FAQ - Line lengths - what difference does the length make

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bigmark100
Posts: 2238
Joined: Mon Nov 01, 2004 10:05 am
Location: 27m below a kite

So , what difference does it make to have longer / shorter lines on your kite?
I assume it will make a difference to control and power. But when and how and why would I want to change the length of my lines.
Cheddaz
Posts: 636
Joined: Wed Nov 03, 2004 5:25 pm
Location: London

One reason is on holiday...

I bought shorter lines so I could launch on potentially more dangerous beaches... :wink:

I work on the basis that you should be 3-4 line lengths from any objects so shorter lines mean beaches can be narrower. Not sure if this is reasonable though.

Shorter lines - I think - mean less power in a power stroke, the kite however moves quicker as the lines are shorter.

Pros use them for KiteLoops as the kite has less distance to travel before its back to square one for the second loop.

So they are nippier with less power??
and maybe better on narrow beaches???
Airbourne Oakie
Posts: 543
Joined: Mon Nov 22, 2004 4:11 pm
Location: 31,56,46,18S 115,48,40,98E

Not really sure about the narrow beach idea chedz, after all, if you get lofted and travel 20 feet, whether your lines are short of long, you still travel 20 feet. :(
Cheddaz
Posts: 636
Joined: Wed Nov 03, 2004 5:25 pm
Location: London

True...
I like my theory but have yet to try out the lines (sitting in a bag withering away)
nickgrant
Posts: 1611
Joined: Sat Oct 30, 2004 11:07 am
Location: London

I learnt on 20m lines - they seem to give you a bigger windrange, but you can't jump as high. I reckon this might translate to smaller loftings and drags as a beginner, but then again, you have to work the kite more, so going upwind is harder.
skyte
Team/Shop Rider
Team/Shop Rider
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Joined: Fri Oct 29, 2004 11:37 pm
Location: North Wales, Flexifoil Kites and Boards

a kite on shorter lines will travel from one side of the window to the other quicker, because this distance is shorter (the radius - line length - of the arc is shorter) The kite doesn't actually fly faster, it just appears to because it's window is smaller.

It therefore takes less time to loop the kite. Short lines help you do those kiteloops where you are higher than the kite because the kite can get get round a loop circumference that has it's base lower than you in the time it takes for you to land. Imagine a cone with your harness hook at the pointy bit and it's base made from the loop the kite makes. the same angle cone with longer lines has a bigger circumference at the base so the kite is gonna take longer to get round. Unless you are at some serious height, you will land before the kite completes the loop.

I think short lines = lower jumps because the kite has less distance to accelerate when you send it so it is generating less power at the boost part of the jump.

Cheddarz... i would have to disagree with your line length safety margin theory! At least you had safety in mind tho!
david_hazell
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Nice analysis there skyte...
karlquartz
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Joined: Fri Nov 12, 2004 10:38 am
Location: London :-(

hmm, but skyte, if the jumps are lower, being further down the cone isn't helping you much with the kiteloop scenario???

just a thought.

Also, think of a wheel. If you are near the hub you are turning much slower than out on the rim. If you use that analogy, the kite on short lines is near the hub and moving slower.

But the fact is, you aren't on a wheel or a cone.

Kites on short lines do move much more quickly from one side of the window to the other, because it is a shorter distance.

Line stretch also comes into it - short lines more responsive, minimal stretch.

Don't think anyone has mentioned one of the big things about short lined kites - related to wind shear.

Wind is slower nearer the ground due to friction effects. On short lines you get significantly less power - my method of getting out in high winds as a lightweight is to reduce line lengths - I've used a 7m on 10m lines more than once. Not fun, but at least you get out, and like everything, do it a lot and you get used to it and develop the skills to deal with it.

I think Lou Waiman has talked about using lines down to 5m regularly in a kite mag interview.

There is one school of tuition which teaches on bloody big kites - starting on leader lines and increasing progressively in 3m stages as the students get confidence and skills. Would not advocate it, but there are times that some points can be taken from this.

So in high winds you can be out on a bigish kite on very short lines and find it very manageble in terms of power but a bit weird and fast in terms of control. Takes a fraction of a second to go accross the wind window and therefore power is very off/on untill you get your technique down. Small mistakes - oversteering on the bar etc have a big impact on the kites movement - hence although less power, it can be dangerous if you aren't well practised on flying skills.

