Nylon 'Parafoil' Parachute

If a job is worth doing, it is worth doing well. Although this parachute takes a lot of trouble to make, it is very impressive and well worth the effort. Extra special thanks to Mauricio Cedaro in Argentina for helping me with this one.

Materials and equipment

For this parachute (and its drogue), you will need . . .

• 3 metres of nylon fabric (be adventurous again - go for bright red);
• a reel of thread of the same colour;
• a glue stick;
• around 40 metres of light nylon cord;
• a mug of cold water;
• a soldering iron;
• a small open flame (like a candle);
• a sewing machine;
• 7 plastic rings (about 2cm diameter); and,
• 0.3m elastic cord.

Shroud

Go to the rib drawings page, save and print out the drawings making sure that the final scale is correct - 75dpi (the end rib should be between 60 and 70cm long). Glue the templates to a piece of cardboard (a Cornflakes Packet is just about right) and lay the nylon on top. You should be able to see through it to the pattern underneath.

Cut out 2 end ribs and 9 inside ribs using the soldering iron (making sure that you keep the direction of the material consistent). Measure the distance along the top (continuous curved edge) of the end rib and mark out a rectangle of nylon 106cm along one side and the top distance (T) along the other, cutting out with the soldering iron. Repeat the process but this time using the distance along the bottom of the aerofoil as the distance (B) (the bottom of the inner rib), again cutting out with the soldering iron.

Mark out each of the two sheets with lines (in a water washable pen) every 10.5cm so that you end up with 10 bands, each 10cm wide with a 0.5cm gap between.

To the leading edge of each of the inner ribs, fold over and sew (using sewing method 1 below) the edge (diagram 1). If you want to be ultra symmetrical (bear in mind that sooner or later, someone who should get a life will point out to you that all of the seams travel in the same direction and shouldn't they be symmetric?) make 4 of them go one way and 5 the other (it doesn't really matter which way).

Likewise, to the leading edge, the lower leading edge, the bottom edge and the trailing edge of the end ribs (diagram 2), fold over and sew the edges (making sure to make the two end pieces mirror images :-) Then, do the same to the longer edges of the top and bottom sheets.

Once you have done this, take one of the inner ribs (one of the five) and sew the upper edge to the centre line of the upper sheet (using sewing method 2) so that the front, upper corner of the rib meets the front seam of the upper sheet (which you, of course, remembered to have the folded edge on the lower side). You need only do the first stitch in the method as far as the end of the inner rib but continue the second stitch for the full length of the upper sheet thus making a small rib that runs the entire length (diagram 3). If you don't do this, the upper sheet will become curved and wrinkled. Also, be very careful not to stretch the fabric as you sew otherwise, the ribs will end up different lengths.

Repeat this process for the other 8 inner ribs and then sew the upper edges of the end ribs along the full length of the sides using sewing method 3. You should now have something looking like diagram 4 (You are half way there).

Next, using sewing method 2 and starting in the middle as you did with the upper edges of the ribs, sew the lower sheet to the bottom edge of the inner ribs (diagram 5) and then, once you get to the end, sew on the end rib (again using sewing method 2) along the line that follows the same profile as the inner ribs - this should give you an overhanging flap.

Repeat this process working from the centre in the other direction and then, finally, just run the sewing machine along the trailing edge of the bottom sheet so as to form a seal with the top sheet at the trailing edge of each cell (diagram 6).

Now, make 28 little tabs (~2cm x 0.7cm). If you number the ribs 0 to 10, make a mark in the four places on the underside (corresponding to fixing points A, B, C & D on the end rib plan on the rib drawings page) on ribs 0, 2, 4, 6, 8 & 10 and additionally in position D (trailing edge) on ribs 1, 3, 7 & 9. Sew the tabs onto these positions using the rib so that no extra aerofoil material is used up. You should put the tabs on ribs 0 and 10 (the end ribs) on the outside so that the flap will have the cords running on the outside of it. Now the parafoil shroud is finished.

The next thing you should do is give it a good soak for a few hours in warm water to get the glue out.

