Thinking (outside the box) about the subject of capturing wind
energy, cost-effectively - and "in the abstract" so to speak...
It is logical that - first and foremost - a derivative aim of
building the most cost effective wind-energy device would focus on
the design of an apparatus which presents the largest possible
(steerable) surface area to react against the wind vector, while
at the same time using the least amount of structural material.
Duh.
The standard solution of course is the wind turbine where the
frontal area available is pi*r^2 but where, unfortunately, only
the outer third of the blade is actively capturing energy - and
the centrifugal stresses can be severe. The largest turbine ever
built lasted only weeks. In fact the bulk of material used is in
the tower, which is inactive. Thus the high cost per unit output.
The vertical axis mill is a potential improvement over the turbine
in that more of the structural material is utilized, and at lower
stress levels. But is there more?
This was the situation that the ladder-mill attempted to improve
on with wings. Of course it is as yet unproven as a unit, even
though the component parts have been well-studied.
If there was a better or more practical solution than ++wings++
for capturing and using wind energy, we would probably see
evidence of that in nature. There isn't ... but using wings
presents its own unique set of problems - like ... converting lift
into usable energy, but keeping everything relatively stationary.
However, this morning it "dawned on me" coincident with the rising
sun, of course, that since a large wing can be tilted so that it
captures wind energy as both "lift" which is the normal method,
but also in compression (dive-mode) when the wing is tilted in a
slightly different angle, and since the angular difference between
the two is small - less than 30 degrees ... [all of which is
inherent in the modus operandi of the rotating ladder-mill]
...that there may be an improvement over that scheme. And it is
one which can be used on land - so that electricity can be
produced directly. Since computers can control the angle of
wing-against-wind (known as the 'angle of attack') and do it very
rapidly and precisely with stepper motors, then wow! ... an
unexplored option is still out-there (dare I say, "waiting in the
wings"?) and that is to maximize the frequency of 'angle of
attack' changes, and thereby convert the horizontal free energy
vector into a very short vertical vector. It is only possible with
rapid and accurate computer control and perhaps that is why it has
never been imagined before.
That option can be called a 'reciprocating ladder mill' which is
somewhere in between the stationary and the rotating version. From
a distance, one would imagine that the wings will appear to "flap"
since the changes are rapid, perhaps a frequency of every few
seconds -but it is not true avian flaps.
Imagine the strongest possible lightweight tower structure. Here
are some fitted with turbines:
http://www.otherpower.com/otherpower_wind_towers.html
... but you want to avoid the need for guy-wires. Carbon fiber
masts on sail-boats are strong enough on their own, for use
without guy-wires up to about 20 meters, but a stronger solution
for this idea is the triangular cross-section open skeleton tower,
itself made of carbon spars. A single wing can be mounted
permanently of a number of wings-units can be engineered to
elevate up the tower, on command when the wind picks up and to be
lowered for maintenance. Once in place they "lock" and begin the
coordinated 'attack-changes' which will cause the tower to
reciprocate. The tower need not be 'literally' vertical to earth
and can slope at perhaps 20-30 degrees away from the wind.
The idea is to outfit a tower with ladder-mill wings but arrange
the whole device so that the power is extracted from reciprocating
motion of the tower going up-an-down, or nearly so. The tower is
steerable at its base to rapidly face into the wind. IOW there
will be an excursion length of perhaps a few meters and the wings
will appear to be "flapping" as they change the angle of attack at
the bottom and top of each excursion. Springs can be used to
achieve a damping resonance. You do not need an actual "crank"
(other than 'present company' that is) as a single hydraulic
piston attached to the tower at the base will convert the linear
motion into high pressure fluid for use with a small rotary
hydraulic take-off pump and electrical generator - standard
hydraulics.
Well... if this concept does prove-out to "hold water", or air,
then it is the dawning-result of a long fascination with the
Hillerman mystique and glorification of the Navajo - as it was
forthcoming from the sunrise blessing ceremony, replete with corn
pollen ... or at least a gringo substitute...
Jones
