Building Kites 101

Blurb

This is a bunch of tips for kite building. Most are aimed at the inexperienced builder, but some of the tips here might be useful for even the most hardened. Well, maybe not. Some are sensible, some are not. Your mileage may vary. Don't run with scissors. Keep away from children and animals. Yes, we have no bananas.

Before you even think of starting

Ask yourself this question : 'Do I really want to be doing this?'. Building your own kites, especially from your own designs, is a long, tedious and frustrating process. It can involve significant materials and tools expenditure, eat up vast quantities of time that would be better spent on the flying field, and can often result in a kite that is less good than a commercially available model. Not only that, but once you factor in your own time, it probably costs more than just going out and buying that commercial kite.

Having said that, it is immensely rewarding to go out with something you've made with your own fair hands, get dragged around the flying field and generally have a laugh, then have someone come up to you and ask where they can buy one.

Equipment

Sewing machine.

Choice of sewing machine is up to you. For the fanatics amongst us, nothing short of an industrial monster machine will do. If you want one, the cheapest way to do it is to find a sweatshop that's going out of business. You'll need a van to pick it up with, though. And take someone along to check out the machine - the rag trade is notoriously cutthroat and you are likely to buy yourself a dog otherwise. Industrial machines will happily sew through plate steel (and do have a number of other useful benefits), but the sheer size of the things tends to be a deciding factor for most people.

So, most of us use home machines. For my money, the only home machine that's really worth a damn is the Pfaff 130 (I am rather biased, as I own, and dearly love, one). This cast iron teutonic marvel was probably designed for sewing together tanks or something, and weighs a ton. It's a precision engineered piece of equipment - when it says 5mm stitch, it means 5mm. Not 4.5mm, not 5.2mm, but 5mm. It does forwards, reverse, straight stitch and zigzag. If you really want to do embroidery and stuff, it can be cajoled to do that too, but that's not where it excels. So, basically, it does everything you need.

Anyway, the way to buy a machine is to find a second-hand sewing machine shop, and start looking. Don't buy from streetmarkets, as the machines on display will almost inevitably have parts missing, rusty or bent. Make sure the machine you buy has been serviced. Insist on this. When looking at machines, don't be overawed by the million useless stitches. You only need straight and zigzag. A cast iron machine in good nick will outlast and outsew any plastic tat. In the shop, the machines tend to have a scrap of fabric to test on. A good machine (like my Pfaff) will have a scrap of heavy leather...

If you're feeling really retro, eco-friendly or cheap, get a machine with a treadle rather than a motor. Hand-crank machines aren't worth the effort for kites, as you'll need both hands to guide that slippy ristop.

If you can't afford to shell out on a machine, borrow one. Your Gran's 1920s black cast iron model is better than your mum's plastic one. And not only are you less likely to break it, but Gran will be so happy to see you using it, she'll probably will / give it to you, which could end up saving a few quid.

You may have noticed I'm rather fond of cast iron machines. There is a reason beyond the aesthetic - they have machine steel innards, and if properly cared for will go on forever. Plastic machines, especially the cheaper ones, tend to be filled with plastic cogs and cheap pressed steel bits, which strip and bend and generally foul up. They really don't make 'em like they used to.

Needles.

Use big bloody needles. Go directly to size 18. Do not pass go. Do not collect a load of broken bits of spring steel in your carpet / dog / feet.

Only use sharp needles. Once they've begun to go blunt, they will be a nightmare to sew with, you'll drop stitches and get knots. It's not worth the tuppence saving to have to repeatedly unpick seams.

Scissors.

With scissors, you get what you pay for. You'll need at least 2 pairs. One pair of good quality dressmaker's shears, and a pair for doing small closeup work and cutting thread. Never, ever, use these scissors for cutting paper, tape, spectra or electrical cords. So you'll need another pair of household scissors for that job.

Steel Rule / Straight edge.

Steel rules are very useful, and I've seen them in sizes up to 2m. The only downside to them is that they have sharp corners that can rip fabric, which is probably not what you want. I use a painter and decorator's straight edge, which is 1m long, has rounded tips and a big plastic handle bonded to one side. It doesn't have measurements marked on it, but I can live without that. It's cheap and effective, from the DIY store.

Hot cutter / Soldering iron.

