Complex extrusion howto I want to extrude a profile (either a mesh or a curve) along a &quot;guide&quot; curve such that:

Its local Z axis is and remains parallel to the global Z axis at every point of the extrusion
Its X axis must always intersect the center axis, parallel to the global Z axis
The rotation of the profile matches that of the guide-curve, which may be non-linear

What are my options? I am looking for an automatic way of doing it, i.e. not by a vertex-by-vertex manipulation. Should the only way possible be via python programming and you can englight me, please do so!
Perhaps you might wonder why I would want such particular restrictions, so you might find it useful to know what I am trying to do. I am trying to model a vertical wind turbine (VAWT), such as the one in this picture: 
I am modeling one of the blades. Note that the blades' profiles remain perpendicular to the radius of the turbine at all times (see top view), and also remain parallel to the horizontal plane (see side view).
Update
Well I had not thought it necessary to show exactly what I was trying to model. I thought that the sample image of a VAWT would suffice to have blenders out here provide the right answer to my question. However, to quit puzzling readers, here I post an animation of the paths I want the blade profiles to follow:
There's a lot of different ways to do this. I suggest using modifiers for a non-destructive workflow. You can get the specific result you're looking for by using a few different modifiers, but perhaps the most straight forward is the Simple Deform Modifier.


Add the mesh for the propellor blade, with the origin centered along the Z-axis, and the mesh offset along the Y-axis. The origin position is key for the modifiers to work right.



2.Add an Empty, and rotate it accordingly (you will likely need to adjust the rotation after Step 3, depending on your configuration).


Add a Simple Deform modifier. This will be used for the bending of the mesh. Set the Origin field to use the Empty you created in step 2. Set the mode to Bend and adjust the Deform Angle as desired. 


Add another Simple Deform modifier. This second modifier will control the amount of twist. Set the modifier mode to Twist and once again adjust the Deform Angle as desired.