a small kite, flown actively mostly in horizontal gliding, flatspin
or diving mode.
the urban ninja needs little space like parking lots, courtyards
and parks.
at normal winds it hangs up there, good for kids.

the flight card shows the flying style for our kites, at the moment
in german only, sorry.

when the winds are becoming too gentle for a rokkaku battle, take
your ninjas and enjoy them dancing together in the sky.

choose your weapon:
bridle 580 mm for wild and fast moves,
bridle 600 mm for a smoother style,
bridle 620 mm for laidback flying

nominal span: 1'360 mm
height: 1'000 mm
total weight: 57 g
unfolded sail area: 0.71 m2
effective wing loading in horizontal flight: 84 g/m2

first read this article completely, then start with preparing all the parts shown on the bill of material.

when done, print the ninja-stencils.pdf plan. it's 800 mm x 420 mm.
check the 500 mm bar to make shure your print is properly scaled.
cut away the part left of the center fold of the panels.
punch 4 mm holes at the corners, spine and leading edge marks.

or download the plan in dxf format, set the dimensions probably to cm,
import text as text, preseve faces, the file is a 2d plan.

fold icarex sharply, lay the the stencil on top of it and align the left edges of both.

mark all the points through the holes, including the bridle and leading edge
marks for the upper black panel.
remove the stencil plan, then cut the still folded panels with a straightedge
and a sharp cutter.

for the leading edge marks of the upper black panel cut a small wedge as guide
for drawing the marks on both sides of the panel.

here are the measurements for direct drafting onto the sail, again folded first.

press transfer adhesive tape, 6 mm or 1/4 inch wide, to the back side
of the black panels, leaving a few millimeters free at the center fold.
place one half of the white panel over the highly visible tape liner and
roll it back.
remove the liner slowly and let the white icarex drop back onto the
adhesive tape.

lay the left side of the white panel on to its right side, adjust the position
exactly for a good symmetry.
remove 1/2 inch of the tape liner at the center and fold it tightly up at 90°

lay the left side of the black panel on to the white panel,
adjust the position accurately and lock it with weights.
pull out the liner very slowly, be careful not to displace the
press the black icarex to the tape with the fingers, do not
rub to avoid distortion of the seam.

the assembled sail with the profiled keel:        last chance to check for perfect symmetry

before sewing, make compound patches of an adhesive dacron 12 x 20 mm and two
adhesive icarex pieces 9 x 40 mm.
place the compound patches for the bridle and the z-line attachement exactly at the
center fold. two of them start on the white panel, this will make three layers at this tension
loaded point.
the upper bridle attachment is centered at 110 mm above the end of the black panel
or 104 mm from the end of the white panel.
then triple zig zag the panels together, 4 mm wide and 3 mm long is a nice stitch. at the
center you may shorten the stitches to 1.5 mm for improved resistance.

sew first the folded icarex trailing edges, avoid tensions as much as possible.
maybe a long double zig zag, reduced upper and lower thread tension and a
double fabric transport will help.
then sew the leading edges with a narrow medium length triple zig zag.

for the wingtip cut pieces of icarex-coated kevlar 6 x 16 mm and
self-adhesive icarex 10 x 10 mm and16 x 40 mm. place the small
adhesive icarex patch at the outer end of the leading edge.

fold the icarex piece sharply, fold the paper liner back and place the
kevlar piece onto the adhesive

press half of the icarex piece to the leading edge using the fold as
a positioning guide, turn the sail and press the second half down to
the back side. punch a hole, diameter 5 mm.

place the leding edge spar reinfocement patch and cut out the leading edge:
the opening is 9 mm deep and 80 mm long, the lower end at 20 mm, the
upper end at 60 mm from the silver mark.

the tail:
make a compound of adhesive dacron 20 x 50 mm folded at 30 mm and
a piece of dacron 10 x 40 mm for the spine end pocket.
place it accuratly aligned with the center fold and sew it to the sail with
two straight stitches.

front side of the spine end:
melt the thread ends down and press them to the fabric.

back side of the spine end:
punch or melt with a soldering bit two holes, diameter 3mm.

for the nose:
adhesive coated dacron 25 x 50 mm with two beveled corners and two
cuts 5 mm long and 5 mm from the center fold.

fold half of the paper liner sharply back and press the nose piece to the sail,
the sharp folds will help in positioning and centering accurately.

sew the nose to the sail, seal the front tip with a lighter, and punch 3 mm holes.
prepare a 85 mm long 1.8 mm bungi cord with good flanges at both ends.

