I was flying my new Venus II last weekend (second time out with it since building it new) and while flying knife edge from right to left the plane sort of porpoised twice with no change of input. In other words, it was holding the line at first for say 75' then the nose dipped down, then back up to normal, then down, then back up to normal. The first time this happened I practically suffered cardiac arrest because I have never had a plane act like this in knife edge flight so I thought for sure I was going to lose total control and crash. But I leveled it out, brought back around and tried some other maneuvers that went fine and then tried knife edge t again, and wham, the exact same result, two sort of porpoise or bobbings (if you will) in a row, really really strange. I tried it a third time after yelling at everyone to watch and they all said "wow", I thought you were doing that with the sticks...but I was not. The plane seems to fly great every other way that I have tried out so far...e.g. inverted, loop, rolls..etc, also engine (a YS110-S) was really really running well so that can be ruled out.

I landed it and checked the stiffness of the rudder horn, connection rod and servo and they check out great. Also I am using a new hi-torqe Futaba I think 3020(?) BB servo (I can never seem to remember the servo numbers anymore). I was wondering if anyone might know what may be causing this? Note: I thought about trying knife edge in the other direction to see what happened but did not get a chance before I packed it up and called it a day. thanks in advance