Make a parachute

I'm new here, someone has some link or tips, to make a parachute, manually, In a diferent way of richard nakka?
- Will be a 8 gore chute, about 100 cm diameter, nylon ripstop. (for a small rocket)

thanks

+1

Let's engage in some questions first, to really understand your need. Stitching together gores to make a parachute is necessary if you are making an elliptical parachute like Richard. Note that most small parachutes have no gores--they are made from a single sheet of fabric (parasheet). Because they take less time, they can be sold for less as well. So....do you need to make an elliptical parachute (like Richard), or would a parasheet do the job? Also, if you are going to start stitching, other types of parachutes are possible. For example, a cruciform (X-type) parachute is simpler to sew than an elliptical. It needs to be larger, but has the advantage of less opening shock. Personally, this is my favorite chute.

As @ep29030 said, there are several things to consider when deciding upon an ideal parachute design. Personally, my rocket fleet is mostly a mix of hexagonal chutes cut from heavy duty trash bags or multi-gore ripstop nylon elliptical parachutes (I usually go for 20 gores because I like that look, see below)



When you say 100cm diameter, that's a bit bigger than a lot of parachutes for mid power rockets. How much do you expect your final rocket to weigh? Also, have you determined the exact dimensions of each gore yet? If so, stitching them together is pretty easy. The method I use is to lay one gore on top of another with a thin strip of newspaper underneath. The paper is there to allow the sewing machine to actually grip the fabric and move it along since ripstop nylon can be a bit too slippery against the metal parts.



From there I stitch the edge, tie the ends, cut off the excess thread and rip the paper out. Then I move on to the next gore.




Once all the gores are in place and the canopy is complete, I attach my shroud lines (I like to use 0.5mm nylon) by stitching it in place BACKWARDS (going from the edge toward the inside) for one inch, turning it around and then stitching it back down so there are two inches worth of anchored shroud line at every point. Each shroud line is made twice as long as necessary so for a 20 gore parachute, I end up with 10 loops. I finish off with a metal S-hook holding the whole bundle and a piece of heat shrink to keep them from slipping around.



This is just my way of doing it, but there are lots of little tweaks and variations out there. I hope this gives you some ideas on where to go with your project. Keep us posted on your progress!

I forgot to add this picture of the shroud line attachment.

In a previous life I worked as a sail maker for sailboats, built sky diving teddy bears and I built high performance kites for a living. We built stuff that needed 500lb test in any decent breeze. The best fabric for parachutes is not the same fabric that is used for kites or sails. The issue is stiffness of the finish, the stiffer finish that makes sail clothe so nice to sew on makes it tough to pack well and it wont open quickly when used as a parachute unless the rocket is falling pretty fast.

The best stuff for a chute is super soft and is a a pain to cut and sew. It is designed for parachutes and actually stretches a little when the chute inflates.

As mentioned a 100cm chute is pretty big for a smaller rocket. The Vatsaas Bros web page has a great pattern for larger chutes (like yours).

For my smaller chutes I have developed a very simple system for making 6 gore chutes that hold air well, pack easily and are not so tough to sew. I start with a 60deg triangle that has a height of about half the diameter of the chute I want. Now make a mark on the base side roughly 2" from the corner. Now draw a line perpendicular to the base at this point. This line will intersect the side. This is basically the skirt. Where that line intersects the side I use a large circle template like a pizza pan and blend the corner into a nice smooth curve.

What you end up with is a flat topped chute with a skirt. The skirt is a big deal because it traps the air under the crown of the chute and makes it more stable. The skirt is what separates this chute from a flat sheet style chute. With the small chutes like this I simple use my hot knife to make a small hole and tie in the shroud lines. For the loop I make a spliced loop out of small para-cord or Dacron kite line. I then glue the shroud lines inside the loop.

Once upon a time I stitched all my shroud lines and then made a loop of kevlar webbing that I stitched them inside of. I would still do this for a larger chute if I were to make one but anything under 36" doesn't really need all that. I have made chutes over 72" across and made two micro ram air style chutes, for that kind of stuff every detail needs consideration but for a basic recovery chute I try to keep it simple.

