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Author Topic: Bridle Modification  (Read 4424 times)
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Spz0
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« Reply #15 on: May 29, 2009, 08:20 AM »

In flight each leg of the bridle is pulled tight. The tow point pigtails get pulled a tiny bit towards each other when the lines are wrapped, but the geometry of the bridle doesn't change.

Even in a dynamic (turbo) bridle setup? 
Im not contesting, Im just trying to understand this more.  Wink
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Spz0
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« Reply #16 on: May 29, 2009, 12:55 PM »

hehe, that is essentially my next step. I've already swapped out the lower spreaders with P200's and the solid ferrule with a hollow core ferrule, and next Im going to swap the leading edges.  P300s are 2 grams heavier than the P200s.  The ferrules used are also solid core, which are 2 grams heavier than the hollow core.  Replace those with hollow core and I save another 4 grams per side (including the nock end ferrules).  So, with the spreaders and the leading edge upgraded to P200s, I will shed almost an ounce.  22grams by my count.

I was thinking about the whole pendulum theory with the oversteer factor on the widow.  Good to hear someone else is as well.  lol
My opinion on the Widows oversteer is weight, the Widow Maker doesn't really suffer from it, the Widow does, especially in light winds. Since the kites are identical in sail shape and you've corrected the bridle (some early production models had bridle problems) and still find the oversteer to be objectionable you might try reducing some weight. The Widows P300 frame is 14 grams heavier then the Widow Makers Nitro frame. I don't know what would happen to the kites response & handling if you swapped out the lower leading edges and even the spreaders for P200's but if you fly mostly in low winds it might be another option to look at if you have some spare rods about.



Agree.

Also might change out those end nocks and ferrules.  Those suckers are heavy...   

Just replaced the nock ends and ferrules.

I weighed them just for kicks,, and the stock nock ends with the ferrules and line attached were 4 grams each side.
The new nock ends and hollowed ferrules I replaced them with (with shorter, lighter weight line) are now 1.5 grams per side.
2.5 grams in weight reduction per side.
That might make a slight difference, being as all that weight is in the last 3 inches of the wingtip.
I'll post when I fly her next.

-cheers
~Jon
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anOldMan
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« Reply #17 on: May 29, 2009, 01:52 PM »

Spz0,
Allen is correct. You are thinking that the kite is a static entity in the air. It is not. When the kite is flying, it is a dynamic entity. There is pressure on all bridle lines. (except of course during slack line movements). So you should be looking at the tow points only and not the tow line. Even with a turbo bridle the dynamic tow point and pressure on all lines is true.

I don't know the length of line that you are using but unless it is 5 meters or less there is very little difference in the angle of the line to the tow point from a rapped line and an unwrapped line.

The rap will always be closer to the person flying the kite than to the kite. To verify this, put 3 or 4 raps in your line. Put your hands in your neutral position and fly the kite to the top of the wind window. Look at when the rap is positioned. Now do the same thing but put you hands together in front of you. The line rap will be closer to you. I order to have the rap closer to the kite (and then have some effect on the placement of the tow point), you would have to have your hands about 8 meters apart.

The difference in flight characteristics that you feel is probable due more to the timing between when you input  (pop a line) to the kite and when the kite reacts. With a rap there is always a small delay unless you have 100 % no friction between the lines. That is why sport kiters want very slippery lines. You do not want to change your input depending on the number raps you have on you line.

The only trick I can think of that you would want a rap of your lines as not have the rap is a Yo-Yo. And that is to have a higher percent of have both lines catch the Yo-Yo stoppers.

Just out of curiosity, what are you going the call your kite when you are finished with the modifications. It is going to be Widow in sail design only.

Good winds (and you are going to need them to test all these modifications.) That said, you will probable know more about the Widow than anyone but the designer.
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Hill  :-? :-?   What hill?   I don't remember any HILL!!  :-? :-?

anOldMan
Spz0
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« Reply #18 on: May 30, 2009, 06:21 PM »

It'll still be a widow my friend.  I think I'll name it -- Widow "Voided Warranty Edition".

K, so I just snapped one of those hollow core ferrules today.  The ferrule that connects the lower spreaders together?   Yeah.  Shredded it.  so, out the door go my new P200 lower spreaders (the right side spar fractured right where the snap occurred).
I Love throwing away money.. Really!  I do!  Embarrassed
I'm pretty sure theres no strength difference from P300 to P200, but those ferrules....
Now Im wondering if it is a good idea (when I reframe the leading edge) to use hollow core ferrules to connect the LE spars?
Probably not I would assume.  It wouldnt be going through quite as much stress as the Center T does, but there is always tension and flexing happening on those LE's.

Is there such thing as a solid core lightweight ferrule?


`Jon
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Allen Carter
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« Reply #19 on: May 30, 2009, 07:08 PM »

Hollow core ferrules (really just hunks of pultruded rod) are usually OK on SUL frames, but I wouldn't use 'em in UL or heavier frames. I don't know if the various brands (2 or 3?) of solid ferrules I've used vary in weight. I just want a ferrule to be strong.
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Allen, AKA kitehead
Spz0
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« Reply #20 on: May 30, 2009, 07:23 PM »

Agreed.   I think Im in the trial and error stage of kiting and modifications.
Just sucks I blew $20 on these spars to have them break in 15Mph winds.

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Allen Carter
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« Reply #21 on: May 30, 2009, 07:40 PM »

What kind of spars?
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Allen, AKA kitehead
Spz0
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« Reply #22 on: May 30, 2009, 08:34 PM »

Skyshark II P200's.

