Stopping the line from "jumping"...  

@lunatic,

Thank you for your feedback. You are right, in order to move freely you need to press on the CTRL while dragging the mouse. There is another option and it's to uncheck the Snap to Grid.

Do you still need help with your profile image?

I'm just learning Fusion, but a lifetime ago I was a structural draftsman (pre-CAD if you can imagine it).

I used your method of 'fit point spline' to create my airfoils, but for some reason they "rounded" the trailing edges, so I just made a spline for top and bottom surface - that worked ok.  Then I could not get the 'sweep' to work (the TE upper-surface had jagged surfaces spiking out of it!!) so I copied and scaled the root profile to make the mid profile (same airfoil).  After that I simply lofted between the root and mid, and the mid and tip.  Great result.   Using the spline, as you point out, creates a beautifully smooth surface - awesome.

I am now trying to work out how to "twist" the airfoils to create the progressive washout required for this model.

My thought is to rotate the airfoils by the required degrees, then using the "allow lines to be drawn in 3D" option, either edit or replace the planform sketch to pick up the trailing edge points that have moved.  This may or may not require re-lofting.

For future reference, if you understand why the trailing edges rounded off instead of staying relatively straight to the TE point, please let me know.  I've attached a couple of screen shots to illustrate.

Any comments on my plans to rotate the airfoils will also be welcome.

Thanks, Steve.

@lunatic,

In order to avoid a rounded corner, the top and the bottom lines must be two separate lines that are connected coincidently to each other.

I hope it makes sense. If not, then please attach the file and I will show you.

If you think about it, most aerofoils do not join at a point a trailing edge, unless you're designing a starfighter.

Model aerobatic model aircraft have a thick flat trailing edge for example as this gives more aerodynamic power to the control surfaces. The Piper Cherokee has at least 3mm- 4mm flat edge as this is where the skins join.