Hi Bruno,

> 1. How did you find the rial curves for the segments (attachment)

To set it up I drew in a line across using "Perp" snap like this:





Then I used that line to trim the profiles and used Rebuild (http://moi3d.com/3.0/docs/moi_command_reference10.htm#rebuild) to make those into single segment curves instead of being made up of 3 segments.


> 2. Is there any reason why you connect one of the 'radius' of the curve to the
> perpendicular part of the other one and not with the 'radius' of the other one ?

It's to give a more gradual transition to the straight parts. If you match radius to radius it will make for a very sudden transition in a stretched out zone here:



If you turn on control points for that you can see the straight segments have stations that are slanting and stretching a lot, especially with elongating into a kind of sharp spike at the tip:


That type of slanting will usually have some undesirable effect on the surface's shape in those areas, it just becomes more difficult to control the shape.

If you match it the other way and then look at the same section you can see a much more orderly arrangement of stations, the more that they resemble regular planar formations it tends to give more controlled surface shaping there as well.



This kind of thing comes into play when you're trying to connect together outlines that have zones of different length from each other. Just matching things by "small feature to small feature directly" can produce shearing and so can just an overall "match full length to other full length".

- Michael