Imagine if a 30 metre rope was chained on to your ankle at one end and at the other end it was tied to a helicopter and in order to prevent yourself from being dragged into the air when the helicopter took off you had 30 seconds to tie the rope to a steel pole using a traditional scouts knot that would hold strong enough to stop yourself being dragged into the air and snap the rope?
What type of knot would you have to do?
This might explain my question better
Anyone seen or heard of the infamous downtown Beijing skyscraper helicopter chase between escaping criminals in a private single blade helicopter and PLAAF pilots flying a twin blade helicopter?
It’s full on how dangerous this helicopter chase is, the escaping criminals fly at high speed dodging high-rise buildings and the PLAAF helicopter try to follow weaving inbetween skyscrapers.
The escaping criminals often chain a child at the ankle with a 30-40 metre rope connected to the door of the single blade helicopter. The poor unfortunate child gets dragged through the air
Which leads to my original question
Imagine if you were the child in that situation, a 30 metre rope was chained on to your ankle at one end and at the other end it was tied to a helicopter and in order to prevent yourself from being dragged into the air when the helicopter took off you had 30 seconds to tie the rope to a steel pole using a traditional scouts knot that would hold strong enough to stop yourself being dragged into the air and snap the rope? What type of knot would you have to do?
A kid really did this back in the early nineties. Pretty brave yeah
Assuming you’re not talking about a lengthwise pull along the pole, here are some options:
https://notableknotindex.webs.com/midspan.html
(second diagram)
https://notableknotindex.webs.com/timberhitch.html
(second diagram)
What do you mean by a length wise pull along the pole??
From your suggestions I think the second diagram looks like the right one
The thing is the rope was tied to a industrial hand rail like this one
But you have to picture a knot tied around two horizontal iron poles
If you look closely at the second diagram on the Timber Hitch page, the rope is not shown between the two lines, indicating that the rope is passing behind a single object.
By “lengthwise pull”, I mean the the load of the rope would be pulling down the long axis of the rail or pipe and would need to grip it. But this does not seem to be a concern for your proposed scenario.
Problem: Pulling along/lengthwise on pole is strongest for not bending pole, but weakest for locking hitch
vs. more right angle across pull is best to lock hitch to pole, but most likely to bend pole
full tool chain set must be considered.
(for across pulls would consider hitch to pole low as possible, and pulling backwards against pull high as possible)
.
Ashley reports correctly, that ‘lengthwise pull’/parallel along a host rail/spar etc. is WORST angle to pull rope at.
While rope pulling at right angle is most proper.
.
Thus chapter_21 HITCHES TO SPAR AND RAIL (RIGHT-ANGLE PULL) opens with HH variants, then trusty Timber.
then chapter_22 HITCHES TO MASTS, RIGGING, AND CABLE (LENGTHWISE PULL)
calls foul loudly against Timber etc. pulled lengthwise to host mount/rail
and precedes with HH to make 'Killick '(named earlier w/several spellings)
“To withstand a lengthwise pull without slipping is about the most
that can be asked of a hitch. Great care must be exercised in tying
the following series of knots, and the impossible must not be expected,
particularly on a wet and varnished spar, or on a polished brass
fireman’s pole” -chapter_22 1st opening lines of pre-ramble.
.Other notations show they’d treat slick masts with dry ashes, or even lay line onto spar with varnish still tacky
but best was slit open innertube wrapped to host mount pole first.
.
A single 180degree arc on opposing side of host mount than imposed load pull
is simplest ‘single bearing’ of resistance , and should get simplest inline angle/single dimension of pull /right angle only.
double 180degree arcs on opposing side of host mount than imposed load pull
give more complex ‘double bearing’ of resistance for more complex pulls of not single dimension (if needed)
(also on a small host mount of more intensely compacted frictions, can spread the wear out more evenly)
In any linear /focused mechanix, 90 degrees from best angle is worst angle of push/pull
(besides perhaps backwards directionally reversed pull)
.
Double (or more) bearing, also gives a load side arc, the 3 (or more) 180arcs combined
now more have the tools to form proper structural lines that MAY resist the ‘errant’ lengthwise pull(s)
.
Asserting this by preceding HH (as pass thru /not termination of force) is also a kind of direction converter to me for this.
.
In scenario helicopter pull straight over pole is worst angle, better as 'copter drifts away from this axis.
would try for some kind of 4 tuck/8 turn prusik in bight around pole,
but would want to seize bight to a bolt head/ platform rise etc. to kill any creep etc.
If comes off seize /stop, continue to hold bight pulling away from pole hard and hope to jam at end of pole decoration/flag/other deformation
(but pole may be tapered, making worser scenario yet..)
