RE: Building the Proctor Nieuport 11
wphilb,
I am kind of surprised that your GTM rudder warped.I covered my rudder a couple years ago and it hasn't changed.I liked the method so much I used it on my DVII for the tail and ailerons as well as my current Albatros.
Regarding using alum tube for the outlines,it does look good but is near impossible to repair. I bought a crashed Ponnier that has alum. tube on the rudder and I am going to have to make an all new outline for it.