I have always considered the amount of "overhang" to be the measurement from the line attachment point or line pivot to the wrist's centre or the control centre, same as with a bell crank.
(But rarely do I see it measured or mentioned that way.)
So even if you have a straight bar as a handle it will still hang over the pivot point at least the distance of your palm.
Now if you accept this as logical, then surely a zero overhang attachment point is inline with the wrists pivot point?
(So it is amusing to hear discussions about minimising overhang to reduce loads as much as possible.)
Anyone seen or tried the above described theoretical zero overhang handle?
Actually Chris, the exact subjects you bring up were discussed in detail in print in the Feb. and March 1985 issues of Model Aviation Magazine (the official AMA magazine. In addition to covering the wrist hinge point you address as primal in terms of overhang it also addressed the negative aspects Brett mentioned re the negative effects of zero overhang handles. The articles included some simple hand drawn figures and tables showing and/or describing the relationship between overhang and control force inputs necessary to deflect the controls. I'm familiar with these articles because I wrote them and have photo copies in my library.
Somewhere in my articles in the I addressed a personal lesson on the effects of overhang. Several California fliers were at a US Nats when Bob Hunt showed up with a fantastic looking new handle with an inflight neutral adjustment cleverly engineered into it. It was so cool that at least two of us, Gary McClellan and myself bought two of them to try as replacements for our standard Hot Rocks (the handles I had been using since about age eleven). Both Gary and I managed to pull out of our first reverse wingovers with Bob's handles about a half inch too low (on a grass field) with our Nats stunters fortunately with no damage.
There were two items at play in that event. The first that Bob's handles were molded with noticeable down ("natural") bias and, second, the "arms on his handle were approx. three inches long or about three times that of the Hot Rock. I subsequently shortened the overhang to match that of the Hot Rock which improved the input force issue but was unable to accommodate the bias and, as a result, I abandoned the handle--but not the lessons I learned from using it. it was that experience combined with the loss of a brand new Nats bound stunter due to a failed up cable in my modified Bob Baron handle that led me to research better alternatives. That initiative plus caddying Paul Walker's hard point handle at the Shanghai World Champs that led me to "design" (probably an unfair word considering the legends of the stunt event whose minds I picked without their knowledge but also without subsequent recriminations) the Precision Pro Handle that I "marketed" for a couple of years before passing on the rights to Carl Shoup and which is now known as the "Ted" handle and utilized by many fliers with some success around the world.
A final note on overhang that might be of interest to readers. A hands on experiment to experience the effect of more or less overhang would be to construct a fake handle that fits their hand with interchangeable "up" arms of say, zero to six inches, to which can be attached a gallon bottle of water (which weighs about eight pounds if picked up with a normal grip around its handle. Then pick it up sequentially with the longer "up" arms attached and note the increased effort required. (Technically, it must be admitted, not an accurate measure but enounh to convince most of the concept. If skeptical one could connect the bottle to a control line, run it over a mounted pully and back to the handle to get a truer measure.
Chris, you might find the articles of interest and they can be downloaded from the AMA website. I could, if necessary, scan and post them here but have had only modest success with doing so.