Jump to content


Photo

LE center stack line


  • Please log in to reply
11 replies to this topic

#1 kwmf

kwmf

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 586 posts
  • Gender:Male
  • Location:Durban, South Africa

Posted 22 October 2012 - 07:09 AM

Hi there

I'm going to be making some stack lines shortly and that got me to wondering ... :innocent:

Is the stack line in the middle of the leading edge actually needed/relevant, and if so, what is it's function?
I've only flown a stack briefly, so I don't have an in depth knowledge of their mechanics so I'm looking for input here.


Just thinking about the mechanics of the setup and this is where I'm at...

The stack lines on the verticals (top and bottom) I understand are critical for control.
The outer leading edge links would be both for control (although to a lesser extent than on the vertical ones) as well as keeping the trailing kites from twisting/rotating relevant to each other too much



The one in the middle is where my brain isn't getting it...

When a Rev cups the wind the curve in the leading edge would induce slack in that link would it not thereby rendering that line ineffective?

At any point in the stack, the kite closer to the front will be taking more strain than the kite to the rear of it, so the front kite will always have more leading edge curvature than the one behind ... so that center line would go from slack to tight as you progress from the front to the rear of the stack.


I'm not sure what I am missing, but I just can't figure out that lines purpose ... hopefully someone can fill me in.

BTW I am not trying to save a buck by not making a center line, just trying to understand the mechanics.

Steven

#2 RevWizard

RevWizard

    Rev Guru and Historian

  • Forum Admin
  • PipPipPipPipPipPipPipPipPipPip
  • 3,401 posts
  • Gender:Male
  • Location:Europe & North America

Posted 22 October 2012 - 07:17 AM

You need that center line.
Take look at the bridle. It is built so that it keeps the center from bowing too much as the wind increases.
If you were to delete the middle stack line then the REVs behind the first would bow too much in reference to the first REV.

Long John (formerly Mr. R)

STACK International Executive Committee - 6/1996-6/2008
International Rules Book Committee and STACK International Head Judge - 6/2004-6/2008
World Sport Kite Championship Judge - 2004-2005-2006(Chief Judge)
13x 1st - 12x 2nd - 6x 3rd places in 37 overall Quadline individual competitions


Web Site - http://www.johnnmitchell.com/index.html Check it out today!


#3 Watty

Watty

    Forum Veteran

  • Forum Member
  • PipPipPipPipPipPipPipPip
  • 1,867 posts
  • Gender:Male
  • Location:Vancouver, WA

Posted 22 October 2012 - 09:35 AM

You need that center line.
Take look at the bridle. It is built so that it keeps the center from bowing too much as the wind increases.
If you were to delete the middle stack line then the REVs behind the first would bow too much in reference to the first REV.


Aye, really just maintaining the bridle connection points throughout the stack.

Spence "Watty" Watson

Posted Image Posted Image Posted Image Posted Image

 


#4 RevWizard

RevWizard

    Rev Guru and Historian

  • Forum Admin
  • PipPipPipPipPipPipPipPipPipPip
  • 3,401 posts
  • Gender:Male
  • Location:Europe & North America

Posted 22 October 2012 - 09:38 AM

Clear enough! Great answer!

Long John (formerly Mr. R)

STACK International Executive Committee - 6/1996-6/2008
International Rules Book Committee and STACK International Head Judge - 6/2004-6/2008
World Sport Kite Championship Judge - 2004-2005-2006(Chief Judge)
13x 1st - 12x 2nd - 6x 3rd places in 37 overall Quadline individual competitions


Web Site - http://www.johnnmitchell.com/index.html Check it out today!


#5 SparkieRob

SparkieRob

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 392 posts
  • Gender:Male
  • Location:Perth, Western Australia

Posted 22 October 2012 - 08:23 PM

What kites are you stacking? Your B2's or your 1.5's?


Tapatalk for iPhone.

"Inbetween heaven and earth, there are kites."


#6 kwmf

kwmf

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 586 posts
  • Gender:Male
  • Location:Durban, South Africa

Posted 22 October 2012 - 10:52 PM

Aye, really just maintaining the bridle connection points throughout the stack.


Best answer I've seen ... simple, obvious, neat.

I've seen photos of stacks with the center line loose relative to the others and couldn't figure the mechanics based on leading edge curvature, but this answer just says it all. B)

#7 kwmf

kwmf

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 586 posts
  • Gender:Male
  • Location:Durban, South Africa

Posted 22 October 2012 - 10:56 PM

What kites are you stacking? Your B2's or your 1.5's?


