How to draw a two dimensional airfoil using Sketchup and public domain tables

I am a retired guy who has an interest in Radio Controlled airplane modeling. I recently built a hot wire foam cutter. I'd like to cut

template(s) for specific airfoils with it. I have the tables of lofting ( I think that is what it is called) for the specific airfoil.......thus....

NACA 0006

(Stations and ordinates given in per cent of airfoil chord)

x y dy/dx

percent upper curve; lower curve

0.0000 0.0000 ********

0.5000 0.6107 0.5910

0.7500 0.7424 0.4749

1.2500 0.9470 0.3579

2.5000 1.3074 0.2387

5.0000 1.7773 0.1514

7.5000 2.1000 0.1104

10.0000 2.3414 0.0844

15.0000 2.6726 0.0509

20.0000 2.8688 0.0289 and etc. through 100%

L.E. radius = 0.397 percent chord

Seems simple enough..I could draw it out on a tablet easily enough... but I'd like to specify the desired length i.e. 25 mm and...then add the table somehow into Sketchup, and then have the program draw the curve(s). Any help appreciated. thanks Rich

Rich,

Sounds like a fun project!

You can import x,y,z data as SketchUp "guidepoints" by using the "Cloud_V8" plugin.

(See this page):

http://sketchucation.com/pluginstore?pln=Cloud

I took your supplied data, added z-data (all=0.0), and imported into SketchUp, to produce the attached image. Connect the guidepoints with lines, and you've got your root profile curve, or part of it, at least. (I'm assuming those are x,y data points, of course. Am I wrong?)

I've used this method to import similar profiles. If the root and tip profiles are the same, you can do a "push/pull" to extrude the wing to the proper span, then scale the tip profile to a smaller size. If necessary, the tip profile can then be moved fore/aft to the appropriate sweep of the wing.

Did I lose you? If you supply more data/info, I should be able to walk you through it.

Regards,

Taff

Rich,

I used an Excel spreadsheet of NACA 0006 data, in ".csv" format, to import into SketchUp as guidepoints. I rotated the set of guidepoints around the red axis, since they import "flat" on the ground plane.

I connected guidepoints to form a face. This face is then push/pulled to form a "straight" wing. I then scaled the tip profile, and moved it aft a bit.

After you've done it once before, to familiarize yourself with the tools and plugin, it goes pretty quick and easy.

(Oh, yeah, I also used the "weld" plugin, to connect the line segments into a "polyline" curve. This makes a smooth extrusion of the wing, rather than one with visible, unsmoothed line boundaries.)

Any questions?

Taff

NACA_0006.csv

NACA_0006.skp

Yep, you guys have it! I'll mess around more later today. Sounds like one needs various plug-ins to get Sketchup to do a variety of

projects. I'll find and download those two mentioned today.

While was in the shower this morning ( where I do some of my best thinking! )..I thought that I could also just use the graphing

function of any spreadsheet program to do the same thing. Put my data in; set up a formula to use the length variable ( 25mm here ) to produce a column of accurate numbers...... and then just graph that column. Right away, though, I could see that the NACA data isn't linear ( ?).. i.e. the various stations are different distances from one another. Many stations are specified for the first part of the curve, and fewer stations specified as the foil extends its chord / width.

Clearly, though...Sketchup is the better program for my intended use.

Love this. Thanks for your help.

Anyone have a listing of "MUST HAVE" plug-ins ( and download locations) for this kind of work? thanks again Rich

RichG

Non uniform sampling is not a bad thing. Only 2 points required to define a line but more as the curve changes quickly is desired so, more samples early is good for you. The spread sheet graphing should easily handle that and in fact some like Excel have a trend line or mathematical curve fit capability along with a correlation coefficient for the fit as a accuracy measure. Correlation equal to 1 is what you want but will usually not get

There is no such thing as must-have plugins. It depends on your needs.

A good master resource list

http://sites.google.com/site/sketchupsage/resources#TOC-SketchUp-Scripts-Plug-ins-Add-ons

Many notable plugins are liberally promoted throughout the pages on the Sage site based on their relevance to different workflows.

Rich,

As catamountain wrote, desired plugins are a matter of the user's area of interest. Architects will use plugins that are of no use to a mechanical engineer.

That's what makes SketchUp such a versatile program -- you can customize it to your own interests. Check out the resource list URL catamountain provided, as that includes The Ruby Library Depot link, along with several other sites.

