For tying Kevlar to nosecones and motor blocks / centering rings I use a taught-line hitch (probably because it is the most common knot I use for most things). I also put a dab of wood glue on it if it is in some inaccessible place.
I suck at knots
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I was talking to some other scout leaders a couple of months ago as we were teaching knot tying. There seems to be something about knot tying that needs to "click" for people -- some tacit knowledge or some fundamental understanding -- once that clicks for you knot tying becomes easy. If it does not then it is always confusing.
I am not 100% sure what it is but I think maybe it has something to do with understanding how the rope binds to or holds itself in half-hitches and/or knots. I see kids try to tie knots and they do not seem to notice that the ropes are not oriented in a way that it will be stable -- to me it is obvious that they will simply unwind but they are just going through the motions and not really looking at the loops to see how and when they will lock the rope into the knot.
I am not 100% sure what it is but I think maybe it has something to do with understanding how the rope binds to or holds itself in half-hitches and/or knots. I see kids try to tie knots and they do not seem to notice that the ropes are not oriented in a way that it will be stable -- to me it is obvious that they will simply unwind but they are just going through the motions and not really looking at the loops to see how and when they will lock the rope into the knot.
To attach a shroud line to the parachute (lpr) I use two half hitches. Fast, simple and it does not come loose.
I love the taut line hitch. Adjust the length of sunshade or rainfly guylines WITHOUT one of the little plastic or metal doohickeys, just rope. PFM!
PS, my user name is short for Asst. Scout Master and the troop number my boys were in.
I love the taut line hitch. Adjust the length of sunshade or rainfly guylines WITHOUT one of the little plastic or metal doohickeys, just rope. PFM!
PS, my user name is short for Asst. Scout Master and the troop number my boys were in.
Frankly it looks a little bit difficult to do at small sizes. I'm just going to need to get some thread and practice and see.
I understood "doohickey".
That is very plausible. I generally have good spatial reasoning, but knot proficiency has eluded me, no doubt from lack of effort and practice as much as anything. I would love for it to click at some point.
Taught-line hitch looks complex but basically just a loop around the fixed structure, two wraps of the working end around the long end inside that loop, and finally one half hitch around the long end outside the loop.
Frankly it looks a little bit difficult to do at small sizes. I'm just going to need to get some thread and practice and see.
I understood "doohickey".
That is very plausible. I generally have good spatial reasoning, but knot proficiency has eluded me, no doubt from lack of effort and practice as much as anything. I would love for it to click at some point.
You are basically just looping the working end around the long end of the rope three times -- 2x inside the loop and 1x outside -- and the outside loop needs to be tucked through itself to make a half hitch to hold the knot closed.
I always think of those two as looking a bit like an elephant. Even if it has three ears, it should only have one trunk.
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I am excellent at tying knows [edit: knots. . . Note to self: when making smarty pants comments, pay attention to autocorrect. . . /edit], but only in certain materials. Orange extension cords and water hoses are one of my preferred materials, as I can tie a bunch of knots without any effort at all!
Sandy.
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This blew up fast; I'm up to post #12 and will try to read the rest later. But here's my 2¢.
I use a figure 8 a lot. It's good for most of the situations where one might use a square knot, and two advantages: 1) it is a little bit quicker to tie and B) the line exits the knot in the right direction. What to I mean by that?
(Purple lines are the lines holding something, red lines are the loose ends.) With a square knot, the line tends to want to take a turn at the knot.
(That's grossly exaggerated to illustrate the point. If you get it wrong and tie a granny knot then the four lines are darn nearly at right angles. Despite its reputation as a mistake, even granny has her occasional uses.)
With a figure 8, there's a lot less turning.
(Also an exaggeration; the figure 8 is not perfect in this regard.)
For attaching a small line to a large one, there's a knot called the sheet bend, which is well worth knowing. It's almost the same as a square knot, just one little move different. It has a super simple variant that is less prone to slip, when you need that. It doesn't need one line to be bigger, and might be a good choice for shroud line loops; I'll have to try that one day.
A bowline is good (not the best) for making loops, but it's kind of a PITA if you're not well practiced at it. I use them, but I mess them up about half the time and have to do them over.
I've read here that gluing a knot, while keeping it from slipping out, also weakens it by stiffening bits that ought to be able to flex. That's probably not an issue in the vast majority of LPR applications. Another way is to capture the (or each) loose end with its nearest holding line (and perhaps the entire knot) in a piece of shrink tube. Still, a really slippery material, like, like polypropylene, could even slip out of that.
I use a figure 8 a lot. It's good for most of the situations where one might use a square knot, and two advantages: 1) it is a little bit quicker to tie and B) the line exits the knot in the right direction. What to I mean by that?
(Purple lines are the lines holding something, red lines are the loose ends.) With a square knot, the line tends to want to take a turn at the knot.
(That's grossly exaggerated to illustrate the point. If you get it wrong and tie a granny knot then the four lines are darn nearly at right angles. Despite its reputation as a mistake, even granny has her occasional uses.)
With a figure 8, there's a lot less turning.
(Also an exaggeration; the figure 8 is not perfect in this regard.)
For attaching a small line to a large one, there's a knot called the sheet bend, which is well worth knowing. It's almost the same as a square knot, just one little move different. It has a super simple variant that is less prone to slip, when you need that. It doesn't need one line to be bigger, and might be a good choice for shroud line loops; I'll have to try that one day.
A bowline is good (not the best) for making loops, but it's kind of a PITA if you're not well practiced at it. I use them, but I mess them up about half the time and have to do them over.