Hot cutters are great. They are also expensive. A beefy (30W+) pencil type soldering iron with a round, pinsharp tip will do quite adequately. You will still be able to solder with it afterwards, but it's worth getting another tip for soldering with unless you particularly enjoy having to retin the iron every time you use it. If you use a pencil type iron, get a stand. Otherwise you'll have to put something on it to stop it slipping / rolling off your worksurface, and it's inevitable that you'll pick that something up, the iron will slide, and you will have one or more of the following - A burned hand, a melted carpet, or a big melted hole in your kite.

Don't be tempted to use gas-fired soldering irons - they give off a lot of heat and will damage your kite.

Fine point marker pen.

Some people use pencil, some use ballpoint. I use a fine point indelible marker. Horses for courses, really.

Worksurface

Big. Flat. Hard. Tough. Clean. A toughened glass dining table would be good. A toughened glass dining table with a sewing machine inset would be better. Make sure it's well lit. Clean it before you put any fabric on it. This avoids getting lasagne stains on the kite. If you're intending to hotcut on it, it's probably worth making sure it's heatproof. Perspex surface or your nice shiny dining table are probably not the best choice of hotcutting surfaces.

The collected patience of several saints.

'Nuff said.

Other stuff that might be handy:

Quik-Unpick

Well, you will foul up seams. Believe me.

Materials

Thread.

Choice of thread is also up to you. Use fully synthetic rather than synthetic / cotton mix, as it won't rot when it gets wet. Nylon is stretchier, which will give your seams some 'give'. Go for as heavy a size as you can. Gutermann make a thread called 'extra strength' which rocks. It is, however, not cheap. You can buy it in industrial quantities if you know the Gutermann part number, though. Some people use a lighter thread on the bobbin as it means your bobbin runs out less often (not a problem for industrial machine users). I use the same thread on both, as I want max strength.

Fabric

Don't use 'ripstop seconds'. Don't use Carrington. Both of these fabrics are horribly floppy, heavy and absorbent. If you don't know why this is bad, just trust me and don't use them for making kites. Use them for making stuff sacks for the finished article. You'll be saving a lot of heartache, believe me.

This leaves you with a choice - Chikara / Norlon / etc or Icarex. Icarex is probably only worth while for XXL or ultra-high performance kites. You probably don't want to be making one of these as a first build, so I'd go for Chikara.

Fabric is best bought from one of the specialist suppliers. In the States, Hang 'em High come highly recommended, in the UK I like The Highwaymen. If you're making lots of kites, or can get a group of people together who can decide on a single color they like, it's much cheaper to buy fabric on the roll. 100m at a time tends to be the minimum order, though so make sure you like that colour.

Tape

Taping seams can be useful to speed up construction time, make stronger kites and seal sewing holes. Use lightweight tape. The 'adhesive transfer' systems are great - there's no substrate to the tape - it's basically a thin layer of glue with peel-offable backing. Use tape that slit as thin as you can get it. That generally means 6mm.

Bridle line

Spectra / Dyneema. Not braided nylon. That is all.

Making up the parts.

This job is a real nuisance. It takes a lot of time. Personally, I do it as I'm going - I'll cut out 6 ribs, sew them up, do the next 6, etc. If you are feeling thorough, you might prefer to do the cutting first, then the sewing.

Most patterns come from computer programs these days, and the most widely used of these is foilmaker. Now whilst you could print out the entire plan using your home printer (or the one at work ;-), sticking together bits of paper is a mighty pain in the arse. If you can get access to a bigger printer your life will be much easier. It's not too expensive to get stuff printed out on A0 (or even A0 oversize) at some printshops, but you need to make sure you have the format of output they can handle. Most can do Adobe's PDF, which can be got the following way.

If the printshop has a plotter, they may even be able to plot direct onto the fabric. IF you can find a company with a laser cutting machine who don't want to charge you an arm, a leg and your firstborn son, then you're laughing.

Either way, getting stuff plotted onto A0 is worth the effort. You can easily eat up the cost of having it done by printing off 200+ sheets of A4 on an inkjet, then having to stick them all together accurately. Sadly, the last version of foilmaker I looked at laid up all the parts on separate sheets, with no option of doing them all on one. So there will be an amount of 'pre-processing' needed, probably using something like Corel Draw, to lay all the parts up on big sheets.

