The loop appears to be viable. Appears.
Maybe it is, maybe not. At some level obviously it could work, as no physical laws are violated and it has been demonstrated by Dave S. (among others?).
I've found there are often unforseen aspects that manifest operating machines.

A few aspects I can think of to check for here:
1. Centrifugal force: The cable itself may fly off the wheel by centrifugal force at some speed.

2. level of tension vs RPM vs power: more power can be transmitted at higher speeds of tether loop travel, just as a driveshaft can transmit more power at higher RPM, being limited by max torque. In the case of the loop, power trtansmitted is limited by tension that may break the cable, or pull the assembly downward.

3. How much power can you make at what linear speed of looping cable before the tension in the line is pulling the lifting body back to Earth? Lower speeds for a give level of power will entail higher tension levels. then again higher speeds many be too fast to be practical i.e. mach numbers and centrifugal force around capstans and bullwheels.

4. Tether contacts itself in opposing directions: could be friction and abrasion problems here, or even lockup of the machine if it gets caught or twisted together.

5. Upward pull: It seems that power transmitted by upward tension will be limited by how hard the machine can pull upward (downwind). I am not sure about this but I get the feeling (seems mathematically unavoidable) even for my own machines that a certain amount of the energy will be "used up" by just providing the energy to keep the thing in the air. As in a helicopter need fuel to stay aloft. Unless you are relying totally on helium etc., for support against gravity, it would seem that the continuous energy required to support the structure against gravity must be subtracted from the usable energy output.
Anyway a few simple engineering calculations could tell a lot about the tension/centrifugal force aspects.
I found for example in building regular wind turbines that even a chain drive is challenged at small turbine RPMs by centrifugal force due to low diameter sprockets and high RPM.
I would recommend someone mathematically model a complete hypothetical looping tension power transmission system and check for these realities.
Calculate: tether loop tension on both the upwind and downwind traveling parts of the loop. Add that combined tension to the amount of thrust/lift needed to keep the system aloft. Calculate how much power can be transmitted by said tether at said speed. Calculate how a tether would respond to centrifugal force around pulleys at that speed and tension level. Calculate, using the coeffiecient of friction, whether the cable can even remain in contact wioth the capstan/bullwheel at that speed/tension level, considering centrifugal force. You may find out you are trying to "puch a rope" in the sense that the max power transmissable by this method may be severely limited. I haven't run any such numbers but that is my 2 cents on this otherwise seemingly workable concept.

Else just build them and show the numbers of the working systems.
With my own machines, they are so close to what is already known that little math or calculation is needed to design and build them, as I can just look at other machines and power levels and size everything appropriately, even magnets and airgaps etc. I manufacture and sell great alternators but have never done a flux calculation or simulation in my life - just shoot from the hip and after a few trials and errors, hit the target. But this looping thing would seem to be in a position now to benefit from such simple and straightforward engineering calculations as I mention. Maybe someone has already done that.

At least the concept is straightforward enough that it should be possible to build decent-sized models without too much head-scratching, though it is always 1000 times easier to talk than to build.
Doug Selsam
http://www.USWINDLABS.com
~<brawk!

Two more cents in a quick sketch.

Wow I didn't realize you had all the details worked out.
OK then so what's stopping your from building them?
Why not build a 1 kW demo? If all basic questions have been satisfactorily answered, it seems like a weekend project to me.
What component are you missing? Can I be of any assistance?
:)
Doug S.

scale to thousands of meters. No hard structure comes close. Etc, etc. Dozens of old posts elaborate these themes.
AM
speed of looping cable before the tension in the line is pulling the lifting body back to Earth? Lower speeds for a give level of power will entail higher tension levels. then again higher speeds many be too fast to be practical i.e. mach numbers and centrifugal force around capstans and bullwheels.
gravity, it would seem that the continuous energy required to support the structure against gravity must be subtracted from the usable energy output.
level. Calculate, using the coeffiecient of friction, whether the cable can even remain in contact wioth the capstan/bullwheel at that speed/tension level, considering centrifugal force. You may find out you are trying to "puch a rope" in the sense that the max power transmissable by this method may be severely limited. I haven't run any such numbers but that is my 2 cents on this otherwise seemingly workable concept.
thing would seem to be in a position now to benefit from such simple and straightforward engineering calculations as I mention. Maybe someone has already done that.
allows the lifting kite to be feathered into strong
we are really here for.
[AWECS] Loop transmission of mechanical energy

1) What is a COTS? voltage? RPM? Do we get one in advance so we can tune our system to it?
2) What if someone has an alternate method that doesn't involve the looping tether?
3) 1 lb. seems a bit small to get any significant power - larger size?

Wow I was thinking you were still pursuing the "wind turbine hangs from a kite or balloon" with a looping tether. Sorry about that.
That's why I said it could be a weekend project:
You have kites already - and lots of them and other people you know with many more, so lifting something up is not a problem.
Wind turbine rotors are available off-the-shelf, or very lightweight high performance rotors can be cut from raw lumber easily in a couple of hours or less.
Generators are ubiquitous in many forms.
You have line that can be looped.
Then you mount a generator in gimbals of a bicycle fork, or,
The rear wheel of an electric bike can have the tire removed and the rim used as a pulley, and you might even stick it on the front fork for directional flexibility of leave it on the back and clamp the front fork for mounting. Or fabricate from scratch. Even lumber works if you don't weld.
But I guess from what you're saying, you are now thinking the old laddermill idea from the 1970's is the way to go. I still like the laddermill too and have a lot more thoughts about it as time goes on.
Good luck!
:)
Doug S.
PS I would be wary of the impetus for decisions at each point.
Typically the pie-in-sky scenario of crackpot would-be inventors goes something like this:
1) identify promising nascent technology;
2) realize the next step is to build one;
3) identify reasons why this could not quite be built yet;
4) return to the all-talk format.
What I see are mainly step 3: identifying reasons why one can't be built yet:
1) not high enough for jet stream on first sttempt (gee ya think?)
2) too many regulations (and more can always be found)
The cure: The real step 3:
If your idea works for real, it will work to some degree at any scale within reason and at any height. Build it at any scale and get it going so you see what goes wrong and build the next one etc....
Current definition of HAWE: High Altitude Wind Excuses
;)
Join the
National Redundant Excuse Laboratories (NREL)
or
Almost Ready to Produce Another - Excuse (ARPA-E)
Can you say: "wahhhhhhhhhhhhh! " ?