3D Printing Design/Product Idea: LPR chute detangler

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

neil_w

OpenRocketeer
TRF Supporter
Joined
Jul 14, 2015
Messages
16,704
Reaction score
11,547
Location
Northern NJ
If this has been done before I haven't seen it. After pondering it for a while I decided that there was zero chance I could do it myself, so I'm throwing the idea out there if anyone wants to give it a go.

The idea is: a little piece that holds the shroud lines of a typical hexagonal LPR (or MPR, I guess) parachute in a de-tangled state. Hex parachutes are usually connected up like this:
1686275084118.png
Each shroud line connects to two adjacent vertices of the chute, in a generally symmetric fashion. When you attach the ends of the shroud line through a loop, though, they invariably come out a bit tangled. It's unavoidable with this type of shroud line connection.

My idea here is a very small printed piece that attached at or near the end of the shroud lines to cleanly arrange them. I have thought of about 20 ways to do this so far, but have no idea which is best or which would even work at all. There are two basic varieties that I can think of:
1) pieces where you actually attach the shroud lines. Then, somehow, the piece must be attached to a snap swivel or nose cone eyelet or whatever. Here's one very rough example (again, there are many ways to do this):
1686275373582.png
The shroud lines come from above, loop over the hook at the bottom, and route through the grooves on the side. Another piece would be required to lock everything into position, and then some means of attaching the whole thing to a loop.

2) Something where you attach the parachute directly to the snap swivel/eyelet as before, but the piece inserts just above it to route the shroud lines cleanly.
If something like this existed I would put one in every single rocket I own. The tangle of shroud lines on the parachutes drives me absolutely batty, despite the fact that I rarely have deployment problems.

So that's the idea. There are some challenges here but I feel like they're solvable... by someone that knows what they're doing. :)
 
To avoid the tangles, change how you attach the lines to the corners. Rather than adjacent corners for all, start with one pair, then move out to the next corner left and right, then the next left and right, and so on until you get to the final adjacent pair on the far side. Pick up the lines and they all lie parallel.
 
I did something like that with a piece of dowling for my L3 rocket. I sawed grooves in the outside of the dowling, ran the shroud lines through them, then taped the beejeebers out of it to hold them in.

I think you have a good idea, but think about maybe putting a "cap" over it to hold the lines on, maybe your eyebolt can go through the center and hold it all together.
 
Interesting idea. I can't wait to hear how well it works.
 
To avoid the tangles, change how you attach the lines to the corners. Rather than adjacent corners for all, start with one pair, then move out to the next corner left and right, then the next left and right, and so on until you get to the final adjacent pair on the far side. Pick up the lines and they all lie parallel.
Yes, that is possible, although I haven't tried it yet. Doesn't help with commercially-purchased nylon chutes, however, which seem to always come hooked up as shown in the first post.
I think you have a good idea, but think about maybe putting a "cap" over it to hold the lines on, maybe your eyebolt can go through the center and hold it all together.
Yes, something like that would be very good. It'll take some fiddling and iteration to get it right. As I said above, I do not have a printer and am unable to pursue this. Am still hoping someone else might pick it up and run with it.
 
Ooh, ooh, I think I've got it. Maybe. If you're using an eye bolt (not screw eye) then I think this should work. Replace the eye bolt with a piece of threaded rod and a stop nut. Take a second nut and file a groove into each face. Make sure to leave no burrs, sharp edges, etc. Lay each shroud line into a groove and tack it down with a drop of CA, looping around the center hole.
1697648728644.png
When this nut is tightened against the stop nut, with the lines between them, the the lines are held after the CA gives way (which it will, sooner or later).

Alternatively, if you use a dab of epoxy instead of CA then you probably don't need to loop the lines around the hole.
1697649094773.png
 
Back
Top