top-flite 60 size F4U wants to tuck under
 

Ok all you builders out there who will have an answer. Top-flite F4U 60 size, built to plans, wants to tuck under at high speed. Do I need to add down trim or correct the c/g. I have the c/g set up with the gear up as all the weight of the wheels and struts move aft as they go up. I have an awful lot of up trim just to get her to fly level. I have been building for many years and this is the first one that has me baffled. Once trimmed out it was just fine. Just hate to have all the up trim if I can change something like motor or wing incedence. Any help appreciated. My bird weights about 11 lbs. dry.