Build Thread - 9 ft, 24 Gore, Semi-Elliptical Chute

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Handeman

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This is part of my L3 attempt. I'm documenting the build of the rocket in this thread Performance Hobbies Performer 150, My L3 Cert Build.

I decided to make my own chute for this rocket. I've made most of my own chutes and figure I shouldn't stop now. I did feel it was better to document making the chute here instead of in the build thread for the rocket. Although the two are related for me, there is no reason they need to be for anyone else.

As stated in the title, I'm building a 9ft diameter elliptical chute with 24 gores. I will alternate the gores, red and white. The classic colors. I would match it to the rocket, but I don't know what colors the rocket will be yet.

The chute will be built using 1.1 oz ripstop material. The shroud lines are 550 parachord. The cords will extend from one riser, across the top of the chute, and back down to the other riser. The risers will be made from 1.5" wide nylon webbing. The webbing will be 3 ft long, folded in half with a 4000 lb D-ring at the fold. 6 shroud lines will be attached to each end of the nylon web creating two risers. There will be two nylon pieces making up 4 risers. The two D-rings will be attached to a single point when attaching the chute. I will use 5/8" wide nylon webbing as re-enforcement on the bottom and top hems. The upper hem will form a 12" diameter spill hole in the top of the chute. The 550 parachord will be zig zag stitched to the seam between gores.

I used the View attachment Parachute size calculator.xls spreadsheet to determine the size of chute I needed. The estimate for the rocket weight was 40 lbs.

I used the View attachment Parachute gore size calculator.xls spreadsheet by R. A. Nakka to calculate the size of the gore I needed. I added a converter sheet to make conversion of metric easier. I used the COORDINATES sheet to layout and cut a pattern from 1/8" pressboard. I had to buy a 4x8 sheet to get one big enough.

0117152000.jpg

0117152052.jpg
 

RKeller

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subscribed, thanks for doing a build thread!
 

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This is something I am extremely interested in. Thanks for the thread!
 

astronwolf

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Very interesting project. I just sewed together my first parachute this evening. The 2-foot chute was my learn-to-use-a-sewing-machine project. I am looking forward to learning more about parachute construction as you work through this build.
 

Handeman

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First off, let me explain the gore pattern. The calculator said I needed 36 cm wide gores for the 275 cm diameter chute. Since my fabric tape measure has centimeters on one side and inches on the other, it's just easier to use the whole number on the centimeters then the inches. So, from now on, I'll be giving dimensions in centimeters. Just divide by 2.54 to get the equivalent inches.

The gores need to be 36 cm at the base. I will be using French Fell seams between the gores and they will be 1.5 cm wide. That means I need to add 4.5 cm to the width of the gores for their full length. Here's a pic of how I came up with that.

gore hems.png

I haven't even cut out any of the material yet, but I'm considering my first construction decision. Along with the French Fell seams between the gores, I'll be using a rolled seam on the top and bottom. These will be 2 cm sections rolled twice and stitched to the gore. The 5/8" nylon webbing will be stitched to that as reinforcement. I've add 4 cm to the top and bottom of each gore pattern. I plan to run the 550 paracord shroud lines up and over the chute, stitched to the seams between the gores.

The question is, do I install the shroud lines after assembling the chute and sew them to the top of the chute? This would have the white paracord on top of the red seam on one side of each red gore. It would look better if the line was inside the seam and not showing.

If I want to put the shroud line inside the seam, the top and bottom rolled seams needs to be done on the top and bottom of the gore before the side seams are done. This will make the side seam thick and hard to sew at the top and bottom of the chute. It will also make the side seams more difficult to do with the cord inside them.

The alternative is to do the side seams first and then the rolled seams on the top and bottom. This would allow putting the nylon reinforcement inside that rolled seam. The shroud lines would then go over the top of the chute on the outside. This would be an easier assembly method, but wouldn't look as good.

I don't believe either method would make the chute any stronger then the other. Right now I'm leaning toward the more difficult but better looking method of putting the chords inside the intergore French Fell seams.

