Jules wrote:
On Thu, 12 Feb 2009 21:51:03 +0000, Arthur2 wrote:
If instead of blades they had the things you see on some wid speed
measurement devices
that have 3 or more cup shaped receptacles on horizontal bars fixed to a
vertical axis.
The wind can hit these assemblies at any angle it chooses with no difference
to the efficiency
of the 'machine'.

I suspect it's a bit harder to 'feather' those sorts of designs so they
don't self-destruct during really high winds. Other than that though, not
sure...

Related note: aren't the "egg beater" vertical turbines supposed to be
more efficient than horizontal-axis ones, and will also (like the
anemometer) work happily with wind blowing from any direction?


I don't believe the Darius rotor is more efficient, but the
multi-directionality is an advantage. Another attraction is that in
principle it could be cheaper to build. Numerous attempts have been
made to design a practical Darius rotor, but none has taken off (so to
speak). One major problem with the design is that the blades experience
oscillating loads as they rotate - on half the cycle to force is towards
the axis, on the other half it is away from it. This tends to cause
fatigue failures in the blades. (I speak with feeling: I am still a
shareholder in a more-or-less defunct company that was started with the
aim of developing a commercially viable Darius rotor.)