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foxturtleman · Joined: 04 May 2004 Posts: 57

Well the subject about says it all, I made a traditional 12' genki, the verticals and diagonal spars are 6mm pultruded Carbon and seem to perform fine. I started with a horizontal of 10mm pultruded Graphite, but when I went to first launch the kite it simply bent in half and completely tore the internal fiberglass ferrule to shreds. Since then I have not dane any work on the kite. I would like to know what you would reccomend for both the 12' spar and for ferruling it together.

thanks in advance,
chris

Doug LaRock · Posted: Tue May 04, 2004 11:28 pm Post subject:

Chris

For spars under bending stress I prefer external ferrels because they are stronger and they spread the stress over a bigger area. Did the ferrel fail or did the Graphite spar split?

Doug

imagin · Joined: 22 Oct 2003 Posts: 234 Location: Moncton, NB Canada

Like you Foxturtleman, I built my 12' Genki with 10mm pultruded Carbon. I used external ferrels and have had no trouble with splitting. However, I must fly it in low winds. Anything more than 12-15 mph winds is just too hard on the kite, bends way too much. I wish I'd made the rings to accept a larger spar. I still may redo it to go heavier on the spars.
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Knowledge is limited. Imagination encircles the world.

stevef · Posted: Wed May 05, 2004 8:55 am Post subject:

Can we see a picture of the front and back of your kite? Can you describe how you ferreled the horizontal - is it in three pieces? Linear Graphite should always be ferreled externally, unless you are Thread Wrapping or adding additional material for hoop strength.

What kind of winds do you most often fly in?

Where did the spar break?

Consider adding either an Epoxy RET505 or RET524 (same ID, different wall) as the central spar of the horizontal. 10 mm slides inside these spars, and the fit can be made perfect with one or two wraps of tape. So, you would have two 10 mm's on either side of the 524. The 524 is a little stiffer than the 10 mm and nore "durable" imo. This way you can use the same size end fittings.
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Steve Ferrel
Go Build a Kite!
Measure once, buy twice!

foxturtleman · Joined: 04 May 2004 Posts: 57

Well to be exact at first it was the Graphite spar that split, I had ordered a spare, so I swapped it out the next time I took it out. The wind was about 12+ approximately and that time the internal fiberglass shredded. I had thought about sleeving the center portion of the spar with a heavy duty fiberglass that would fit over it, to reduce flex and so on, that seemed to have been one of the suggestions. Also I was unaware that Carbon should be externally ferruled, I will do that from now on. As for how the horizontal spar attaches to the sail I borrowed a bit of tech from a rok I built. It simply slips into pockets at the end and has a tie down where it passes over the vertical spars. Bow is achieved with a line run through the ends of either spar pocket.
I modified the bridle from havind two vertical primaries runing from keel to keel to have two horizontal primaries attached to the secondary, that way there is only one point to adjust and I can affect the AoA quickly and easily to suit the winds.

does this give you a better idea of my problem? where did I go wrong?
thanks,
chris

stevef · Posted: Tue May 25, 2004 5:14 pm Post subject:

I think the internal ferrel was the killer. Have you had a chance to fly it since you converted it to externals?
_________________
Steve Ferrel
Go Build a Kite!
Measure once, buy twice!

Dorsal · Posted: Tue May 25, 2004 9:27 pm Post subject:

On my AfterBurner, I uses internal AND external Ferrels, with custom Rev SLE rods. The internal ferrule is half-glued into one rod, and the external ferrule is half-glued onto the other rod. Slide them together, and Voila, the joint is triple thick!

Skyshark makes some 12mm rods, btw - that's what is on the Thor's Hammer.
_________________
"The wind is the perfect reminder of God.
The only way we can prove it exists is by observing the things it affects. "
Dennis
AuctionSniper.com

KiteSquid · Posted: Wed May 26, 2004 7:29 am Post subject:

I wonder what Premier Kites uses in their 114" wide Genki...

I Need to make a phone call or two to find out...
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VR/
KiteSquid
AKA TakoIka
AKA Harold
King George VA

P.S. Yet another post by the Squid..... Shocked

Doesent he ever shut up???

P.P.S. The wind is like the air, only pushier.

kitepoor · Posted: Wed May 26, 2004 8:16 am Post subject:

I have one
IIRC it has pultruded with an external epoxy ferrel. I will look, and see if I can tell for sure
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Randy
a kite a nice thing
kite in the air a beautiful thing
kites to share the coolest thing

KiteSquid · Posted: Wed May 26, 2004 8:18 am Post subject:

Check the ID and OD for us...
_________________
VR/
KiteSquid
AKA TakoIka
AKA Harold
King George VA

P.S. Yet another post by the Squid..... Shocked

Doesent he ever shut up???

P.P.S. The wind is like the air, only pushier.