Any ideas either way?
 

jcato

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<snip> The question is, do I install the shroud lines after assembling the chute and sew them to the top of the chute? This would have the white paracord on top of the red seam on one side of each red gore. It would look better if the line was inside the seam and not showing.
<snip>
Any ideas either way?
Jeff, here's a quick summary of how I do my chutes:

My gore patterns represent the *exact* gore on the perfect surface of the canopy - no seam allowance. I mark them with (typically) a ballpoint pen. I then cut the fabric with a generous 1" overcut (or more - probably more for your chute). I then sew the apex and skirt edges - using some 3/8" ribbon weave tape in the skirt seam -- the canopy fabric just simply rolled over the tape and stitched 1/16" (or so) from the bottom edge of the gore (on that marked pattern line) and then cut the excess fabric and roll again into the inner edge of the tape and stitch a second time - which finishes off the skirt edge. Do effectively the same thing at the apex - unless I would rather add the apex reinforcing *after* canopy completion - which I did on the ringsail (I think there's a pix or two posted showing the kevlar tape reinforcing). In that case, you simply just do a folded hem at the apex - 2 to 3 layers of fabric (depending on how close you cut it.) I generally do my first fold and sew a straight stitch right off the fold, cut the excess fabric to twice the width of the hem, roll that cut edge in (butting right up to the first stitch) and then stitch again - about 1/16" from the inner edge of the hem.

Yes, this does thicken up these edges when you join the gores along the radial seams, but I've never really had that much of a problem with that -- as I 'walk' the sewing machine thru those 4 or 5 stitches at each end. Do this for all gores - then pin-baste two adjacent gores together ('right' side to 'right' side) and sew a straight stitch (from the 'wrong' side - which is what is facing out) right on the (marked pattern) seam line. Cut off the excess back to twice the width of the seam width you would want (i.e. thru both of the overcuts of the two gore panels). Open the pair of panels out and roll that into your fell seam (which will be half the width of your cutoff) and sew a second stitch about 1/16" off the inner edge of the seam. This will only be thru one of the two gores - *to the side* of the main (first) stitch - be consistent and do it either to the left or right on each radial seam. (This is just like the hem stitch noted above - but with two layers of fabric this time.) Technically, this is not the 'French fell seam' as you diagrammed, but you have 4 layers of fabric forming that 'tunnel' - and (because you got the apex and skirt hems already done) there's no real restriction for running your suspension lines INSIDE these 'tunnels' - thus hiding them from view either from the inside or the outside of the canopy.

Rolling those seams and sewing with the skirt reinforcing in place is a little tough to sew thru (you've got two layers of the skirt tape + 4 layers of your canopy fabric), but, again, it's not as bad as you may think (best is to make up a little 'trial run' mockup of the seam construction and discover for yourself). One benefit of this is that you are getting a little extra reinforcement there at the skirt *precisely where* you need it (i.e. two layers of skirt band) -- where the suspension line enters the canopy. The alternative is to wait and put your skirt band in after the canopy is complete - and, in that case, you are only having to sew thru 4 layers of canopy fabric as you join the two gore panels -- and 4 layers of F-111 is trivial for even the most minimal of sewing machines.

Join 2 - 2 panel pieces into a 4 panel 'quad' - join those into an 'octet', etc until you get the entire canopy completed. Tie off and finish all the loose threads and then you are ready to run the lines. I would measure the lines under some kind of weight (especially if you are using the 550 cord - as it stretches pretty significantly) - and I would let this be several pounds (the logic here is that you stand a better chance of getting all your lines nearer to the exact same length if marked and cut 'tensioned'. Mark them at the exact apex, the edge of the apex vent, the skirt and the confluence point tie-off (with a good foot of extra at the bottom) - something like a Sharpie is fine. Run the lines thru your seams - align your marks and 'tack' them to the canopy with, oh, a 6" zig-zag stitch at both the skirt edge and the apex vent edge - but leave the rest of the line untacked between those two points. This allows any localized stresses in either the canopy or the line to relieve itself without stressing the other component. It's not going to be necessary to anchor the line all the way from skirt to apex - as the canopy proper will easily transfer those drag forces to the suspension lines. (Remember, with the suspension lines cut under tension, this will most likely 'gather' your canopy fabric, since the dimension from skirt to apex is only 'right' under load (for the lines) - yet the canopy itself is 'right' in a relaxed state - but there's your stress relief for the canopy proper).

Once the lines are in place and tacked down, you can then sew in your skirt band (if you elected to hold off till now) and the apex vent band in place - generally on the interior of the canopy (think about the suspension line tryin to 'tear itself thru' the skirt and you can see that having the skirt band on the interior gives resistance (and reinforcement) to that possibility).

I'll try to rush up the continuation of the ringsail thread where I can illustrate with some pix - but a 'camera issue' has played some role in the delay.


