OK, I've regrouped... yes the page I was referencing had flaps as options, but I was reading off the correct curves.
I've un-installed and re-downloaded and re-installed JavaFoil... same results.
At RE = 9E6
Maximum Cl
A&VD JavaFoil
NACA 0012 1.6 1.209 25% Low
NACA 4415 1.64 1.882 15% High
I'm a little concerned that I get different numbers than you and here I'm getting different numbers relative to a well established bible in the industry. AND what's really bad... the estimates are conservative in one case and optimistic in another.
Basically, this tells me...
(1) if this is the state of the art for approximate versus real world... its not a very good approximate!
(2) ... and this is just a sampling out of two foils (of the same class of foils)
(3) What if I go to something relatively exotic... like a standard 07 foil. Is it going to be off by 50%... and which way?
(4) Then going way out into left field with the symmetric version... which appears to violate several of the dependencies of the analysis. Namely 3D flow starts (guessing) somewhere around 75% of the chord.
With all these things I'm ticking off, I'm convincing myself that I would need to oversize at least 50% just to account for the fog.
Dennis
From: Dennis Cox <dec720@att.net>
To: harryproa@yahoogroups.com.au
Sent: Sat, August 21, 2010 10:47:36 AM
Subject: Re: [harryproa] My Little Mule - JavaFoil
Hi Rick
Just starting JavaFoil up, changing nothing which defaults to NACA 0012.
Going to the Polar page,
Changing only RE and checking Cd at zero degrees, I get:
RE = 1E6, Cd = 0.00923
RE = 10E6, Cd = 0.01114
What's even stranger, I pulled out my Abbot and Von Doenhoff, p. 462. Put in
RE = 3E6, 6E6 & 9E6
The largest Cl @ (AOA=16) is Cl = 1.6
JavaFoil at the same point is Cl = 1.136
Dennis
From: Rick Willoughby <rickwill@bigpond.net.au>
To: harryproa@yahoogroups.com.au
Sent: Fri, August 20, 2010 11:18:04 PM
Subject: Re: [harryproa] My Little Mule - JavaFoil
Dennis
I checked your section and it was almost identical to what I got despite the fact I used 61 points. You can get variation with the number of points but not so much if the section has gentle curves.
I used smooth finish. I can get what you got by using painted fabric.
Check a NACA0012. It should be around 0.009.
The Javafoil data I got aligns well with the old NACA report I referenced earlier.
Rick
On 21/08/2010, at 11:46 AM, Dennis Cox wrote:
Rick Willoughby
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