topic Re: Airplane wing with endcap wont' thicken in Fusion Design, Validate & Document Forum

Airplane wing with endcap wont' thicken

rwetzler — Sat, 27 Mar 2021 14:42:44 GMT

Hello - I'm experimenting around with few airfoil/endcap designs and wondering why these surfaces won't thicken. I'm somewhat new to surfacing so maybe due to this type combo of faces it's just now possible. The model stiches fine so more curious than anything. Trying to achieve a wall thickness of between .2 and .4mm for possible 3D-Print project in the future.

Thanks

File attached

Re: Airplane wing with endcap wont' thicken

jhackney1972 — Sat, 27 Mar 2021 19:57:47 GMT

I tried to download you attached model twice and it just will not open. It gives the error below. The path shown is my location for Fusion 360 files I download from the forum, the error is after that. Please attach your model again.

Re: Airplane wing with endcap wont' thicken

rwetzler — Sat, 27 Mar 2021 21:01:44 GMT

Here's another attachment of the file.

If that fails again here is a link to the shared file

https://a360.co/3fhlRkQ

Thanks

Re: Airplane wing with endcap wont' thicken

rwetzler — Sat, 27 Mar 2021 21:04:46 GMT

John,

Does the file needed to be zipped? I just noticed the error message in your screenshot.

Re: Airplane wing with endcap wont' thicken

TrippyLighting — Sat, 27 Mar 2021 21:34:43 GMT

Yep, not a surprise!

There are two issues that make this seemingly simple geometry very challenging:

1. You are using fit point splines, which in FUsion 360 are 5-degree multi-span splines. These harsh transitions are where the rails are and they over-consrtin the surface.

2. Te training edge of the loft is a point, which means you are lofting into a singularity.

Re: Airplane wing with endcap wont' thicken

rwetzler — Sat, 27 Mar 2021 23:44:18 GMT

So if I use "Control Point" type splines for the rails it will reduce the harshness of the transitions and most likely address the first issue, is this correct or is there another method in Fusion to address this.

For the 2nd issue (I assume you mean to say " The trailing edge") place a very small 3-point arc and required split to eliminate the singularity. I assume this will address this issue.

Another note is it an ok practice to combine ,e.g. arcs, lines, with splines or is this generally a bad idea? Splines are much more challenging for me to get nice clean geometry with so I'll mix and match from time to time.

Thanks for the response, I hadn't heard about the "Fit Point Spline" being what you mentioned. Always learning that why sometimes it's best to reach out.

Thanks,

Re: Airplane wing with endcap wont' thicken

TrippyLighting — Sun, 28 Mar 2021 02:21:59 GMT

If you want to get into technical surfacing, here's a link to the Autodesk Alias Theory Builders.

I recommend this as a basis for anyone wanting to really understand lofting in Fusiosn 360 as it creates NURBS surfaces, but the documentation in Fusion 360 is kept artificially at the layman level.

You can create smooth surfaces with Fit point splines and in many cases, they are also my go-to tool, but this wing tip is not simple. Unless you absolutely must to have completely uniform wall thickness I'd actually create a second loft for the inside and stitch that to the thickened inside of the wing.

Using Control point splines will not automatically create better surfaces and comes with its own challenges.

I would try to create the wing profile with 2 splines only, one for the top and one for the bottom, or perhaps even just one. Use as few fit-point spline control points as you can. It takes a good bit of patience to manipulate the spline handles so the curvature combs are smooth. In that case-control point spline might work better.

The rails you used for the wing tip would really only have three, or perhaps only two spline control points.

Re: Airplane wing with endcap wont' thicken

davebYYPCU — Sun, 28 Mar 2021 02:26:09 GMT

I prefer one spline top and bottom, your leading edge radius is causing trouble.

Rebuilt as I would do it, won't thicken or shell, so fudged aproximate 1mm thickening.

Fusion Loft inherently wants to shrinkwrap in my experience.

Might help....

Re: Airplane wing with endcap wont' thicken

TrippyLighting — Sun, 28 Mar 2021 02:28:01 GMT

@davebYYPCU can you explain what you mean by "shrinkwrap "?

Re: Airplane wing with endcap wont' thicken

davebYYPCU — Sun, 28 Mar 2021 02:37:32 GMT

This tip has 3 rails, between each rail the surface seems to carry tightening (slight you can see them in the map) - that I see all the time.

In the Op's file he did not use the second sketch as a profile, and shows it better.

Re: Airplane wing with endcap wont' thicken

TrippyLighting — Sun, 28 Mar 2021 11:12:34 GMT

Yep, that means you are over-constraining the loft and need to break the loft down into smaller patches.

Your loft looks good and I am not sure I would try to get much further using Fusion 360.

If this model would be 3D printed or hand-manufactured then this is all that is needed.

If you wanted to present a high-end rendering or VR presentation where glossy reflections would be subject to the discerning eyes of experienced industrial designers in the automotive or aerospace industries this would not be enough.

Re: Airplane wing with endcap wont' thicken

rwetzler — Sun, 28 Mar 2021 14:15:29 GMT

Dave,

Thanks for sharing, very clever idea using the offset/split work around. Your geometry is a little cleaner than mine and looks nice. I played around a bit and found with your version I could thicken the stitched bodies in a range between -.4 to -.8, wouldn't however thicken with symmetry or positive values wouldn't work. Overall this is what I was looking for as 3D-Printed RC Plane model parts must be printed with extremely thin walls due to weight requirements.

Thanks to all who posted!

Re: Airplane wing with endcap wont' thicken

davebYYPCU — Sun, 28 Mar 2021 16:25:08 GMT

I am not complaining, gotten used to it, and happy with my process - results, but never know what others may be expecting so mentioned it in case. My work usually doesn’t take me to manufacturing this bit either.