topic Can't thicken a loft (building a wing) - file attached in Fusion Support Forum

Can't thicken a loft (building a wing) - file attached

kim.volz — Thu, 02 Feb 2023 18:37:39 GMT

I have reviewed the "create Solids from Surfaces and even tried the "solved solution of thickening a loft". I've tried numerous different ways to create and simplify the airfoils, but nothing seems to provide a thickened part. Including redrawing everything with "Control Point Spline".

I can reverse engineer based on the timeline if someone actual is able to accomplish the task...

I have created a very simple wing and provided the ribs for the outside and inside shape. How do I create a thickened skin?

Re: Can't thicken a loft (building a wing) - file attached

jhackney1972 — Thu, 02 Feb 2023 23:27:47 GMT

Your small wing profile has some real problems in the front and since you brought it into the model, it cannot be edited. I cleaned it up using the Mesh Section Sketch tool to get a Lofted surface. The trailing edge is so small, I can then on thicken it to 0.5mm. You may be able to get a little more but I go tired of trying different values. Mode is attached, such as it is.

(view in My Videos)

Re: Can't thicken a loft (building a wing) - file attached

kim.volz — Thu, 09 Feb 2023 01:06:31 GMT

Hello John,

Thanks for taking a look. I wasn't able to determine what you actually did so...

I'm using the scripts & add-ins of the "Airfoil_dat_to_Spline_v20 and I saw in other tutorials. I pulled in an airfoil and started to try and make a wing. Obviously, I wasn't able to make that happen. The trailing edge doesn't have to be that thin and I expect it to be around 4mm thick. I was going to make this as my next steps, so maybe I have the wrong order of making the wing.

I know I'm asking a lot, but if you could make a video like you did to loft and thicken a wing, that would be GREAT. If not, I understand and will continue my journey using mock-ups to get things right.

Thanks for the help you provided!!

Sincerely,

Kim

Re: Can't thicken a loft (building a wing) - file attached

TrippyLighting — Thu, 09 Feb 2023 01:50:47 GMT

@kim.volz wrote:

I'm using the scripts & add-ins of the "Airfoil_dat_to_Spline_v20 and I saw in other tutorials.

Yep, that unfortunately never gets old 😕

Sometimes it works and then some well meaning folks make tutorials including workflows that are not reliable.

A spline follows very specific mathematical rules. The spline most people use is a fit point spline, which in Fusion 360 is a 5-degree multi span spline. This is quite a complex mathematical construct and also uses proprietary algorithms that don't translate across applications (as opposed to a control point spline).

The algorithm that calculates the points for an airfoil also follows some mathematical rules, but those are distinctly different rules than those of a fit point spline. If you try to fit a spline through those points, sometimes that results in bad curvature problems as errors compound and that often results in these loft/shell/thickening problems.

Often the best approach is to use the imported points as a visual guide and use a control point spline to approximate the curve. I'd start with one 5-degree control point spline with 6 points (which makes it a single span spline) each for the top and bottom curve.

Re: Can't thicken a loft (building a wing) - file attached

kim.volz — Tue, 14 Feb 2023 17:51:22 GMT

OK, I got it!! I followed your suggestion and brought in the airfoil and then "traced" it with "Control Point Spline". After a couple of tries, to know where to stop and start the spline, I was able to get a skin with thickness. For others, realize that you will have to make the spline the INSIDE edge of the object and thicken to the outside, at least that's what I had to do.

Thanks for the background details, it all made sense after that.