I recently stumbled upon a device which one of my dad’s friends purchased (foolishly in my opinion) to preform the specific function of tying an airplane against something while you hand prop it, and then being able to release it quickly and go once you have started it. I am sure that there are several knots for this. The majority i can think of are related to a simple chain sinnet. Any other examples?
A quick release loop has been published in the Forum by Alan Lee, and I believe the same knot, or something very similar, is also in ABoK. It has a lot of “old and forgotten knots” … like the ABoK#1991 = Weston knot, as I was able to remember only recently ! 
I suppose it depends on the nature of the connection and if it needs to be released under high strain or not, but here a few ideas:
http://notableknotindex.webs.com/slippedbuntline.html (with one option for heavy load release)
http://notableknotindex.webs.com/triggerbend.html (you could make a sling with this one)
http://notableknotindex.webs.com/timberhitch.html (Tumbling Timber Hitch)
http://notableknotindex.webs.com/tumblehitch.html
http://notableknotindex.webs.com/haltersiberian.html
http://notableknotindex.webs.com/sailorhitches.html (if slipped)
http://notableknotindex.webs.com/sheetbend.html (slipped version of sheet bend in a sling configuration)
Have fun.
Oh, sorry, I thought i attached a picture of the device, but apparently it didn’t work. Here is the actual device used. It is not a hitch, and also ideally all of the rope would be retrievable without leaving the airplane (ie, you can pull on the slipped end and retrieve the entire rope.
Your pictures are not improving…
It looks like the device is trying to mimic a dissolvable-from-a-distance bend. So you could tie a sling (rope circle) to capture the two anchor points and then tie the dissolvable bend of your choice with the release element left extra long to extend to your position.
If there is little or no tension involved, a Slipped Sheet Bend will do. If you have a situation where significant tension is involved, a Trigger Bend would work.
I like the Highwayman.
I don’t know if such a class of hitch would be applicable to this thread, based on the info we have thus far, but there are improved alternatives to the highwayman’s hitch:
The situation is only generally indicated by this problem statement;
can you specify the details? E.g., to what is the line attached (both
ends)? What is the desired release action --i.e., later it’s opined that
it might be nice to release (& retrieve cordage, or leave @site?) from
the cockpit (!?). Is the line under tension during release?
One can surmise some candidate solutions, and some end-2-end
joint seems favorable in that (1) it would be the single connection
to release (rather than, say, hitches at both ends), and if it’s made
to close a loop/circle of line, it would bear only half the overall force.
I think that many supposed solutions will not be all so good
if the line’s in tension, as Roo notes. A general tactic of the
knot to be releasable under tension is to have a series of parts
connected where at each connection the force is reduced,
so that the ultimate toggle is under low force and thus
easily released; but one must be chary of possible unintended
lock-ups of the prior connections --things that hold even though
they aren’t supposed to (such as a nipping loop, sheepshank-wise)!
Re the highwayman’s hitch workings, compare that knot (which
got some stern rebuke at rec.knots (?), noting its vulnerability
to failure --partial or complete) to the very similar one at
Roo’s site. In the former, the heavy load is delivered smack
onto the toggle bight (“slip tuck”, a term I use), and not only
will that impede release, but --worse-- it is prone to collapse
this toggle in half and pull it through the supporting “frame”,
with either catastrophic result or a locked hitch that won’t
readily release (which might lead to catastrophe); in the
slightly altered variant shown by Roo, the full load bears
into the frame and only indirectly into the slip-tuck, yielding
better performance. (But I’d a long and unsuccessful time
arguing w/Grog about its merits, over broad conditions, and
admit to its limitations as rope-to-object size gets small (RS/OS+n).)
–dl*
If a really easy release is needed then how about something along the lines of ABOK 1921 but using 2 interlocked bights ie take one bight up through the other and insert the toggle to lock them together? Attach the toggle to the main rope via a piece of thin cord so as not to lose it.
Barry
Thinking along the lines of a tethered toggle, as did Barry, I wonder about the toggle staying in place if the affair should lose tension or have a case of jerking motions.
If one of the sling’s eyes could cinch down on the toggle to impede this inadvertent release and not reduce the ability to be drawn out when needed, it would be a great solution.
SS
So, do you need a knot that explodes off the anchor upon pulling the slipped working end?
Or do you just need a knot that comes undone upon pulling the slipped working end?
What exactly do you mean explodes off the anchor? I think that would be ideal, as i don’t want the rope getting stuck, and just coming undone sounds like it allows more possibility of entanglement. Also, ideally it’d be something simple enough to teach with relative ease.
On an unrelated note, I notice that the device used has three ropes attached. Are there any of these types of knots that use a separate line as the release, but use the other to lines as the functional piece? Do they have any potential benefit?
Just so we don’t waste time, please describe (1) the anchor on the ground, (2) the anchor on the plane/wing, (3) the type of rope, and (4) the relative size of the rope compared to the anchors. I’m sure the answers are obvious to you, but they’re not obvious to me.
We don’t have a rope in the airplane as it stands, so it could be any type of rope. As far as the anchor, I have heard of a trailer hookup on the back of a truck being used, but the intention would be so that you could start the airplane at stops on cross country flights, so the anchor would be whatever is available. All I can say for sure is that the rope will not be stretchy at all, because that would defeat the purpose.
The question remains - what is the attachment point on the aircraft? Surely that’s not going to be dependent on where it is! As far as the rope goes I strongly suggest that you decide on a type and diameter of rope you think suitable and which you have available (or are you hoping that a suitable rope will be around when you land?)
Barry
On the aircraft, I would probably attach one to each main wheel strut. As far as the rope, if that is the case I would probably wind up using some beat up manila or plastic fiber three strand twisted rope, about half an inch in diameter.
I am not sure I understand your situation well, but it reminded me of the issues addressed when mooring and unmooring a boat. The simplest way is to tie a line (on a boat, you don’t say rope unless that is the actual name of the line, ie bell rope) to a cleat, pass it around the mooring (in your case anchor) and then tie it off, preferably to a different cleat. When you are ready to leave, even if the line is under great tension, you simply uncleat one end and pull the line back in.
Since your aircraft probably doesn’t have cleats, you would probably need to alter this, but the principle would remain the same, keep both ends of the line tied within your reach, with a bight passed around or through the anchor. Tie quick releasing knots for both ends, and when you are ready to cast off, just free one side, and pull the line back by the other. The possibility of the line catching on something is minimal because there should be no knots in it. And if it does get stuck, you can untie the other side to abandon the line.
Hope this is applicable. Even if this isn’t, you might want to look up methods of mooring boats because the requirements sound similar. Also, in rock climbing, and canyon(eer)ing in particular, there are many creative ways of building a bomber anchor for the rappel down that can easily be retrieved from the bottom.