Help with NACA generator......

[epoxyman]

Hate to ask a maybe silly question but can someone help me how to understand the NACA 4 digit point generator's results in terms of x and y coordinates?

http://www.pagendarm.de/trapp/progra...les/NACA4.html

[Flumixt]

I dunno. Not sure just what your question is. First # is X second is Y. The (-) results are for the profile below the x axis.


I reduced the number of points to 18, which is 18 on each side of the foil, copied em to a spread sheet then using brute force did a lot of editing to separate the x and y components since they were both in the same field.

The opposite sides did not come out symetrical since the minimum camber setting is 1 (one). The plots lookt ok.

[jehardiman]

After pressing the "show points" button, the foil offset data is calculated in the window on the right. The total # of offsets is given by the "# points" slider and are ordered along the outline of the shape CCW starting from the first one forward of the trailing edge on the top surface (i.e 100 points will have 49 on the top surface starting from the first one in from the trailing edge, one at the very nose, 49 on the bottom starting from the first after the nose, and one at the trailing edge).

The offsets themselves are given as:
X Y
where X and Y are the decimal % of the cord with the origin 0,0 at the nose. So the X values go from 1.0- at the trailing edge top to 0 at the nose to 1.0 at the trailing edge bottom. The Y values go from 0+ at the trailing edge top to 1/2 thickness at top maximum to 0 at the nose to - 1/2 thickness at bottom maximum to 0 at the trailing edge bottom.

FWIW the applet is nice, but offset data presentation could be better. I was able to get camber to 0 so I don't understand Flumixt's comment.

[Flumixt]

I had the 5 digit series - sorry about that. 4 digit goes to zero.

Still. I didn't see how to separate the coordinates except to copy one at a time or copy all, paste twice and then separate em.

[jehardiman]

Originally Posted by Flumixt

I had the 5 digit series - sorry about that. 4 digit goes to zero.

Still. I didn't see how to separate the coordinates except to copy one at a time or copy all, paste twice and then separate em.

if using excel there is a text to columns option. Paste to a .txt file and then open the .txt file. It will come up as an option.

[epoxyman]

Thanks. I was thrown a little by the fact that the x points are not uniformly separated. But I guess that makes sense so that you get more points in the forward part of the foil.

The other foil generator I found is the NACAGen which is apparently older. The x is in 20 uniform increments so there is too much guesswork in the first 10 percent of the chord.