Hi James.
I got part of the way through rewriting a spreadsheet this morning.
I will post it later. With it you can enter a lower pitch, a rotation angle for the lower pitch and a higher pitch. It will spit out similar data as I posted earlier. I think I will add another column that tells you the delta change between the rotation and actual higher pitch so it will be easier to see.
LeoP's F1L flies slow for F1L. The prop is part of the equation, but is certainly not all of it.
Regards.
Mike Kirda
--- In Indoor_Construction_at_yahoogroups.com, James Alderson <aldershine@...> wrote:
>
> Thanks Mike! I really value your input. Thanks for the quick response. "Oversimplication" is okay for now. I can get educated as I go along. I already suspected uniform spars and blade flex were crucial factors. I have one 25" pitch block I got from Jake Palmer that I will use for F1L.
>
> Higher Times!
>
> James Alderson
>
> Sent from my iPhone
>
> On Sep 8, 2013, at 8:19 PM, "mkirda_at_..." <mkirda@...> wrote:
>
> > Here are the numbers.
> >
> > 22.5 26
> > Angle 3.5 Angle
> > 1 74.4 77.9 76.4
> > 2 60.8 64.3 64.2
> > 3 50.0 53.5 54.1
> > 4 41.8 45.3 46.0
> > 5 35.6 39.1 39.6
> > 6 30.8 34.3 34.6
> > 7 27.1 30.6 30.6
> > 7.5 25.5 29.0 28.9
> > 8 24.1 27.6 27.4
> > 9 21.7 25.2 24.7
> > 10 19.7 23.2 22.5
> > 11 18.0 21.5 20.6
> > 12 16.6 20.1 19.0
> >
> > Column one: At each inch station
> > Column 2: 22.5"P helical block
> > Column 3: Same 22.5" blade rotated +3.5 degrees
> > Column 4: 26" helical block
> >
> > Note nearly +2 degrees AoA at 1". Move in a bit and there is a bit of wash-out in the middle of the blade. At around the tip of an F1L prop (7-7.5") there is no difference. Only when you get further out do you see the wash-in again.
> >
> > At the risk of oversimplification, I see someone who has a block that is pretty close in pitch to what they needed, made a blade and mounted it to the spar rotated to the pitch they needed. As you can see, rotating the blade a couple of degrees makes very small differences in AoA over the blade overall.
> >
> > I suspect it will be far more important to have the prop spars with equal torsional rotation when loaded and blades that flex similarly.
> >
> > Regards.
> > Mike Kirda
> >
> >
>
Received on Mon Sep 09 2013 - 07:32:35 CEST