Lofting a Wing Surface Parametrically

[Joblack]

What would the best way to loft/skin a wing surface where I have leading and trailing edge profile curves and a root foil and tip foil. Would then like to be able to modify the leading/trailing edge profile curves (ie make the foil chord longer or shorter depending on the profile geometry I would like) and have the foil sections scale up or down automatically with each tweak or mod of these profile curves.

 

[NYITGUY]

You use circle to control Leading edge and Trailing edge,right? and you use spline curve for creating leading edge and trailing edge,right?

 

[NYITGUY]

Sorry, I forgot to attach picture.

 

[NYITGUY]

I think ,for me,I am going to use the circles telling leading edge & trailing edge radius to control leading edge and trailing edge profile and I am going to link 2 circle with line(length),but you have to change it to be construction element as well.

 

[Joblack]

Thanks NYITGUY, I was looking for a way to change the planform leading and trailing edge lines and the having my chosen foil section update (ie scale up or down with the resultant chord line getting longer or shorter). Have managed to do it with the two rail sweep command. I can now fiddle with the planform shape (LE & TE curves) as desired and the fin foils and skin update automatically. I have taken sections off of the sweep to check them against the original input (profile) foil and a section taken off towards the tip is off in thickness about 0.15mm over the aft side of the foil on a chord length of 100mm, which is negligible.
See attachment for example of what I did.
I want to be able to put this in a power copy so I can reuse this for other projects. Also would like to try this with the blend command, but this might be quiet difficult as the foil profile curve would need to be attached or fixed to the LE & TE guide curves somehow.

 

[NYITGUY]

First of all I have to say that I am quite an expert in creating wing,but I have some experience in creating airfoil(blade in jet-engine). I ever work at Chromalloy(Thailand) before as Reverse Engineer. I am not quite sure about your 3d curve because from my experience I prefer to use 2d curve more(in plane). Can I ask you something? How can you get 3d curve? From reverse engineering or.... I have no idea. Do you have point data??? Before you get the curve??? Because normally we create it from trailing edge and leading edge which we know the radius value
for example leading edge at 2.5 mm = 6.0 mm
trailing edge at 2.5 mm = 7.0 mm(measuring from the end of it) and we have maximum thickness

chord length = 100 mm for example...

And after that we create spline curve by define point in spline curve and we adjust curvature to smooth it. But I just want to tell you that adjusting chord length is the most difficult thing for me because all curvatures are changed even you adjust length longer or shorter. And we have to adjust curvature to be smooth again,but that is my experience from Solidwork. I'm sure about Catia(it adjust curvature automatically or not). Maybe you wait for anyone which he/she has direct experience,it's better for you..

 

[Joblack]

Yes, we have found the 3D curve much easier to work with, also it can be kept on a plane if required, it is much easier than the Sketch and GSD splines to work with and to get fair, not only can you move the control point freeform you can also edit the coordinates for each control point.
In our case we draw the 3D curve (LE & TE) first and have the foil shape tied to this thru the sweep command. We are not designing the foil section shape; that we do with xfoil or use a standard section.

 

[itsmyjob]

well, we use aero computation software to create LE, TE, PS, and SS... and we use the result of that computation as a surface in V5 for all our blades.

If you want to control the control points of your LE with a circle radius, you should have a lot of serious formula defined in you CATPart.

have fun!

Eric N.
indocti discant et ament meminisse periti ​

 

[Joblack]

It is not about controlling the LE radius with a circle, but by controlling the planform shape by adjusting the 3D curves that define the LE and TE shape and having the surface update correctly using the chosen foil shape.