NAR competition chutes are another subject as well....LOL....LOL

ebruce1361 said:

As @ep29030 said, there are several things to consider when deciding upon an ideal parachute design. Personally, my rocket fleet is mostly a mix of hexagonal chutes cut from heavy duty trash bags or multi-gore ripstop nylon elliptical parachutes (I usually go for 20 gores because I like that look, see below)

View attachment 407397

When you say 100cm diameter, that's a bit bigger than a lot of parachutes for mid power rockets. How much do you expect your final rocket to weigh? Also, have you determined the exact dimensions of each gore yet? If so, stitching them together is pretty easy. The method I use is to lay one gore on top of another with a thin strip of newspaper underneath. The paper is there to allow the sewing machine to actually grip the fabric and move it along since ripstop nylon can be a bit too slippery against the metal parts.

View attachment 407398

From there I stitch the edge, tie the ends, cut off the excess thread and rip the paper out. Then I move on to the next gore.

View attachment 407399
View attachment 407400

Once all the gores are in place and the canopy is complete, I attach my shroud lines (I like to use 0.5mm nylon) by stitching it in place BACKWARDS (going from the edge toward the inside) for one inch, turning it around and then stitching it back down so there are two inches worth of anchored shroud line at every point. Each shroud line is made twice as long as necessary so for a 20 gore parachute, I end up with 10 loops. I finish off with a metal S-hook holding the whole bundle and a piece of heat shrink to keep them from slipping around.

View attachment 407401

This is just my way of doing it, but there are lots of little tweaks and variations out there. I hope this gives you some ideas on where to go with your project. Keep us posted on your progress!

Click to expand...

Your thread tension is a bit off....LOL If you are using a sailmakers thread getting it just right can be tough because it is so slippery.

I really like your S-Hook and shrink tubing trick.

ThreeJsDad said:

Your thread tension is a bit off....LOL If you are using a sailmakers thread getting it just right can be tough because it is so slippery.

Click to expand...

Quite true, but that's what I get for using a ten-year-old bargain Walmart sewing machine and regular polyester thread. Also, I should note the green parachute in the above pictures was the first one I made, and the orange/white ones came later as I improved my techniques. I just didn't have a better up-close picture of the shroud line anchor point.

I no longer have a heavy duty machine so like you I am making due with a low end Brother. I have a nice old style Kenmore I need to get timed. There is a company here in NC called the Thread Exchange where you can get nice thread pretty cheap. I like a V-30 for doing chutes. You can make a simple spool holder from a piece of plywood and some heavy wire.

The details you put into your chutes is impressive. I did a tiger stripe rectangle steerable chute ONCE.....never again !!

When sewing on this stuff it is tough to get the top tension light enough because the bobbin carriage tension is set at the factory for the most part and the material offers no drag tension for the thread.

For keeping your pieces from slipping use your soldering iron/soldering iron to do small tacks in your seam allowance. Line of both pieces and just touch the iron in a few places and it will heat weld the pieces together.

ThreeJsDad said:

What you end up with is a flat topped chute with a skirt. The skirt is a big deal because it traps the air under the crown of the chute and makes it more stable.

Click to expand...

Have you ever measured Cd for a chute such as this?

ebruce1361 said:

This is just my way of doing it, but there are lots of little tweaks and variations out there. I hope this gives you some ideas on where to go with your project. Keep us posted on your progress!

Click to expand...

I notice you just use a plain seam - nice and simple. What diameter chutes do you use this technique on? At what point do you think it is necessary to go with a more reinforced seam? Have you ever had a seam failure?

I made a 60" semi-ellipsoid once, and used a flat-felled seam. It looks good and is strong, but it's also a lot of work! Wondering when this becomes a necessity rather than a choice.

Kelly said:

I notice you just use a plain seam - nice and simple. What diameter chutes do you use this technique on? At what point do you think it is necessary to go with a more reinforced seam? Have you ever had a seam failure?

