Originally posted by BMatthews
Bernie-
You're right on this. A model like you are describing here would indeed maintain the same bank but it would fall off into a spiral dive and change it's heading as it spirals down.
Not sure why you talk about spiral. If you fly a pattern plane, bank it, slightly, say 25 degres, and do nothing else, it will continue to fly, straight like an arrow, on a slight dive. If you bank it, 60 degres, and do nothing else, it will continue to fly, straight like an arrow, but the dive will be much more obvious, and a bit shorter...
if the model do not do what I describe, it's simply because it's not built, or setup, properly, If the nose fall down in a "spiral", it would be because the center of gravity is too much forward.
You are talking about secondary effects all the time, maybe because you have never had the opportunity to experiment a plane "pure" enough to have no, or very small, secondary effects.
All pattern planes that I have seen and flown behave that way, and do not change heading a bit ! (Would make knife edge problematic, if they did.)
Bernard