Folding a Flat Parachute

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troj

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The techniques to fold a flat parachute are very similar, but not identical, to folding a hemispherical.

Start with your parachute laid out flat, and inspect it for any burns, tears or other damage.

flat-1.jpg

Next, straighten out the lines. Because of how the lines are attached (often in loops where a line is connected to two adjacement points, you won't be able to get rid of all of the twists. Remove as many of them as possible. In this instance, I've tied a simple overhand knot near the "bottom" of the lines, to provide an attachment point for the rest of the recovery system.

flat-2.jpg

Once the lines are untangled, grab the center of the canopy with one hand and the bottom of the lines with the other, pull everything out straight, and lay it on the floor. fine out all of the gores, so that the lines are all on one side, and the fabric on another. Since we're dealing with a single flat piece of fabric, it likely won't be perfect, but take the time to get it as close.

flat-3.jpg

Now, hold the canopy in place with one hand and take a moment to pull the lines taught again (they'll creep as you fine the gores). Next, grab half the gores and flip them to the other side, so we have to piles of fabric, each with half the gores, and the lines coming out of the middle.

flat-4.jpg

Hold the bottom (skirt) of the canopy down with one hand, grab the lines near the middle with the other, and pull the lines up into the canopy. You want the majority of the lines on the fabric, with a short "tail" below the skirt.

flat-5.jpg
 

troj

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How you proceed from here depends on the size of your parachute, and the space you need to fit it in. You can fold it into a long, thin shape, something short and squat, or something in between. Experiment at home, on the floor, and figure out what works best for a given parachute in a given airframe.

Here, I've taken each of the gores and folded them inward, to start a bundle that's longer but thinner. The monitor cord is serving as something to hold it down, so I could get pictures. Riggers use beanbags to help control the canopy as they fold.

flat-6.jpg

Next, I've folded the apex down towards the skirt, then folded it in half two more times, resulting in a long, thin bundle. Perfect for small diameter body tubes.

flat-7.jpg

Another option, resulting in something a bit fatter but shorter, is to fold the gores back over.

flat-8.jpg

I next fold them in half again, resulting in a very short bundle. Be sure to admire the monitor cord.

flat-9.jpg

The canopy is then Z-folded from the top, resulting in a short bundle that's a bit fatter than the first one, but which would still fit in a fairly small tube.

The key is to fold it neatly, and keep the lines under control. Most importantly, don't wrap the lines around the canopy.

Thanks to Top Flight Recovery for providing the parachute I used for these pictures -- they were generous to provide me a new 36" parachute, specifically for this purpose.

-Kevin

flat-10.jpg
 

Pem Tech

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OK, now your description via email makes much more sense.
Thanks!!!
 

Kirk G

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I agree, troj, the pictures are very clear.

I intend to use your instructions when I fold and attempt to use my first "homebrew" parachute soon.

I assume that before you insert this into the airframe/body tube, that you insert waded up recovery wadding or "dog barf".
Do you have any suggestions for how tightly to pack either the wadding or the chute...(or perhaps how tightly NOT to pack it in?)
 

troj

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I assume that before you insert this into the airframe/body tube, that you insert waded up recovery wadding or "dog barf".
Do you have any suggestions for how tightly to pack either the wadding or the chute...(or perhaps how tightly NOT to pack it in?)
I tend to use heat shields, and wrap them around the parachute, but dog barf works, as well.

Don't pack the dog barf -- just drop it into the tube.

The parachute needs to be able to slide easily into (and out of!) the tube -- if you have to shove it in with a stick, you're asking for trouble.

-Kevin
 

mrichhcirm

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Question: if you don't wrap the shroud lines around the canopy, what do you do with them to keep them from tangling?

Okay, one more question: I'm experimenting with a slider to slow deployment (poor man's DD) to minimize wind drift. where do you recommend putting it in the BT: Above the canopy? below? alongside it?
 

mrichhcirm

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Question: if you don't wrap the shroud lines around the canopy, what do you do with them to keep them from tangling? Oops, you already addressed that. Sorry, should have paid more attention.

Okay, one more question: I'm experimenting with a slider to slow deployment (poor man's DD) to minimize wind drift. where do you recommend putting it in the BT: Above the canopy? below? alongside it?
Since the slider starts at the top of the shroud lines, it looks like it needs to be inside the canopy, yes? where would the slider be in a skydiving/parafoil chute?
 

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Comon' Kevin,

My son's wad it in a ball and force it to fit method works, well, ocassionally.
 

troj

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Since the slider starts at the top of the shroud lines, it looks like it needs to be inside the canopy, yes? where would the slider be in a skydiving/parafoil chute?
The slider gets pushed up against the skirt, and folded up with the canopy, as it is folded.

Here's a video of a man-rated rig, and you can see what he's doing with the slider. It starts at about 9:30 into the video. Note that he's packing a multi-cell chute, so the technique on what to do with fabric is a bit different. You'll also note a lot of discussion about the need to make sure lines are straight and orderly.

[video=youtube;VIB6XQ3bpJk]http://www.youtube.com/watch?v=VIB6XQ3bpJk[/video]

-Kevin
 

Lowpuller

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I'm a parachute rigger, so I will add my two cents.

Great job flaking the canopy but I would highly recommend against putting the lines inside the canopy, for two reasons.

First his is very likely to cause line burns on the fabric during opening, however this is really only a problem for heavier rockets. In fact the reason you fine the canopy is to remove the canopy material from the lines to prevent line burn.

