AIR blades incorporate well the basics for quiet operation at high TSR,
which basics few manufacturers are going to discuss with you, because we all
have our twist (pardon me) on this. Noise from the AIR is primarily from
the blades going into flutter at high tip speed ratios, as relative load is
lost at high wind speeds. Rounded tips could be used to reduce lift, and
probably performance, and delay the onset of flutter to higher wind speeds.
The result would be a machine running quieter more of the time in a given
wind regime.

The same result of delaying the onset of flutter could be accomplished by
attaching a larger alternator. It would not be unreasonable to speculate
that the move from the AIR303 to the AIR403 was a combination of a little
bigger alternator and a better performing airfoil. The effect of the larger
alternator may well dominate resulting in an overall quieter machine.

Sincerely, Elliott Bayly, President
WORLD POWER TECHNOLOGIES, INC
19N Lake Ave
Duluth, MN 55802 USA
Phone: 218-722-1492, Fax: 218-722-0791
Web: www.worldpowertech.com


> -----Original Message-----
> From: Jeff Gilbert [mailto:jeffgilb@...]
> Sent: Wednesday, August 11, 1999 5:46 AM
> To: awea-wind-home@egroups.com
> Subject: [a-w-h] Re: AIR 303 & High Winds
>
>
> Corey,
>
> Check the blade edges for bits left behind from the molding
> process. I have a new AIR 403 demo unit that I am borrowing
> from AWEA, and I noticed that the blades need to be cleaned
> up around the edges. I would expect that this extra scrap
> would make them noisier.
>
> Also, have you noticed the difference in the new 403 blades?
> They look a little thinner (less wide near the tip), and they
> have a squared off blade tip where the 303 blades were more
> rounded. I wonder if these changes were made to help reduce
> noise. Does any one out there know - Elliott?
>
> Jeff Gilbert
> Potomac Region Solar Energy Association
>
>
>
> Windkid1@... wrote:
>
> > Hi everybody,
> >
> > Well, yesterday my AIR 303 was at my doorstep. The machine
> was down for 19
> > days while being sent back to Southwest Windpower in
> Arizona, repaired, and
> > returned back to Minnesota. I was surprised to receive a
> phone call last
> > week asking me what I wanted to do with my turbine. My
> options were to
> > simply repair the machine with standard 303 parts, or to
> upgrade to a set of
> > 403 blades, a 403 regulator and a 403 body at an extra
> charge of $88 I
> > believe. I decided to stick with the 303 parts since it
> still has another 2
> > years of warranty, and I didn't have the 80 some bucks to
> upgrade. Well,
> > when the machine arrived at my place, I immediately opened
> it up (kind of
> > like Christmas!) and noticed that I was given a new set of
> 403 blades, and it
> > looked like I received a new 303 body with my tower clamp
> and alternator
> > attached to it. I haven't gotten to getting it on the
> tower yet, but I took
> > it outside yesterday with the new blades attached and held
> it into the wind.
> > The blades sounded a lot louder than the originals, but it
> always did get
> > noisy while running open circuit. I plan on getting the
> machine back on the
> > tower by this weekend.
> >
> > Corey
> >
> >
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