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GrossApproximator

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Hello all. I know that there have been threads on making your own parachutes in the past, and I've read a few of these. However, does anyone have a good tutorial for the first-time 'chute builder? I ask because I have a few square yards of ripstop nylon fabric (1.5 oz I think) and a big roll of 90-pound test kite string (sorry, I don't know what kind) that I would like to use up. I'm only interested in mid power parachutes, and I'm fine just building a "gathered parasheet" like what the small rockets use. Any advice or proceedures?
 
I read a thread some time ago where a guy used a soldering iron to cut his rip stop material in a circular configuration. Granted this eliminates the need for hemming the chute because the edges are fused. I liked this idea and applied it to the X chute pattern I was using. The X chute has proven to be an advantage to me in that it doesn't drift like round or octagon shaped chutes will. So, I made it more efficient and weigh less. The shroud lines had been made with upholstery thread which was really very strong but burnt into way too easily. I opted to go with refurbishing them with "Omniflex braided 30 lb fishing line ( available at your local Wally World ) that I sewed into each corner. You will have 8 shroud lines with an X chute but your descent will be way more direct. Little to no drifting. I do have specs available if you are interested.
 
Gary Byrum said:
I read a thread some time ago where a guy used a soldering iron to cut his rip stop material in a circular configuration. Granted this eliminates the need for hemming the chute because the edges are fused. I liked this idea and applied it to the X chute pattern I was using. The X chute has proven to be an advantage to me in that it doesn't drift like round or octagon shaped chutes will. So, I made it more efficient and weigh less. The shroud lines had been made with upholstery thread which was really very strong but burnt into way too easily. I opted to go with refurbishing them with "Omniflex braided 30 lb fishing line ( available at your local Wally World ) that I sewed into each corner. You will have 8 shroud lines with an X chute but your descent will be way more direct. Little to no drifting. I do have specs available if you are interested.
Click to expand...


Cool stuff :). I live in Michigan and my launch fields are small, so low-drift chutes would be nice. Can you make the specs available here on TRF, and can they be scaled up or down to make small "practice" chutes?

By the way, does anyone know why X-form chutes drift less?
 
Gary Byrum said:
I read a thread some time ago where a guy used a soldering iron to cut his rip stop material in a circular configuration. Granted this eliminates the need for hemming the chute because the edges are fused. I liked this idea and applied it to the X chute pattern I was using. The X chute has proven to be an advantage to me in that it doesn't drift like round or octagon shaped chutes will. So, I made it more efficient and weigh less. The shroud lines had been made with upholstery thread which was really very strong but burnt into way too easily. I opted to go with refurbishing them with "Omniflex braided 30 lb fishing line ( available at your local Wally World ) that I sewed into each corner. You will have 8 shroud lines with an X chute but your descent will be way more direct. Little to no drifting. I do have specs available if you are interested.
Click to expand...

Chutes should "always" be hemmed. Not just to hide the raw edge but for structural strength. It is best to roll a light weight single ply "not tubular" webbing or support tape into the skirt and apex seams. For small chutes you can use ribbon. If I have time later I will post a picture of some commonly used parachute seams.
 
Here's what I have. I made the two smaller chutes of the 4 in the attached pdf with the length of shroud line I used. The two bigger ones have never been made so I do not know the shroud length. You'll have to do the math. I made templates from some cheap poster board I got at Staples and used those as a guide for my soldering iron. The shroud lengths may be a bit long but that was necessary because of the way I secured the gathered ends. After I sewed the shrouds in I CA'd the "sew points" for extra security.

View attachment X Chutes.pdf
 
Cool. Thanks. On the pdf, only one of the sides of the chute is dimensioned. Are all the sides the same (forgive me if this is a newb question)?
 
jazzviper1 said:
Chutes should "always" be hemmed. Not just to hide the raw edge but for structural strength. It is best to roll a light weight single ply "not tubular" webbing or support tape into the skirt and apex seams. For small chutes you can use ribbon. If I have time later I will post a picture of some commonly used parachute seams.
Click to expand...