Sewing Methods

These are the sewing methods used to make this parafoil chute The main problem with sewing nylon is that it does not stay folded and taking the normal course of action and using pins will lead to a time consuming drudge that will seem to take forever (making a parafoil is bad enough without additing to the process unecessarily). With this in mind sewing is aided with a gluestick which will be washed out later on. This is a lot more flexible than using pins and leads to better results and less pain.
1	Sewing an edge
	There are two ways of doing this: a single step method and a double step method. This is the double step method . . . Put the edge of the fabric on the sewing machine (it doesn't really matter which way around you work - these diagrams just show the way that I did it); Apply a smear of glue stick; Fold over the edge so that just under the width of the seam goes over; Sew the entire length of the seam - apply the glue and fold over as you go (even the glue won't hold it all of the way around if you are dong a curve); Once you have completed the seam, apply glue again as before; Fold over the length that you glued; and, Sew all of the way along again, doing a couple of inches at a time. You will end up with a double stitch on one side (picture) and single on the other.
	This is the single step method (slightly more difficult to do but quicker). Again, place the fabric on the flat bed of the sewing machine; Apply the glue-stick as far as you need; Fold over - around 4mm; Apply another smear of glue-stick; And fold over again. Now you have a length of triple thickness nylon, glued together to form a double folded edge; and, Sew.
2	Making a 'T'
	This method allows you to join a second piece of material to the first, part way along the first and in such a way that with the thickness of nylon we are using, there are no problems regarding left or right handedness. The top (or bottom) sheet is laid out flat; Glue is applied along the part where the second pieces of material is to be joined; The second piece of material is laid along the glue so that the edge matches up with the line on the top (or bottom) sheet; Sew along the join approximately half way between the edge of the second piece of material and the limit of the join (0.5cm total so sew approx 0.25cm from the edge of the second piece of material in this case). You should correct the allignment as you go and be careful not to stretch either piece of material; Fold over the single side so that the stitch that you have already made is now at the edge. Sew around 2mm from the edge, making sure that the existing stitch keeps its position at the edge. The stitch you are now putting in should go through four layers of nylon; and, Open out. You should now have a 2mm high rib with a piece of material sewn into it. This rib can be used to sew tags onto.
3	Joining two edges
	Like method 1, this can be done in two ways: a double step or triple step method. This is the triple step method. Lay out flat one of the sheets; Glue the edge to be sewn; Carefully position the edge of the other sheet so that the overlap is consistent (about 4mm); Run the sewing machine along the middle of the overlap; Fold over one of the sides (you can turn it the other way up so that you can see it better if you want - these diagrams are only here to show what happens to the material and for clarity's sake do not necessarily show the best orientation of materials); Sew away from the new edge (this means that the last stitch you make will hold down the rest of the join); Fold over the other piece; and, Sew again. You now have a tucked lap join (for want of a better term).
	This is the double step method which, although is a lot more difficult to do, is a little quicker (once you get the hang of it). Lay out flat one of the sheets; Glue the edge to be sewn; Carefully position the edge of the other sheet so that the overlap is consistent (about 4mm); Run the sewing machine along the middle of the overlap; and; Keeping the two sheets of material in the same position, fold over the join and stitch twice. This is very difficult as the material wants to straighten out all of the time - applying glue can solve this to some extent but I would still recomment the previous variant of this method.

Cords

The parafoil chute differs from the other chutes on this site in that it is supported in the centre as well, instead of just around the edges.

Again, the cord used is cut by holding it for a second or two in a small flame such as a candle and then solidifying any molten plastic by quickly immersing it in a mug of water so as to make a sealed end as in the blow-up on the left. The actual cord is only 1 or 2mm wide.

The parafoil cords form four basic groups A through to D with some additional cords for the rear section D. There are 6 cords of each length and I allowed 8 cm extra for tying knots et cetera. The lengths are as follows . . .

Cord	Nominal Length	Length with additional for knots
A	80cm	88cm
B	85cm	93cm
C	94cm	102cm
D	102cm	110cm

Cut 6 of each length, tying a loose knot near one end of the B cords (this is because they are so similar to the lengths of the A cords that if you don't take some steps towards identifying them, you will run a higher chance of confusing the two later on when it matters).

