Link to Clark-Y 3d printed airfoil template for hot wire foam

[Charentejohn]

Basically what it says in the title. I had to make printed airfoil sections for a project and thought they would also make a basis for templates.
Allows resizing in the slicer so can do different chords and tapered wings etc. Just a basic shape so you don't have to draw one.
https://www.thingiverse.com/thing:3263570 also has ideas on how to change it. Clark-Y is a popular general airfoil so I'm told.

 

[Merv]

The University of Illinois has thousands of airfoils in their data base. You may find one there.

 

[Charentejohn]

Good link, it mentions all but the http://airfoiltools.com/ site I used. If you check the thingiverse link it says that is the source of my airfoil shape. Interesting the Illinois pages don't include the airfoiltools info. One thing it does include is the incomplete guide https://m-selig.ae.illinois.edu/ads/aircraft.html which has the Clark-y all over it, amazing variety of aircraft use it hence my giving it a go.

I originally used this route to find actual profiles. As an example a while ago I wanted one for a Lysander, look up on the incomplete guide and you get RAF-34, then type this into the search on airfoiltools and you get the details with the .dat files to load into your cad program. It's a wonderful internet world, so much info available.

 

[Merv]

I have had success making airfoil printouts using the data U of I provides, they have plotting points for each airfoil. You can manipulate them to suit your needs. I use Excel and graph the points, changing the shape, thickness and cord, by stretching the graph until it is what I want. Glue the printout on a template stock and cut it out.

I have found foam with the edge covered with foil tape makes a great hotwire template.

 

[b-29er]

If you're trying to simulate NACA airfoils, this program is a lot of help

https://tracfoil.com/airfoils/index.php?page=en_gnaca

You give it a NACA airfoil number, it spits out a coordinate sheet. Use Notepad++ to do a little editing and you can pop this into Autocad LT as a spline, then re-scale.

 

[Charentejohn]

Hi guys, just to clarify I am personally not looking for anything.
Any info you can post here will help me and others but all I did was to post a link to the Clark-Y profile suitable for foam cutting. I have all I need, just passing on info for others.
For me I am happy to just use existing airfoils as there are hundreds of them available. My system, such as it is, is to take the simplest route to do something. So here are my thoughts and what I use and why, with this (all free) you can do the same thing for any airfoil using the links previously posted.

Slicers are great, you can put anything in them and reshape it. I use Cura 3.6 as it has the new 'gyroid' infill option. With this you can load an airfoil .stl and pull it in all directions using the Scaling option (uncheck uniform scaling). You can make it thicker or thinner using by changing the Y axis, or longer shorter by changing the X axis.
You can also make a wing section by increasing the Z axis by a lot. I just tried it and a 200mm chord wing section made 200mm long in the Z axis with gyroid infill at 2% (all you need) 0.6mm walls comes in at 70g, so a 1000mm wing will weigh 350g. (photo attached)
So all you need is an airfoil .stl file and a slicer to make a wing or tail. Haven't tried it but for a tail you could just shrink (Y axis) of a wing airfoil to be thin enough to use.
Slicers are greatly underused I reckon when it comes to manipulating parts.

So how do you get your profile then. Use the incomplete guide to find one you like. Then use Airfoiltools to find the .dat file for it.
Airfoiltools is very straightforward. It has a search where you can put in a name (say Clark) or chord parameters and it will find any that match.
It also has an Airfoilplotter option where you can view an airfoil and then manipulate it, rather than use a slicer. You can then save it for import to Cad. Saves as a txt file but to import just change it in file explorer to .dat and it will work.

I use Freecad which is a cad package and as the name suggests is free. Does all I want to do, has some quirks but excellent support as it is supported by the many people who wrote it. Like any such thing it takes getting used to but will produce most basic shapes by manipulating cube or cylinder models, or draw from scratch, part design workbench is the one I use most. Loads of tutorials online.
So to import an airfoil does need a sequence of events.
You will need the airfoil-create-V21 macro downloaded to a folder so you can open it in freecad. I just created a freecad folder and put a folder in it called macros. I put the .dat files there too.
Install Freecad, click Macros and create a new one, copy paste airfoil macro 2.1 text into it from here https://www.freecadweb.org/wiki/Macro_Airfoil_Import_&_Scale This creates an executable Macro.
Next you need a .dat file so go to Airfoiltools, select an airfoil then click the 'Selig format dat file' and a window of co-ordinates opens. Create a new txt file and paste the complete data into it. Save the txt file into (in my case) the Macros folder with a suitable name. Next change the .txt to .dat do the Macro can read it.
Next in freecad click macro on the top of the creen and then the macros option. It will ask for a macro, select the 2.1 airfoil one you just created. This then asks for a .dat file, navigate to the one you created from airfoiltools (or elsewhere) and select it. It then asks for a chord length, in mm so 200 is a good start point with 'make D' wire selected. This produces a one dimensional airfoil.
Click on the surface of the airfoil and it will turn green, and click 'Pad' from the top toolbar, the airfoil is now a 3d object and can be manipulaed saved as .stl and printed. Save saves the freecad file, export exports to .stl.

Phew, that is a lot of stuff to take in, and type
If you want to make airfoils, or anything, this is a cheap and fun way to do it. Freecad and Cura have their learning curve, as do all such products. Someone said 3D printing in itself is a hobby within a hobby.
No money to pay but if you can master all of this in a weekend (even allowing for my excellent explanation) I will be impressed. Took me ages and still get caught out. The one Freecad tip I have is keep saving your part. What can happen is you create it, champfer and round off bits then decide to change the size a bit or add/subtract from it, then loads of other bits say error (usually champfers and rounding off so do them last). You can delete changes back to a working version but be prepared to just start again a few times.

Good project for a rainy weekend.

 

[CartCurt]

This is some very good information. If you are 3D printing the airfoil shapes to use as hotwire templates, how do you keep the hotwire from melting the plastic? My experience is that the hotwire rides along the templates to create the airfoil shape. I would think that the hotwire would just melt into the plastic as you are dragging the hotwire over the template to cut the airfoil shape from the foam.

Curtis

 

[Charentejohn]

Best way is glue or screw a bit of thin plywood to the template, trim close with a knife then sand to the profile.
I find Pla tends to resist sanding but a piece of thin ply doesen't. The printed bit is really just a way of getting an accurate and copyable / scalable profile.
My woodworking is not that good, I did try putting two bits of ply together with a paper template on top then jigsaw and sand to shape. Sadly they still ended up slightly different. Not a massive problem but I like a bit of precision.
Sanding like that I always end up with a sloping edge to the wood, 3mm (1/8") ply not so much. If you get a piece of pla and some 120 grit sandpaper you will see what I mean, it will sand down but not quickly.

I did try aluminium foil duct sealing tape around the outside too, worked ok if you don't hesitate.

3D printers are very accurate, I have found, and I have a decent cheap one. Creality CR-10 mini, I find the height I can print wing sections is fine, the non-mini one does great height but thinwall printing that high (300mm) can cause problems, 180-200mm is my max.