NX 7.5: Create NACA 0010 Airfoil Using text file coordinates 1

[RealSaladsamurai]

Hello All,

I have searched this topic and find that I am still unclear on how to do this. I am able to retrieve the airfoil geometry from sites such as

http://airfoiltools.com/airfoil/details?airfoil=naca0010-il

from the Dat File section.

Now it is my understanding that the points from the site above actually lie on the airfoil surface. Is there a way to import these points and then fit a curve to them? I tried from within the Sketcher Environment using Insert > Curves > Fit Spline and then used the open file dialog. But that creates a spline using the airfoil coordinates as "poles" and so the curve does not pass through the points. Using the method above, I do not see a "through points" option, so I am sure I am just doing this wrong.

Can anyone offer some guidance on this?

Than you.

 

[cowski]

Insert -> Curve -> Spline... then choose Through Points and Points from File; navigate to your .dat file and press OK. This is done outside of a sketch in the old Spline command; this spline command may not show up in your menus. If it is not there, you can use the command finder and/or customize your menu to get access to it.

The above procedure will create a spline through the points in the file. If you want/need to see the actual point objects, go to Insert -> Datum/Point -> Point set and choose Spline Points, Defining Points. Point objects will be created at the defining points (the points listed in the .dat file).

Starting in NX 8.5 the process will be a little different; you will create the point set from the .dat file directly then fit a curve to the point set.

www.nxjournaling.com

 

[Toost]

One of the methods to import point data (in 7.5 and older versions) to create actual points was/is the way Cowski describes, use the spline thru points -points from file, then create the points as described and finally delete the spline.
Then you can use the points for whatever use, Insert -curve - fit spline.

Regards,
Tomas

 

[RealSaladsamurai]

Hi cowski. This is great. Thank you. I have a couple more questions if you have time. I am still pretty new to all of this, so forgive me if they sound stupid.

1) I have always been under the impression that curves that do not live in SKETCHES are *bad*. I believe that is because they are not "tied" to anything. But since these curves are defined in space by their coordinates, than they would be OK right?

2) I was thinking that if I did want to get the spline into a sketch, I could go into SKETCHER and use Project Curves to get it into the sketch. When I do this, the endpoints of the spline are not constrained (using Dat File below). This confuses me. Shouldn't all of the points be fully defined by their (x,y,z)- coordinates?

3) The NACA Data files are clearly based on using (0,0,0) as their origin. But there will be many (if not all) times when I do not want the leading edge of the airfoil at (0,0,0). I could alter the dat file coordinates (with a lot of work), but there I am sure there is a much better way to do it? I should be able to project the sketch into a sketch and then move/constrain its overall shape to other objects.

Thanks again.



NACA 0010 Dat File

1.0000     0.00105
0.9500     0.00672
0.9000     0.01207
0.8000     0.02187
0.7000     0.03053
0.6000     0.03803
0.5000     0.04412
0.4000     0.04837
0.3000     0.05002
0.2500     0.04952
0.2000     0.04782
0.1500     0.04455
0.1000     0.03902
0.0750     0.03500
0.0500     0.02962
0.0250     0.02178
0.0125     0.01578
0.0000     0.00000
0.0125     -0.01578
0.0250     -0.02178
0.0500     -0.02962
0.0750     -0.03500
0.1000     -0.03902
0.1500     -0.04455
0.2000     -0.04782
0.2500     -0.04952
0.3000     -0.05002
0.4000     -0.04837
0.5000     -0.04412
0.6000     -0.03803
0.7000     -0.03053
0.8000     -0.02187
0.9000     -0.01207
0.9500     -0.00672
1.0000     -0.00105

 

[cowski]

Curves that don't live in sketches are not necessarily "bad". I've worked on complex parts, some of which made extensive use of the sketcher, others didn't use a single sketch; there were "good" and "bad" examples of each. In the end, the sketcher is just a tool. A very good and useful tool, but not the best tool for every situation. The sketcher, in its current state, imposes some of its own restrictions on splines that may limit your freeform models.

I don't recommend projecting the resulting spline into a sketch. The result will be a fixed curve in your sketch, the position of which depends on the position of the original curve. Use the original spline and if you need to move the spline, use the "move object" command.

www.nxjournaling.com

 

[RealSaladsamurai]

Hi cowski

Thanks again for your help. Here is an issue I am encountering: The data file for the NACA airfoil leaves the training edge "open" like at the top of this -> /there is a "gap". In a sketch, I could add an arc that is coincident to the endpoints and tangent to the airfoil. But outside of sketcher, I am not sure how to accomplish this?

 

[cowski]

The easiest way to close that off would be with a bridge curve (Insert -> Curve from Curves -> Bridge...); it will also give you a good deal of control over the shape and continuity of the transition.

www.nxjournaling.com

 

[mathisudar2007]

Hello,

Inside the sketcher you can use the 'Insert > Curve from Curves > Add existing curves'.

This can move the spline into Sketcher environment.

Thanks,

Mathi K

 

[RealSaladsamurai]

Thanks again everyone for helping out on this. I am sure I will have more questions and I appreciate the help so far.

 

[RealSaladsamurai]

Hello all. Thanks again for the great information. Now that I have done this a few times for different airfoils, I am wondering if there is a way I could improve the workflow of this a little bit. Is there a way to put my spline coordinates into a spreadsheet or some other container so that I can create a bunch of different airfoil profiles. Then I could move them to different layers for analysis.

Thanks again for all of your help.