Second and frankly most importantly, the lines should stretch out completely before the canopy opens to reduce opening shock on the parachute. I like to equate it to going 90mph in your car and slamming on the brakes or gently slowing down. If the canopy inflates prior to line stretch it's like slamming of the brakes.

Sliders serve two functions they slow the opening and help control the lines during opening. The slider is intended to insure you have line stretch before the canopy inflates, but this also increase opening time. Not needed in my opinion unless it is a really heavy rocket. BASE jumpers frequently leave the slider out to get a quicker opening, but only when they are opening very soon after jumping and not moving quickly.






Sent from my iPad using Rocketry Forum
 

troj

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this should get you started
There's the answer....with one significant exception -- do not wrap the lines around the canopy

Lines wrapped around nylon canopies is asking for the lines to shift in flight such that they get hung up and the chute doesn't deploy. I've never had it happen to me, but I've seen it several times.

-Kevin
 

dhbarr

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What are gores and what is flaking?
gore: curvy triangle piece of many parachutes
fine: fold the gore in half so the lines are together

Good pics at the top of this thread.
 

ascastil

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I watched a video on youtube and it makes a lot more sense. Couple questions. Since Im not wrapping the lines anymore and I put my folded parachute into a lets say 2.5 inch diameter rocket, it seems the parachute might sort of come undone a little. Am I right and would that be okay?

Secondly, little off topic, anything special on inserting a long shock cord? I was thinking multiple S shapes then dropping it in.
 

Lowpuller

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Exactly the same, but I do wrap the lines around the canopy. This helps insures line stretch before the canopy can inflate. Slower softer opening, which is a good thing.
 

ascastil

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I have always wrapped mine too. Gonna try something different. Whenever its wrapped it doesnt come undone in the body tube. With the new to me technique, seems itll come undone a little on bigger bodytubes. I keep thinking as long as the ejection charge pushes the cone off, the weight should pull everything else out. "S" shaped shock cord underneath parachute, one should follow the other, right?
 

Lowpuller

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Opening sequence is the most important thing to protect the canopy. Even on plastic Estes canopies.
 

tab28682

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With my RC Chute Sled, I do pack the flat chutes with the lines bundled into the chute as the OP shows. This is also the suggested packing method for the JL Chute Release.

After ejection, with the rocket parts coming down under a streamer, a small drogue chute or without either one, with the main chute strapped down to the release, the parts are falling slow enough that there will not be any danger of the lines friction burning the canopy and the opening shock is minimal.
 

Lowpuller

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I would recommend always packing to prevent a hard opening. You never know when you might open by accident on the way up. A proper pack might, might I say, save you.

Apollo proved you can safely opening a parachute when your going extremely fast.
 

Handeman

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I would recommend always packing to prevent a hard opening. You never know when you might open by accident on the way up. A proper pack might, might I say, save you.

Apollo proved you can safely opening a parachute when your going extremely fast.
I understand where you're coming from, but the way I look at it, if the chute opens on the way up, you have much worse problems then a chute opening sequence issue. I've lost body tubes every time I've had an early ejection, even when the chute shredded too. I'm not sure anything but wrapping the lines around the chute for a very slow opening can help you and even that is probably won't prevent damage.

As far as opening a chute going fast, there are super sonic chutes designed to open when speeds are above Mach. You can open them at almost any speed, the effectiveness of the chute at slow speeds is usually not good if it's designed for high speed deployment. That is why I always design and pack for the "normal" deployment. If I get a rare anomalous opening, I just make repairs or pick up parts and go on. I look at it as a cost of rocketry, like CATOs, lawn darts, etc.
 

Lowpuller

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I agree you packing for a normal opening, but in a manner that assures proper opening sequence. Proper opening sequence allows the chute to opening at higher speeds without failing.
 

tab28682

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I agree you packing for a normal opening, but in a manner that assures proper opening sequence. Proper opening sequence allows the chute to opening at higher speeds without failing.
For certain rockets that I am currently flying with the RC Chute Sled, I am working towards consistent low altitude chute openings on command. 100-150 feet for mid power and 150-200 for lighter high power. Rather analogous to base jumping. I will take the slight risk of a high speed chute deployment under power to have the fastest possible chute opening for low altitude deployment.

Right now i am 8 for 8 with the RC chute sled. I have only had two chutes opening at high speed over time, none with the RC Chute Sled. One in 1996 (l284 cato at mid burn) and one last year (I140 early ejection, about one second after burnout) Both times the model survived with some zipper damage and minor chute damage.

Only larger high power models boosting at higher speeds where I am not planning low level manual deployment, i will likely follow good chute packing practices for possible high speed deployments. In the past, when deploying the main chute via motor ejection on level 1 rockets, I have routinely used a ring to slow the main chute opening in case of a high speed deployment.
 
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Christopher

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"Don't wrap lines around the canopy", well I guess I now know why the shoot deployed but did not open. Thanks!
 

Incongruent

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"Don't wrap lines around the canopy", well I guess I now know why the shoot deployed but did not open. Thanks!
What parachute was it? I had a 12in Estes chute fail to open last launch with the fold lines inside method, which I blame on the stiffness of the material. Fortunately no damage was done.
 

Christopher

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It was a 12 inch plastic parachute in the Estes 7000 Bullpup. The lines were wrapped around it. I packed it the night before, I figured talcum powder would do the job but it didn't.
 

rharshberger

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It was a 12 inch plastic parachute in the Estes 7000 Bullpup. The lines were wrapped around it. I packed it the night before, I figured talcum powder would do the job but it didn't.
Was it cold out ? If so those chutes can get stiff enough not to open.
 
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