I found many of my favorite plugins at The SketchUp Community Forums, where you have to read through the discussions to find the ones that pique your interest. This is the section I monitor:

http://forums.sketchucation.com/viewforum.php?f=180

(Note that, while some of these plugins are in development, they often can't be found anywhere else.)

As long as plugin authors keep providing such powerful add-on tools, SketchUp is unlikely to fall behind the capabilities of comparable 3D competitors.

Taff

Rich,

If you're interested, I generated the airfoil ordinates, using my own Excel spreadsheet (attached.) I just modified it a bit, therefore it doesn't generate the same values I provided earlier (in ".csv" format.)

Right now, it's set up to generate 35 data points for one-half (top) of the complete airfoil profile. You don't have to rely on published data-point tables, as such a spreadsheet can produce them for you. I compared the spreadsheet results with a couple of tables I obtained online, and they produce the same profile.

While the spreadsheet produces a 6% thickness, it is set up to produce other thicknesses. I haven't yet constructed a spreadsheet that includes camber calculations (but may incorporate that later, time permitting.)

Regards,

Taff

Wow...what nice work. I haven't had time to even look at the suggestions from yesterday. A home project has taken priority!.

I've saved the spread sheet and will look at it further in a day or two.

You are a CHAMP. and thanks for your help. I'm just muddling my way through all of this.

I did find time to cut my first Clark Y airfoil from foam today. That template I got off of an image on the net, though. regards, Rich

I love math problems, so I went ahead and incorporated airfoil camber parameters into an Excel spreadsheet (attached.)

I've also posted a resultant model, demonstrating cambered-wing construction, to the 3D Warehouse:

https://3dwarehouse.sketchup.com/model.html?id=6e17d6fe1eccb34df05ef6b6a92076fc

Taff

Taff... THANKS again! You are so far ahead of me on this subject ( and probably most additional subjects) that I cannot believe it.

After I digest and try to understand all that you have done...and apply it to my foam cutting project...I'd like your permission to post

a LINK to your work on some of the R/C aircraft groups that I follow. Would that be OK? regards, Rich

Sure thing, Rich, go ahead.

I searched R/C forums, myself, and found some references to spreadsheets, but any links provided were dead. I never did find a spreadsheet I could use/study, which prompted me to develop my own.

Once I found the formulae, and a means to produce chord-intervals that were "weighted" towards the leading edge, it wasn't terribly difficult. (Using the spreadsheet "COS" function, to "bunch" the x-intervals at the leading edge, was a "eureka" moment, as I was falling asleep.)

I'm hesitant to look into NACA 5-digit calculations. That might be more fun than I'm willing to endure right now!

I'm gratified to hear that the attached spreadsheets are of interest to you (and possibly others.)

Now, for the problem of getting SketchUp to print-out full-size templates....

(Not a trivial task, unfortunately.)

Taff

It seems like Rich may be interested in a DIY CNC https://phlatboyzmobile.ecwid.com/. Forum http://phlatforum.com/xenforo/. [updated 5/8/16]

catamountain,

That DIY CNC foam-cutting machine looks interesting!

I've already got a rotozip & flexible extension (2 of the main components,) so it shouldn't be an expensive prospect for my basement workshop. I'm definitely going to research it further.

Taff

If that tickles your fancy, then how about a DIY laser cutter http://flightsofideas.com/?cat=14 [5/8/16 dead link, Simon Beard developed a SVG export plugin, now on GitHub. 'Recent' update on SketchUcation by TIG.]

There are a lot of innovative SketchUppers out there.

That spreadsheet could be done in Google Docs and shared as a webpage too.

RC modelers may like to be able to share and tweak the data publicly or within a closed group.

I tested the Google-Docs-spreadsheet route yesterday, but it wouldn't display graphs or images(equations) .... Abandoned that prospect.

_______________

Last night, I was continuing my reading about the NACA 4-digit calcs, and found that the last bit of formulae I used are simplifications of the complete NACA equations. The "thickness" is supposed to be offset ninety-degrees from the mean camberline, rather than vertically (ninety-degrees to the horizontal chord.) While it is unlikely to have a visible effect in a SketchUp model, it could possibly affect a "real-world" R/C design.

I've found the correct final equations, and will revise the spreadsheet to incorporate the proper offset orientation. It should be interesting (to me, anyway) to compare the final results, side-by-side.