[edit: 1-20-15 - 2:00pm]:

I've found a little diagram that helps quite a bit on the fell seam discussion from above:

flatfell.gif

This is pretty much how I do it - except at 'A', I trim both my pieces of fabric to the same width (after the first stitch) - equal to the width of the lower piece here (or twice the width of the finished seam). Notice that the upper piece of fabric here is the width of your finished seam +- and the lower piece is twice the width. The stitch is exactly 'on' your pattern line.

At 'B', you fold the lower, wider piece over the upper piece. Some instructions will have you iron this down (which is surely workable), but I've found that, with the lightweight ripstop material, it's really not necessary.

At 'C' is where you 'unfold' the fabric, taking the lower layer of fabric over to the right of the seam (the 'wrong' side is now facing up on both pieces of fabric). If you can visualize that your seam would now 'stand up' when you lay out your fabric as shown, then just lay that seam down to the left to get image 'C' to look like it does here.

Your final (second) stitch at 'D' is on the left of the seam and is the only stitch that goes through 4 layers of fabric.

Some of the diagrams on the French fell seam would have you interfold both pieces of fabric before running the stitch (those that show both stitches going through 4 layers of fabric) - like this:

French-fell-seam.jpg

... which is virtually impossible to sew with accuracy. Pin-basting your two panels together (aligning your pattern lines) and making that first stitch through just 2 layers of fabric (like in 'A' in the first diagram) is, truly, about the only rational way of doing this seam.

In your case, I would design for a 1/2" (or 1 1/2 cm) finished seam, min. (make it 2cm - as that will give you enough width for the 550 cord) - but sew up a little trial mockup and verify your seam widths. This would make the lower layer 'selvage' 4cm -- but *don't* try to cut your fabric initially with that width selvage. Ravelling will make things a mess before you get to finish the seam --- cut your fabric W I D E - allowing generous margins and then trim to your final widths right before sewing each individual seam.

That should explain things a little clearer.

-- john.

edits: 1:07am EST: semantic clarifications
2:00pm EST: fell seam diagrams/discussion
 
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Handeman

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From what I understand, I am doing the seams exactly like your picture. I just allow different seam amounts on the two sides like in A when I cut the pattern. I've found it is easier to cut the patterns to include the seam allowance. I use a hot knife to cut the ripstop. I bought a $5 20W soldering iron and flattened the tip. That works great for cutting the nylon ripstop. It melts its way through instead of actually cutting the material. This causes the threads on the edges to melt together and there is no fraying while working with it. I did my first chute with just cutting the material with a scissors. It was fine until I threw it in the wash machine after a cow chewed on it for a while. It came out a ball of unraveled threads. I will only use a hot knife on ripstop from now on.

I think I will probably leave the reinforcement webbing on the vent and lower edge until after the shrouds are in place.

I really like the advice for cutting the 550 under tension. The question is how? I need about 12' across the canopy and 8' down to the riser. I plan 18" risers of 1.5" nylon and 9' to the confluence point. That would give me about six inches of overlap to stitch the 550 to the 1.5" webbing. That means I need to put have 28' of line under tension to measure and cut.

I'm thinking attach one end to a 5lb weight, drop it over a horizontal dowel and then stretch the line to the right length and cut. Does that sound reasonable?

BTW, how do you thread the lines through the tunnel?
 

jcato

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<snip> I really like the advice for cutting the 550 under tension. The question is how? I need about 12' across the canopy and 8' down to the riser. I plan 18" risers of 1.5" nylon and 9' to the confluence point. That would give me about six inches of overlap to stitch the 550 to the 1.5" webbing. That means I need to put have 28' of line under tension to measure and cut.

I'm thinking attach one end to a 5lb weight, drop it over a horizontal dowel and then stretch the line to the right length and cut. Does that sound reasonable?
Understand, it isn't just 'cutting' under tension, you also need to *mark* the critical points (exact apex, edge of apex vent, skirt edge and, finally, riser connection point) under tension - as, once you take the tension off, any marking in a relaxed state will (technically) be wrong. One thing you *don't* want is to have those lines (or your marked points for the apex vent and skirt edge) to be _longer_ than the radial seam - which would mean that, once the suspension line stretches under load, it'll put added stresses on the canopy fabric - better to have the *lines* take those loads and not the canopy fabric.

