ORIGINAL: Razor-RCU
For the knife-edge coupling you might consider mixing in a tad of down elevator when rudder is used- That should straighten out your KE

Do you have a computer radio?
Nice looking plane, I like the checkers you added---
I love my St G-90, it is on my 46 sized Funtana and has enough power-
Thanks Razor-RCU, I do have a computer radio (Airtronics VG-6000) and I was checking this out but I don't seem to have the mix for rudder to elevator. No big deal, I'll just feed it in manually.