For builders of the Petrel, the all-moving tail poses a bit of a dilemma... A quick bit of History: there were three Petrels built originally; one crashed, two remain. The best known of the two is Graham Saw's red Petrel, but here's the rub...Sometime during its history, the AMT was substituted with a conventional tailplane, that of a Rhonbussard if I remember correctly. I think most would agree that the AMT is a much more elegant shape than the substitute, so here we have a situation where even the iconic full size is not 'scale'. (The other 'scale' Petrel has been beautifully restored to it's original wood & varnish finish in the USA)
So, I make no apologies for using the original tailplane set up. I hope the diagram makes clear how it works: the tube in the fin hosts the AMT joiner bar, and the bellcrank rotates around the tube in the fin...