For cutting, I personally mark the sewing lines, cut roughly around and trim excess after each seam. Others mark the cut edge and use a stop on the machine to ensure even seams. Others again mark both lines. But they're mad.

If you're cross-venting ribs, don't cut big fat holes in the centre. The ribs will distort in flight. use a soldering iron and burn some pinholes in the trailing 30% of the rib instead. You don't need too many. Or you could make the trailing 25% or so of the rib from gauze. Or just cut off a couple of cm off the trailing edge of the rib and leave it open.

Whatever you do, make sure your crossvents are open. This is very important on kites with 'closed' (i.e. non-vented) sections, as if your crossvents don't work it won't inflate at all. Make sure internal seam allowances don't obstruct the crossvents. If you're using internal valving, make sure it's got some slack, as if it hasn't the valves may well slam shut the instant the kite takes off.

Don't cut cross-vent holes in the tip ribs. It sounds obvious, but...

Cut your crossvent holes before attaching ribs to skin. Very important if you're using a soldering iron to cut them, as otherwise you run the risk of burning big holes in the outer skin of the kite.

Preparation (H)

Proper preparation is a pain, but absolutely essential.

Checklist:

It's worth putting together a list detailing construction order if you're new to this, or if you're trying something different. Doing this will allow you to think through some of the problems you're going to encounter. And you will encounter problems.

Construction

So, you have everything you need. Your machine is set up to produce the right tension. You've practised sewing ripstop with your machine. You're ready to go!

So stop.

Before the first needle punctures the fabric, think through construction order again. If you get it right, there will be a minimal number of times where you'll need to feed the entire kite through the arm of your machine. If get it wrong, you'll have to spend the entire sewing session trying not to sew the kite to itself due to having the whole thing under the arm.

Use the biggest stitch your machine can handle. On my machine, that's 5mm. For areas that require more strength, use a zigzag stitch, otherwise a straight stitch will do.

Overlock the beginning and end of all seams. Nothing worse than having a seam start to open up after you've been flying a while, as Murphy's law as applied to kites states that any seam that fails will always be inaccessible.

The leading 25% of the profile generates all the lift. A clean leading edge makes for a good kite. Pay maximum attention when sewing the leading edge.

If you're putting W/V lines on the ribs, sew them in place before attaching the ribs to the surfaces. If you're just running a line along the lower surface, do it at the same time you attach the ribs. For sewing lines onto fabric, use a cording foot and not too much foot pressure.

Generally, people sew the ribs to the lower surface, then sew the upper surface in place. This works well enough. Remember to sew from the leading edge to the trailing edge, not vice versa. This way your leading edges will all meet up and you'll have a nice smooth kite. The trailing edge can always be trimmed...

If you're making a shaped skin kite, it's possible to keep all the seams internal - i.e. no thread outside the kite. This is good as it keeps the number of holes in the external skin down, and stops stuff snagging on / abrading the outside threads. Do this by creating a seam between the two skin panels and sewing the rib to this. You can use a zigzag stitch here for maximum strength.

D-ribs are a nice touch, and make the shape of the kite much better in flight. If you use foilmaker to generate d-ribs, cut them down before fitting them. I use 'V' shape d-ribs, one per bridle attachment point. The tops cover almost the entire chord of the rib. D-ribs are probably too much hassle for a first kite.

For valved kites I'd use tube valves rather than flaps. They work better. They're as easy to make. They are reversible, thus allowing you to easily let the air / sand / water out. For tube valves, make them big enough to get your arm in, and at least 1/2 the depth (chord) of the kite. Make them from lightweight ripstop rather than anything else (like condoms) and you won't have to keep replacing them.

Tube valves can be stopped from reversing when you don't want them to by putting a loop of bridle line across the vent hole. One end of this should be removable in order to allow the vent to be reversed when you want it to.

If you're making a kite with d-ribs and tube valves, the best cell to put the valve in is the one with no d-ribs.

If you gauze the inlets on a valved kite, don't forget to make some other way of emptying it. Sand, water and dogshit all pass in through gauzed, valved inlets quite happily, but once in there, they want to stay..

Pre-taping seams is useful, but make sure you have the tape on the right side of the right bit of fabric. As ever - measure twice, cut once. Pay attention. Don't do this at 2AM after a bottle of wine ;-)

Sewing through tape shouldn't be too much of a hassle, but your needle may gunge up. Clean it with lighter fuel. Some people recommend silicone spray on the thread before sewing, or a silicone impregnated pad to preclean the needle. I've not used either, nor have I found it necessary, as long as the needle is sharp.