I might agree with you if it was a chute that had to withstand a lot of pressure. Maybe even in High Powered rocketry. This is small scale. Rip Stop doesn't tear so fusing the edges is adequate. I know because I have done it. It's easy to work overkill in a method as well as it is to not have enough to support the function needed. Case and point...I hemmed edges to smaller chutes that wouldn't even deploy. They just followed the rocket downward. The lighter the better. None of my chutes show any drawbacks so far.
 
Thread hijack! But while we're on the topic, where does everyone buy their ripstop? The ripstop at my local fabric store seems 'Rough" compared to all of my other manufacturer's chutes.

Alex
 
ParaGear.com

They have real parachute weight ripstop, not that heavy fabric store stuff.
Buy the Lo porosity fabric or the 1.1 ounce dont use the zero P (porosity) for rockets.
 
Jazzviper1, just curious, why not use zero P for rockets?

Wouldn't a spill-hole offset the porosity? Or allow a smaller chute?

Besides, they have that fabric in groovy neon colors!

For me, I can typically see my neon green chutes the best, depending on the sky (clear skies I like black, if cloudy I go green)


BTW, thanks for the heads up for a place to buy the fabric.
 
GrossApproximator said:
Cool. Thanks. On the pdf, only one of the sides of the chute is dimensioned. Are all the sides the same (forgive me if this is a newb question)?
Click to expand...

That one measurement applies to every edge of the chute meaning, all cuts will be the same. This may not be a typical "X" chute like you might have seen popping out of the rear of dragsters. It's more of a 'thick' X. I believe the reason X chutes descend more directly is because air flows through the 4 corners more evenly than a typical chute. Round chutes may very well act somewhat like a saucer rocket does going up. Most saucers I have seen tend to wobble up. It's likely that a round chute can't evenly distribute the air on the way down.

To answer another question, the rip stop you are getting at the cloth stores probably has sizing or (stiffeners) in it and needs to be washed in warm enough soapy water to remove the sizing.
 
Zephhyr said:
Here is a place to get 1.1oz ripstop at a good price, the 1.1oz Calendered, is the fabric to use for a light weight chute.
https://www.efabricsupplier.com/category_s/63.htm?searching=Y&sort=13&cat=63&show=10&page=1
Click to expand...

I actually just got back from the post office and picked up a shipment of this fabric from them. It really seems like good stuff - though perhaps a bit more "breathable" than I expected. It is VERY light/thin, and it's pretty slippery (should be a challenge to sew).

They actually list their wares on Ebay for slightly lower prices, and shipping cost is very reasonable. Shipping was also quick.

rec'd.

s6
 
Gary Byrum said:
I believe the reason X chutes descend more directly is because air flows through the 4 corners more evenly than a typical chute.
Click to expand...

Generally, they just descend more quickly because of lower drag. X-style 'chutes don't drift less than any other parachute design with the same drag.

See: https://www.rocketryforum.com/showthread.php?t=28072 (and probably about a dozen other long threads of the subject <grin>).

-- Roger
 
jadebox said:
Generally, they just descend more quickly because of lower drag. X-style 'chutes don't drift less than any other parachute design with the same drag.

See: https://www.rocketryforum.com/showthread.php?t=28072 (and probably about a dozen other long threads of the subject <grin>).

-- Roger
Click to expand...

Well, I've only been using the ones I made for a year now and maybe it's just how I designed them but I have noticed a difference between the old plastic octagons and my chutes. Not everybody makes or has the same X chute design, just like everybody sounds different playing the same guitar. Maybe I have a design that works better than the average X chute. I sure don't have to chase my rockets down like I used to. The pic below shows what it looks like deployed. Almost box like. Never mind the failed recovery because the chutes got caught up on the fin pods.

X Chute.jpg
 
Last edited:
Gary Byrum said:
Maybe I have a design that works better than the average X chute.
Click to expand...

Your 'chutes do look good in the photos. But, they aren't going to drift less than any other design.

