Airfoil loft problem

leha44581_leha

I can't make a loft between 2 airfoils, tried using some guides and paths, but it just doesn't work.
If i won't use any, it creates a self intersecting shape.
Imported airfoils with the aerofoil script by Darren Lynch.
https://cad.onshape.com/documents/fb5b49751cbc52193856bd7a/w/f93f7747c84f3d910949a03e/e/5aec9d002344d5629b842c3d

GregBrown

Lofting those profiles as single curves is going to be extremely problematic and lead to poor a quality surface. Have a look at the curvature of them.. (select the curve and hit Shift-C)

A better approach might be to edit the Profile generator feature and change the Spline type parameter to "Upper and lower splines". This will give you two spline curves which you can use to create a  surface loft for the upper, then a surface loft for the lower. Here is a quick test:

If you try something like this you'll still have to check the curvature of this resultant surface, and it will still not be great. This is because of the foundational curves you are using. A much better approach will be to remake these curves (using the Profile generator curves as a guide) in a new sketch and use a Bezier curve with far fewer control points.


I would also look at your Loft 2 feature and consider using "Connections" rather than those guide curves. You can experiment very easily with Connections... That transition in the root of the blade (i.e. Loft 2) could also have some tangency condition applied. Lots of possibilities! 

S1mon

@GregBrown
Ideally, a proper “rebuild curve” feature would make this much easier to do in an automatic controlled way. Hint, hint…

GregBrown

S1mon said:

@GregBrown
Ideally, a proper “rebuild curve” feature would make this much easier to do in an automatic controlled way. Hint, hint…

Agreed, and in the meantime the

approximateSpline

function is something to try if you wanted to extend that Custom Feature....

billy2

I've worked with many medical companies using scanned data and curve definitions based on points. It is possible to create lofts from splines with 100's of nodes, but it won't last, all subsequent features will suffer and your project will crash eventually.

Clean the input data up 1st, you'll be glad you did.

This is a common problem in the industry.

glen_dewsbury

As you can tell, I couldn't get to sleep last night.
Switch the profile generator from single spline to upper and lower will let you select the face of the profiles with out the loft connections. The rest is just me  playin around to see what I could come up with.
https://cad.onshape.com/documents/0de5a971db26bab87c5bfce9/w/68128340bd6c29e967a751a3/e/48b8e0a979c257228049d79c

billy2

@glen_dewsbury your's is a nice looking prop.