> Paul
>
> Thanks, I'll try to get all of the data to you at once.  Two easy
questions.
> It appeared your props are roughly 9% more efficient than the same size
> comparable Hartswell.  Is that a fair estimate?
>
> Second, what type of material are the props on your Lancair constructed
> from.
>
> Thanks
>
> Doug Fir

Hi, Doug!
   My three-blade was made by Craig Catto; it is fibreglass over a wood
core. As far as efficiency vs Hartzell is concerned, I would guess that
my prop is anywhere from 3% to 9% more efficient in cruise, depending on
the model of Hartzell. That would give 1% to 3% more cruise speed on the
same power. Of course, if we're talking about mine in a CS model, I
would guess it will be as good if not better in takeoff and climb. It is
very important to have the root section of a CS fitted with a glove or
fairing so as not to have a high drag, circular form, projecting into
the free-stream! This also keeps the root section from appearing as
another tip with attendent drop of differential pressure and lift.


Paul Lipps

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