It's just simple physics. If the wind is blowing at speed x and it takes y amount of time for the rocket to descend, then the distance, on average, that the rocket will drift is x times y. The design of the parachute has absolutely no effect on that. Generally, X-type parachutes cause less drift simply because the rocket falls faster. There might be some subtle differences - for example, if it takes the 'chute a while to open, then the rocket will fall faster until the 'chute opens and, therefore, drift less. And 'chutes that generate lift might glide. But, the average drift distance = x times y formula is always true for a parachute that isn't guided.

Please see the thread I previously referenced for a more detailed discussion.

-- Roger
 
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GrossApproximator said:
Would kite fabric work for parachutes? I found this website that sells factory seconds at a low price.

https://www.kitebuilder.com/catalog...8_230?osCsid=ea81536485172355cb05c8ea94596cf4

One person wrote a review on these "seconds" and said that in a 10 square yard lot of factory "seconds," there was only about 1 square centimeter of flawed material.
Click to expand...

The "material" that I got form KiteBuilder would work fantastic for kites as it is exceptionally stiff - much like paper. I was not successfull making a useable chute, and wound up tossing the stuff.
 
jadebox said:
Your 'chutes do look good in the photos. But, they aren't going to drift less than any other design.

It's just simple physics. If the wind is blowing at speed x and it takes y amount of time for the rocket to descend, then the distance, on average, that the rocket will drift is x times y. The design of the parachute has absolutely no effect on that. Generally, X-type parachutes cause less drift simply because the rocket falls faster. There might be some subtle differences - for example, if it takes the 'chute a while to open, then the rocket will fall faster until the 'chute opens and, therefore, drift less. And 'chutes that generate lift might glide. But, the average drift distance = x times y formula is always true for a parachute that isn't guided.

Please see the thread I previously referenced for a more detailed discussion.

-- Roger
Click to expand...

Thank you Roger. Finally someone that understands the physics.

A parachute and rocket will come down with ZERO speed relative to the air mass it's falling through. It doesn't matter what type of chute it is, it will come down in the air mass and it's speed relative to the ground is the same as the speed of the air mass.
The only exception to this is if the parachute is designed to have a speed relative to the air, such as a multi-cell parasail like skydivers use. They travels about 20 MPH relative to the air they're in. If you use one of these, you have to have some method of controlling the direction because it will deploy and move in any random direction without some type of positive control, like RC to steer it.
The only way to get a parachute to drift less is to make it come down faster!
 
Last edited:
First time poster, long-time maker of parachutes ;-)

The point about chute shape being irrelevant to drift is correct, BUT makes certain assumptions.
The most vital assumption is that the chute and the shroudlines are perfectly symmetrical. Given that very few chutes are truly symmetrical, chute-shape then DOES have an influence.
A 'round' chute (i'm including hexagonal and octagonal chutes in that), rigged assymetrically (even by a tiny amount) will act as an inefficient aerofoil section and tend to glide. A cruciform chute however, vents the airflow differently and will not glide to anywhere near the same extent.
This explains why, although the above posters are absolutely correct with the physics of descent through a moving air column, in the 'real-world', with slightly imperfect chutes, we tend to experience less drift with cruciform chutes.

Hope that clarifies things... or have I made a confused situation worse? ;-)

V.
 
valley said:
First time poster, long-time maker of parachutes ;-)

The point about chute shape being irrelevant to drift is correct, BUT makes certain assumptions.
The most vital assumption is that the chute and the shroudlines are perfectly symmetrical. Given that very few chutes are truly symmetrical, chute-shape then DOES have an influence.
A 'round' chute (i'm including hexagonal and octagonal chutes in that), rigged assymetrically (even by a tiny amount) will act as an inefficient aerofoil section and tend to glide. A cruciform chute however, vents the airflow differently and will not glide to anywhere near the same extent.
This explains why, although the above posters are absolutely correct with the physics of descent through a moving air column, in the 'real-world', with slightly imperfect chutes, we tend to experience less drift with cruciform chutes.
Click to expand...

I said that the "average drift distance" isn't affected. If the 'chute glides, it will drift more or less on a specific flight, but the average distance a gliding parachute (or a glider) drifts over a number of flights is the same as for any other parachute.

So, while a gliding 'chute might drift more than a non-gliding one, it's just as likely to drift less.