I'd do it like this: make up some 'line rollers' - something like a 6" piece of 1/2" pvc pipe that you can anchor to a wall somewhere (big lag bolt, etc) - such that it rolls easily - may need 2 of them (and make sure they are exactly parallel to the floor - for two reasons: 1) so that both lines over these rollers are the same length and 2) so the lines won't pull off the rollers when you are measuring. Might could make the rollers shorter and use a large 'fender' washer to keep the lines on the rollers). Put a screw hook (or cup hook) up about head high on the wall; down near the floor, put one of your rollers; then, 1 foot over, put the second roller again at head high. Take your line (cut a little long - but, then, it'll get longer under tension), fold in half and tie the two ends together (temporarily - just a half-hitch). At the midpoint, put a mark and hook that over your screw hook - wrap with masking tape so it won't shift on you. Route your (double) lines down over your lower 'roller', back up over your top 'roller' and then attach your weight to the end where you've tied the two tag ends together (realizing that these rollers need to handle that 5lb weight at the end.) At some point (either before or after that first set) mark your critical points on the wall - and, with the line hanging over these rollers, mark those points. 3 routes (down, then up, then down again) at head high would equal something like 20' - since the lines are doubled, this equates to 40' of total line length (less whatever allowance for the weight at the end). This whole approach could be adapted to a horizontal method, but I think what I did was do it vertically - with the 'offset' of those roller (pulleys) for those larger chutes (my largest was the 7ft red/white). I have an 'out-building' with about a 12' gable end height that I used - which gives me about 20' total line length vertically (i.e. with doubled lines) without having to use the 'rollers'.


Handeman said:
BTW, how do you thread the lines through the tunnel?
I used some of those big-eye quilting (or 'needlework') needles (monster things - but may still be too small for the 550 cord) - hardly have any point on them, very blunt nosed. Something like this:

https://tinyurl.com/tapestry-needle

(except mine aren't bent points)

Simple thing here is use a long enough piece of some Mason's line as a 'messenger' - thread it first, tie to the 550 (nice, smooth joining knot - or wrap with a little masking tape to smooth out) and use that to pull the 550 through. Better yet, just form a loop in the 'messenger', thread 3" or so of the 550 through the loop, fold over and tape to the standing portion with some masking tape - won't need to be strong, as pulling the lines won't demand that much knot strength.


-- john.
 
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Handeman

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Glad to hear my ideas for threading through the tunnel wasn't too far off.

I like the idea of using vertical pulleys to tension the lines. I hadn't thought of that, but I'll figure something out. That idea opens up a whole bunch of possibilities. Thanks...
 

Handeman

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I started cutting the gores from the ripstop that arrived.

I ordered standard ripstop from Hancock Fabrics. I found a 50% coupon so used it on two orders, one for red and one for white material. Saved about $40 even with paying double shipping.

One of the things you will notice about the ripstop nylon is that it has a top and bottom. I consider the dull side the top and the shiny side the bottom. YMMV.

0120152029.jpg

I bought a cheap soldering iron a few years ago and flattened the tip to make hot knife. It has worked very well over the year for cutting nylon. You want to use a hot knife to cut nylon because it cause the cut edges to melt together and prevent fraying.

0120152028.jpg

Here's one of the gores that I got cut out tonight. I only got the red ones done. It was sort of a pain. I have a piece of "concrete" board that is used as wall board in shower areas as a cutting surface for the hot knife, it only comes in 5' lengths. In this case the pattern was longer then the cutting board. This required moving the pattern and fabric for each cut, but it turned out that the melted nylon sticks to the pattern so it make moving the whole thing without losing alignment pretty easy.

0120152153.jpg
 

Handeman

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It took a while, but I have all 24 Gores cut out. I couldn't believe how much static built up while I cut the white gores. There was almost none with the red. I can't believe a different dye would make that much difference. I got one shock I felt all the way to my shoulder! It was kind neat at times, I could hold my hands out about 6" over the gore and it would float right up and stick to me.

Anyway, as jcato had suggested, I made a bunch of test seams. I got the sewing machine set up for the material and the thread I'm using. I used a couple of scrap pieces to duplicate the 4 cm hem that will be on the top and bottom of the gores. I used those to play with and adjust the tension, stitch length, etc. I then joined the two pieces together with the same French Fell seam I plan to use on the chute. Once that was together, I threaded a piece of the 550 cord through the tunnel. That actually worked out pretty well.

Next, I sewed a piece of the nylon webbing I'll be using as reinforcement to what would be the bottom edge. It turned out it wasn't very difficult to sew, but I do need to slow down and manual spin the machine as it makes a few stitches over the 550 cord. Last, I added some zig zag stitching to tack the 550 cord to the chute at the area where the reinforcement is.

