On Sat, 02 Jul 2005 00:32:29 -0700, Brian Cleverly wrote:

Evan Gatehouse wrote:
Brian Cleverly wrote:

I used this prog years ago and now that I need to use it again I find
its not on my system anymore.

Every link I've tried to NACA4GEN comes back with page not found
error...

Seems Harold has moved.

Does anyone have a working link to Harold's Home Page or NACA4GEN ?

TIA,

Brian C


Try Profil (Profili?) - it's an Italian foil generation program that is
much more user friendly, offers DXF export to export to your favourite
CAD program, etc. Also allows you to fine tune a foil if you're smarter
than I am...

Evan Gatehouse

Thanks Evan.

I tried it and it does far more than I need.

For just profiling a rudder NACA4GEN is super easy to use (even tho it
is a DOS prog). Select profile #, enter chord and voila you have a
co-ordinate list.

Thanks to the other kind sole who mentioned a link for 4GEN.

Brian C

Oh, for people who just want rudders, there is a simple equation to
generate the base NACA0020 data. Other versions are just scaled. For
example, to generate NACA0012, you would just multiply by 12/20.

Anyway, I guess I'll post the equation here for the benefit of those who
might be looking (google and all). I know it took me a long time to find
it. ;-)

y/c = 0.2969 * sqrt(x/c) - 0.1260 * x/c - 0.3516 * (x/c)^2 +
0.2843 * (x/c)^3 - 0.1015 * (x/c)^4

Variables:
c- chord
y- ordinate
x- distance along cord from leading edge

So for NACA0012, just multiply all the y values by 12/20, and for
NACA0006, multiply by 6/20, etc.

The source of this information is NASA Technical Memorandum 4741 which is
titled _Computer Program To Obtain Ordinates for NACA Airfoils_ and was
published in 1996 by NASA.

With a spreadsheet it is pretty easy to lay out any uncambered 4-digit
NACA foil you might be interested in this way.

The memorandum explains how to generate data for just about any NACA foil.

--Mac