We Were Warned in 1998

[Don Bradner]

On 5/13/2008 at 8:34 PM Dorn Hetzel wrote:

>One good thing about the migration to larger and larger turbine units is
>that as the blade diameter goes up, the RPM goes down.
>
>At some point in that progression, they will probably cease to be much of a
>danger to birds.

Might be a wash. Double the diameter, halve the RPMs, and have a blade tip speed
that is exactly the same.

However I suspect it is the big blades that cause the greatest grief. Consider a
big one around 5 RPM, so a blade goes by (3-bladed) every 4 seconds. Sort of
like a bird flying low across the road where cars are passing every 4 seconds
(and the bird gets hit). They would never consider it if the gap between cars
was a tenth of a second.

Don Bradner
90 PT40 "Blue Thunder"
Posting today by satellite from Wenatchee, WA