The first pic is the piece I was playing with. The next two are close-ups of the inside and outside of the lower edge where the gore meets.

0125151634.jpg 0125151634a.jpg 0125151634b.jpg

I won't have quite as many lines of stitching on the actual chute and I "intend" to be much neater. We'll see.
 

jcato

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<snip> Anyway, as jcato had suggested, I made a bunch of test seams. <snip>
The basic rule is: "You build it the first time to see how to build it the *second* time."

The trick is: "Don't build it the first time -- just make up a few test runs with some scrap material and make your mistakes (and adjustments) *there*."

I've been thinking a little more on measuring and cutting the suspension lines and a few things have come to mind:

1) Don't try to make up some of those 'pulleys', just use some old, empty thread spools - that should work..... or, some empty spools that fishing line comes on (4" dia x 1" wide or so). That larger diameter would rotate easier and make your tensioning weight work a little better.

2) Use a length of non-stretchy line (like some kevlar fishing line that came on that spool above) to measure out your line lengths (makes it easier to not have to calculate, etc the distance around your pulley spools). Since it's non-stretchy, you don't have to worry about measuring/marking things wrong - just route thru your pulley system and mark the points where they occur.

3) As to the tensioning weight, I was thinking you should load the suspension lines to some multiple of the 'steady state' load (i.e. 1g), such that you are assured that the lines take (at least) some major part of the load through most 'normal' deployment regimes. 40lbs on 24 lines = 1.67lbs per line (1g) - so 5lbs (/2) at least gets you to 1.5g loading (per line). You might could even go 10lbs - which is about 3g loading.... but, 5 lbs should be good enough (not aware of any 'standard' to the tensioning on lines - so this is kind of a judgment call). You just want to make sure you have sufficient load on the lines such that the lengths all come out about the same (and you might as well make that such that, in steady-state descent, the lines are carrying all the load (and not the canopy fabric)).

FYI,

-- john.

p.s. Your 'trial runs' look fine.
 
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Handeman

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jcato, Just a few comments inserted in color

The basic rule is: "You build it the first time to see how to build it the *second* time." So true, I think everything I've built has been much better the second time. Even if it's just using the learned technique a second time.

The trick is: "Don't build it the first time -- just make up a few test runs with some scrap material and make your mistakes (and adjustments) *there*."

I've been thinking a little more on measuring and cutting the suspension lines and a few things have come to mind:

1) Don't try to make up some of those 'pulleys', just use some old, empty thread spools - that should work..... or, some empty spools that fishing line comes on (4" dia x 1" wide or so). That larger diameter would rotate easier and make your tensioning weight work a little better. I'll look around, I'm sure I have something like that which will work.

2) Use a length of non-stretchy line (like some kevlar fishing line that came on that spool above) to measure out your line lengths (makes it easier to not have to calculate, etc the distance around your pulley spools). Since it's non-stretchy, you don't have to worry about measuring/marking things wrong - just route thru your pulley system and mark the points where they occur. Excellent idea. I think I'll put the pulleys on an unfinished door frame.

3) As to the tensioning weight, I was thinking you should load the suspension lines to some multiple of the 'steady state' load (i.e. 1g), such that you are assured that the lines take (at least) some major part of the load through most 'normal' deployment regimes. 40lbs on 24 lines = 1.67lbs per line (1g) - so 5lbs (/2) at least gets you to 1.5g loading (per line). You might could even go 10lbs - which is about 3g loading.... but, 5 lbs should be good enough (not aware of any 'standard' to the tensioning on lines - so this is kind of a judgment call). You just want to make sure you have sufficient load on the lines such that the lengths all come out about the same (and you might as well make that such that, in steady-state descent, the lines are carrying all the load (and not the canopy fabric)). That would mean the weight used to measure the length would have to be more then the steady state load. Then the lines will be shorter with the lighter steady state load, not stretching/loading the canopy. So 10 lbs might be a good number sufficiently larger then steady state and also give some margin for opening loads.

FYI,

-- john.

p.s. Your 'trial runs' look fine. Thanks....
I think I got the measurement part down now. Thanks for the ideas/advice.

This is why I love rocketry so much, you learn a lot of really neat and cool stuff and get to use that when you build things!
 