In addition to these, make a further 4 cords of 40cm length (these are going to be the extra D cords that you will need) and a further 6 cords of 20cm length - these will tie the rings together in a meaningful way later on. With 7 rings and the shock cord, you are now ready to begin.

Take the four sets of six cords, A, B, C & D and divide each into two sets of three cords so not you should have eight sets of cords. Take a D cord and hold one end with a 40cm cord, tying the two together at the end of the shorter cord (top and second diagrams on right showing D cords). Repeat this with the second D cord so that you have 2 doubles and one single D cords (at this point, I tied the D cords together loosly with four knots, the C cords with three, B cords with two and A cords with one knot. This made it easier to identify the groups during the procedures upto and including final assembly).

Pass the single ends of the D cords through one of the plastic rings (ring 2 on the bottom diagram) and tie the ends to another plastic ring (ring 3 on the diagram). To ring 2, tie the ends of the C cords. To ring 1, tie the ends of the B cords (opposite to the ends with the identifying knots) and the ends of the A cords (do these alternately A B A B A B so that there is no overall twist on the ring when it is eventually in tension). To rings 1, 2 & 3, tie a 20cm length of cord and then tie the cords for rings 1 & 2 tightly to the shock cord ring (ring 4) and the cord from ring 3 (the trim for the parafoil) loosely so that the ring sits approximately half way between rings 2 and 4 (this is a a reasonable starting point for the trim of the chute). The loose ends of the cords used to trim the chute can be seen in the picture on the right of the underside and rigging pegged out to dry on our washing line. Note the bottle top used to fasten the shock cord to the top of the rocket.

Repeat this process with the other sets of cords, tie on the shock cord (passing the other end of the shock cord through a hole in a bottle top and knotting it) and you are now ready for final assembly.

Assembly

Put the parafoil chute on its back on the floor. Place a chair with its back to the chute such that the leading edge of the chute is next to the chair. One by one, starting in one corner (I would suggest starting with the leading edge cords A) undo any identifying knots and tie the ends of the cords to the tabs on the shroud being consistent with the amount of cord that you use for each knot. Remember to undo the extra identifying knots in the B set of cords. Also remember to keep left and right cord sets separate.

When you get to the trailing edge cords D, remember that the two sets (on each side) of double cords go to the outer pairs so the single D cords go to ribs 4 and 6.

Once you have finished this, the job is done - you have your completed parafoil chute. Phewhh!!!

You should also make a drogue chute - the details for this are on the Circular Nylon Parachute page.

Adjustment

The trim of the chute can be altered by pulling or releasing the D cords on either side. You can make the decent slower by pulling them (making the length of the 20cm length of cord that secures ring 3 shorter by tying it off with the ring lower down) or you can make it travel in a spiral by trimming the sides differently - remember that shortening them too much could lead to the chute stalling. Alternatively, you can use a radio control to adjust them in flight.

Packing

This chute is not as obvious to pack as the circular chutes. Holding it up by the cords makes it want to concertina and then, you can zig-zag fold it like a circular chute. With plenty of talcum powder, I have found that this method does work but I am open to suggestions from anyone who knows better.

Circular Nylon Parachute

If a job is worth doing, it is worth doing well and making a circular nylon parachute will give you skills in cutting and sewing nylon as well as a good quality chute that will last (you can wash this one if you really want to).

Materials and equipment

For this parachute (and its drogue), you will need . . .

• four feet of nylon fabric (be adventurous - go for bright red);
• a reel of thread of the same colour;
• a glue stick;
• around 20 metres of light nylon cord;
• a mug of cold water;
• a soldering iron;
• a small open flame (like a candle);
• a sewing machine;
• 2 plastic rings (about 2cm diameter); and,
• 0.3m elastic cord.

Shroud

Lay the nylon fabric on the floor and then pick it up from a point that is halfway between the sides that are closest together and the same distance from one of the other two sides (where the green lines cross on the diagram). By doing this, you will get the largest area (outlined in blue) and have the most spare to make a drogue chute.Mark this point with a cross.

Then, use a piece of string, the same langth as your radius, to mark out sixteen points at equal intervals (on the imaginary blue line). Then, join them by drawing a straight line with a pen, using a ruler to make a regular, sixteen sided polygon. At each of the sixteen points, make sure that the line that you have drawn, extends around 1" towards the centre of the shroud. Next, put a mug in the centre of the shroud and draw around it. You now have a polygon, marked in ink and ready to cut.