I've read here that gluing a knot, while keeping it from slipping out, also weakens it by stiffening bits that ought to be able to flex. That's probably not an issue in the vast majority of LPR applications. Another way is to capture the (or each) loose end with its nearest holding line (and perhaps the entire knot) in a piece of shrink tube. Still, a really slippery material, like, like polypropylene, could even slip out of that.
I think if you extend the shrink tube over the knot that would pretty much anchor it in place. For most applications, of course, that is overkill.
boatgeek
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I came to this hobby from sailing, so I tend to use sailing knots:
Shroud lines to parachutes: either a bowline or two half hitches
Collecting all the shroud lines together: figure 8
Loop in the middle of a shock cord for a chute: alpine butterfly
Joining two lines together: sheet bend (or double sheet bend if the lines seem slippery)
If I want to make a knot permanent, I rub Elmer's school glue over it and pull it tight while it's drying. I don't have data, but I feel like that glue is flexible enough when dried that it doesn't make the hard spot that @jqavins mentions.
Shroud lines to parachutes: either a bowline or two half hitches
Collecting all the shroud lines together: figure 8
Loop in the middle of a shock cord for a chute: alpine butterfly
Joining two lines together: sheet bend (or double sheet bend if the lines seem slippery)
If I want to make a knot permanent, I rub Elmer's school glue over it and pull it tight while it's drying. I don't have data, but I feel like that glue is flexible enough when dried that it doesn't make the hard spot that @jqavins mentions.
The "single bowline on the bight" is a good knot for attachment along an existing shock cord.
Since the six or eight shroud lines are actually three or four droops, I hold them as if one, pass them through a rigid look (nose cone base or one side of a swivel) and make a lark's head.
Single half hitch or figure 8 on a bight. Yeah, I know, but it hasn't made trouble for me yet.
I like the pass through, because it's east to replace that leader. For the loop around the base of the MMT, I settle (again) for the half hitch on a bight, then both the knot and the loose end go back up inside the rocket to hide my shame.
Neil said he sucks, knot bights.
Nyuck, nyuck.
Nyuck, nyuck.
I think, at least for me, it's deeper than that. There are, all too often, important differences between what I see in my mind's eye and what I see in my face's eyes. I have trouble with knots beyond very simple ones, and I can't draw a kitty any better than the average five year old, and I think there's a common deep reason for both weaknesses.
Don't you also put your right hand in and shake it all about?
A piece of string walks into a bar and walks up to the counter.
The bartender says, "Sorry mate, we don't serve pieces of string in here, get lost."
Upset, the piece of string walks out the door. A sudden thought strikes him. He ties himself in a knot and messes his hair up.
He walks back into the bar and approaches the counter. The bartender says, "Oi, aren't you that piece of string from before...?"
"No," says the piece of string, "I'm a frayed knot."
OK but seriously I am challenged at knots too. My biggest problem is remembering them. Then for rocketry purposes my problem is tieing them uniformly. I used to do some fishing and would use bowlines to tie on hooks. Now most of my rocketry knots are in thin kevlar shock cords or thin nylon shroud lines. Neither line holds a know well so I started using the double bowline knot but for some reason recently when I try it the thing just slides open in my hands. I don't know what I'm doing wrong. I've tried the perfection knot and it seems to work but is a little harder to tie. What I need is a knot I can tie easily in thin nylon shroud lines but more importantly I need to be able to tie it to the same length for all 6 shroud lines. I'll worry about it more the next time I need to rebuild a parachute with new shroud lines.
The bartender says, "Sorry mate, we don't serve pieces of string in here, get lost."
Upset, the piece of string walks out the door. A sudden thought strikes him. He ties himself in a knot and messes his hair up.
He walks back into the bar and approaches the counter. The bartender says, "Oi, aren't you that piece of string from before...?"
"No," says the piece of string, "I'm a frayed knot."
OK but seriously I am challenged at knots too. My biggest problem is remembering them. Then for rocketry purposes my problem is tieing them uniformly. I used to do some fishing and would use bowlines to tie on hooks. Now most of my rocketry knots are in thin kevlar shock cords or thin nylon shroud lines. Neither line holds a know well so I started using the double bowline knot but for some reason recently when I try it the thing just slides open in my hands. I don't know what I'm doing wrong. I've tried the perfection knot and it seems to work but is a little harder to tie. What I need is a knot I can tie easily in thin nylon shroud lines but more importantly I need to be able to tie it to the same length for all 6 shroud lines. I'll worry about it more the next time I need to rebuild a parachute with new shroud lines.
That used to be my biggest problem too. My solution was to decide that it's not more important. For little LPR parachutes, a quarter inch difference in shroud lengths won't keep it from bringing the rocket to a safe landing. I just had to curb my perfectionism, and it became no big deal to make them match acceptably.
That's one of many times I've had to relearn that it's easier to be good when you stop trying to be perfect.
When tying the shroud lines to my Angled Invader parachute, I had a devil of a time controlling exactly where the knot ended up and how much extra would be left over (at least, with the non-slip mono knot on that particular thread). Fortunately I found that it tended to average out about the same, and everything ended up pretty even. Even enough, at least.
It does definitely *feel* better when you know exactly where the knot is going to land, but agree that for LPR chutes it's not completely critical. I might swap that one out for a nylon chute anyway.
For loop-in-the-shock-cord, I tried out the Alpine Butterfly Loop:
That is a pretty nifty knot I must say. Very easy and absolutely solid. Worked well in my test piece of Kevlar as well.
Between this one and the non-slip mono I think I'm set for a while.
That is a pretty nifty knot I must say. Very easy and absolutely solid. Worked well in my test piece of Kevlar as well.
Between this one and the non-slip mono I think I'm set for a while.
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