The average distance an X-form and any other design 'chute drifts is the same.

-- Roger
 
Last edited:
valley said:
The point about chute shape being irrelevant to drift is correct, BUT makes certain assumptions.
The most vital assumption is that the chute and the shroudlines are perfectly symmetrical. Given that very few chutes are truly symmetrical, chute-shape then DOES have an influence.
A 'round' chute (i'm including hexagonal and octagonal chutes in that), rigged assymetrically (even by a tiny amount) will act as an inefficient aerofoil section and tend to glide. A cruciform chute however, vents the airflow differently and will not glide to anywhere near the same extent.
This explains why, although the above posters are absolutely correct with the physics of descent through a moving air column, in the 'real-world', with slightly imperfect chutes, we tend to experience less drift with cruciform chutes.

Hope that clarifies things... or have I made a confused situation worse? ;-)

V.
Click to expand...

jadebox said:
I said that the "average drift distance" isn't affected. If the 'chute glides, it will drift more or less on a specific flight, but the average distance a gliding parachute (or a glider) drifts over a number of flights is the same as for any other parachute.

So, while a gliding 'chute might drift more than a non-gliding one, it's just as likely to drift less.

The average distance an X-form and any other design 'chute drifts is the same.

-- Roger
Click to expand...

I would have to agree with that Roger, since the direction the chute "moves" is going to be random on every flight, the average should come out to be zero.

Valley, Just how much drift is induced on a slightly imperfect chutes because of imperfections? Are we talking a few feet of side ways (1:50 slope) movement per 100 feet of drop, or is it more like 20 - 30 feet sideways (1:5 slope)? If it's only a few feet, 20 - 50 feet of extra drift on a 1,000 foot drop is NOT significant in my book. 200-300 feet per 1,000 foot drop is very significant.

Also, isn't the sideways movement of a chute only an issue when the chute comes down perfectly straight with no spinning? If it spins, which almost all chutes do, the movement should be in a corkscrew pattern and the overall effect should be minimal. I would think the slightly imperfect chute would be more likely to spin then a symmetrical "round" chute.

Also, with the slightly imperfect chutes, when they rock back and forth as many chutes do, isn't the "forward" motion of the chute parallel to the rocking motion and as it is going back and forth, isn't it zig-zagging down? Again this would tend to cancel out any sideways motion from a slightly imperfect chute.

I guess my point is that in the 'real world', doesn't the slightly imperfect chute's sideways motion (unless is it a significant amount) have little or no effect on most recoveries because of other factors like spin or rocking? This gets us back to the statement that there really isn't any difference in drift because of chute shape.
 
Last edited:
Handeman said:
Also, isn't the sideways movement of a chute only an issue when the chute comes down perfectly straight with no spinning? If it spins, which almost all chutes do, the movement should be in a corkscrew pattern and the overall effect should be minimal.
Click to expand...

Yes, a typical "gliding parachute" is probably going to travel in small circles, so it's drift won't be much different than a non-gliding one that descends at the same rate. A parachute design to glide (like a Ragallo wing or parawing) might take off in a straight line, but it'll be a random direction (unless the 'chute is guided). So, the average drift distance will still be the same as a non-gliding one that descends at the same rate.

-- Roger
 
Got a ton of stuff from efabricsupplier. Looks great. Now as soon as that awesome Janome HD1000 sewing machine shows up and I get enough practice, I'll sew up some chutes, fix my pants, rebuild my old backpack, sew baby clothes... Well, probably not the baby clothes but you never know. The Girl will be 8 months on Monday!
 
kenstarr said:
Got a ton of stuff from efabricsupplier. Looks great. Now as soon as that awesome Janome HD1000 sewing machine shows up and I get enough practice, I'll sew up some chutes, fix my pants, rebuild my old backpack, sew baby clothes... Well, probably not the baby clothes but you never know. The Girl will be 8 months on Monday!
Click to expand...

I was fortunate that my old boss gave me a Pfaff that he wanted to unload. Great machine. Kinda old but still did the job. I hemmed my daughters clothes and mine, made a bunch of things I never could before and now it spits out parachutes. I'm a happy camper on that note.
 

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