Repeat the bove process on a smaller section - around 1.5 feet in diameter - for the drogue.

If you cut nylon with scissors, you will produce an edge that will fray given half a chance. Cutting nylon with something hot gives a good, seals edge that is very resistant to fraying - in addition, it is quicker and easier to cut nylon in this way.

Lay out the nylon shroud and run the hot soldering iron along the lines that you have drawn. If you make sure that the nylon is not in contact with a heat dissipating surface such as a metal sheet, it will cut quickly. If you press the nylon down so that it is in contact with a metal sheet, it will take ages to do it. When you have finished, you should have your main and drogue chutes ready to sew.

Sewing nylon is not as bad as it sounds. The main problem is that it does not stay folded and taking the normal course of action and using pins will lead to a time consuming drudge that will seem to take forever.

On the left are the steps that you need to take to make a good seam for the centre hole in your nylon shroud. You should get your skills on this bit and the rest will be quite easy.

1. Put the edge of the fabric on the sewing machine (it doesn't really matter which way around you work - these diagrams just show the way that I did it);
2. Apply a smear of glue stick to around one or two inches;
3. Fold over the edge so that just under the width of the seam goes over (around 2mm for the hole in the middle see how large the thread is in comparison to the width of the seam);
4. Sew all the way around. Apply the glue and fold over as you go - even the glue won't hold it all of the way around;
5. Once you have done a complete circle, apply glue again (to between one and two inches of seam);
6. Fold over the length that you glued; and,
7. Sew all of the way around doing a couple of inches at a time. You will end up with a double stitch on one side (picture) and single on the other.

Tie off and you have your centre hole made.

Next you need to sew around the outside edges.

1. Again, place the fabric on the flat bed of the sewing machine;
2. Apply the glue-stick to one full length of the outer edge;
3. Fold over - around 4mm this time;
4. Apply another smear of glue-stick;
5. And fold over again. Now you have a length of triple thickness nylon, glued together to form a double folded edge;
6. Sew.

Once you have completed one section, repeat for the other fifteen.

Having completed the main shroud, you can repeat the process on the drogue chute.

Having done that, soak the chutes in warm water for a few hours to get rid of the glue - doing this will make the seams more flexible.

Cords

Take the nylon cord and cut off roughly 2½ metres - placing this to one side. To the remainder, fold it in half, then in half again and so on until you have 8 lengths, just over 2 metres long. Cut it into these lengths and seal the ends by melting in a flame for a second or two and then putting the melted end into the mug of cold water (left). Instead of using a knife or scissors, nylon can be cut by putting it in a small flame thus automaticaly sealing the ends.

Take one of the eight pieces and fold in two, forming a loop. Thread the loop through one of the plastic rings and then pass the two loose tails through this loop. Pull tight, tie a knot (not to stop it from coming undone but just to provide a bit of resistance) and repeat for the other seven lengths. You should now have sixteen ends coming from one plastic ring. Then tie the elastic to the ring (as in the photograph) - tying a knot in each end so as to stop fraying.

Now, make a smaller one with six or eight cords around one foot long for the drogue.

Assembly

Place the plastic ring in the middle of the shroud and lay out the cords so that they intersect the edge of the shroud at the sixteen corners. Make sure that the cords are in the order that they are on the plastic ring as this will make it easier to sort out any tangles that you may get into later on in the field.

At each corner, pinch about 1cm of the seam and tie a knot around it very tightly. Then, just to make sure, tie another. In the picture (right), you can see that the end of each cord is also tied in a knot.

Repeat a further fifteen times and then perform the same task on the drogue chute.

Nylon 'Parafoil' Parachute Rib Plans

Rather than print off these two plans from the browser, right-click the mouse and then select 'Save Picture As...' from the menu.

They are scanned in so that if you print them out at 75 dpi, you should get the right scale. Alterately, you could print them out at some other scale and then blow them up on a photocopier. The important thing to note is that printing from the browser will not give you reliable results.

Inside rib	End rib