The right kite bridle can make a lot of difference to how a single-line kite flies. This doesn't apply to single-liners with keels, such as most Deltas, Parafoils and Flowforms. With a few exceptions, these types are designed for a certain wind range and can't be adjusted.
This page is devoted to the bridling of flat, bowed or dihedral kites only. That's about all we fly around here, except for the occasional Sled or Delta. OK, so there was the Soft Series for a while. But now it's the Paper Series, which is back to dihedraled kites again.
With flying quite a few different types of kites, ranging from 29 cm (11 1/2") up to 2.4 meters (8 feet) in span, I have fiddled with the odd kite bridle over the last few years :-) I've pushed the limits of flyability with single-leg bridles and enjoyed smooth sailing with 5 leg bridles on kites that suit them.
A few things can be learned about bridles from looking at various MBK kite designs.
From the tiny 1-Skewer ones right up to the absolutely huge Multi-Dowel kites.
On this page, I have chosen to illustrate with photos of Dowel Series kites and one Multi-Dowel Series monster - the 2.4m Rok. On that note...
Making Dowel Kites is a PDF download of printable step-by-step instructions. Also handy if you're not online 24/7!
Down below, I've gone through some bridle examples from these proven kites, starting from 1 leg and working up to 5 legs.
In all the photos, a yellow dot represents a bridle line attachment point. Each photo corresponds to the kite highlighted in bold type, closest to it in the text.
I guess this is only really a bridle if you attach a single short line to somewhere on the kite. Terminated with a large knot so you can attach a separate flying line! Otherwise, if the flying line is just directly tied to a spar, it's really a 0 leg kite bridle, don't you think? That's what the MBK Tiny Tots Diamond uses, for the utmost simplicity. Just tie the flying line on, and leave it like that for the life of the kite!
However, the much bigger MBK Simple Diamond uses a separate short line tied around the crossing-point of the spars, with a small Loop Knot tied into the free end. The crossing-point is exactly 25% of the distance from nose to tail, along the vertical spar.
A Diamond constructed and bridled like this is not the smoothest flier, but with enough tail it will stay in the air reliably over a fair range of wind speeds. Some fliers actually appreciate kites that wiggle about a lot, tracing their erratic motion in the air with a long thin tail!
In theory, any flat or bowed kite will fly on a single-leg bridle if it is attached at just the right spot. However, I found that some of my smaller designs had terrible flying characteristics with a single-leg bridle! The 1-Skewer Sode in particular.
So, 1-leg bridles work fine for 25% Diamonds, but cannot be guaranteed to be much good for anything else, particularly in the smaller sizes. I do remember seeing an incredibly ornate and rather large Wau kite from Malaysia on a single-leg bridle though. And it flew great!
Also, there are those who like to modify larger kites to make them fly reliably from a single attachment point. These designs are known for being able to cope with a very stiff breeze since they flatten out and offer low resistance to the airflow. The trailing edge is almost as high as the leading edge in flight so the kite is 'floating on top' rather than straining away at a high angle to the wind.
Deltas or any other types with a single keel, are really using the equivalent to a 2-leg bridle. The leading and trailing edges of the keel take the place of the 2 legs...
This arrangement is very versatile, and is used on a large range of single-line kites. It is a good compromise between simplicity and good flying characteristics. I use a 2-leg bridle on the MBK 1-Skewer Sode for example.
The most noticeable effect is that the kite's nose is prevented from bobbing up and down in response to changes in wind speed. Instead, the kite just rises or sinks smoothly. If the air gets too slow, a bit of wing waggle can occur as the kite struggles to keep flying.
Diamond kites in particular sometimes show the opposite behavior as well, getting up a wing-waggle as the wind speed approaches the maximum the kite can handle.
No kite bridle is immune to a very sudden drop in wind speed however. If this happens, the kite will flop forward onto its face and float down until the wind picks up again.
So, almost any accurately made and balanced kite will fly on 2 legs.
A 2-leg bridle does have 1 important limitation. The horizontal spar(s) had better be strong enough! Near the top of the kite's wind range, a lot of bending force occurs near the middle of the spar. Of course, the stronger and therefore heavier the spars are, the more limited the light-wind performance of the kite will be. My little 1-Skewer kites are reliable fliers, but aren't great in very light wind! They fly best in a moderate breeze.
I'm quite fond of the 3-leg bridle as another step up towards smoother flying. With the horizontal or upper horizontal spar restrained at 2 points, the wings can't waggle any more. The kite flies more smoothly over its entire wind range.
The bridle consists of a loop going from one side of the horizontal spar to the other. Another line then goes from the middle of this loop to well down the vertical spar.
Most Diamonds fly on 2-leg bridles, but the MBK Dowel Diamond uses 3 legs to fly better. Small to medium Rokkakus also do nicely on a 3-leg bridle, which saves a couple of knots compared to the standard 4-leg bridle!