try to make a square knot or reef knot, called the samariter-knoten in
switzerland. use the pliers to arrange it and tighten it with a continuous pull.

voila!  the accurately placed holes and the bungi will hold the spine exactly
at the center.

to make a flange: let 4 mm out of the pliers.
all given lengths of lines include this allowance:
the z-line is 130 mm when cut, with the two flanges melted down it will
be 122 mm, ready for the loop.

for a nice, compact flange:
melt the bridle line and press it even and gently to the pliers
with the plastic part of the lighter.

make a loose loop like this:
the line shown is the z-line and will pull down the spine to the spreader.

lay the loop around a slightly conical pen and tow the line until the
flange stops at the knot.

tighten the loop around the pen to proof the strength of the knot.

tie the z-line, the y-line and the bridle to the sail and tighten the knots
carefully, again with the slightly conical pen.
the leader line has an overhand knot, stopped with a flange at each end.
larkshead the bridle around a knot of the leader line.
use the lightest bridle line you can find, we like our all black 320 n spectra
core bridle line. lenghts given are for this line, if you are using heavyer
stuff, lengthen all lines a few millimeters at each end.

insert the spine:
at the tail use two half hitches (zwei halbe schläge) or even a round turn
with two half hitches (rundtörn mit zwei halben schlägen) to tie the y-line
around the spine.

shown here a simple two half hitches, front side view of the kite.

tension the bungi at the nose, putting first the knot into the jaco, then the
second strap. the jaco is cut at the ring and shortened by 12 mm.

you may also shorten the 995 mm spine a little bit, depending on the strength
of the bungi line and the strain in the fabric used. most fabric will get longer
under tension over time, so let a couple of mm space between the jaco and the
tip of the nose, especially if the sail is nylon..

make the upper ends of the leading edge tubes as round and smooth as
possible, at least polish them with your fingers.
insert the leading edge tubes fitted with the vinyl stoppers from top
through the cutout into the leading edge and at the wingtip out again
until the upper end is at the cutout.
place first the loop of the x-line, then the apa connector above the stopper
and shove the tube up again into the leading edge.

extend the loop of the z-line to form a double loop around the spreader.
this is the neutral standard setup for all of our kites and wings. with a single
loop, the z-line will be longer, with three loops it will bend the spine closer
down to the spreader.

the following pics show the urban ninja with the standard setup:
it will park at 60 m in medium to stronger winds. in zero or very gentle breezes
it has a light, but responsive pull.
the short fly aways or dives will show an extreme nose up tendency, so you
will be able to turn back anytime.
the kite rolls backwards gladly and recovers to a nice horizontal glide within
a few meters. slacken the line to do this.

the dihedral can be adjusted with the length of the z-line. as an additional effect
of a shorter z-line the spine bend increases and flatspins become tighter.

draw the numbers onto both faces of the sail with a black marker pen. we use comics-like
wide fonts, like this one called "field day filter" and numbers, which clearly indicate the
orientation of the ninja on its wild flights, even from the back side.
here's a real scale pdf of this font designed by ray larabie. you can print it on a4 sheets.
your name is to identify your personal kite on a crowded field, all urban ninjas look the
same after all.
we would be also delighted about a mentioning like "powered by horvath.ch".       thanks

the most important adjustment is the tension of the whole sail. shorten or
lenghten the y-line on the field to adjust the effective span of the spreader.
this affects directly the span of the kite and the slack in the sail.

the urban ninja flies best with a very very slack sail, resulting in a deep billow
and an accented keel area. a slack sail slows the fast little kite down and lets
the airflow pass a softer, flexible surface, especially if the icarex is somewhat
crinkly, hence tension the y-line at will.

with a lighter bridle setting, the kite will fly more agile and respond to light, but sharp
pulls on the flying line. this is good for the urban ninja flying style.
shown here the agressive 580 mm bridle, or 600 mm using heavier bridle line.

lay 50 m of spectra line (called dyneema in europe) to the ground, attach it with
a larkshead loop to the leader line and fly!

here is a movie of a flight with our commercially available
the long way home
we are working on a movie showing also the wilder moves of the urban ninja style.

never fly:
• higher than 60 m - 180 ft
• near airports or roads
• in stormy weather
• near powerlines and railroads

have marvelous flights !

if you would like to place a link to our website, please use  www.horvath.ch

thomas k. horvath, zurich switzerland, summer 2006