Taff

Taff, If you say it is OK....then it is OK with me. I await your next SS. Rich

Rich,

( I am humbled by your confidence in me.... )

I completed the spreadsheet, and compared the results with the preceding version.

NOTA BENE: Anyone reading this discussion thread should note that the spreadsheet attached to this particular post is the ONLY complete, correct version. (Unless I find another deficiency, that is!)

As I expected, the leading edge is where the effects are most apparent. (I've attached some SketchUp-export images to demonstrate.) If the camber percentage is low, the differences won't be too great, however, when greater camber percentages are applied, the differences become much more extreme.

Both versions of the cambered spreadsheets use the same camber/median line. Only the upper and lower airfoil surface coordinates required revisions.

Interesting exercise....

Regards,

Taff

I continue to be impressed by your work on this project. When I started out, I was looking for a simple way to do a complex job. I

had no idea how complex the job was, and I fully expected to type in the lofting figures provided in various books to produce a rough approximation of the airfoil in question.

What you've done is investigated; calculated; and produced a far superior worksheet\spreadsheet that does it all. And, it does it

accurately, far more accurately than anything I can even begin to cut.

By now, you know how impressed I AM..

If I pass this on to the R/C family ( many thousands of them! )...is there a location where I can tell them to go to view; use; and then re-copy onto their own computers? i.e. is there a public location to which I can send them?

I'm afraid that if I just post a SS, ( even giving full credit to you, of course)..it will have less meaning than if I can send them to

Google Sketchup-Airfoils or some such address.

regards, and thanks thanks and thanks again. Rich

Rich,

You can send people to the discussion thread...

http://groups.google.com/group/SketchUp3d/browse_thread/thread/68865aa2fc881e30

...or to the 3D Warehouse model...

https://3dwarehouse.sketchup.com/model.html?id=6e17d6fe1eccb34df05ef6b6a92076fc

...since the model page also has a link to this discussion.

__________________

You're right, in that the context of the discussion helps understand the process (i.e.; development & use.)

Taff

OK...before I posted this wonderful tool on the R/C Groups etc. sites..I wanted to print out one example and then resize it into a

number of templates.

As you know, one might choose to use the particular NACA airfoil on small, medium or larger airplanes. That necessitates printing out templates in varying sizes. Or, one could be building a tapered wing, which would require a larger template for the "root" portion of the wing, and a smaller one for the end/tip of the wing.

I first tried to copy the resultant "graph" to move it to MS PAINT so I could re-size it. That didn't work. I did as I normally do...and

that is highlight the "graph" area; hit CONTROL-COPY (even tried going to EDIT and hitting COPY there)..and then open MS PAINT and then use CONTROL-V.. I also tried just hitting PASTE.

I assume that neither operation worked because the "graph" is a result of the calculations..and not a picture by itself??

Then I tried to isolate just the "graph" so that I could print just that portion of the spreadsheet. That didn't work,, probably because

I am unfamiliar with setting " print area commands" in Open Office. ( I do not have Excel, but normally, the free Open Office calculator program will open any XLS spread sheet and allow me to operate as if I had Excel)???

Since whoever might want to use this fine tool will need to "size" their own NACA template...have you any suggestion on how I can get the "graph" onto a program that allows resizing? Perhaps one column of the data could be exported to Sketchcup..then printed from there, in varying sizes.

I wish I knew more about Sketchup so I wouldn't have to waste your valuable time. If moving the data to Sketchup is the practical

solution, then I will have to ask the R/C Group bunch to download and learn something about Sketchup before using the Airfoil XLS

Spreadsheet. ??? If Sketchup is the answer, I'm afraid that I will need some hand-holding on how and what to "move" from the SS to Sketchup and then what to do to produce varying sizes...and finally, to print those results out.

Sheeesh, this is much harder than I envisioned, but valuable, none-the- less

thanks and regards, Rich

You have to go back to the beginning of the discussion, where SketchUp importing was described.

X,Y,Z coordinates can be imported into SketchUp, as long as they've been exported from Excel in the proper file format -- that being ".csv" (common-separated-values.) A "csv" file is simply a text file, and can be edited with Notepad (although I've never had to do so.)

The "Cloud_V6" plugin expects three columns of data, and as many rows as there are data points.

