Martin,
you can use this method.

1. Use loft (normal mode) to build a surface; Draw a circle.
2. Select the circle; Array -> Dir;
3. Select the circles -> Loft (caps off) -> Flow tool. Use cylinder as base surface.
4. Now you've got more curves, so you can variate the power of loft by selecting and deselecting those curves.

This method works good with any curves. I could write a script, but, unfortunately, I haven't free time for it now.