Disclaimer: This folder
is a work in progress and is not a
finished treatise nor a guide. This folder is but a place for
exploratory study. Tethering humans in kite systems is a most grave
matter where death and serious injury may too easily be a result of
incomplete engineering or safety practice. Work with experienced tether
and tow people, especially when human life is involved, like in
man-lifting in kite systems, towing manned hang gliders, towing gliders
and sailplanes, parakiting, etc.
(files are being built by interested persons)
In other kite applications magnets are considered in tether
parts for generation.
But it looks like you have the kite hang glider towing safety link
"Tommy" link for the rare-earth option for exploring!
In first blush on the
Tommy Link I am flashing on
mini-soft cover protectors. And variations to consider: slide,
face-to-face, graded plates that tune the G level wanted (magnet
standardized, but facing plate grade for total strength wanted); seems
like an avenue for the dial-a-G-safety-link direction also. Must explore
the Tommy Link!
Parameters and aspects
Recoil protection. Covers with slight overhang.
Dirt clearance. Keep it clean and dry.
Testing could be done just prior to flight.
Slide or face-to-face? Study each.
Cam-break switch for release
Consider pilot-controlled release systems using the Tommy Link
principles. Pull cam breaks tethering.
Age-stamp the assembly. What degrades high-quality magnets?
Fail mode seems to be in the wanted direction: weakening.
Dial-a-strength or G level by various methods. Perhaps graded film
interleave? Perhaps dialed-face area? Perhaps graded face plates?
Calibrated breaking points? Tommy Link might lend itself to
various calibration methods; explore.
No more buying of cord;
no more knots;
different quality control.
Maybe a totally simpler system.
Consider axially magnetized rod magnet with ring magnet; compare
with face holders and the cleaning issue.
Strength of break can be tested easily with weights.
Magnet shape choice could be fine tuned. First look at
standard commercially available products for the assemblies to be
What side would the magnet be? Far toward tug or close-side to
HG? Would it ever matter? The mass of the magnet may be much
larger than the mass of the opposing iron plate; this may lead to
keeping the magnet on the tug side, as recoil at HG-pilot side would
deal with less mass. And maybe pilots in queque could have plates that
give calibration for their personal G needs.
Quick clean at each use. Non-destructive pull test just before use.
Two magnets or just one and a iron-facing plate or tube, etc.,
depending on the final shapes wanted.
Mounting or connecting the magnet to the tether assembly?
Keep items that may be injured by magnetic fields away from the
magnet. Procedure for storing the Tommy Link?
Coloring the Tommy Link assembly with red and magnetism
symbol. Keep away from certain electronic devices. What are the
distances for the caution?
Test the consistency-of-opening of the Tommy Link against the
consistency-of-opening of other safety links. Cycles? Abuse and
then cycles? Dust abuse and cycles? Finger oil?
Dew? Grit? Clear case for seeing dirt. Manual
test. Perhaps strain gauge could be handy for immediate kpre-flight
Note that destruction does not occur upon pull testing; integrity
Life of the Tommy Link?
Game: fishing pole with string with magnet on end of string; players
"fish" for objects that have iron-based receivers on the objects. The
objects are contacted when aim is good. Contact made and the objects may
be reeled into the player. Player pulls hard enough to release the
object. Player gets to keep the object. Do this in reverse for
safety-link for HG towing, perhaps.
Considering an encapsulation that prevents slap contact upon re-mounting
the two parts of the Tommy Link; clean proofing and then re-mount; ease
re-mount; proofing. Then use. An indicator could prove depth reach of
the re-mount. To prevent slap engagement, I envision a peristaltic tube
that slow engagement, but permits full engagement; if the tube of
engagement is clear vinyl then visual confirmation could be made; also,
if a indicator mark was available on the inserting iron, then that would
be nice redundancy; the pull test just before use would be a third
redundancy check. Air-release hole also might be employed might also be
employed here. Wanted: prevent slap join of magnetic working
Pull force can vary significantly as a result of surface conditions.
Magnet-to-magnet gives more hold force than magnet to steel plate.
How to "see" that separation distance is cleanly zero? Or cleanly
holding graded non-magnetic separator that might be used in calibrated
dislocation force? Perhaps test up to 90% and, if passed, then
accept it; thus the hold is there up to the tested amount, at least.