Just to clarify, I mentioned only that spoilerons cause the nose to pitch up, converse to what intuition would suggest, because flaperons also cause the nose to pitch up and require some down trim to compensate, as Rich alluded to.

I do not use any elevator mix for spoilerons with the Venus. Spoilerons were used for landing only, so I just let it descend with a nose-high attitude, using throttle to tweak the glide path, and a bit more than normal elevator to flare.

I have used flaps (not flaperons) with sailplanes and on a couple of other scale planes with flaps (again, inboard flaps, not flaperons) and they require some down elevator trim.

However, it is my experience (I must stress IMHO because I don't have a wealth of experience like many longtime RCU'ers) that flaperons are not a good idea. Yes, they slow the plane down, but they also create wash-in at the wing tips, which is an open invitation to a low, slow (and disastrous) tip stall when landing. This why real flaps are at the root of the wing, because it is desirable for the wing to stall from the root out when landing. When a sailplane is set up with Crow (aka Butterfly), the flaps are down and the ailerons go up a bit (aka Reflex) to keep the tips from stalling, with a lot of down elevator mix. If you want to really slow a plane down safely, this is the way to go, but you have to have separate flaps to do it.

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