Scratch Built Chute???

Discussion in 'Low Power Rocketry (LPR)' started by lakeroadster, Jun 21, 2018.

  1. Jun 21, 2018 #1

    lakeroadster

    lakeroadster

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    Instead of buying a lightweight chute for my scratch build X-Wing, why not build one?

    Anybody here build their own chutes?

    Any Tech Tips?

    Thanks in advance...
     
  2. Jun 21, 2018 #2

    cwbullet

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    I do. Start small and test a lot. Going big first can be a recipe for disaster.
     
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  3. Jun 21, 2018 #3

    Gary Byrum

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    Made a lot of them. Many different ways. What particular part of the process are you needing to know?
     
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  4. Jun 21, 2018 #4

    lakeroadster

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    Just a 12" chute. Needs to be light weight as it is fitting in a BT-50 tube, with only 4" of usable tube length. I have a 12" chute made from 1.7 ounce nylon material and it is too bulky. Rocket weight is about 3.9 ounces.

    Some type of high visibility material would be ideal.

    Why 12" for a 4 ounce rocket? It launches from 8,200 feet.
     
  5. Jun 21, 2018 #5

    Gary Byrum

    Gary Byrum

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    Here a page from the site where I get mine. You can get .5 oz breathable or non breathable if you need it that thin. I usually burn a square (for instance 12" x 12") then burn off the corners with a hard square card/board (I prefer a 3.5 sq") This makes a type of X chute. I bought a wood burning iron to burn and seal the edges. No stitching required. They say you can use a soldering iron but that just wasn't hot enough for me. Your burning surface needs to be flat, smooth and not hard as a rock. It helps if it will give a little. 1/6" Poster board should suffice. I usually have to keep it clamped while burning the edges so it wont slip.

    https://ripstopbytheroll.com/collections/breathable-nylon-fabric
     
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  6. Jun 21, 2018 #6

    jlabrasca

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    Emergency blanket mylar. It is strong, and packs small. It is not, however, flameproof. You will still need wadding or dog barf in the tube. I use kevlar thread or nylon kite string for shroud lines.

    Some folks report good success using the barbell-style tyvek jewelry price tags as shroud line anchors. I've gotten good results with Avery self adhesive disc labels or just transparent office tape.

    Tim Van Milligan has a video on stringing a parachute over the top of the spill hole. I like this technique, insurance against shredding the chute in the case of a too-short or too-long delay.

     
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  7. Jun 21, 2018 #7

    rharshberger

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    I do as well, so far up to 16gores and 60" diameter. If using ripstop nylon from local fabric stores it will be the heavier weight ripstop, for lighter weights Ripstop by the Roll is a good source, but for the lightest weights kite making suppliers are the best (I have found so far) like https://www.flymarketkites.com/34-oz-ripstop-nylon/ I have used them before
     
  8. Jun 21, 2018 #8

    GlenP

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    For LPR and <4oz you can get by with a plastic chute, I use a grocery/department store plastic bag, or a hefty garbage can liner. You can tape over the corners before you hole punch for the string, or use those ring-reinforcement rings for hole punched paper. Pretty easy to fold a hex or oct shape. For shroud lines I got some heavy cotton thread, like for carpet/upholstery.

    Here is a 12" chute I made for a 13mm downscale cardstock model, Centuri Bulldog clone, from a Target shopping bag, liked how the colors coordinate, and the Bulldog kind of reminds me of Bulls Eye, the Target mascot dog, you know?
    [​IMG]

    [​IMG]
     
    Last edited: Jun 21, 2018
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  9. Jun 22, 2018 #9

    jqavins

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    I was wondering if an urban tumbleweed would do.
     
  10. Jul 10, 2018 #10

    lakeroadster

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    Sorry.. misfire. :rolleyes:
     
    Last edited: Jul 10, 2018
  11. Jul 10, 2018 #11

    lakeroadster

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  12. Jul 13, 2018 #12

    lakeroadster

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    Any reason 50 lb Kevlar, 0.015 dia thread, is a bad choice for parachute cord on a LPR?

    I have some and since it's much more fire resistant than carpet thread and kite thread, just wondering if there is a good technical reason to not use it.

    Thanks,
     
  13. Jul 13, 2018 #13

    kuririn

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    Nope, as a matter of fact some manufacturers provide Kevlar thread for shroud lines in their kits.
     
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  14. Jul 13, 2018 #14

    K'Tesh

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    At least two manufacturers use Coats & Clark Button and Carpet Thread... I suspect that Estes does as well.
     
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  15. Jul 13, 2018 #15

    lakeroadster

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    I'll check the local crafts place for that... looking at it though from a flammability standpoint, and since recovery hardware space in my X-wing is minimal, my thinking was that the kevlar may be the better choice?

    I had some polished hemp twine and tested it... it's way too flammable. I thought maybe it had been treated with something.
     
  16. Jul 13, 2018 #16

    jlabrasca

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    In low power rockets -- some with with packing volumes as small as that in your X-wing -- I've used braided Dacron kite string, Kevlar thread, some kind of lightweight and flexible cotton string that I had lying around in the shop, even cotton embroidery thread. I've burned holes in more than a few canopies but -- so far -- I've never had a shroud line burn through.

    There just isn't a lot of surface area on the shroud lines to absorb the radiant energy, or to intercept the hot gas/burning powder, of the ejection charge -- and most of that area is going to be folded up inside the canopy when you pack the chute.

    I'd guess that the space blanket mylar from which you cut your canopy will be destroyed by any failure that puts your shroud lines at risk of burning.

    One thing to bear in mind. Rocket parachutes are consumables. With care, and good fortune, they last for many launches, but you should certainly expect to replace the parachute at some point.

    EDIT --

    I don't think I answered the question. There is no reason not to use Kevlar thread, if you've got some handy. I use it to anchor the shock cord to the body in small diameter rockets (where I expect it to be a more-or-less permanent part of the rocket), and have used it for shroud lines. Its expensive and a PITA to cut.
     
    Last edited: Jul 13, 2018
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  17. Jul 16, 2018 at 9:20 PM #17

    Micromeister

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    Lakeroaster: I've been using Kevlar Shocklines and chute/streamer shroud lines since Kevlar was released to the public. It's outstanding HEAT RESISTANT properties make it a great way to extend the life of your rockets recovery system and completely does away with burned off chute shroud lines.
    I've found over the years that 30" of 70 to 90lb Kevlar tied to another 30" of 1/8" oval elastic makes an outstanding Motor mount wrapped Shockcord that generally outlasts the rocket (30-50 flights). if you want to extend the usable life of the rocket beyond that install a 6 to 8" stainless steel 30lb fishing leading around the motor mount with the kevlar/elastic added to this Stainless shock cord anchor. I have some larger MPR rockets with this set up the have more than 70 flights.
     
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  18. Jul 16, 2018 at 11:10 PM #18

    hcmbanjo

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    The shroud lines in the more recent Estes kits are crap, easily broken with a good pull. They aren't using the same button and carpet thread they used to.
     
  19. Jul 16, 2018 at 11:13 PM #19

    hcmbanjo

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    Try using wire cutters on the Kevlar.
     
  20. Jul 17, 2018 at 2:27 AM #20

    jlabrasca

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    Thanks. I've actually got a pair of electrician's scissors that do a pretty good job with Kevlar thread. I stand by my comment though. Cutting kevlar thread with straight-blade shears is a frustrating experience (and a really good way to ruin the shears).

    Maybe you could clarify what kind of wire cutters work well on Kevlar?
     

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