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The green and the orange/white chutes in the above pictures are 21" diameter with a 2" diameter vent hole. I had two bring down the booster section of my 1:100 Saturn V that weighed in at about 500g (Modified with a 5x D12 cluster, was supposed to have three parachutes but one tangled due to an early separation; not a parachute malfunction, I mixed up the motors for my staggered ejection). Thus far, I have had no damage whatsoever with any of these. I haven't built any bigger, so I can't say much to what point stronger stitching may become necessary, but I do have a 42" eight gore chute made from a recycled umbrella canopy that will be bringing down almost a kilogram. I might just get silly and sew right on top of the existing seams for added strength since umbrellas aren't exactly designed to hold up like a parachute in terms of strength.

ThreeJsDad said:

For keeping your pieces from slipping use your soldering iron/soldering iron to do small tacks in your seam allowance. Line of both pieces and just touch the iron in a few places and it will heat weld the pieces together.

Click to expand...

That's not a bad idea! Up till now, I've just gone slow and sweated holding the nylon together by hand, but that would make things easier! And now I'm thinking about accomplishing two things at once: I wonder if I can use a strip of masking tape to do the job of the newspaper PLUS hold the pieces together like your soldering iron trick. Just lay one gore onto half the sticky side, lay the next gore on top of that, fold the other half of the sticky side onto the second gore, run through machine, peel off tape.

Kelly said:

Have you ever measured Cd for a chute such as this?

Click to expand...

I have not, I got the idea for this design from an old book I have lying around. They had done studies and found that a flat chute with the corners just tucked or gathered had nearly the same drag as a true hemi. I have compared this design to a flat chute the difference is remarkable. Where a flat chute will wobble and slip to the side my design stays stable and does not colapse on itself even with the lightest of loads. If you go low enough in load a flat chute will actually slip sideways and collapse.

I have done some back yard tests on fabrics and have found that with zero porosity fabrics the vent hole creates lift in the right sizes but with a slightly breathable fabric the hole did not help. Some bleed through creates a low pressure area on top of the chute. On the other hand the hole adds stability.

ebruce1361 said:

That's not a bad idea! Up till now, I've just gone slow and sweated holding the nylon together by hand, but that would make things easier! And now I'm thinking about accomplishing two things at once: I wonder if I can use a strip of masking tape to do the job of the newspaper PLUS hold the pieces together like your soldering iron trick. Just lay one gore onto half the sticky side, lay the next gore on top of that, fold the other half of the sticky side onto the second gore, run through machine, peel off tape.

Click to expand...

I used this same method with stitching kite skins. In some cases I needed to stitch 3-4 pieces together at the same time and the old Elmers glue stick only worked So well. A few quick tacks and I was off to the races.

ebruce1361 said:

As @ep29030 said, there are several things to consider when deciding upon an ideal parachute design. Personally, my rocket fleet is mostly a mix of hexagonal chutes cut from heavy duty trash bags or multi-gore ripstop nylon elliptical parachutes (I usually go for 20 gores because I like that look, see below)

View attachment 407397

When you say 100cm diameter, that's a bit bigger than a lot of parachutes for mid power rockets. How much do you expect your final rocket to weigh? Also, have you determined the exact dimensions of each gore yet? If so, stitching them together is pretty easy. The method I use is to lay one gore on top of another with a thin strip of newspaper underneath. The paper is there to allow the sewing machine to actually grip the fabric and move it along since ripstop nylon can be a bit too slippery against the metal parts.

View attachment 407398

From there I stitch the edge, tie the ends, cut off the excess thread and rip the paper out. Then I move on to the next gore.

View attachment 407399
View attachment 407400

Once all the gores are in place and the canopy is complete, I attach my shroud lines (I like to use 0.5mm nylon) by stitching it in place BACKWARDS (going from the edge toward the inside) for one inch, turning it around and then stitching it back down so there are two inches worth of anchored shroud line at every point. Each shroud line is made twice as long as necessary so for a 20 gore parachute, I end up with 10 loops. I finish off with a metal S-hook holding the whole bundle and a piece of heat shrink to keep them from slipping around.

