RE: Predator 500 Problems
1 degree off should be able to be trimmed. 2 degrees off could definately cause the problem you are talking about, but I'm guessing yours is off more than that.
V-tails can be a bear to get right. My suggestion is to take that fairing cover off, and crack the tail loose. If you used Epoxy, heat it with a heat gun until it softens the epoxy and comes loose (be carefull not to melt the covering however).
Once its loose. Put an incidence meter on the wing (bolted to the fuze) and shim the fuze with whatever you have handy until the wing is exactly at zero degrees (or level to the ground). Once your there, put sand bags or something on the plane to hold it steady. Now take a small bubble level and place it directly in the center of the V-tail. Shim the tail up in the front until the bubble is centered in the level. You may also want to check the firewall at this time, to make sure that is perpendicular to the wing.