All due respect to pilots, but wtf is that?
It is a series of half hitches / nipping loops (1), a safe, secure, simple way of tying up or down anything ( airplanes included).
I prefer to protect my airplane from the elements, by putting it inside a box… 
http://storrick.cnc.net/VerticalDevicesPage/Ascender/KnotPages/KnotHitchSeries.html
And it looks like the first half hitch has been reinforced by taking the working end back over the hitch. Seems a clumsy way of doing this even if it does hold.
The general argument for the Versatackle does include its continually adjustable nature to equalize things, but it doesn't stop there. It also takes less effort to get more tension, and doesn't require any real dexterity or expert skill to prevent the loss of your peak heaving tension.
I agree - the versatackle is a great system but it seems that pilots are trying to avoid applying tension. The rope in the video I saw using a trucker’s hitch was not pulled very taut - the TH was used simply as a way to secure the rope not to apply tension (http://www.youtube.com/watch?v=1qinEa2PN7A). If there should be a degree of tension the versatackle would be an excellent choice.
Barry
I think that this is a very difficult question to answer - and it would be answered someday, one way or the other, only by detailed experiments. Do we really reinforce a half hitch/nipping loop, by taking the working end over/through the hitch/loop another time ? Does a double nipping loop hold better than two single ones ? Or does the internal friction that is “wasted”, so to speak, within the two turns, diminishes the nipping power of the half hitch/nipping loop, instead of reinforcing it ? Why one has to spread the friction along a longer segment, making a second turn, if the Amontons second law of friction is valid in this scale ? And is friction coefficient a constant of each material, independent of the geometry of the loading ? (1) It is said that physicists’ best kept secret is their deep ignorance about the phenomenon of friction…
- Static Friction Coefficient Is Not a Material Constant, Phys. Rev. Lett. 106, 254301 (2011)
O. Ben-David and J. Fineberg,
Kd8eeh’s pictures are the way most seem to tie their planes down. I watched a bunch of you tube videos last night and quite a few follow that basic structure and design. There was a guy who used the Trucker’s Hitch in one video and quite frankly, that was the best option IMO. The only thing different he did was to keep the Trucker Hitch relatively loose, no cranking down was done. In this form, the TH performs exactly what the plane’s pilot wants in the tie down scenario.
One thing I’ve learned on this forum is that if you ask a knot question, you’ll get ten different answers and they’re generally correct. There’s more than one way to skin the ole cat and knots prove that to the highest degree. Heck, two half hitches and a somewhat loosened taut line at the other end would work perfectly for an airplane tiedown. A loosened Trucker Hitch works, the Versatackle works, Gleipner would work too, lots of options.
quote knot4u
All due respect to pilots, but wtf is that?
so, i think you can plainly see why i don’t like the way pilots tie down their airplanes. with any luck, i’ll be able to actually teach pilots how to tie a trucker’s hitch, but i have little faith they will learn it well. a versitackle, being a few steps more complicated, would be even harder to teach a pilot, as most of them are already incapable of higher knotting. also, to tie a good trucker hitch, i need a good loop to teach, that is easy to learn and even if they fail miserable tying it, it will still be secure. any ideas?
so, i got around to trying to teach my parents (who are pilots) a trucker’s hitch. i have absolutely no idea what it is. however, they got an in line figure 8 mostly right, and is seems to be pretty secure even when tied horribly wrong. i will try some other ideas for loops, but they can only learn so many knots so fast. as far as the other half of this mess, hopefuly i can teach them at least two half hitches. they seem to really like slipping the final loop. also, i found that in the past, one of them has been in groups where they tied down their airplanes with a slippery hitch. so, it’d be really great if someone could figure out something better to teach them.
Taking into account that you are looking for the simplest rather than necessarily the best solution I would try a simple overhand knot noose - this should be easy to undo as the tension is not great. Using a more permanent loop is fine except that the rope will always rub against the same part of the loop potentially damaging it over time. There are better solutions but I would avoid eg the bellringer’s knot (single or double) simply because of the lack of tension. If you’re going to use a slipped half hitch then use a normal half hitch first and slip a second one. This video which I referred to in an earlier post is at least better than most - http://www.youtube.com/watch?v=1qinEa2PN7A - and shows how to tie an overhand noose.
Barry
Hi Sweeney and X1,
My own opinion is that,during the making of the solution shown by kd8eeh, the"doubling"of the first Half hitch in this way makes effectively sense, since its use prevents,while the tail is tensioned to make the second Half hitch, the risk of the capsizing of the first, having it to support he alone all the load that is applied at that time.I think that the way to achieve the Bowline shown here, is helpful to understand how easily this can happen during the construction of the tie-down solution in question:
http://daveroot.netau.net/Knots/Knots_SingleLoops.htm#Bowline (Method #2)
In this thread linked above by knot4u, there is shown a similar doubling of the Half hitch (later identified by dfred as Abok #1854(perhaps one of the worst drawings by Ashley)):
http://igkt.net/sm/index.php?topic=4044.msg24177#msg24177
Bye!