.
Good day Boku.
Odd scenario to be in.
But, if I were to be in that situation, without a knife (never), I would grab as much of the rope and while using it doubled, wrap as much of it around the pole as tightly as possible. Then just tie as many tight half hitches (using the doubled rope still) as I could in the time left.
I believe that as the load quickly increased, the rope would break. Hopefully…
SS
Well, reminds me of trying to cut some substantial rope
with a knife, and, um, I think more than 30sec.s elapsed
whilst I was hacking away … !
What size rope isn’t mentioned, but we must be thinking
it’s smaller than about half-inch diameter, and the pole
perhaps a strong 2" diameter or so?
Now, which way would you do this wrapping?
I.e., coil upwards (getting a rolling hitch sort of loading),
or coil downwards (for a ProhGrip/Klemheist/Chinese-finger-trap
gripping)?! Ah, wouldn’t one be wanting to have just read
some good comparison testing on this point !!!
(In my recall, I think I’ve seen things done both ways
fail to hold; but the coil-AWAY (lower) method seems
to be more sure.
One could wrap a bight --well, that’s more or less given–
intending to tie off the bight end to the SPart so that it’s
all loaded (no wasted, just-along-for-journey twin wraps).
Same, pretty much. I would have been tempted to use what the river rescue people call the No Knot: just wrap it plenty of times and then secure the end. If I understand the scenario correctly I would wrap upwards, and then return down to hitch below
/P?r
Yeah, my thoughts would be to use something like pipe hitch-like using the rope doubled. And Very Fast !
A knot that almost suggests itself as useful in the situation you describe is the “Folded-line Stoppered Clove Hitch” described at
https://igkt.net/sm/index.php?topic=5873.msg39699#msg39699
It takes about ten seconds to tie even if you’re a bit out of practice. So maybe, before you tie the line to the railing, you might have time to tie an overhand knot in the line in order to weaken it by perhaps 40 percent. You can tie this knot by making a coil in the line and simply walk through the coil.
I hope you’ll never find yourself in such a situation, but now you know how to get out of it.
What a lovely little thought challenge. I like it particularly because it forces us to address the elephant in the room that all knot tyers tend to try to ignore, namely that all knots weaken their cordage.
This little exercise requires us to a) firmly secure ourselves to the railing, and b) arrange for the break to be on the helicopter side of the hitch (although any break in, before or after the hitch will effectively disengage me from the helicopter.
I am reminded of my father’s ability to snap Sisal baler twine in his hand. This classical ‘hairy string’, the stuff of my childhood, could easily support the weight of an adult, yet could just as easily be snapped in the hand with a single away snap of the fists, while it would attempt to cut your hand in two if only a steadily increasing load was applied. The trick was to focus a single hard snap (shock load) into the two interlocked (single diameter) bytes held in the palm of the hand.
So, which do I go for first? Little point in fashioning a weak spot, if it meant I ended up dangling from a seriously weakened rope. Therefore, I need to go for a fixing first.
I don’t know how much force a helicopter can muster, but lets presume we have been tethered to the chopper by a length of the now ubiquitous 8mm Polly prop nom breaking strain ca 2,000lb.
My goto fixing for speed, simplicity and ‘get-it-rightidness’ would be six turns around the anchor rail. even assuming a modest coefficient of friction of say 0.4, this would give me a force magnification factor of ca 3 million - way more than enough for me to be able to hold the 2,000lb load needed to straight pull break the rope. Even if I only managed to wrap three turns on before the chopper took off, I would still have a magnification factor of ca 2,000 meaning I would only need to exert over a 1lb anchor force in order to beat the rope strength.
It’s when you are standing there though, heroically holding back the helicopter with just one hand, that you notice the bolts fixing the anchor start to fly out. Then you ponder on the wisdom of deciding not to throw that OH on the byte into the rope first…
AH, that idea of not only securing but weakening
the line escaped me --good show!
Yes, some quickly done wraps,
tied off,
then an “EDK-backed-EDK” knot to weaken the line
–AND TO BREAK, not capsize into plain line (hence
the 2nd, back-up knot!).
And we should note how much easier any of this
is to do while gleefully responding to a WWWeb post
than having the whirring helo blades and imminent
do-or-die moment nigh --though that can really
focus the mind and spur action,
just hope it’s wise/good action.
AFTER we decide whether if the snap of line
against the pole makes a sound and so it’s ring-loading.
In this situation I would think that I would use a bag knot (ABOK 1244) or a ground-line hitch (ABOK 1245). I favor the former, but the latter has its name going for it. 
JP