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Vim
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karlquartz wrote:Also, think of a wheel. If you are near the hub you are turning much slower than out on the rim. If you use that analogy, the kite on short lines is near the hub and moving slower.
Um, so a similar analogy would be a bicycle wheel. Where if you're on a spoke nearer the hub you're turning slower than further out near the rim on a spoke... I think that's wrong.

Any point on a spoke on a wheel turns at the same speed, no matter how long the spoke. Otherwise you'd have some weird bending spokey wheel thing, going on.

You may feel larger centrifugal/centripetal forces the further away from the axis, but you don't actually turn faster...

That's physics, innit. :wink:

Skyte wrote:a kite on shorter lines will travel from one side of the window to the other quicker, because this distance is shorter (the radius - line length - of the arc is shorter) The kite doesn't actually fly faster, it just appears to because it's window is smaller.
I'm with Skyte on this one... same speed, smaller radius to travel across at same speed means quicker for same angle (about 180degrees).
carlos_c
Posts: 1454
Joined: Fri Oct 29, 2004 10:27 pm
Location: Crystal Palace

also to do with the length of the power stroke - in lower winds with longer lines..your power stroke is longer ....therefore you get more of a chance to develop board speed before you get to the upstroke...which is usually where you stall and sink.

Also you have longer for the kite to accelerate and reach max speed.

On Flysurfer kites they have segmented lines as standard so that you can increase/decrease the line lengths at will.

For arcs and leis you just need to start with short lines and have a set of extensions with larks heads on each end - then extend when you need them
karlquartz
Posts: 1467
Joined: Fri Nov 12, 2004 10:38 am
Location: London :-(

So Vim

time to go stand in the corner with the tall pointy hat on again...
did a lot of that at school did you...

Points at different distances along the spoke from the hub.

Point a travels through a short distance over arc x and over time y.

point, further out near the rim travels through a much longer distance over arc x and time y.

bigger distance
same time

equals

faster

Or have you got bendy spokes on your bike?

Bend over boy.
RichT
Posts: 437
Joined: Fri Nov 05, 2004 9:30 pm
Location: On the beach!

Vim, Karl is right. Your angular velocity is the same on hub or rim (ie - the number of degrees you turn in a second), but a point on the rim will have a greater distance to travel, therefore it's velocity is greater.

However, I would also have said that Skyte is right too, as the kite speed is probably actually the limiting factor and should be vaguely similar regardless of line length.

Something tells me the actual physics will be a combination of numerous factors!

But wtf do I know!
macca
Posts: 1758
Joined: Sat Oct 30, 2004 9:31 am
Location: North East

IMHO

I use 24m lines.

They (24) give you a better connected feel, turn quicker, relaunch better.
With 30m, bigger stroke = more power.

Would think all good Manufactors would like to hand over to younger blood.

xcheers
karlquartz
Posts: 1467
Joined: Fri Nov 12, 2004 10:38 am
Location: London :-(

Vim being wrong about the velocity doesn't make Skyte wrong.
I think Vim actually meant RPM as opposed to speed, but let's not let him off the hook.

On the true effects with a kite, probably has little to do with a wheel analogy, just chucking ideas in.

I think you are right to say the kite speed is one limiting factor. On short lines it has shorter distance to travel across the arc - takes less time if the kite is travelling at its fixed max speed in both instances.

So quicker to loop.

Why does something that seemed simple and logical stop seeming simple and logical as soon as you (make that I) think about it.

I'm sure it must still be simple.

I'm confuddled.
Fred
Posts: 3434
Joined: Mon Nov 01, 2004 4:27 pm
Location: Redhill

You're all kind of half right, but Skyte's observations are spot on.

With a wheel rotating at a set angular velocity (i.e. RPM), a point at the edge of the wheel will be travelling faster (higher linear velocity) than one nearer the centre. However, that's not really how to look at it. The approriate analogy is that if two cars are travelling at the same speed (linear velocity) then one with the smaller wheels will have the wheels turning faster (higher angular velocity) and therefore the wheel will take less time to make a rotation.

A kite flying at a set speed will fly across the wind window quicker if the lines are shorter. It will produce a similar amount of power but for a shorter time.

I still think that K.I.T.E.S. system is a load of crap though. If it wasn't we'd all save money by buying one kite and loads of sets of lines. (Or a reel bar!) A big kite held near the ground and not travelling across the window will still be dragging your sorry arse across the sand in high winds whether it's 10m away from you or 30m.
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