Scratch Built Chute???

[lakeroadster]

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...

 

[cwbullet]

I do. Start small and test a lot. Going big first can be a recipe for disaster.

 

[Gary Byrum]

Made a lot of them. Many different ways. What particular part of the process are you needing to know?

 

[lakeroadster]

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.

 

[Gary Byrum]

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

 

[jlabrasca]

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.

 

[rharshberger]

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

 

[GlenP]

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?

 

[jqavins]

I was wondering if an urban tumbleweed would do.

 

[lakeroadster]

Sorry.. misfire.

 

[lakeroadster]

Thanks for all the tips here fella's... started building my own mylar chute... details here starting with post #149 https://www.rocketryforum.com/threa...alpha-build-thread.145115/page-8#post-1798838

 

[lakeroadster]

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,

 

[kuririn]

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,

Nope, as a matter of fact some manufacturers provide Kevlar thread for shroud lines in their kits.

 

[K'Tesh]

At least two manufacturers use Coats & Clark Button and Carpet Thread... I suspect that Estes does as well.

 

[lakeroadster]

At least two manufacturers use Coats & Clark Button and Carpet Thread... I suspect that Estes does as well.

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.

 

[jlabrasca]

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.

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.

 

[Micromeister]

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.

 

[hcmbanjo]

At least two manufacturers use Coats & Clark Button and Carpet Thread... I suspect that Estes does as well.

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.

 

[hcmbanjo]

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.

Try using wire cutters on the Kevlar.

 

[jlabrasca]

Try using wire cutters on the Kevlar.

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?

 

[lakeroadster]

I've been using a sharp Exacto knife... works great.

 

[Gary Byrum]

I take a grip clamp and clamp a single edge razor blade in. Sharp side facing upward. Then bring the string down over the sharp end from both sides with both hands. Cuts like a breeze.

 

[hcmbanjo]

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?

Here's the style wire cutter I use. These are heavier duty, about 6 1/2" long.

 

[lakeroadster]

Just noticed I neglected to update this thread with the finished chute....

I ended up using 50# kevlar for the shroud lines and used a fishing line swivel.

 

[kuririn]

Looks good. Does it pack more compactly than the Top Flight chute?

 

[lakeroadster]

Does it pack more compactly than the Top Flight chute?

Night and day difference.

Biggest reason the TRF nylon chute packs bulky is the hem doubles the thickness around the perimeter of the chute.

 

[Gary Byrum]

Night and day difference.

Biggest reason the TRF nylon chute packs bulky is the hem doubles the thickness around the perimeter of the chute.

That's why I burn mine off. No hems, packs pretty compact.

 

[jqavins]

Its... a PITA to cut.

I've used, interchangeably, an Xacto or my pocket knife. As long as the blade is good and sharp* then the thread is cut with no difficulty and no special technique. Cut it like any other string.

* I can shave with my pocket knife when it's freshly sharpened, which it's not at the moment. Today it can barely open an envelope. And I don't have access to my stones.

 

[lakeroadster]

I did some testing today on the mylar chute and found a problem. The shroud lines easily cut through the mylar / shipping tape..... just a slight tug zippered right through.

After revising the design to utilize Scotch #8959 Bi-Directional Filament Packaging Tape I tested the arrangement by adding weight, about 1 lb each test, until the test chute failed.

Maximum load was 21.7 lbs, using 4 shroud lines.

Assuming a Safety Factor of 1.5 that means the Hexagnal Chute, using 6 shroud lines, should be good for a drag load of about 20 lbs, with the upgraded reinforcement to the Scotch #8959 Bi-Directional Filament Packaging Tape.

The other option would be to run the lines all the way over the chute... as shown in the Apogee video here:

Still on the fence as to which way I'll go. The more I think about the continuous lines, the more it makes sense.

 

[JStarStar]

I cut homemade chutes out of polyethylene plastic tablecloths available in almost any color at the dollar stores.
Use carpet thread for shroud lines and blank adhesive labels as tape tabs.
One tablecloth ($1.00) can make you a dozen chutes, and the scraps are good for streamers.
Loop the shroud lines through snap swivels and switch 'em out flight by flight as needed.