Either ...
I can't justify the $$$ for a permanent stack, but I would like the links available to so that I can made a vented-mid-standard 3 stack from time to time.

I will be making it tough enough for either option.

#8 SparkieRob

SparkieRob

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 392 posts
  • Gender:Male
  • Location:Perth, Western Australia

Posted 23 October 2012 - 12:35 AM

When I put my B2 with one of my 1.5's I had to shorten the centre link line as the second kite was bowing more than it should've. I think this has to do with the scaling from small kite to big kite and all my link lines were 4.5 foot, from a stacking kit.


Tapatalk for iPhone.

"Inbetween heaven and earth, there are kites."


#9 kwmf

kwmf

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 586 posts
  • Gender:Male
  • Location:Durban, South Africa

Posted 23 October 2012 - 12:44 AM

I knew the center line would be a bit shorter just by the way it all fits together, but the rear kites bowing more than the front kites was something I did not expect.

Between that surprise fact and Watty's answer I have all I personally need to know - even if I didn't understand it, it's apparent that it needs to be done all the same.;)

#10 REVflyer

REVflyer

    Rev Guru

  • Forum Member
  • PipPipPipPipPipPip
  • 1,293 posts
  • Gender:Male
  • Location:Germantown Maryland

Posted 23 October 2012 - 03:30 AM

there's kinda' a "black art" to tuning a multi-kite stack, most folks who go to all that trouble leave it that way permanently.

If you're only messing with a 3 pack stack (or so) you could just make stack lines (4) that connect the bridles together, from the down spar end-caps in front (to the bridle of the kite behind). That way you could take 'em off and on easier. This is a significant tuning compromise which offers greater flexibility to you on when & what kites to include on those stacking days.

Make pig-tails that face forward and larkshead loops that are behind the end-caps. Carefully mark or label each connecting stack line too, so they always go into the same locations

If the kites oscillate or pitch unevenly then you're not "tuned" and something needs to be adjusted. These adjustments take time and micro-precision, like a single over-hand knot applied in 90# spectra.

They should lock-in flight together when moving forward, some folks prefer a slightly shorter last kite on the bottom connectors, so it fetches up tight FIRST, as it has further to travel. As a pilot you'll watch the back kite.

The heaviest frame goes into the front kite,

ideally the stack lines should tie into the bridle spreading the stress

The less knots you have,.... the better you'll shed a tangle

When you're alone, a stack is easier to set-up on the ground when used with the TC Ultra plexi-plastic handles. The handles are drilled out to reduce weight and you can tension the stack against a stake at a predetermined angle by using the holes on the TC handles.

A stack is more fun with friends too, someone to undue the tangles, or fly it while you stand directly underneath and see what needs adjusting

A stack is a fiddlers' dream, there's always something that needs attention.

I like the mini-Ryv stacks the best, (36 or 42 inches for the leading edge). They're bumblebees on amphetamines, you fly 'em on ONLY the width of your thumbs! 24 wraps in less than a second, yet you can still walk a slow inverted side slide, depending on what wind range you're after. Eventually they get all out of tune and I'm too lazy to take on the repairs. I've flown baby-stacks in a steady 50 mph wind and walked 360's on a hundred feet of line in a dead calm.

I have no experience with the large sized stacks, they pull too hard for busted-up old guy like myself.

KiteSquid made these baby stacks back in the summer of 2000. We tied a twelve pack together to see how they would handle the stress, and before the experiment ended (badly!) we captured this photograph. It was great explosion, first three kites split like coconuts under a fallen building. NoTE: we know to slide .125 carbon tubes inside the 2P SS leading edge tubes on the first three kites now and we only fly as a six pack.

Attached Thumbnails

  • BabyRYVs3.16 copy.jpg


#11 aai

aai
  • Forum Member
  • 26 posts
  • Gender:Male
  • Location:Netherlands, 's-Hertogenbosch

Posted 24 October 2012 - 11:11 AM

I use 6 stack lines that I attache to 6 small tails.

For the rev in the middle I use 2 separate tails.
One in each direction.

With just 3 kites there is not that much bowing in the centre.

The 7th line, in mine experience, puts much stress on the mesh in the center of the leading edge.

andré

Attached Thumbnails

  • 1.jpeg
  • 2.jpeg
  • 3.jpeg
  • 4.jpg


#12 jburka

jburka

    Regular Poster

  • Forum Member
  • PipPipPipPip
  • 357 posts
  • Gender:Male
  • Location:Washington, DC

Posted 25 October 2012 - 09:00 AM

Aye [...]


Oh, crap, now he's even starting to talk like JB...




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users