I know many very knowledgeable U-Can-Do 60 folk hang around here so I'm asking for a little advice. I've had a UCD 60 with a 91FS for a year or so and generally enjoyed the experience. So when I piled it in after a plug failure while hovering I bought another. It's built identically with the same servos & linkages, engine etc from the other plane. From what I can remember the CoG is in roughly the same place, just shy of 6inches from the LE. The big difference is that knife edge flight has a massive tug to the u/c. Previously 10% up elevator mix, and 5% opposite aileron was sufficient to fly KE straight as a die all day long.
This one I'm up to about 35% elevator mix but as I continue to increase rudder it's not enough with an exponentially increasing fierce tuck to the u/c. KE loops are impractical because tuck under becomes so fierce it's uncontrollable.

The behaviour is so different from the previous one that I'm looking for ideas from experienced owners as to the possible cause. Things like adjusting CoG, wing camber, incidence and so on. I'd just like to get it to the state I had with the old one. Anybody else had this problem and cured it?

PS. I have added right thrust to get to nearly 4degrees, just like the last one, and it seems about right. I haven't adjusted the down thrust from as supplied but didn't on the original one either.
--
S