup width is waaaaay smaller than in the video, even with 18g (but i like faster rollups by personal preference). The other triks doesn't seem to lose any of the performance and the taz machine seems even more stupid easy than before (i'm not a 99% taz-machine-success-rate-guy but i  was able to cascade it). Usually if the tail weight is exaggerated you can have some problem in cometing it, but i didn't see any degradation in performance with 22g tail weight. Of course it is still under test and i hope to fire another video that when the weather, and expecially the wind, will be better.


No bumping during the pumping of the kite, even with low wind, it goes stright up and seems to have good pressure even in very low winds. I don't even feel the need to design an UL, and probably stick directly to a ghost version)

PS: the video was already with 22g (i moved the standoff and came back to 18g, and then 22g again)
« Last Edit: February 21, 2013, 05:09 PM by KiteChemist » Logged
Ca Ike
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« Reply #6 on: February 21, 2013, 06:07 PM »

Does your spine have the large end at the nose or tail?  I've seen it both ways and that alone can shift weight around by about 3g iirc.  YOu can try going to a 5mm or p100 upper spreader but 6mm should be fine.  Curious about the p3x LLE though as far as weight/mass goes.  I'd think a 5pt or p200 would be better if the p3x is similar to a p300 in spec.  Less weight in the LLE might help with the rollup.
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KiteChemist
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« Reply #7 on: February 22, 2013, 09:40 AM »

Does your spine have the large end at the nose or tail?  I've seen it both ways and that alone can shift weight around by about 3g iirc.  YOu can try going to a 5mm or p100 upper spreader but 6mm should be fine.  Curious about the p3x LLE though as far as weight/mass goes.  I'd think a 5pt or p200 would be better if the p3x is similar to a p300 in spec.  Less weight in the LLE might help with the rollup.

Hi

The spine actually has the thinner part in the nose.  I chose the p3t-P3X configuration to have a more tail heavy kite (to use less tail weight) and for solidity reasons (to avoid breakage of the spars during failed 2 point landings that become tip stabs). Actually I was thinking that increasing the lower leading edge weight actually shifts the balande downwards and speeds up the yoyo (just like adding tail ballast weight). Heavier LLE does slow up the rollup in yoyo's? Why?


Pics:
https://picasaweb.google.com/116440615366198099089/LilithNewProject2013?authkey=Gv1sRgCLv0qo_Mn4OJVA#5829917056550732098


« Last Edit: February 22, 2013, 10:08 AM by KiteChemist » Logged
sugarbaker
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« Reply #8 on: February 23, 2013, 04:58 PM »

Heavier LLE does slow up the rollup in yoyo's? Why?

Rotational inertia. My understanding is that a mass distrubuted to the circumference of rotation will take a much greater force to rotate than the same mass focused at the center.
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Ca Ike
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« Reply #9 on: February 23, 2013, 06:16 PM »

Does your spine have the large end at the nose or tail?  I've seen it both ways and that alone can shift weight around by about 3g iirc.  YOu can try going to a 5mm or p100 upper spreader but 6mm should be fine.  Curious about the p3x LLE though as far as weight/mass goes.  I'd think a 5pt or p200 would be better if the p3x is similar to a p300 in spec.  Less weight in the LLE might help with the rollup.

Hi

The spine actually has the thinner part in the nose.  I chose the p3t-P3X configuration to have a more tail heavy kite (to use less tail weight) and for solidity reasons (to avoid breakage of the spars during failed 2 point landings that become tip stabs). Actually I was thinking that increasing the lower leading edge weight actually shifts the balande downwards and speeds up the yoyo (just like adding tail ballast weight). Heavier LLE does slow up the rollup in yoyo's? Why?


Pics:
https://picasaweb.google.com/116440615366198099089/LilithNewProject2013?authkey=Gv1sRgCLv0qo_Mn4OJVA#5829917056550732098



For pitch tricks mass in the spine has a greater effect since it is in line with the center of rotation.  Mass in the wing spars will help with rotational tricks such as back spin, however,  too much mass/weight in the LLE will actually hurt yoyo's because that weight being in a different rotational circle will start to create drag and slow the pitch.  BaSically when you want the kite to roll up you want it to roll up nose over tail within the radius of the spine.  Too much weight on the wing tips and the kite tries to roll up nose over wing tip and thats where you see the lazy layover or really wide pitch circle.  Try p200 or 5pt in the LLE and  you will feel a difference.
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KiteChemist
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« Reply #10 on: February 24, 2013, 08:23 AM »

I have some P2X camo to tray maybe  Smiley

THe NSE15 has P400 lower leading edges and it still rotates like hell  Grin

Anyway i chose P3X to avoid tip wobble during strong winds  Smiley

Changing P3X with P200/P2X seems only to change the balance by 4g, since the CoG of the spar is somewhat between center-T and tail the change of balance is merely of 3mm (the same effect can be attained using 1.5g difference in tail weight). Just for curiosity i will add a couple of grams for each wingtip to see if the yoyo performance is degraded.

« Last Edit: February 24, 2013, 11:50 AM by KiteChemist » Logged
Ca Ike
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« Reply #11 on: February 24, 2013, 03:05 PM »

Remember it's not the static balance were working with here. It's the dynamic balance or how the weight orientation affects flight. By lightening up the wing tips you are also transfering the % of mass ratio more to the spine  area. Not only should roll up change but fade should be mor stable as well. Once you get wind on the sail dynamic balance tends to trump static balance pretty fast.
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KiteChemist
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« Reply #12 on: February 24, 2013, 04:26 PM »

How can be the fade stable if the kite is becomes nose heavy reducing mass in the lower leading edge? Also dynamic balance seems to depend more on the sail shape than on the mass balance ( http://www.ian.ourshack.org/kitedesign/design.html ). In fact nose heavy kites have trimmed upper spreaders (changes the sail shape reducing the upper exposed sail area). Actually the effect of the dinamic balance can totaly overcome the effect of the static balance. In fact, moving the standoffs changed the sail shape and the yoyo is much more faster and tight than in the video, just without adding or removing any mass.  Smiley
« Last Edit: February 24, 2013, 04:41 PM by KiteChemist » Logged
Ca Ike
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« Reply #13 on: February 24, 2013, 06:16 PM »

With more mass in the spine than the wing tips a kite has less tendency to roll off axis (wobble) and lock in more.  However as you are learning its a delicate balancing act.  In one swap you can make a fade stable side to side but increase the likeliness it will drop the nose and fall out.  THats one reason for using tapered rods in the LE.  YOu can concentrate more of the mass around static center(the line you want the kite to pitch around) making spreader and tail weight as well as sail shape in the nose and keel more effective.  YOu either have to love to tinker or be a masochist to build and tune a sport kite (a love for kiting helps too) Tongue 
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KiteChemist
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« Reply #14 on: February 25, 2013, 01:02 AM »

  YOu either have to love to tinker or be a masochist to build and tune a sport kite (a love for kiting helps too) Tongue 

 Cheesy Cheesy Cheesy I love to design and build kites  Wink
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