The roof is
alive now. This is my favorite part of the spectrum. There is hardly
a break for the orchestra. The Musicianís Union is having a cow!
Thereís always at least one genny spinning, more often, all three; each
competing for center stage. Strong gusts are frequent and accelerate
the rotors vigorously. This is power!
are howling, working hard, almost non-stop. The short-bladed gennys
spin furiously now, I canít even see the blades. They seem to be
most comfortable at this speed and they perform better than I expect.
The bearing whine has peaked out, but itís hard to say for sure, as it is
overpowered by the rising voice of the wind-howl. They are a little
less likely to lose the wind at this speed but when they do, itís
dramatic. As the sleek body spins out, the rotor rapidly loses
energy and the blades decelerate. Itís eerie, it seems like the
Air-X wind-howl shouts itself to an instantaneous whisper...sound
manifests where there is no sound!
My best guess
is that the human brain, in order to compensate for the abrupt stimulus
change, invents a sound to deal with the void. In any event, the
void doesnít last long for as soon as the unit spins out, its own momentum
carries it around in a full circle smacking it right back into the wind.
instantly responds and accelerates wildly and the music continues.
Watching, listening, feeling the Air-Xís action, I imagine a sleek,
high-spirited Arabian running at a full gallop . . . head down, mane
plastered back, firing across a meadow with her large black eyes ablaze
with fury. Sheís running for no other reason than
she smells the wind, and because thatís what sheís bred to do.
the southwest side, the big green Mallard gets a five-foot armful of air
and responds to the challenge. The previous sewing machine hum
breaks off and transforms seamlessly into a growl. Now the air
pushing through the blades sounds like the fan on a big American-made,
early 70ís, V-8 Cadillac with 10 times more air flow passing through.
Smooth, powerful, surprisingly responsive, it feels like he has power to
Power output is fine in this
regime. The Air-Xís are pumping out a little over 300 watts each when
steady. Thatís feeding in 25 amps or so per unit.
The Mallard, the big green
Cadillac, still lags behind at around 15 amps at best. Odd, because it
just sounds so powerful!
hear many different opinions from folks about the viability of a small
wind farm. In discussing it, sometimes I have to deal with
irrational fears like helicoptering the roof off or the fear that it will
attract bats (I donít know where that one came from). Other concerns
are more realistic: like lightning strikes or potential EMF interference,
etc. Most of the time the discussion boils down to: ďhow much power
do you get from those things?Ē
To put things in perspective, weíre not talking about huge
amounts of power here. The Air-Xís, under the right (but rare)
conditions, will over-power
and produce a maximum of 550 watts each, the Mallard is rated at 800 watts
and may actually put out more. Combined, the power output is way shy
of 2 kw. But, the wind doesnít blow constantly and when it does it is a
single wind generator or a small wind farm is a great way to get started
in the energy production arena. Depending on the setup, this could
easily power a single room with lights, a modest amount of computer time,
TV and a few other goodies in turn. A single room powered only from
alternative energy sources while the rest of the house is still grid tied
not only works to reduce the monthly bill, but also begins the mental and
lifestyle adjustment toward conservation that is crucial to the successful
deployment of a non-fossil fuel or nuclear based society.
fire now! Thereís a big whopping difference in the energy available in the
wind from 25 to 35 mph.
itself is howling now and the Air-Xís howl right back at it not giving an
inch except when they get thrown out of the stream. A lot is going
on inside the gennyís at this speed. Itís like the brain telling the
body, ďEat any more of that double chocolate fudge cake and Iíll make sure
you regret it!Ē I donít always listen, neither do the Air-Xís.
principle, the Air-Xís max out at around 28 mph and their brains, the
micro-controllers, attempt to slow the rotor down. Output power, as
a consequence gets throttled back. But the blades are furious.
As fast as todayís electronic feedback circuitry is, it canít always keep
up with the wind, and with a good strong gust, the blades often accelerate
way past the pre-programmed shut-down speed. I n addition, the body has
difficulty in maintaining a stable heading in the fierce winds and it
oscillates slightly about its vertical axis as it gets buffeted by the
turbulent slipstream on the downside of the foil. You can see it
happen as it wiggles and shudders, occasionally letting go and spinning
right out of the wind with a howling sigh. In this wind regime, I
start to get tense. I canít tell if itís excitement or anxiety -
they seem sometimes to be one and the same.
upper end, the Air-Xís are wild. I feel the dawn of a strange
uneasiness about to unfold. Now, they are running like a
thoroughbred, ears pinned back, nostrils distended as if snorting the
smoke from an unseen fire. The Air-Xís are fighting to hold their
space in the wind. The dual howls combine to produce a soundtrack
that could easily accompany the climax of a Hollywood thriller-chiller.
Intensity builds and builds, the excitement is almost too much to handle,
and with one last furious gust of air... just as Jack Nicholson breaks the
window and is about to say ďHeeeereís Johnny!", just as the east side
Air-X aligns it self back in the wind... just as...no, no, a thousand
first time you hear a carbon-fiber composite blade go into a flutter state
youíll get goose-bumps. All over! Itís like a door being
unexpectedly slammed right in your face. It only occurs for a brief
few seconds and usually in a sequence of two or three blasts separated by
a second or so.
were kids, we used to shove balloons into the rear spokes of our bicycle
and peddle like Satan himself was chasing us. If you can recall that
auditory delight and multiply it a hundred, you have some idea what
flutter sounds like.
onset, the quick shift from a fast moving aria to the auditory chaos of
flutter, makes this a most objectionable sound. You can bet this
will wake you up. It may even resurrect the recent dead. For
the brief second or two that it lives, it imparts a sense of
self-destruction. But not to fear: Flutter was actually a
designed-in safety feature of early Air-Xís to limit the rotational speed
of the unit. It does a marvelous job at hauling down the speed of
the rotor, but at the cost of a highly unpleasant auditory experience.