P.S.Hey X1, beautiful your airplane!Maybe I too,can afford this,I’ll do a little thought ..and I think I can afford to buy even the box where to keep it, it would be a shame to leave it at the mercy of the elements! 
In a “series of Half hitches”, only the last one is a genuine, proper half hitch. All the others are nipping loops, because both their legs are loaded - just as the nipping loop of the common bowline, the Water bowline, the ABoK#160-161, and the Sheepshank. Of course, if one insists to “see” a half hitch in the bowline, he can baptize every nipping loop a “half hitch”, he will discover a relation between the bowline and the Sheet bend, and he will keep repeating the mistake of Ashley during the next millenium.
Now, my point is that “two Half hitches” ( i.e., one nipping loop and one half hitch ) are better than a doubled one - and four “Half hitches” ( i.e., three nipping loops and one half hitch ) are better than two doubled ones ( i.e., one double nipping loop and one doubled half hitch, like the one shown in the picture of kd8eeh )
One may ask : Why then we use double nipping loops, and doubled half hitches ? I believe that this has to do with other things - we do not use them because they nip the penetrating segment more forcefully, but because they form a longer "tube’, so this penetrating segment is aligned better - and being aligned better, it is nipped by the next nipping loop / half hitch better ( as in the ABoK#1854-1857 you are referring to.)
There may also be some other reasons : In the Gleipnir, for example, it is beneficial to use a double, or even a triple nipping loop, so the “tube” formed by the multiple coils will be sufficiently long to encircle two twisted penetrating segments/tails - two segments/tails that make half a turn around each other, in the form of a double helix. This enhances the friction in between those two segments, not between each one of those two segments and the coils of the nipping loop…
Of course, this is only a theory, that was initiated by the shock of the Gleipnir : the unexpected effectiveness of the nipping loop, without the help of any collar. I hope that somebody will someday test the gripping power of the single, double and triple nipping loops, and settle this issue once for all.
The video provided by Sweeney is about the easiest way to tie a Trucker Hitch.
To me, it looks easier than the example knots you provided that you say pilots use. The guy in that video explains the whole thing clearly in one minute, and the video is not too short either. As Sweeney said, an airplane tie-down is an application where the Overhand Noose in a Trucker Hitch is acceptable because the user is not cranking down hard to generate high tension.
I otherwise do not like an Overhand Noose in a Trucker Hitch because of its tendency to bind up under high tension. Also, a slip loop at that location is less secure than a fixed loop.
Hi X1,
Yes,OK,but talking about the(practice)contingency regarding of when someone runs(moment after moment) the knot of we’re talking about,in my opinion , one runs(of course, unaware of better solutions) this"doubling "of the(first) Half hitch because maybe someone merely asked himself:"How can I prevent it from tipping over?"Because, I agree with what you write, but until will not run another Half hitch during the execution of the knot(moment after moment), the last executed at that point will be a half hitch, and not a nipping loop, this also applies especially for the first, that is not "closed "(remains a no tightened loop)like the others which follow,and that, again, in the contingency of the moment, is what holds all the load that one decide (or find himself) to apply before it is realized the second.
Drop a few periods please. That’s difficult to read.
are you using swipe?
Noope ! The last knot would be a Half hitch, iff it will remain the last, and only during the time it remains the last - iff it will remain tied around the penetrating main line without any further involvement of its tail. If we are going to tie another, second half hitch after/below this first one, around the same line, we have to use the tail of the first as standing end of the second, so this tail will not remain a tail any more… Moreover, to tie this second hitch, in a way that the first ex-half hitch ( and now nipping loop) and the second half hitch work in tandem, and grip the main line together, the ex-tail of the first ( and now standing end of the second ) should be loaded - otherwise the second half hitch will be just a loose bight wrapped around the line…There is no point to call a bight around the main line “a half hitch”, if both its legs are unloaded !
There is nothing strange about a knot being something at one point, and being transformed onto something else later on. At a given instance, there is only one proper half hitch in a " series of half hitches", the last one. The others are nipping loops. It does not matter what they were before this instance - now they are nipping loops, because both their ends are loaded - and this series of nipping loops is closed by a half hitch.
When we see a segment of a rope, we can not see, but we can know if it is tensioned or not - and we should call it with its proper name.
There are also some indications/signs that can reveal its true character. A proper half hitch is able to absorb the tensile forces acting on its loaded end, because one part of it is “riding” on another part - and this other part, that is squeezed underneath the “riding” part, in between the “riding turn” and the penetrating main line, can not slip. At a nipping loop, the two legs can be crossed, but none of them absorbs the 100% of the tensile forces acting on the other leg - both are tensioned, and the direct consequence of this bilateral tension is the shrinking of the diameter of the loop and the nipping of the penetrating main line.
Hi X1,
But(even if my above words seem to contradict) I totally agree with all this!(Indeed, perhaps one could talk if even the last performs the function of a Half hitch in the structure as is presented ..)and I do not discuss that, looking at the finished structure shown by kd8eeh, the “doubling” of the first Half hitch(shape)appears to be superfluous;my speech,in the end, was a conjecture about the practical reason because of which it is however made during the construction of this structure.So,you’re right, because I would have been more specific, I would have to speak not of “Half Hitch”, but of"Half hitch in shape but not in function" ,given that it is pulled also by the tail, and not only by the SPart;but I think that it is precisely for this reason that, being the first, is in danger of tipping over when it is pulled by the tail,so maybe someone has thought:“let’s avoid this risk!”,then maybe decided to apply this “doubling”.