Handeman

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I got quite a bit done today. 5 - 6 hours in the rocket lab. Not all of it was on the chute, I'm still refining the av-bay and doing internal fillets on the fin can.

Anyway, I got all the shroud lines cut, all 12 of them. Each one is about 32 ft. long. I bought a 1,000 ft roll of paracord and only used about 400 ft of it. Guess I'll have to figure out something else to use it on.

0131151747.jpg

I used some old bobbins from my old sewing machine as pulleys when I measured out the lines.

0131151748.jpg

A nail at the top as the center point, pulley at the bottom and another offset near the top. You can see the mark six inches below the nail. That is where the line was marked for the 12" spill hole. I used some 1/8" tubular Kevlar to measure out the distances, transferred the marks to the doorframe and marked and cut each shroud line the same.

0131151748a.jpg

The piece of wood attached to the door frame was there already for another use. Putting the pulley on it worked very well since it let the weight hang free without interfering with the door frame.

One note here. The distance from the spill hole to the bottom edge of the gore was measured after I had sewn the top and bottom hems on the first gore. I made sure all the gores were made the same length so that length will be consistant. The next post should explain it better.
 

Handeman

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I did the hemming of the gores today. There was a 4 cm allowance on the top and bottom of each gore for the rolled hem. The 2 cm part is folded to the 4 cm line, than that is folded onto the gore and sewn.

I used the shiny side of the nylon as the inside and folded all the seams toward that side. This pic shows the difference in finish of the material pretty well.

0131151314.jpg

I used the gore pattern that was used to cut out the material for measuring the hem locations. I use a sharpie to draw heavy lines at 4 cm and 6 cm from the edge.

0131151439.jpg

Once the gore was positioned on the pattern, the lines could be seen through the material. I used a pencil to put marks on the fabric. You can use a pen, but the ink, being a liquid, will soak through and leave a very visible mark on the other side of the fabric. It doesn't hurt anything, but its aesthetics.

NOTE: I used the dull side of the material up when I cut it out. The gore pattern was made from a folded piece of paper, but there was some differences in how the pattern was cut with the jig saw. Laying the material on the pattern with the shiny side up reversed how it was originally cut. There was some differences. I don't believe there is enough to make any difference. If you are concerned, the key is to make sure your pattern is exactly symmetrical when you cut out the material. Mine was close enough, but everyone's idea of acceptable is different.

0131151657.jpg

Next fold the edge to the 4 cm line and crease the fold. You can iron it if you want, but its faster to just crease with your thumb and works well enough.

0131151658b.jpg

Next, fold the creased edge down to the 6 cm line and pin baste the seam.

0131151659.jpg

I stitched the seam with a double line of stitching. There will be more lines of stitching added when the nylon webbing reinforcement is added.

The next thing I did was clamp the hemmed seam back onto the gore pattern.

0131151703c.jpg

I had marked a "finished" line on the pattern at the final length of the first gore. The seam at the top end of each gore was then folded and pinned so its length would exactly match the first gore. This was done by folding down the end to the "finished" line and then fold that crease onto the gore and pin baste it so the finished size of the gore matches the size of the first one.

0131151703b.jpg

Once it got going, it went pretty fast. It only takes sewing couple of gores to get a good rhythm down. I was down to less then 6 minutes per gore. Of course with 24 gores to do, that still took close to 3 hours.

Next up, sewing the gores together! It will actual start looking like a parachute! :D
 

Handeman

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OK, It's time to sew the gores together.

This post may have more to do with how to sew rather then how to assemble this parachute. Sewing the seams is pretty straight forward, but for those that haven't done it before or are new to sewing, these might help. I haven't searched Youtube for "how to sew" videos, but I'm sure there are a lot out there. I'll just post a few pics and show you how I did it.

As I explained when talking about the gore pattern, I left 3 cm of hem allowance on one side and only 1.5 cm on the other. Here is where that comes into play. Two gores are laid, one on the other, with the "outer" sides facing, or "wrong side out". The top and bottom hems were done by folding the hem to the "wrong" or shiny side. Make sure the hems are on opposite sides. You don't want to have to take a seam apart, believe me.

I took an old wood ice cream spoon and sanded each edge until it was 1.5 cm wide. I use that as a guide when pin basting the two gores together. In this case, the 1.5 cm hem of the white gore is laid 1.5 cm from the edge of the 3 cm allowance of the red gore. If you allow the same amount on both sides of you pattern, then you would just line up the edges. Your seam is one layer thicker, but it might save you a little bit of time.
0205152115a.jpg

Once all 12 of these seams are done, all of the rest will have the 1.5 cm of the red gore laid on the 3 cm allowance of the white gore.
I also pinned the top edge after doing the bottom edge. That ensures the two will be pin basted evenly.

