Building Sport Kites





Introduction

These instructions cover the general steps of making a two-line stunt delta. Be sure to study the specific notes supplied with your plans. Just take one step at a time, and if you get sick of it, go flying or something until you're in the mood. These instructions are by no means the best or only way to make a kite, as each kite maker adopts a unique style. Study a finished kite to clarify the various construction methods.

Terms


Hem – the folded and sewn edge of fabric

Seam – the joint between two pieces of fabric

Leading edge (LE)

Trailing edge (TE)

Cyanoacrylate cement or Superglue (CA)

Sewing


Any well-tuned sewing machine should work for kite making. Ideally, a three-step zigzag, plain zigzag, and straight stitch are best but a simple straight stitch can be used by making two parallel stitches in place of zigzags. Learn to sew by practicing on kite bags or camping gear, things that aren't so critical. Read the manual, ask for help but stick with it. A lap seam and a simple hem are the basic requirements to sew kites.

Examples of three-step zigzag seam and straight stitch hem

Choose a plan

A simple design with good instructions is a good start. Some plans have no instructions at all and consist of a sail plan drawing, spar sizes and bridle layout. Save these kites for when you have had some practice. A kite with a one or two piece sail, pultruded spars and a dynamic bridle would be a good place to start. You can always use fancy materials later as you gain experience.

Make a template

The goal here is to get that half-sail plan onto a piece of stiff cardboard to use for layout and cutting at full size. The positions of spreader connections, T and standoffs are then marked on the template.

Plans are available as drawings in vector formats such as CDR, AI, DXF or bitmaps like JPG, GIF or BMP. In this case a drawing or bitmap program is helpful to print the layout at full size, or you can have someone with graphics skills to print them for you. I use Corel Draw, but AutoCAD, Illustrator and others are also good. Bitmaps can be handled with Window's paint program or the shareware Paint Shop Pro.

Graphics files can usually be transferred between programs fairly easily, so you can usually find a way to get it on paper.

In the printer's dialog window set to print tiled pages, then preview the layout before printing. You should get a series of pages that can then be pasted to a sheet of poster cardboard. Align the sheets carefully when sticking them down and then cut the perimeter with scissors.

Plans are sometimes given as coordinates on a grid or by drawing a triangle and adding curves to its sides to develop the kite's profile. These will require some drawing to lay out the grid and mark the coordinates of the sail lines, but isn't difficult. If a plan says "Do Not Scale" on it, that means it must be laid out as lines by measurements because that drawing is inaccurate although the dimensions are good.

This sort of task involves measuring from left to right, then up and making a mark on your cardboard. Connect the marks and you have a curve. A spar with an adjustable bow string is a good guide to smooth these segments into a more graceful curve. Cut out the resulting template with scissors.

Cut the panels

A wood burning tool from a craft store or a soldering iron with a sharpened tip cuts the fabric with a sealed edge that reduces fraying. Some kite fabrics resist fraying better than others, and can be cut with scissors or a razor knife.

Before cutting the fabric panels, be sure to leave an extra 10mm for the trailing edge to be hemmed, and an allowance for panel seams. One way to do this is with a simple flat washer having the distance from the hole to outer edge that matches your seam or hem allowance. This is used as a pencil guide to mark a line around the template onto the fabric. The leading edge can be hot cut directly along the edge of the template on a glass or masonite surface. An old window pane with the edges safely taped is best, but I use masonite for convenience. The heat of the cutter may vary as it heats up, and trial and error will show you when the cleanest cut occurs. If you're handy with wiring, a standard light dimmer can be used to regulate heat. Practice first on scraps and be sure to work in a well ventilated area to avoid breathing fumes.

When the LE is cut leave the fabric stuck down to the work surface and slide the template into a position to guide the cut along the lower TE pencil line. Shift the template into position to cut align with each section and cut it.

For a one-piece sail, fold the fabric in half along the spine parallel to the weave. Crease it down the spine and unfold it. Lay the template on one half of the sail at a time and cut each wings. For a two-piece sail, each half should align the weave with a line from the wingtip to the center of the spine. On multi-panel kites the weave is aligned in each panel to be parallel to the nearest spar or edge to distribute the load that may stretch the sail. To see what this means, pull opposite corners of a handkerchief, and then pull from opposing edges. This is what is best along spars and edges to reduce stretch. Allow an extra 4mm along the spine for each side of a two-panel sail to create an 8mm lapped seam.

Join the panels

The one-piece sail won't need any assembly here. The two-piece sail should have one panel stuck to the table with bits of tape to keep it flat and unwrinkled. The second panel is taped down over it so the overlap at the spine is 8mm wide. A thin bead of Fabri-Tac or a smear of Glue-Stick is now used to fasten the seam together. Handle this carefully as you sew it together with a zigzag stitch down the middle as shown. Multi-panel sails are done in a similar way but are laid over a pattern to keep them aligned. Folding the sail in half occasionally is a good way to check for symmetry at each step. Maintaining symmetry will minimize the effects of slight errors on the kite's performance.