Example contents for 25 airfoil points:

0.00000,0.00000,0.00000

0.00214,0.00085,0.00000

0.00856,0.00339,0.00000

0.01921,0.00750,0.00000

0.03407,0.01305,0.00000

0.05307,0.01982,0.00000

0.07612,0.02755,0.00000

0.10313,0.03593,0.00000

0.13397,0.04462,0.00000

0.16853,0.05321,0.00000

0.20665,0.06131,0.00000

0.24816,0.06847,0.00000

0.29289,0.07426,0.00000

0.34065,0.07824,0.00000

0.39124,0.07996,0.00000

0.44443,0.07956,0.00000

0.50000,0.07778,0.00000

0.55771,0.07447,0.00000

0.61732,0.06951,0.00000

0.67856,0.06276,0.00000

0.74118,0.05413,0.00000

0.80491,0.04357,0.00000

0.86947,0.03102,0.00000

0.93460,0.01649,0.00000

1.00000,0.00000,0.00000

The "Cloud_V6" plugin takes care of the rest. SketchUp guidepoints are produced, as in the attached example.

The only Excel work you need to do is to copy-and-paste x,y data columns to a new blank spreadsheet, then add a z-column. (Cloud_v6 expects 3 columns.)

I copied x(U), y(U) columns, for the upper surface (25 rows.) Copy the x(L),y(L) columns beneath those (an additional 25 rows.) Add a third column of zeros.

Once you have three columns, 50 rows, in the new spreadsheet, "save as..." in "csv" file format.

Once "Cloud_V6" has imported the data points, you can "connect the dots" to produce the boundary for the airfoil profile face.

You can then scale the profile to the desired size, and print-out the template full-scale. If you want a tapered wing, scaling the tip profile to a smaller size is no problem. You can even choose a different NACA profile for the root and tip airfoils, if you want. Again, see the 3D Warehouse model, for two example wings:

https://3dwarehouse.sketchup.com/model.html?id=6e17d6fe1eccb34df05ef6b6a92076fc

So, all you really need is Excel and SketchUp. You're making it harder than need be :)

Taff

Sorry, I modified the spreadsheet for 25 data points (each; upper & lower), instead of 35 datapoints. I hope that didn't confuse...

If you're unfamiliar with Excel copy-paste functions, you need to "copy" the x,y cells, then "paste VALUES" in the new blank spreadsheet. This will paste the numerical formula results, rather than the formulae in the origin (copied) cells. If you just "paste," Excel will copy the formulae -- definitely NOT what you want.

Attached is a resultant ".csv" file (that's "comma-separated-values",) for testing SketchUp "Cloud_V6" import.

NACA_8412.csv

Rich,

I compared my Excel spreadsheet results (for NACA 6412) to the "n6412.dat" file from this site...

http://www.ae.uiuc.edu/m-selig/ads/coord_database.html#N

...and the airfoil profiles fit perfectly!

So, only now, am I definitely confident that I reproduced the NACA formulae correctly!

(It would have been rather embarassing, otherwise, yes?)

I figure that, eventually, someone is going to ask about the NACA 5-digit series airfoils.

To pre-empt the question, I've attached 2 spreadsheets; the one for 4-digit, and another for 5-digit NACA airfoils.

Taff, you are TOO MUCH! --That is a very good thing, I think!! -- I can't even find the time to do the simple copy and paste process

that you recommended, and yet you find the time to create another new SS! What with the Holiday weekend ( in the U.S. ) and visitors today, tomorrow and Sunday...I still don't think I will get around to it before Monday or Tuesday. Sheeesh, you are great.. Thanks, again....Rich

Taff, found some time early this morning to work on the airfoil project. Even using the Open Office SS version of your SS..I am able

to save the columns in csv. The process is different than XLS, but it seems to work .

I also just posted a query about how to get cloud v6 into my version of Sketchup. Once that comes back, I should be able to do a test. Then, I have to learn how to scale and measure in Sketchup and all will be well. Thanks again for your help and regards, Rich

Wow..I may have it. Somehow ( I have to go back and be certain that I can duplicate it) I was able to export the top half csv values to a notepad file. I then, when asked by cloud 6, imported that data into SU. The top half "graph" of the wing airfoil dotted the page

perfectly!!!

I will keep trying to see if I can also get the bottom half of our airfoil to come into SU. If so!!!! I do believe that you've done it!

The export into CSV took more time than the program and the SU processes. Wow again regards, Rich

I think you'll soon see why I consider the "cloud" import plugin to be one of my "absolute necessity" add-ons.

Looking forward to seeing a completed model (or, at least, the wing.)