Just as a sewing tip. Line up the needle on the inside edge of the hem and start the machine in reverse so the initial stitching is to the end of the material. Once you've sewn that far, release the reverse button and sew back over the stitching you put in while going backwards. This locks the stitching in place and keeps the stitching from coming out later.

0205152118.jpg

When it comes to pins, as this pic shows, the head of the pin is going to go directly under the presser foot. As I'm sure your machine instructions say, remove the pin. Don't try to sew over it.

0205152119.jpg

If you noticed on the previous pictures, I put a piece of blue tape on the sewing machine. This was lined up 3 cm from the needle. As long as I keep the edge of the gore along the tape as I sew, the line of stitching will stay 3cm from the edge.

When you get to the end, do the same thing you did when you start, reverse the machine and sew back over the line of stitching and the hem. I actually let go of the reverse button when it's sewn to the back edge of the hem and let it sew a forward to the outer edge again. This give the final end three pass of stitching to held everything together.
 

Handeman

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Once the first line of stitching is done 3 cm from the edge it is time to fold and pin baste again so you can sew the second line of stitching.

I start by laying the two gores out, outside face down, and stretching the material to tighten the line of stitching.

0205152123.jpg 0205152122.jpg

Start making the seam by folding the 3cm allowance of the red material over the 1.5 cm white and lining the edge up along the line of stitching.

0205152122b.jpg

Then fold the 3 cm and 1.5 cm allowance over seam and pin baste it in place.

0205152122c.jpg

Use the same techniques on this line of stitching as was use on the first. Start at the inside edge of the hem, sew backwards to the outer edge and then begin your seam. In this case, I just keep the line of stitching about 1/16 inch from the edge of the folded material.

0205152127.jpg 0205152127a.jpg

As these picture show, I sewed right over the pins on this seam. In this case, the heads of the pins did not pass under the presser foot. That allows the machine to sew right over the pins. If you do this long enough, you will probably get the machine needle hitting one of the basting pins and not slide off. It bends the pin and stops the machine. That isn't good, but is very rare.

0205152129.jpg

Once you pull the pins out, the seam is done.

One down and 23 more to go!

I plan on attaching 1 red and 1 white gore to each other. Those 12 seams will be easy. The next six, when I make up 4 gore sets, should also be pretty straight forward. It's when you start putting the 8 gore and final seams together that I expect things will get more difficult because of the large amounts of material you'll be working with.

Once everything is together, I'll check the diameter of the spill hole and the marking of the shroud lines to make sure everything lines up.

After all the seams, it'll look like a parachute. Then it's the installation of the shroud lines.

This may take a while, so........... :smile:
 

Handeman

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Here's something that you will have happen to you at some point if you are using a sewing machine.

You will run out of thread in the bobbin.. When that happens, the sewing stops, even through you may keep on stitching along until you notice there is no seam.

One option is to reload the bobbin and start stitching over the old line of thread and go back and forth over the new line of stitching and the original line to lock everything in place.

What I do is tie off the threads. First I pull one thread through until the thread from the other side is looped through the material. Then pull that loop until you have both the upper and lower threads on the same side.

0207151602.jpg

I then use what I've always called a surgeon's knot. It's basically a square knot, but you twist the thread several times the first time. This allows you to pull the knot tight and it will stay tight while you finish tying the knot. I tie it off three times.

0207151603.jpg 0207151603a.jpg

You have to do this with the ends of the thread where you ran out of thread in the bobbin. Then start resewing an inch before the end of the old thread and when you finish, go back and tie the beginning of that line of stitching. This will keep the stitching from coming loose later.

0207151604.jpg

You may have another way to deal with this issue, but this is the way I handle it.
 

Handeman

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OK, I finally got the canopy done. It took about three hours of sewing to hem the tops and bottoms of the gores. It was about 20 minutes per seam or 8 hours of sewing to finish the 24 seams. But they are DONE!!!!

Here's a couple of pics of the canopy. It's starting to look like an actual parachute now.

0207152002.jpg 0207152002a.jpg

Next up are the shroud lines. I marked those before, but might have to redo the markings. The spill hole was supposed to be 12" diameter, but turned out closer to 13". I'll have to stretch out the canopy and really measure it, but it looks like 13 to 13.5 inch is probably going to be the final size.
 