Sew the TE hem

Fold the hem along the upper (red) pencil line, and rub the crease down with a spoon or roller. The dab of glue stick here and there can help hold the flap down, but it isn't really needed. Sew the hem with a straight stitch from wingtip to spine tip in one pass, keeping the stitch close to the cut edge and away from the trailing edge. This will assure an easier job of inserting the leech line.

Reinforce and cut the center T hole.

Cut two Dacron reinforcements that will accommodate the T fitting hole. A diamond shape is easy to cut with a cardboard template and hot knife. Attach these on both sides of the sail with a dab of glue, and sew the perimeter with a straight or small zigzag stitch. Trim the threads and mark the center of the hole. Cut through all three layers with the hot knife using a large washer or template as a guide to cut the hole for the T to fit through.

Standoff attachments

A template can be made to cut the sail reinforcements for the standoffs. The Dacron is then folded over the TE and sewn through the sail, taking care not to obstruct the hem where the leech line will go. Holes are then made with a hot nail or hot knife to press the sail fitting into place. Gradually enlarge the hole until the fitting pops in snugly. On some fitting types, a light rubbing with a hot knife will flatten the top to prevent snagging lines. Jaco fittings come with a rubber O-ring than grips a groove in the top of the sai. If you are handy, you can install the fitting in the bottom layers first, then sew the top flap over the fitting to make it really smooth. If you try this be careful to have room around the fitting for the sewing foot. Another way us to use fittings that snap around the TE like a clamshell.

Velcro spine pocket

This is a simple way of fitting and adjusting the spine using a strip of Velcro. The fuzzy strip forms the tab that folds over the nock, and the patch of hook material forms a tunnel to center the spine.

Cut the tip of the tail straight across to allow the leech line to pass from one wing's TE to the other. The leech line will be inserted later.

Tack the loop strip to the front of the sail as shown with glue, and lightly tack the hooks strip to the back of the sail. Just glue the sides of it so the spar can be inserted through it later as a tunnel. Sew down each side of the hooks strip through the sail and loops strip. Be careful not to close the hem with stitches.

Add LE tunnels and tip loops

Fold the LE material in half lengthwise and crease it to form the LE tunnels Cut two pieces of the same material 2.5cm x 6cm and fold them twice lengthwise to form two loops to tie the LE nocks in place.

Tack the LE of the sail onto the tunnel strip laying the edge of the sail along the crease as shown. When the sail is attached to one side of the strip fold the top flap over the sail and mark the wingtip for trimming.

Insert the folded loop and sew through the LE tunnel, loop and sail with a zigzag stitch, and proceed to sew the entire LE tunnel all they way to the nose.

The nose

A piece of common nylon seat-belt webbing is used to form the pockets for the three intersecting spars and to serve as a bumper. The webbing is folded over the nose and sewn as shown. Be sure to leave enough room for the spars and vinyl end caps to fit into position, and use care in the stitch along the LE. Be sure to put the stitches through the LE tunnel edge. After sewing, cut the excess webbing away with a hot knife and straight edge slightly outside the LE tunnel fabric. Try to make a smooth straight cut in order to avoid snagging lines on the nose when flying.



Cut the Leading Edge tunnel for spreaders

Mark the position of the spreaders on the LE tunnel on one wing using the template and a pencil to put a mark where the spreader will intersect the LE spar. Fold the sail in half and mark the other side to match. Hold a spreader connector in place to see where the cutout is needed, and mark the cutout on the LE tunnel with a pencil.

A template can be used to hot cut this notch, but there is a risk of fusing the two layers together, only to fray as they are separated. Scissors do the job pretty well, and some light strokes of the hot cutter can then seal the edges.

Leaving the LE spar exposed at least a centimeter or 1/2 inch on each side of the spreader fitting allows the sail to stretch or settle with time without binding against the fitting.

The frame

Here's where that droopy piece of fabric starts to look like a kite. The spars are cut to length with a fine hacksaw blade, fine triangular file or Dremel tool, and finished with fine sandpaper to remove burrs. Slowly rotate the spar while cutting to prevent binding and splitting.

Fittings

Be sure you use good quality fittings that fit snugly on the spars. You don't want the spreaders popping out on every hard landing, but you don't want them to be hard to remove either. A sharp drill can open up a fitting for a larger spar in a pinch but try to get the right size at the onset. Replacing them later is a pain in the

Fit leading edge spars

First, test fit the spar and vinyl cap into place in the LE all the way to the nose to be sure it will fit. Now remove the spar, and if the vinyl cap sticks in the nose you can leave it there, but it is usually easier to install it in the next step.

