Import an airfoil


#1

There is a RhinoScript here that imports a database of coordinate files for many airfoils.

http://wiki.mcneel.com/developer/scriptsamples/airfoil

I used this plug in once, some years ago, in Rhino 4.0. I seems to me it actually drew the requested NACA airfoil at (0,0,0).

In Rhino 5, I can’t seem to make it work. It cannot seem to find the unzipped database of airfoil files. Instead, it seems to be looking at an array of Windows System 32 folders. This is a Win 7 64-bit system.

Anyone have experience with this RhinoScript? Can you tell from the script itself how to use it? I am probably missing something basic. Step 1 or Step 2.

Thank you for your insights.

Michael


#2

It works fine for me on Rhino 64-bit in Windows 7.

I just downloaded it, unzipped it, started Rhino, loaded the script (Tools | RhinoScript | Load…), and ran it (Tools | RhinoScript | Run…).

The first thing it does is give you a dialog box to choose the airfoil file you want to draw. From the included folder full of airfoil files, I chose “naca643418.dat” and here’s what I got:

Once the script draws the airfoil, it is up to you to use Rhino to scale it, translate it, and rotate it to your desired size and location…

David


#3

Many thanks, David. I discovered the problem was that the program had been blocked. I learned this by right clicking the unzipped program and looking at its Properties. Probably blocked by my anti-virus, or possibly by Win7. In any event I unblocked it, still in Properties, and after that it worked immediately.

Works beautifully too. Found an old Gottingen airfoil I needed to recreate a FF model wing from 1937…

Best, Michael


#4

Michael,

Be sure to check the curvature on your airfoil after import. Coordinate
points files are notorious for making lumpy airfoils. You want the
curvature graph to be nice and smooth, not jaggy like this:

(You can add turbulator strips to a smooth airfoil afterward, but
lumpy-jaggy airfoils are just “not right!”)

Better yet, de-construct and re-draw your airfoil after import.
There’s a good write-up and video on the subject here:


However, I recommend using the _Fair command instead of
the _Smooth command as the video suggests. Pay particular
attention to the comments about the trailing edge.

The same blog has a great write-up and video on how to make
cool-looking “sheared” wingtips.

Tailwinds,

David


#5

Many thanks for the link to Sky Greenawalt’s essay on airfoils. I will try his cosine point distribution technique and plug in.

However the downloaded airfoil from the U of I is, unlike Sky’s, already a curve, rather than a collection of short straight lines. And the point count is only 33, not too bad. The curvature graph you suggested shows some problems however, so I will try this and that. A rebuild might help. Best, Michael


(David Cockey) #6

RebuildCrvNonUniform can be very useful as it distributes spans based on curvature.


#7

Hi @mcg
Have you tried this free plugin called SeaHorse:
http://www.food4rhino.com/project/seahorsefoils?ufh#comment-6430
Michael VS


#8

Experimenting with Rebuild non Uniform, thank you. The NACA airfoil plugin looks great. Using a non-NACA airfoil at the moment, but I do use NACA airfoils and will give it a try…Many thanks, Michael


#9

Having not yet found a rhino script that accepts a z-axis value, that’s the question, does anyone know a script that creates the curve in 3d space w/o translate-rotate-scale required?

I’ve been creating curves stored as xyz points and could convert them to 0±1 prefer not as the values are for 3d-print & human readable for size if others need to use them, assume there’s a way.

In other tools it was possible to paste them in manually and that’s fine, didn’t yet find how to, novice.

thx for ideas, tom


(Pascal Golay) #10

Hi Tom - I have to confess I’m too dense to figure out what it is you are asking… can you try again to explain what problem you’re having?

-Pascal


#11

Found that you can paste in the xyz points from the selected text as a new point-fit curve and it instantly displays! … so cool, assuming there’s likely a script to do that from a list of files if not will try after looking for one, novice at python-rhino.


#12

I’m going from xyz points in a text file to create profiles curves from to loft. These are from real drawings not cad so first entry. [Or was that about the 0±1 ? … wings use that format in *.dat files for only x,y for chord on a line through the nose & tail]


#13

Does the NACA airfoil database contain airfoils having “leading edge cuffs” such as the Robertson STOL conversions for light general aviation aircraft such as the Cessna 182?
If so, what is(are) the designation(s)?
f not does anyone know of a source of data for any such leading edge cuff airfoils?

Thank you.
David


#14

Hello All,

I have a licence for Rhino for mac and cannot use the script referred to. I am asking if anyone can give me a link to a rhino 5 file containing a NACA 43012A foil curve.

Kind regards,
Hugo Wansey


#15

You can try the script below for importing Lednicer or Selig format airfoil files - it’s a Python script, so should work on Mac. Not sure if this is what you need, but here it is FWIW.

ImportAirfoilDataV1.py (6.0 KB)

–Mitch


#16

i used a java application called javafoil you may have to install java of course and can run it in the browser or as an application. if you dont get it to work or cant find the download (i could not find it anymore at first glance since he has rebuilt it a bit) and are interested i have the functioning java application somewhere in my data trash.

here another web based solution

here a grasshopper definition its from the grasshopper3d site
and here another grasshopper definition from anonymous

i dont know if any of these spit out your foil, the dat files from the script above which actually work through mitch’s python do not contain that foil as i have seen.


#17

Here it is (rename the file to .dat, can’t upload .dat files here):

NACA 43012A.txt (774 Bytes)

Googled and downloaded from here

Rhino V5 file just in case:
NACA 43012A.3dm (231.8 KB)

–Mitch


#18

actually the files from the script suggested in the beginning also contain that foil, named marske5, they are identical along the points, obviously from the same source but from there the foil is a bit smoother due to the leading edge which is continuous.


#19

Thank you all for your replies. I am working on a manually drafted plan (old) for an Australian aeroplane, the Corby Starlet. The ordinate tables are provided, but as expected, the resultant curves are very dirty. In order to have a go at them, I needed some sort of authoritative reference. So thank you Mitch.