As for sewing, tape from the leading edge to the trailing edge.

If you're not taping, don't be tempted to use pins to hold the whole thing together. It might be OK for your mum's dresses, but you don't want to be putting any more holes in the skin of your kite than absolutely necessary. For relatively straight seams, a water spray will make the fabric stick together pretty well, but for sewing sharp curves onto straight edges (such as when you're attaching ribs to surfaces, especially around the tips) you're either going to have to find another way or carefully handfeed unattached fabric. Glue works OK, but I've found it to be too much of a pain to use except for isolated, hard to sew places. 'Pritt' type glue is sort of OK, 'Copydex' is pretty good and can be removed afterwards by rubbing with your fingers.

Bridling

Bridle design is a whole field of its own. I'm leaving it well alone here.

Making up nice tangleproof bridles that are adjustable is a pain. If you're making a kite that should need minimal adjustment (i.e. from someone else's proven plans), splice all the loops in. It makes the whole thing a lot cleaner.

Do your adjustment from the kite end. A loose line end hanging from the kite's undersurface may be unsightly, but it's a lot less likely to get tangled up. Generally, keep the 'coming together' points nice and tidy.

When you've done adjusting (or even when you've done with the more crass adjustments), trim off as much excess as possible. Always heat-seal the end of spectra as it will go all fluffy otherwise and it will tangle itself around everything in sight. Fluffy tangles are worse than knotted kitelines.

Recommendation:

Primaries - spliced loops at the primary towpoint, adjustment at the kite surface. Use a 'bridling knot' as described on Andrew Beattie's site to attach the line to the kite, leave plenty of loose end for later adjustment. When you're happy with your bridle, trim off the excess.

Secondaries, etc. - Spliced loops at the secondary towpoint, loose end at the primary towpoint. It will get a bit tangled but at least there will only be one of them (2 if you're using a crossbridle). Again, when you're happy, trim off the excess (or put a splice in that end too).

Towpoints - Make it obvious which side is which and which is the brake bridle. It makes reattaching lines much easier. I use a braid of 3mm spectra for the main lines, and a single piece of 3mm spectra for the brakes. Different colours for each side (flouro pink == left, flouro green == right, in my case). Spectra in big (2mm+) sizes can be had from any boat chandler.

If you can't be arsed with splicing loops, either sew the loops or use knots with trimmed (and sealed) tails. For knotting, use only figure-eight and bridling knots. Thumb knots move under pressure and are a total nightmare to untie, plus they remove an enormous amount of strength from the line.

If you made a kite with tags, attaching the kite to the bridle is simple. If you're using the 'V line' method or similar, you'll need to poke holes through the kite. Don't use a hotcutter or soldering iron for this. Don't use standard sewing needles. Use either the pinvise/machine needle 'bridling tool' a la Andrew Beattie, or a sailmaker's needle and palm. Both methods are effective, efficient and minimise kite damage.

Testflights

Don't organise testflights and photo sessions until you have finished the kite.

Don't invite friends to testflights unless they are likely to be helpful. The sound of your mates laughing is not conducive to bridle adjustments.

Similarly, don't cut your fingernails before testflights. You will need them for untying those little knots.

Don't testfly 10m kites in 30mph winds. Or 1m kites on zero winds. Make sure your test site has good, smooth wind if at all possible.

No matter what the met office say, it will rain during your testflight. Take warm clothing.

Other Tips

Watch out for dog/cow shit before unrolling the kite. Even if you fail to unroll the kite over it, on takeoff it can be guaranteed to powerdive straight into the nearest turd.

The same goes for trees, barbed wire and children. Avoid them.

All dogs must die. If you regularly fly in a field infested with dogs, mount spikes on the leading edge of the kite. Use ground glass in your lines for extra stylish 'low pass dogcapitation' maneouvers.

Cows like to eat spectra flying lines. Only use braided grass lines and they'll leave you alone.

A couple of little velcro tags on the trailing edge of the kite provide a useful place to attach line attachment points of your bridle if you have to remove your flying lines for any reason. They're also good for unrolling the kite on your own, as you can leave the lines attached and unroll them with the kite on the floor, safe in the knowledge that it isn't going to inflate and take off without you.


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