I could be wrong as I haven't set up a hawk sport, but ALL control arms SHOULD be at a 90 degree angle to the servo I would think.. It is in every other model i've seen anyway... When you say you saw references to setting up control arms at 10 or 15 degrees, you sure you don't mean setting up "pitch" at 10 or 15 degrees? Your collective pitch, cyclic pitch, etc? For that you need a pitch gauge. They're cheap, but borrow one if you must. It's really the only way to be accurate....