Agreed and the figures in the table I'm trying to post you match this
equation. However, it is geometric pitch. The effective pitch has an
additional component/vector related to the forward speed and opposing this
is slippage. Good point about allowing for the width of the protractor.
There ought to be an allowance (God knows how much) also for three blades
since the airflow off the blade is encountered and disturbed by the next
after only 120 degrees rotation rather than 180 in a two blade. Opposed to
this are the points made by Colin with which I also agree.
The Martindale Family
29 Jane Circuit
TOORMINA NSW 2452
AUSTRALIA
phone: 61 2 66584767
email: johnj...@chc.net.au
----- Original Message -----
From: "Kenneth B. Jones" <kenbjo...@cinci.rr.com>
To: "KRnet" <kr...@mylist.net>
Sent: Friday, August 20, 2004 9:45 PM
Subject: Re: KR> Blade angles Warpdrive
> John,
>
> The Excel equation for finding the blade angle for a given pitch setting
in
> inches is as follows:
>
> ANGLE = DEGREES(ATAN("pitch in inches"/(PI()*"diameter")))
>
> "pitch in inches" is the desired pitch in inches.
> "diameter" is 2 times the radius at which the angle is measured. Warp
Drive
> says to measure the blade angle with the protractor mounted at the tip.
> However, the Warp Drive protractor actually measures a little back from
the
> tip (when mounted flush with the blade tip), not exactly at the tip.
Based
> on Larry's information, when you mount the protractor at the tip, you are
> measuring at 1/2" back from the tip, thus the need to use 53" rather than
> 54" for "diameter". (This makes sense if the Warp protractor is 1 inch
> wide, angle measurement 1/2" from the tip.)
>
> Based on this diameter adjustment (for the width of the protractor), which
I
> had not previously accounted for, my pitch is 63.5" rather than 64.5" with
a
> diameter of 58". Obviously, my pitch had to be set higher than Larry's
and
> yours because I have a slower engine (rated at 2300 rpm).
>
> I agree with Larry in that the diameter of the prop has no effect on pitch
> (in inches), but the diameter/radius where you are measuring your pitch
> angle does affect the pitch (in inches) calculation.
>
> Ken Jones
> N5834
>
> ----- Original Message -----
> From: "Martindale Family" <johnj...@chc.net.au>
> To: "KRnet" <kr...@mylist.net>
> Sent: Friday, August 20, 2004 6:00 AM
> Subject: Re: KR> Blade angles Warpdrive
>
>
> > Larry
> >
> > Your prop is identical to mine at 3 blades and 54 inches. I'll try to
> email
> > you and Ken the WarpDrive
> > chart in Excel that someone on the list supplied for a 2 blader. Thanks
to
> > that person whose name now eludes me...sorry.
> >
> > John
> >
> > The Martindale Family
> > 29 Jane Circuit
> > TOORMINA NSW 2452
> > AUSTRALIA
> >
> > phone: 61 2 66584767
> > email: johnj...@chc.net.au
> > ----- Original Message -----
> > From: "larry severson" <lar...@socal.rr.com>
> > To: "KRnet" <kr...@mylist.net>
> > Sent: Friday, August 20, 2004 10:06 AM
> > Subject: Re: KR> Blade angles Warpdrive
> >
> >
> > > Pitch is not related to diameter, but it is on a 54 in 3 blade prop on
a
> > > Revmaster 2100D turbo.
> > >
> > > At 07:16 PM 8/19/2004 -0400, you wrote:
> > > >Larry,
> > > >
> > > >Is that based on a 53" diameter prop?
> > > > >
> > > > > I called Warp Drive. They gave me the figure of 18 degrees to get
54
> > > >pitch.
>
>
>
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