Re: Prop Efficiency

From: John Kagan <john_kagan_at_hotmail.com>
Date: Wed, 30 Aug 2006 00:11:13 -0000

--- In Indoor_Construction_at_yahoogroups.com, "markdrela" <drela@...>
wrote:
> If it spends most of its time in the high-pitch condition, then it
> should probably be redesigned for that condition. Right now, it looks
> like you're flying the blades on the edge of stall for most of the
> flight. Increasing the chords and reducing the pitch slightly will
> unstall the blades, which should increase the prop efficiency and
> correspondingly drop the torque required for a given thrust.

When I said that it spend only a little time at its lowest pitch I
meant just the very bottom part of its range. These kinds of VP
mechanisms change pitch continously instead of changing suddenly from
high-pitch to low-pitch. I hope that means it spends only a portion of
the flight completely stalled until the prop starts changing.

At what Cl would you consider the blades stalled?
Received on Tue Aug 29 2006 - 17:15:42 CEST

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