In short, the gist of my argument is this:a single Half hitch (tied around a ring or pole)is likely to tip over if it is pulled by the tail before it is tight around the object.
Bye!
P.S.I apologize to everyone for not writing well my previous post (and many other posts I’ve written), unfortunately my writing in English is based on Google translator and it is not always easy for me to express myself in an appropriate manner, and therefore not I have nothing else to say except thank you all for your patience!
Something that has been overlooked in this thread is that aircraft sit on an undercarriage that, with varying degrees of stiffness, allow a huge range of movement. Apart from making sure there is no slack, it is almost irrelevant how much tension is put on the rope because the plane will always be able to bounce on its tyres.
Certified conventional aircraft have to be able to withstand a landing (without damage and at maximum weight) at a 400 ft / minute descent rate. This is the equivalent of a free fall drop of 4 metres (12’) - not something you actually want to experience.
What this means is you will probably pull the wings off long before you completely compress the undercarriage.
Also too much tension, even with the plane at rest, can cause damage due to temperature variation. This affects not just the pressure in the tyres but in some aircraft the pressure in the oleo struts that make up the landing gear.
So all the tension that is needed can easily be applied with one hand and any sort of hitch or loop. Therefore the most important consideration is the knot?s resistance to jerking loads.
I have never had any problems with a bowline and a round turn and two half hitches.
Compression of the landing gear and pretension of the rope immensely helps absorb energy. The energy such a pretensioned elastic system absorbs corresponds to the area under the Force (y) versus displacement (x) curve.
When you have pretension, the curve starts out higher, and can immediately absorb energy that otherwise would be accumulated into dangerous kinetic energy.
When you don’t have pretension, the area under the curve starts out very small and can’t absorb as much energy as quickly. With slack, the energy absorption rate is zero for the entire range of the slack and really accumulates dangerous kinetic energy.
Try punching yourself:
- With your right fist held tightly against your stomach with no gap.
- With your right fist held lightly against your stomach with no gap.
- With a one or two inch gap between your fist and your stomach (if you dare).
The landing gear and your tiedown should be a fairly elastic system such that changes due to temperature cause minimal changes in force. Having an elastic aspect to the system also prevents force spikes due deflection, while pretension helps absorb large amounts of energy quickly.
I’d hate to see more people loosely tying down their loads or even leaving slack (! :o) as a result of this thread. The state of affairs in load binding is already so poor nowadays that I hate following people on the highways with tied down loads.
This discussion is losing sight of fundamental things : what is needed
for the aircraft. We’ve read aircraft-official recommendations for having
some small amount of slack in the tie-downs, lest they result in some
damage to the structure. Now, apparently we don’t know how this comes
to be (the damage).
We’ve also see some official suggestions for tie-down material,
which amounts mostly to using a synthetic line to avoid rotting
and to have what is regarded as adequate strength (of about 3_000#).
Roo I think goes wrong (& I) in thinking that slack will lead
much increased impacts : I’ll now surmise that the wing(s)
won’t rise so quickly as to be shocked on coming taught with
the lines, but that they have some overall resistance to slow
the rise; and that this amount of movement and involvement
of the entire wing is what is wanted BEFORE the line tension
figures significantly!? --my conjecture. (Which then leans
hard on how “1 inch” & “some” can be universally correct
across various aircraft --not to mention tie-down material?!)
As I’ve stated previously, it still seems a problem to recommend
a specific slack amount (“1 inch”, or similar) and yet not to specify
the nature of the line (“static”, low-elongation, moderate- to
high-elongation). I surmise that the plot of forces upon given
windage and various lines will look different, and maybe could
be modeled by keeping the line constant but varying the slack
distance or pre-tension amounts. But the so-far-seen official
recommendations don’t include all of these factors. (E.g., that
an elastic, laid-nylon line would not put too much stress on
the wing on the initial rise but then come into strength later,
adequately?!)
Gordon’s Knotting-in-the-Wild observations area awaited; but we
can keep in mind those of my own re cleat hitching, and what sort
of mess of that I found (which is admittedly a task affecting mostly
ease of doing/undoing, not of attachment security). Already, from
some of the on-line sources we’ve seen exposed above, we can
see different methods used.
–dl*
Slack likely won’t be a problem in low to moderate wind conditions. I’m concerned about high wind or hurricane conditions where there is a sudden onset of a high energy gust. That energy has to go somewhere. Some of it will be taken by the decompression of the landing gear (more precisely an increase in potential energy [mgh]), but any energy in excess of this will be converted into kinetic energy in the plane.
By the way, I remember seeing a similar 1 inch rule in some transport manual, but 1 inch of slack wasn’t called for. Rather, they would gauge pretension in the wire rope by making sure the line couldn’t deflect sideways more than 1 inch under 200 lbs of force (like plucking a harp).