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Next up are the shroud lines. I marked those before, but might have to redo the markings. The spill hole was supposed to be 12" diameter, but turned out closer to 13". I'll have to stretch out the canopy and really measure it, but it looks like 13 to 13.5 inch is probably going to be the final size.
I wouldn't do that - mainly because that (slightly) larger dimension of the spill hole just means that it'll gather a little bit of fullness in the canopy fabric and assure that the suspension lines carry all (or nearly all) of the loading. It's actually better this way than if the pre-construction measurements exactly matched the finished vent diameter. Anywhere one can get a little bit of 'fullness' in the canopy fabric only means less stress on the canopy fabric.

Anyway, the difference between 12" and 13" is almost nil (in the final analysis).

The canopy is looking good -- nice work.

-- john.

p.s. When you run your lines, I would also run them thru a steel ring (right at the apex), something like:

https://www.ebay.com/itm/360939084286?_trksid=p2060778.m1438.l2649&ssPageName=STRK:MEBIDX:IT

... which will give you a good place to attach a pilot chute. --jhc.
 
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crossfire

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Looks like you did a very good job. Now by the time you get the lines on you will have over 10 hrs in the chute. This should tell flyers why the larger chutes have to be priced as they are for one to make a profit.
 

Handeman

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Looks like you did a very good job. Now by the time you get the lines on you will have over 10 hrs in the chute. This should tell flyers why the larger chutes have to be priced as they are for one to make a profit.
You're exactly right. Part of what I like about this hobby is building things. That includes parachutes, etc. If I had to include my time, at minimum wage, I'm not sure I could make the chute cheaper than I could buy it. Then again, I'm not sure I could buy a chute of the quality I'm building for any price.

I'm figuring I spent $120 on materials (I'll have some left over for other projects) and I'll have 20 hours of labor in the building process. That would make it $280, which is more than what a 144 " Spherachute would run me.

It's not about the money, it's about building something that works.
 

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You did a great job, it looks great.


TA
 

Handeman

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Now it is time to thread the shroud lines through the seams. This didn't take too long, a couple of hours to thread and sew the shrouds in place.

I bought needles at Micheal's to thread the lines with. I had to use a flat bladed screw driver to widen the slot in the needle a little so the paracord would fit.

0208151218.jpg

I used a couple barbell weight to hold the gores in place as I pull the lines through. The weights worked very well because it allowed me to keep the material taught which made pulling the lines through much easier.

0208151217.jpg 0208151222.jpg

I also tied up the shroud lines as I finished threading them. This really helped keep everything out from under foot.

0208151226.jpg

The last step was to zig zag through the shroud lines about an inch from the top and bottom edge.

0209152229.jpg 0209152229b.jpg

All that is left is to sew the nylon strap reinforcement along the top and bottom edges and attach the shrouds to the risers.
 

Handeman

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OK, it's finally done.

I broke two needles on the sewing machine putting the reinforcement nylon strap on the lower edge of the chute. I think this had more to do with me then difficulty sewing.

Anyway, here's the reinforcement nylon strap attached. I did two lines of stitching, trying to stay and even distance from the edge on each stitch. The first one was the hardest because that also determined the placement of the strap. The second line of stitching just tacked down the strap. Of course, that second line is where I broke the needles.

0213151942.jpg

I intended to add a reinforcement strap along the spill hole at the top, but I reconsidered that. The hole turned out to be larger than what I measured the shroud lines for. Since the shroud lines will keep the stresses off of the upper seam, I decided to skip the nylon strap on that area.

Next was to sew the risers with the D-rings. I used 36" long 1.5" nylon straps as risers. I cut these with the hot knife which worked very well. I inserted the D-ring and taped the two halves together, marking where I wanted the peaks of the stitching to be. I then stitched it all together and removed the tape. Using the tape kept the two halves aligned and provide a good guide to sew to. Not that it helped that much. My pattern leaves a lot to be desired, but it will work.

0213152107.jpg 0213152112.jpg

So the last part went really fast. I use the hot knife to cut the shroud lines to their final length and zigzag stitched six shroud lines to each riser.

It looks like a parachute!!! :smile:

0213152228a.jpg

It's Done!
 

Handeman

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Here's a couple of shots from today at the flying field. It was a little breezy.

0214151115.jpg 0214151115aa.jpg 0214151115d.jpg
 
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