I'm only casually watching this thread and when I saw this link I=20
wondered how long before it showsup here:

<=20
http://techcrunch.com/2014/06/03/kickstarter-simplifies-its-rules-and-lower=
s-the-barrier-for-project-acceptance/>

Kickstarter lowers the barriers to entry and opens up new markets to=20
exploit.
RISC=A9 - "Russel's Investor Sanity Check" comes to mind.  ;-)

Joe W


On 05/30/2014 12:45 AM, RussellMc wrote:
> I posted this to the comments section on the Trinity Kickstarter page.
> (It cost me $2 to become a backer to allow me to do so :-) ).
>
> Graph axis labelling mph -> m/s MAY explain a lot. Or not.
>
>         R
>
> ___________________
>
>
> Summary: The published power curve "breaks the laws of Physics" by a larg=
e
> factor..
>
> The device may work, but nowhere as well as claimed. There may be a small
> but effectively very major error in the graph - MPH shown instead of m/s.
> *IF* this is so the windspeed axis is low by a factor of 2.25. As power
> changes with the CUBE of windspeed the power output would be lower by a
> factor of around 11+ at any given windspeed.
>
> If users are content with a small fraction of the power output claimed (o=
r
> live in a continual howling gale) they may be happy. Otherwise there MUST
> be some disappointed backers.
>
> If you want to check my "bonafides" Google my name and read the
> electronics/power/alternative energy material.
> _____________________________
>
> Details:
>
> ***IF*** the x axis (wind speed) figure was in metres per second (m/s) an=
d
> not MPH then the results would at least be possible. Whether they are
> accurate is tbd.The graph shows 13.5W at 16 mph. Call this 16 m/s or abou=
t
> 36 mph. That's quite a gale and well above what you will get in any real
> world conditions except a strong storm. Ignore that for now. Wind energy
> rises with velocity cubed. At 36 mph you need about 18% efficiency to get
> the claimed output. That is at least conceivable. A good mixed lift/drag =
WT
> will give almost 30% (eg Betz). Trinity is essentially a drag type WT and
> under 20% is expected. SO in a VERY strong wind it may actually make the
> power levels claimed.
> Real world turbines usually achieve rated power at about 10 m/s and "that=
's
> not slow".
> - TSR =3D tip speed ratio =3D speed of blade tips relative to wind. TSR o=
f a WT
> affects its efficiency. A good drag machine approaches TSR =3D 1. A WT wi=
th
> any lift at all will run in the TSR =3D 1 to 2 range. Good modern WTs run=
 at
> TSR's of say 3 to 6 and screaming demons may run at 10:1.
> As a WT's diameter gets smaller the RPM increases for a given TSR (draw a
> picture and look at wind and surface speeds). This is a very small dia WT=
..
> By scaling picture we see it is about 300mm tall and 100 mm diameter.
> Circumference =3D 0.314 metre. At 26 mph =3D 16 m/s and TSR =3D 1 the RPS=
 (revs
> per second) =3D 16/.314 =3D 51 RPS !!!! or 3000 RPM. At TSR =3D2 RPM =3D =
6000.
> Stand clear.


--=20
Joe Wronski
Stillwater Embedded Engineering
www.stillwatereng.net

--=20
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