This step will take some effort, so be careful not to damage anything.

Slide the spar into the sleeve to the lower spreader notch. a little liquid soap may help the spar slide through the fitting here. Hold the fitting in the notch and work the spar up to the top notch and add the top fitting. At this point work a vinyl end cap on to the front end of the spar and push it into the nose. As you work the spars in, twisting the fittings slightly will help the progress of things. Once the spars are snugly in place, slip a nock on one spar tip and tie into place with a piece of round elastic cord through the fabric loop at the wingtip. A square or overhand knot joins the ends while the cord is under tension. A drop of CA glue can lock the knot permanently when the tension is set, after the rest of the frame is installed.

A pair of C-clips below each spreader fitting prevents them from creeping down the spar. Secure them with a drop of CA glue.

Fit the spine

Cut the spine to length and set the T fitting in its hole. Pass the spine through the Velcro tunnel and T fitting and into the nose after adding a vinyl cap. Slip the nock onto the other end and secure with the Velcro strip.

Fit spreaders

Simply cut the lower spar (s) to length based on the plan, slide on the standoff fittings and insert them into place. Cut the upper spreader to length and install it.

Fit standoffs

Cut these a bit long and nibble them down until they fit right. Sometimes small variations in construction can make the standoffs vary from the plan. Resist the temptation to make the sail drum tight with longer standoffs and stressing the fabric near the standoffs and the lower spreaders. Be sure the left and right standoffs end up matching. End caps may be needed to fit the tops into the spreader fitting, and lightly gluing the bottoms into the sail fitting prevents loss.


The leech line

An adjustable line in the hem of the TE to reduce noise.

Bend the end of a piece of thin, stiff wire into a small hook. Pass the hook end through the end of the spine tip and through the trailing edge hem to the wingtip. Cut a piece of braided Dacron line about 1.5 x the kite's wingspan. Attach the end of the Dacron line to the hook with a knot or tape.




Be sure this is a snag-free attachment to avoid damage to the sail, then tie the free end to the wingtip nock with a bowline loop and pull the wire and line through the hem and out the spine tip. Now feed the wire through to the opposite wingtip and tie the other end of the line to the nock on this side. Keep the wire for the next kite.

The leech line is now tied to one wingtip knock, passes through the TE hem to the spine tip nock and to the other wingtip through the hem. At this wingtip, a prussik loop grips the leech line as shown, allowing tension adjustment to silence the kite. Adjust this line when the kite is completely assembled.

An alternative method way of tensioning the leech line is to attach the line with a loop at each wingtip nock and tie loose ends at the spine nock with a square knot that can hide under the Velcro strip.

Trick Line

A line along the rear of the kite to reduce line tangles. Usually connects wingtips and tail of spine, but can have some variations. Your plans should include this if needed.

Bridling

Terms:

Dynamic bridle – The most common type of bridle. Also called a turbo bridle for some reason.

Outhaul – The line tied between the top and bottom spreader fittings.

Inhaul – The line from the middle of the outhaul to the center T fitting.

Tow loop – the loops to which flight lines are attached.

Outhaul

Cut the outhaul 70mm (2.75 inches) longer than the plans show to allow for two knots. Tie one end to the LE spar directly above the top fitting, and the other end below the bottom fitting, using slipknots with overhand stopper knots as shown.


The allowances given are assuming 5-6mm (.1960 -.2300 inch) spars

Another way to attach to the frame is the cow hitch. It is especially useful for bridles that is intended to be removed for replacement or experimentation. The overhand knot in the bitter end prevents slippage.

Inhaul

Cut two pieces of line for the inhauls a foot or 40cm longer than the required length.

In one end of each, tie a matching loop. These are then tied as prussik loops to the outhauls. Measure the inhauls from the prussik to put a mark on the line where they meet the T fitting. Hold both marks together an tie them in a figure 8 knot at the mark. and pass the remaining lines around the T-fitting and tie again in the same way. Trim away the excess line.


Tow points

Cut two pieces of line 150mm (6 inches) long and fold each in half and tie in an overhand knot to form two loops. These are tied as prussik loops onto the inhaul lines on each side.

Adjust the bridle

Adjust the prussik loops and arrange the bridle so each leg matches the bridle plan.Lock the loops into place and go fly your custom-made kite.

Thanks to Harold Ames and Chris Perrin.

Thanks Stan

Stan Kellar of California had a very informative web site aptly named Stan’s Toy Shop. Stan recently retired his website and has granted me permission to reproduce portions of his site. Hopefully this information will prove valuable to you, I know that when I first started building Stan’s site was very helpful.

Thanks Stan!

–Bill


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