Distortion while trying to Rotate Draft Objects

[LVAeronautics]

I have been endeavoring to create a lofted 90-degree transition section between a wingtip and a winglet. Almost there, but have an issue I can’t seem to shake..but pretty sure it is solvable once I am shown the preferred method(s).

Importing/scaling/splining and initially positioning the .dat files between the Draft & Sketcher workbenches was not an issue.

However, when trying to rotate the transition (the 45 degree wire) and the winglet root airfoil spline (90 degree wire) along the longitudinal axis, I was seeing a distortion between the leading and trailing edge points when looked at head-on from the front looking towards the rear (on the record, the leading edge is precisely where I wanted it). See attachments; these should all be on plane, not as depicted.

At left looking towards the Right.jpg (37.88 KiB) Viewed 661 times

Distortion Head-On.JPG (48.31 KiB) Viewed 661 times

When I tried assembling the upper and lower lofted parts using the A2Plus workbench, yes, the leading edges between the upper and lower halves met precisely, but the trailing edges were all kind of distorted and interfered with one another.

I do not think the A2Plus WB is any part of the issue here, because I am able to assemble other stuff without an issue. Also, this distortion existed BEFORE lofting.

To give further context, the airfoil files, when imported, were rotated along the original plane to meet select angles of incidence called for in the design, meaning that the trailing edge point is not on the same plane as the leading edge point. When rotated within Draft WB, I suspect the wire splines somehow distort off-plane behind the leading edge, but not sure why.

Is there something I missing? Can I not simply rotate the airfoils along the longitudinal axis as desired? Do I need to ‘assemble’ the upper and lower halves of the airfoils, rotate as a single sub-assembly, then loft accordingly? How can I avoid this distortion.

To be transparent, the Wingtip Airfoil was 3 degrees, Transition at 0.5 degrees and the winglet root at -2. This is due to the aerodynamic performance desired from the shape.

Using the latest/greatest stable release:

Code: Select all

OS: Windows 10 Version 2009
Word size of FreeCAD: 64-bit
Version: 0.20.1.29410 (Git)
Build type: Release
Branch: releases/FreeCAD-0-20
Hash: f5d13554ecc7a456fb6e970568ae5c74ba727563
Python 3.8.10, Qt 5.15.2, Coin 4.0.1, Vtk 8.2.0, OCC 7.6.3
Locale: English/United States (en_US)
Installed mods: 
  * A2plus 0.4.60f
  * AirPlaneDesign 0.4.0
  * Assembly4 0.12.4
  * CurvedShapes 1.0.4
  * Curves 0.6.4
  * ExplodedAssembly
  * fasteners 0.4.25
  * FeedsAndSpeeds 0.5.0
  * LCInterlocking
  * Plot 2022.4.17
  * Pyramids-and-Polyhedrons
  * sheetmetal 0.2.59
  * Ship 2022.4.11

I’m sure this is a minor issue and likely due to my inexperience. Assistance appreciated; thank you for all help given so far!!!!

[Roy_043]

Something must have gone wrong with the rotation. Just check the Placement of WingletBaseL f.e. What went wrong is hard to tell without more details.

There are also some out-of-scope issues.

Try rounding the values.

[Vincent B]

Positions of starting curves are given by edges.
Then I use a double attachement system to angle your profiles.
first angle handle with datumPlane, second with the LCS.
I hope that's you looking for.

[LVAeronautics]

Positions of starting curves are given by edges.
Then I use a double attachement system to angle your profiles.
first angle handle with datumPlane, second with the LCS.
I hope that's you looking for.

I was thinking about this exact same thing last night....using datum planes to position & rotate the airfoil lines. I'll take a shot at it today. Thank you!

[LVAeronautics]

Something must have gone wrong with the rotation. Just check the Placement of WingletBaseL f.e. What went wrong is hard to tell without more details.

There are also some out-of-scope issues.

Try rounding the values.

The airfoil shape leading edges are positioned where they should be (this wing-winglet transition is both upturned 90 degrees and swept back so the winglet can be where the aero analyses direct it to be), with my intention simply to rotate them along the longitudinal axis. I think this might be solved if I do multiple datum planes and LCS's, so I'll give it a shot.

But yes, the angles should be whole values...not this 90.0046 or anything like that. More to follow!

[LVAeronautics]

Positions of starting curves are given by edges.
Then I use a double attachement system to angle your profiles.
first angle handle with datumPlane, second with the LCS.
I hope that's you looking for.

I am so sorry, but can you elaborate a little further with your workflow sequence? Step by step. I have spent the last few hours trying to duplicate what you did, but had no luck. I'm lost on this.

I am easily able to do multi-plane rotations with sketches, but cannot seem to do it with b-splined wires.

I honestly am lost on this!

[LVAeronautics]

Positions of starting curves are given by edges.
Then I use a double attachement system to angle your profiles.
first angle handle with datumPlane, second with the LCS.
I hope that's you looking for.

It looks like it is, but I am unable to duplicate this with ; I have spent the last number of days looking up every relevant-looking tutorial & video, but cannot seem to close the loop on this. I am running out of ideas on how to do what you did, so I am very much missing something. Any chance you can elaborate, step by step, how you did this? Thanks in advance!

Now, I went about building a sample 'fillet' up a different way:

1. I imported the airfoil, scaled, edited, splined and placed accordingly.
2. I used the "Transform" function to manually rotate along each axis (in this case 45 or 90, then the required angle of incidence needed) to the angle I needed. No axial distortion observed
3. Lofted in the Part WB

Dumb noob tries a complex curve that works.jpg (29.65 KiB) Viewed 331 times

It looks to do the trick for now. Granted, this is a sample unrepresentative of what I am doing with the proprietary geometries, but the technique would be the same. Going to do it again with the project geometries; expecting the desired result.

More to follow...