View attachment 407401

This is just my way of doing it, but there are lots of little tweaks and variations out there. I hope this gives you some ideas on where to go with your project. Keep us posted on your progress!

Click to expand...

thank you so much!! This will help a lot!!!

I like sewing my parachutes too; personally like the strength and finished look of the French feld seems... I use zero porosity 1.1oz nylon from paragear.com.

I make them hemispherical scottbryce.com is sooo helpful [emoji4].

Use the tip of a wire wrapped around my soldering iron to cut the fabric and ironing the seems before pinning makes it easier to form the feld.

My machine only straight stitches so I sew them twice. Hem the bottom of the skirt, lay a binding tape made from bias cut fabric around the spill hole.

Some pics as example







They’re definitely a test of my patience and take some time - estimate 6 hours or so.

Blue skies,

Craig

ebruce1361 said:

As @ep29030 said, there are several things to consider when deciding upon an ideal parachute design. Personally, my rocket fleet is mostly a mix of hexagonal chutes cut from heavy duty trash bags or multi-gore ripstop nylon elliptical parachutes (I usually go for 20 gores because I like that look, see below)

View attachment 407397

When you say 100cm diameter, that's a bit bigger than a lot of parachutes for mid power rockets. How much do you expect your final rocket to weigh? Also, have you determined the exact dimensions of each gore yet? If so, stitching them together is pretty easy. The method I use is to lay one gore on top of another with a thin strip of newspaper underneath. The paper is there to allow the sewing machine to actually grip the fabric and move it along since ripstop nylon can be a bit too slippery against the metal parts.

View attachment 407398

From there I stitch the edge, tie the ends, cut off the excess thread and rip the paper out. Then I move on to the next gore.

View attachment 407399
View attachment 407400

Once all the gores are in place and the canopy is complete, I attach my shroud lines (I like to use 0.5mm nylon) by stitching it in place BACKWARDS (going from the edge toward the inside) for one inch, turning it around and then stitching it back down so there are two inches worth of anchored shroud line at every point. Each shroud line is made twice as long as necessary so for a 20 gore parachute, I end up with 10 loops. I finish off with a metal S-hook holding the whole bundle and a piece of heat shrink to keep them from slipping around.

View attachment 407401

This is just my way of doing it, but there are lots of little tweaks and variations out there. I hope this gives you some ideas on where to go with your project. Keep us posted on your progress!

Click to expand...

How do you put all the shourd lines togeter in the S hook?

I use Scott Bryce Gore calculator online for all of my Gore patterns. I recommend it

tollyman said:

I use Scott Bryce Gore calculator online for all of my Gore patterns. I recommend it

Click to expand...

but i think that dont work for a semi helliptical one, justo for hemispherical

Here's a zip archive of a 2:1 ellipsoid chute template I made. For some reason, it won't let me attach the .svg directly. Unzip it to a .svg and edit it in whatever you use for vector graphics. I like inkscape because it's free and open source, though it does have a bit of a learning curve.

The height of the gore template will be D*0.606, and the width of the gore must be π*D/n, where D is the nominal open diameter and n is the number of gores you want.

2:1 ellipsoid means that if you continued the ellipse all the way around, the equatorial diameter would be twice the polar diameter. This means that if the canopy opened to the mathematical ideal shape, the height would be 1/4 the diameter. Here's an image that may help explain the open canopy dimensions better:

Rocketbegg said:

How do you put all the shourd lines togeter in the S hook?

Click to expand...

When I cut the shroud lines, I cut them twice as long as they need to be, and only make half as many. So for a 20 gore parachute with 20 shroud lines 36 inches long, I only cut ten strings at 72 inches. That way, when I stitch them to the parachute, I'm left with ten long loops dangling from the canopy. All I do then is hook the S-hook over each of the loops, crimp it closed, turn the whole parachute upside down and let the shroud lines settle on their own so they are all as close to even in length as possible, and then slip on the sleeve of heat shrink.