Barn Door kites are fairly unique in that a 3-leg bridle is the obvious, logical choice. One bridle line goes to each crossing-point of the spars. I guess if the horizontal spar was high enough, you could get away with a 2-leg bridle, by attaching the top bridle line to the middle of the spar. A backward step if you ask me!
A little more time and effort is required to make and adjust a 4-leg bridle, but for some kites it's the logical choice. And of course, it is the ultimate for smooth flying, keeping the frame of the kite quite rigid in flight. Of the 7 types of bowed kites I fly, the larger Rokkaku and Dopero are just made for 4 legs.
The big Dowel Sode is interesting from a bridling point of view. I can think of 5 ways of doing it, although a couple of them might require beefed-up horizontal spars! However, the 4-leg bridle seemed quite a natural fit. This kite is a wonderfully smooth and high-performance flier with that bridle arrangement.
With it's 2 rear keels, the MBK Dowel Dopero kite has the equivalent of 6 legs actually, since the keels are anchored at 2 points each. But the keels are small, and most people would look at the lines and think '4-leg bridle'. It's certainly close enough.
With the introduction of Multi-Dowel designs to my growing stable of home-made kites, 5-leg bridles have made an appearance.
In the case of the huge Barn Door, I felt the upper portions of the diagonal spars could do with a little help to stay straight when under heavy strain. Also, with the towing point being between the leading edge and the horizontal spar, it made sense to have some attachment points closer to the leading edge.
With its 5-leg kite bridle arrangement, the Multi-Dowel Barn Door flies smoothly over a wide wind range. Its upper sail area is well-supported and keeps its shape under the most trying circumstances!
The other kite sporting a 5-leg bridle is the Multi-Dowel Rokkaku. Having an extra line coming from the vertical spar, near the nose, allows the bridle lines on the horizontal spar to be spaced further apart. This of course keeps the upper portion of the kite more rigid in fresher winds.
Anything to extend the wind range on a design which is a bit limited in this respect!
The spacing of attachment points.
On a horizontal spar, it's worth considering how far apart the attachment points are.
If the spacing is far too close, then the resistance to wing-waggle is much less. This arrangement is approximately like just 1 line coming from the middle, hence the kite will behave that way too! Also, the center will still be under a lot of strain in stronger winds. No point.
If the kite bridle lines are attached too near the tips, this again causes a bending problem near the middle of the spar. When the wind picks up, your Diamond might start to look more like a Sled, before plummeting to the ground with a snapped spar!
An easy 'rule of thumb' is to try and get a roughly equal amount of sail area on the inside and outside portions of the sail. For most kite shapes, this ends up being a little less than half-way out along the horizontal spar.
Vertical spars can bend too, if the wind is strong enough and the bridle is connected to the extreme ends!
A rough rule of thumb is to place the top bridle line, if any, between the nose of the kite and the horizontal spar. Or the upper horizontal spar if the kite has more than one. The lower line can go between the middle of the vertical spar and the bottom tip - but closer to the middle than the tip!
I've seen box kite plans with the bridle attached at top and bottom of a longitudinal spar - crazy! The bottom line should never be attached too near the tip.
Wonderful things these are! The first application of this that most people bump into is the towing point of a simple 2-leg kite bridle. The flying line can be attached to the bridle loop with a sliding knot such as the Prusik. In flight, the knot stays where it is, setting the length of the upper and lower bridle lines. However, with the bridle in your hand, it's easy to slip the knot along the bridle loop a little to change the lengths of the upper and lower bridle lines.
This is the way many home-made kites are tuned for low or high wind conditions. High wind requires the knot to be a little closer to the nose end of the kite. In low winds, the kite will fly higher when the knot is shifted back towards the tail end a little. A little. Small changes can make big differences in how the kite flies, and this can thwart some would-be kite-makers! The adjustments are a skill soon mastered if the flier persists.
The second main use of sliding knots is holding the center point of a horizontal bridle loop. For example, a typical Rokkaku has an upper horizontal bridle loop and a lower horizontal bridle loop. A 3rd bridle line then connects these 2 loops. Attached at end end by ... a sliding knot. Besides allowing for adjustment to dead-center, one or both of these knots can also be used to trim out any slight turning tendency the kite has. Handy!
I use sliding knots in these ways for all my kites that have more than a single-leg bridle. The Prusik takes some practice to remember correctly, but it works extremely well! I usually tie a simple single knot into the end of the line first though, to prevent the possibility of the Prusik ever pulling right through and gulp ... letting go!
I have always used the same weight for bridle line as the heaviest flying line ever used for the kite. This takes care of all eventualities, and in the case of multi-leg bridles, is more than ample strength-wise. In fact, one day I'm going to experiment with using lighter bridle lines in such a way that the flying line is still guaranteed to break first, in stronger wind conditions. Lighter means thinner, which means a little less drag and hence a more efficient kite!
In the video below, my Dowel Rokkaku demonstrates how steady a kite can be with a 4-leg bridle!