They fractured right at the ends where the ferrule that was inserted snapped.
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Gardner
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« Reply #23 on: May 30, 2009, 09:50 PM »

i'm not surprised the rods snapped.  In a 15 mph wind, there was just too much stress.

You are learning the hard way what many veterans already know -- once the limitation of the rod is exceeded expect disaster Sad.  Even an Aerostuff hollow ferrule will break if overstressed Embarrassed.  And that one short little ferrule costs just a tad more than than two SS tubes.  I know because I did it.

BTW, that Aerostuff  ferrule is only about five or six inches long Cry Sad.

Before someone asks,"Don't you believe a design can be improved by tweaking or tinkering?", I'll answer,"{ Yes, it can."  There are any number of successful designs which have been improved over the years by tinkering and tweaking.
However, there is also a lot of "been there and done that experimenting" knowledge out there which is available for the asking.

I believe almost everyone in this forum will share their knowledge if asked.  A number have responded to my questions and the advice given was good.  There are times I have even tested it to be certain I was wrong. Cry

To answer your question about a lightweight solid ferrule, yes there is -- a carbon (graphite) ferrule as opposed to a fiberglass ferrule.

Good luck with your experiments.  After all the P-51 Mustang would never have been  the best fighter plane of WWI if someone hadn't thought of swapping its original engine out for a Rolls-Royce Merlin.

Gardner


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Allen Carter
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« Reply #24 on: May 31, 2009, 12:22 AM »

Both broke at the same time? At the T? That's odd. P200s are damn strong. 15 should be no problem if the frame is set up right.

It's common to have issues with the spreaders "spreading" off the ferrule. If you have less than an inch or so of ferrule in the spreader, the end of the spreader will split. There are a number of things you can do to make sure the spreaders say put. Longer ferrule. 3.5" minimum. 4" is better. On a lot of kites just angling the standoffs in towards the T even a little bit will do the trick. Standoff/spreader fittings need to be tight or stoppered. My favorite Ts capture the spreaders with friction. Some kites need a rubber band to pull the spreaders together.

Maybe take a look at how it's done on the Skyburner version.

Anyway, with a proper T setup, P200s will do fine beyond 20MPH.

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Allen, AKA kitehead
Spz0
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« Reply #25 on: May 31, 2009, 08:56 AM »

Thats what I thought as well.  I had a 3.5" ferrule glued in on spreader - inserted through the center T fitting (rubber) then the other spreader was inserted to the ferrule (if ya get me).  So there was 1.5" of the ferrule in each side, and 1/2" in the center T fitting.  The snap occurred on the 'non glued' side, fracturing the spar right at the end of the spreader -- where the ferrule snapped.  The fracture is about 1 1/2" long down that spar.  The other spar (with the ferrule glued into it) didn't actually fracture.  It just looks like it (a scratch).   I am not able to get the fragmented ferrule out of that spar, as theres only fragments sticking out of the end.  I'd still use it, but the balance would be off center from the remainder of that ferrule still glued in.
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Spz0
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« Reply #26 on: May 31, 2009, 09:01 AM »

Heres a couple pics.
Note the 2nd pic.  Thats the fracture Im talking about.



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stapp59
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« Reply #27 on: May 31, 2009, 09:57 AM »

If you have a 1/8 to 3/16 piece of music wire 36" long, you can carefully heat the end of the P200 with the broken ferrule using a propane torch to soften the glue.  Then use the music wire to pop out the broken ferrule.  Have done this several times successfully.  You can also wrap the last inch or so of the the non ferruled P200 end with spectra line and glue to resist splitting.

Do use solid ferrules exclusively except with P90 and 2PTs where hollow is OK.  The hollow ferrules break pretty easy as you know  Undecided

Steve
« Last Edit: May 31, 2009, 10:14 AM by stapp59 » Logged
Spz0
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« Reply #28 on: May 31, 2009, 10:14 AM »

If you have a 1/8 to 3/16 piece of music wire 36" long, you can carefully heat the end of the P200 with the broken ferrule using a propane torch to soften the glue.  Then use the music wire to pop out the broken ferrule.  Have done this several times successfully.  You can also wrap the last inch or so of the the non ferruled P200 end with spectra line and glue to resist splitting.

Do use solid ferrules exclusively except with P90 and 2PTs were hollow is OK.  The hollow ferrules break pretty easy as you know  Undecided

Steve

Thanks so much bro.  Smiley   Got the ferule out with no problem.  Smiley   I just used a lighter, using only the blue flame to heat the spar.  Worked like a charm.  Thanks again!

That trick with wrapping spectra around the spar -- is that to patch the one that is split?  Or is that more of a preventative maintenance thing?

-cheers
~Jon
« Last Edit: May 31, 2009, 10:17 AM by Spz0 » Logged
stapp59
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« Reply #29 on: May 31, 2009, 10:25 AM »


Thanks so much bro.  Smiley   Got the ferule out with no problem.  Smiley   I just used a lighter, using only the blue flame to heat the spar.  Worked like a charm.  Thanks again!

That trick with wrapping spectra around the spar -- is that to patch the one that is split?  Or is that more of a preventative maintenance thing?

-cheers
~Jon


I've done both patching and prev maint using wrapped spectra, glue (CA or epoxy), and a little black enamel paint to hide the mess.  Depending on the length and depth of the split, it may just be better to replace the tube than risk another in flight failure. 
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