Aileron Rigging
Hey, i will try my best to answer this query for you, I am actually qquite surprised that you have seen aircraft with the ailerons rigged slightly upwards, the normal procedure is to rig them neutral, but occasi9onally some aircraft call for them to be rigged with a 1/2 inch droop from the mainplane, this in my opinion is to created a tad more lift(Big aircraft A330 for instance have hydraulic aileron droop whih allows ailerons to droop a little when neutral to provide more lift!) or it could be to counter-act adverse yaw, or possibly to pick up any slack in the controls, but i dont think i have personally ever seen aan aircraft with ailerons rigged upwards!, Hope this helps!!