Building Delta Kites

3 Different Low-Cost Options

There aren't any detailed instructions on building Delta kites on this page. For that, head over to the how to make... link over there on your left.

However, this page is worth a browse if you are thinking about knocking together a cheap Delta kite from easily-obtained materials. You might avoid a few pitfalls! This information is just a collection of thoughts, observations and experiences from building Delta kites from my 3 MBK series of designs.

My Deltas are somewhat different to traditional Deltas, since they are constructed 'flat' like a Diamond or Rokkaku, then bowed. Actually, 1 design has built-in dihedral, before being bowed a bit more.

All 3 designs...

• Have sails made from cheap, single-ply plastic bags.
• Have spars made from cheap materials. BBQ skewers for the first 2 designs, and hardwood dowels for the 3rd design.
• Have a keel made from flying line and plastic bags.
• Involve a small amount of wood gluing.
• Have detailed instructions and plans elsewhere on this site! Just check the side-bar over there on the left.

By the time I had got around to making and flying the 2nd and 3rd Delta designs mentioned here, I standardized on using a Template for the sail. This gets construction off to an accurate start by transferring the Template shape to one side of a plastic bag, with the bag edge being the center-line of the kite. It's easy to get the sail shape very symmetrical this way. This means that later, the spars are fitted to the sail, rather than the other way around!

A quick overview of these kites now...

The 1-Skewer Delta is really for small kids, or adults with limited patience :-). As far as Delta kites go, it's quite a quick build and therefore a good workshop kite for kids. With enough tail, this little kite provides plenty of fun in light to moderate winds, on 50 meters (150 feet) of line or less.

The 2-Skewer Delta is a bit trickier to make due to the slightly more gluing involved. This design looks and performs well enough to engage an adult for as long as they want to watch a kite fly! It's quite capable of flying at 100s of feet in the air, and will readily respond to any thermal lift around.

The Dowel Delta is a nice big 'floater', which exerts a satisfying pull on the line due to its significant wing area. As long as it is accurately constructed, this kite easily flies at the legal ceiling which is 400 feet above ground here in Australia. Your country might be 500 feet or 150 meters. Or perhaps you are in the Third World somewhere, where there aren't any Altitude Police to spoil the fun as you fly right up to 3 or 4 thousand feet!

For the following sections on building Delta kites, I'm assuming you are familiar with the basic geometry of the Delta wing and keel...

Building Delta Kites Using Single Skewers

I use 30cm (1 foot) bamboo skewers, which come in packs of 100. At this scale, a tail is usually necessary to take care of stability. There's minimal gluing, just the 3 points where the spars touch each other. My original design was glued at the nose too, but there are 2 reasons to leave some space between the upper tip of the vertical spar and the leading edge spars...

1. Fore-and-aft balance is better, without needing to add any tape across the trailing edges. Save some weight!
2. There's more wing area for almost no increase in overall weight. Hence the kite will fly in lighter winds.

Trimming

If the kite tends to loop around in one direction, it's possible to tweak it straight by adding a tiny amount of tail to one wing tip. Just experiment, so the extra drag on one side is just enough to correct the looping. Mind you, if the wind is just too strong, nothing's going to stop the little Delta from going unstable!

Building Delta Kites Using Double-Skewer Spars

It's easy to double the size of the 1-Skewer Delta just by making each spar from 2 skewers end-to-end. Short reinforcers need to be glued on to make the joins strong enough. This adds a little extra weight, but with 4 times the surface area of the 1-Skewer kite, that's not at all a problem. In fact, I've found the 2-Skewer design has an almost perfect combination of strength and weight.

The original 2-Skewer design was a bit marginal without a tail, so a short tail was added to give enough stability for long flights. In windier conditions, adding even more tail is sometimes necessary.

The attaching of the spar skewers together with short reinforcers has 2 advantages...

1. This results in a slightly stiffer vertical spar.
2. Dihedral can be built right into the horizontal spar, eliminating the need for a bow-line. (Although my original still had one, you might notice if you find the instructions. Perhaps I didn't consider the dihedral to be enough, after the glue dried...)

Trimming

The 'small tail on the wing-tip' idea would probably work fine, but I found this unnecessary for building Delta kites with 2-skewer spars. Since it's twice as big as s 1-Skewer kite, it's so much easier to end up with required build accuracy.

A tip: Try to match the horizontal spar skewers though. If one is much stiffer than the other, there could be problems near the top of this kite's wind range. By the way, with both skewer designs, gluing alone seemed fine to hold the bamboo together. I can't remember a single in-flight failure due to a weak glue joint. So, don't bother wasting time with binding the spars with anything. Also, my instructions and plans specify the right length of reinforcers so that the final joint won't fail.

Building Delta Kites Using Hardwood Dowel

Where I'm from, Tasmanian Oak is the only type of dowel readily available in hardware stores. However, any sort of hard-wood dowel should be fine. The exact density of the wood might make small changes to the kite's characteristics. The heavier woods will result in less light-wind capability and so on.

The MBK Dowel Delta has quite a lot of leading edge between the upper tip of the vertical spar and the upper tip of each leading edge spar. In fact, this is arranged so that each of these 3 spars is 1.2 meters long. The trailing edge of the kite is swept forwards just a little. The end result of this arrangement is a Delta which is well-balanced from nose to tail. When allowed to sink though the air in nearly calm conditions, it comes down vertically. With a small amount of tension in the line, you can pull down the nose a touch and get it to fly around like a model plane!

It's very important to get even curvature in the horizontal spar when building Delta kites the MBK way. If you can find a perfect length of dowel which is the same from end to end, the curvature just takes care of itself. However, in my experience I've found that the density (hence stiffness and weight) can vary a lot along just 2 meters of dowel! What a bummer. All is not lost, since this can be corrected, and I've written it up in the how to make a kite section of this site.

Dowel is not as strong as bamboo! Hence, it's quite possible to snap the horizontal spar if the kite is flown in fresh wind. It also might be the case that the kite simply has too much area for the size of dowel you are using. In any case, I've come to the conclusion that dowel Deltas really need reinforcement over 20% or so of the horizontal spar. Right in the middle, where flight loads cause the most bending. It's easy to do this by simply placing a length of the same size dowel right next to the horizontal spar, and running some glue down the entire length of the join. When dry, flip over and glue the other side also.

Trimming

Apart from getting the horizontal spar to bend evenly when bowed, how else can you trim a big home-made Delta left or right?

A tip-tail would look a bit weird, but should work, just as it does for the smallest MBK Delta kite. Before you do that though...

The horizontal spar 'spreads' the leading edge spars apart. That's why some call it the spreader You can experiment with changing the amount of spread on one side by a small amount, to correct a tendency to loop left or right. What's happening is that you are changing the effective sail area on one side.

On my Dowel Delta, it's possible to let one end of the horizontal spar slip down it's leading edge spar by a few mm. This is achieved by not doing up the tie as tightly as on the other side. You could also file the end of the small bracket dowel a little, for the same effect.

Building Delta Kites - Some Notes About Keels

• Use the same, or slightly heavier plastic as used for the sail.
• Tape lengths of flying line along each side of the leading and trailing edges, in the case of a simple triangular keel.
• These 4 lines serve to attach the keel to the vertical spar at 2 points. The 4 lines coming out at the towing point can be knotted to form a handy place to connect the flying line.
• The leading edge of the keel should attach just a short way forward of the center-point of the vertical spar. If the kite climbs at all, it's not too close to the center point. At least for light-wind flying!

That's it for this page on making Delta kites. Hope you found something handy here, and if you end up making an MBK Delta - Good Winds! as they say...

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Last updated: 1 Sep 2009