Yeah waldo I thought the same thing but on my sig somthing extra if I dropped my flapperons the nose would pitch down and if I raised my flaperons the nose would pitch up.
well now i really gotta investigate this if you are trimming out at full throttle and yet when you chop the throttle the nose doesn't really drop much.
When i put this plane together I put my batt in a hatch just behind the wing just like you showed me and she is balancing out at 4 an 3/4.
How much down are you putting in on the elev from neutral.
as soon as I get my emails done I'll take some measurments an post them