Maxwelljets said:

Here's a zip archive of a 2:1 ellipsoid chute template I made. For some reason, it won't let me attach the .svg directly. Unzip it to a .svg and edit it in whatever you use for vector graphics. I like inkscape because it's free and open source, though it does have a bit of a learning curve.

The height of the gore template will be D*0.621, and the width of the gore mus be π*D/n, where D is the nominal open diameter and n is the number of gores you want.

2:1 ellipsoid means that if you continued the ellipse all the way around, the equatorial diameter would be twice the polar diameter. This means that if the canopy opened to the mathematical ideal shape, the height would be 1/4 the diameter. Here's an image that may help explain the open canopy dimensions better:
View attachment 408814

Click to expand...

thanks

ebruce1361 said:

When I cut the shroud lines, I cut them twice as long as they need to be, and only make half as many. So for a 20 gore parachute with 20 shroud lines 36 inches long, I only cut ten strings at 72 inches. That way, when I stitch them to the parachute, I'm left with ten long loops dangling from the canopy. All I do then is hook the S-hook over each of the loops, crimp it closed, turn the whole parachute upside down and let the shroud lines settle on their own so they are all as close to even in length as possible, and then slip on the sleeve of heat shrink.

Click to expand...

THanks )

ebruce1361 said:

When I cut the shroud lines, I cut them twice as long as they need to be, and only make half as many. So for a 20 gore parachute with 20 shroud lines 36 inches long, I only cut ten strings at 72 inches. That way, when I stitch them to the parachute, I'm left with ten long loops dangling from the canopy. All I do then is hook the S-hook over each of the loops, crimp it closed, turn the whole parachute upside down and let the shroud lines settle on their own so they are all as close to even in length as possible, and then slip on the sleeve of heat shrink.

Click to expand...

so,
instead of 20 strings do you use only ten, connecting two points of the parachute through each string? if this is correct, would you make this connection at adjacent or opposite points? How it works? I dont know if I understood correctly...

Rocketbegg said:

so,
instead of 20 strings do you use only ten, connecting two points of the parachute through each string? if this is correct, would you make this connection at adjacent or opposite points? How it works? I dont know if I understood correctly...

Click to expand...

You're on the right track. Yes, I sew one end of a shroud line to a seam on the parachute, then the other end of that same line is sewn on to the very next point. Here's a diagram that should help:

Now, because I suck at drawing, this parachute has only 12 gores. It is laying flat with all the shroud lines sticking out. The numbers in the middle show the 12 gores, and the outer numbers show the 6 shroud lines looped between each of the canopy gores. The ends of the shroud lines are sewn right on top of the seams between the gores.

ebruce1361 said:

You're on the right track. Yes, I sew one end of a shroud line to a seam on the parachute, then the other end of that same line is sewn on to the very next point. Here's a diagram that should help:
View attachment 408840
Now, because I suck at drawing, this parachute has only 12 gores. It is laying flat with all the shroud lines sticking out. The numbers in the middle show the 12 gores, and the outer numbers show the 6 shroud lines looped between each of the canopy gores. The ends of the shroud lines are sewn right on top of the seams between the gores.

Click to expand...

Thank you so much!!! I'm a member of the recovery system of the newly created rocket team of my university , we are all begginers.

I'm honored I could help! Don't hesitate to reach out if you have further questions, and in light of this as well as other conversations I've had in the past, I think I'll make a video detailing the assembly of my next parachute and put it up on my YouTube channel.

ebruce1361 said:

I'm honored I could help! Don't hesitate to reach out if you have further questions, and in light of this as well as other conversations I've had in the past, I think I'll make a video detailing the assembly of my next parachute and put it up on my YouTube channel.

Click to expand...

OK" Really thanks!! I will ask you more stuff later haha!! I'm sure your video will help a lot too!
What the name of the channel? I'll be a subscribe

B.F.R.A

Stands for "Bruce Family Rocketry adventures". There isn't a whole lot of stuff on there as yet, but I keep adding videos here and there. When I'm done with my current projects, I'll make a parachute tutorial.

https://www.youtube.com/channel/UC2OjQvVKT3iNx0-Tj4dZY0w?view_as=subscriber