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LOOP SPOOL AND GENERATOR DESIGN by Brooks Coleman ******
M988 in open forum :
Re: [AWECS] Challenge: Dynamic length-variable power-transferring
This is the method I have been working on. It is meant as a method to
transfer the mechanical energy from any rotating pulley system to the
ground via and endless loop of variable length. The length of the loop can
be changed while in operation.
I'll post an animation of the device in operation when time permits.
As the main spool (gold elements) rotates, the conveyor belts, which are
geared to the main shaft, travel about 1/2 inch (the line diameter) to
keep the spooled line centered and cancel out the tendency for it to wind
off the ends because of the spiral winding and unwinding.
To pay out line (in blue), the winder/dewinder swing arm assembly (green
elements) rotates counter clockwise (from pictured view). Reverse to take
up line. Line in routed through a hollow shaft with outer roller support
bearings and line will require swivel bearings at 20 foot intervals to
avoid twisting when pay out and take in activation.
Generator (in red) is linked by roller chain to main spool assembly. A
spool diameter of 10 feet and a length of 20 feet should store over 12,000
feet of 1/2 inch line (actually not round, just points on the conveyor
belts. Four belts are pictured but six or eight would be better). This
should give the system the capability to reach several thousand feet of
Ruff CAD files available (missing some structural support details)
PS: This is not the same device I have been mentioning in the past. That
one will be a patented tool available to measure and test all types of
Please copy URL for us when you send a note for this page.
This design is intended to be operational
while winding or unwinding and at any altitude. Depending on the speed of
the wind driven rotation, the unwinding operation may require some braking
of the main spool so that the swing arm can keep up; i.e., if both are
rotating in the same direction at the same speed no line would actually be
This design also makes it possible to operate at any altitude. Note that
the blue "line" in the lower right hand side of the picture is the pulling
element; and the take-up side (blue line at far left) is routed through a
hollow shaft on the left side and through a series of pulleys out to the
"swing arm assembly" and back to the "main spool". The "swing arm
assembly" has a pulley mounted on a track that is servo or gear driven so
that as the swing arm (green element) winds or unwinds it keeps the line
properly placed so as to avoid overlapping or leaving gaps much as a
fishing reel does.
Another item with this design I forgot to mention is
that the actual wind-harvesting element loop will need to be connected via
pulley to this endless loop element which is probably a good thing to do
anyway as winds at different altitudes acting on a system that runs the
full length would be much harder to control. This device is meant only to
transfer the mechanical energy to the ground.
I will add some of the detail views soon to show how each part functions.
Sorry to Brooks for not posting this to JoeF's string
variloop thread earlier, but this is a topic i have worked for several
years now. The finding is that string variloops are a practical AWE power
All you need is a fixed spool that the loop is wound onto over the top of
the spool. As the loop is launched the take-up side of the loop is
passively unwound off the spool. The turbine capstan or bull-wheel is
allowed to roll out the slack return side of the loop as it grows. Once
the loop is fully extended & unwound the turbine then pulls the loop
powering the groundgen capstan or bull-wheel. To retract the process
reverses but the slack side of the loop is now taken up until the loop is
fully wound & landed. Interestingly the loop reverses direction each
session. A detail is that the loop is reverse threaded on the capstans or
bull-wheels each session. One could design to reverse the turbine to
A string loop requires a splice or connector fitting. To add to or hotswap
a loop merely requires adding sections by connecting in. To work on a
moving loop is not that hard, may industrial conveyor systems have
sidetrack capabilities, think of train yard operations as a mega example.
This is how KiteLab's successful KiteMotor 1 variloop is manually handled
& automation seems practical. There are many possible variations in
handling variloops & Brooks approach is also workable. Ideas involving
many always-engaged pulleys do stink, but Dan Parker's idea of using terrain
suspension to hide long side-pulled sections is cool. A single pair of
added split-pulleys suffices & any number of such pulleys can be
completely disengaged for zero added friction during power generation.
[At sites where deep holes are built
to allow water drops, Bob Stuart suggested that few-pulley arrangement
could use the long hole for holding adjustable working endless loop for
tethering an AWECS sky turbine; this has low land footprint and might be
akin to Dan Parker's alternative scheme.]
Two general considerations:
1. loop not-working while let out or hauled in.
2. loop works during variation of let-out skied portion.
[2. loop powers during variation]
"This is a very secondary requirement with
complexity & capital cost penalty-
2. loop powers during variation
Hidden are differences between reel-in & reel-out states. My
recommendation is focus on essential function (for now). A cool trick,
however, is to use the turbine to winch itself down, which happened
spontaneously one time when a wrong splice knot hung in a fairlead."
But the challenge is very distinct for 1.
and 2. operations. Perhaps for 2.
someone will find an efficient solution; such would allow working loop
during skied-loop extending and shortening.
Sorry to DaveS for me not explaining my reasoning more
clearly. I see much advantage to having the loop to be variable length,
as with any AWE system: the goal is to find the wind energy and harvest
it. The best wind energy not always in the same place all the time. I have
several different designs scratched out involving connectible segments,
but for simplicity of automated unmanned operation (MY requirement
for AWE to reach a significant level of operation) the winder arm
was my best bet and easiest to CAD up.