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Issues with loft function

Hello, I’m quite new to Onshape, and I’m having some issues with the loft function.
I’m trying to create a propeller blade (3 cm wide) and add a twist to it. I’ve made curves that the profile should follow, and I used airfoil generators to create the NACA profile. However, whenever I try to use the loft tool to make the propeller solid, it doesn’t work, even though I can see it in the preview.
Here is the link to my project: https://cad.onshape.com/documents/e7419fdbceeb1aedf5a14aee/w/d63c0ac54948ba9f04a9457f/e/974e939ac7dedc81f3eca5e5?renderMode=0&uiState=67e00fb6c2a50f63c220a707
Can someone please help me?
Thank You
Best Answer
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GregBrown Member, Onshape Employees, csevp, pcbaevp Posts: 294
It's a little hard to tell all we need to know from the view-only link (can you make it so we can copy?)
But there are a few obvious things starting with the profiles:
- the curvature is extreme, in fact goes more or less to infinity, at the trailing edge. This won't go well in your loft…
- looking at the leading edge, the curvature is also suspect, but the diagnostic combs can't capture the full extent since they are being scaled by that trailing edge….
- You have a single spline for the full profile. It is much better to have 2 splines, one for top surface, one for lower surface of the blade. This is especially true if you are using a zero thickness (sharp) trailing edge (and the reason for your bad curvature at the TE currently)
- the spline has a very large number of points. It would be better to do some smoothing and reapproximation. What was the data source you sampled these points from?
I think with cleaner profiles the loft would be much more successful, so I suggest looking at that first. The path with 50 sections will be the next thing once the profiles are addressed…
For clean aero profiles there is a custom feature I helped develop last year. Give it a try, there are some links on the description page to provide more background. While there are many (about 95) different profiles included, I don't believe NACA8710 is one of them currently. You might want to contact Holbrook Aerospace if that one is vital.
1
Answers
Your document is set to view only. Cannot inspect it with out being able to copy it.
It's a little hard to tell all we need to know from the view-only link (can you make it so we can copy?)
But there are a few obvious things starting with the profiles:
I think with cleaner profiles the loft would be much more successful, so I suggest looking at that first. The path with 50 sections will be the next thing once the profiles are addressed…
For clean aero profiles there is a custom feature I helped develop last year. Give it a try, there are some links on the description page to provide more background. While there are many (about 95) different profiles included, I don't believe NACA8710 is one of them currently. You might want to contact Holbrook Aerospace if that one is vital.
Thank you so much !
You really helped me with my school project!
As you said, the problem was that I hadn't enabled both splines, and the profiles weren't perfectly aligned.
The result looks great : https ://cad.onshape.com/documents/7a13792ef5967edf864ba0a3/w/176362cd9af67624d0ce8a57/e/b2e99b6f42bc41343b1f6acb?renderMode=0&uiState=67e18b0d1fd24658c07fb50b
I will check out the custom feature.
Have a nice one!
NB: I don't know if my previous answer was sent so excuse me if I wrote two times the same thing!