Oh, I know that airplane very well. Several years back, Phoenix came out with an airplane called Topstar 3d 60 that has the same wing construction. Its broadly like the UCD but the Ucd is longer where this is shorter making it more flip-flop. Its not precision 3d, flies more like a profile. Phoenix also had the Funstar 3d 40 that was even more flipflop, difference being the Topsstar has fixed triangular wing tip upto the ailerons. Recently Phoenix released the one you have and the Hero 3d 40 size.
You dont need to go into rpms for 3d flying that airplane. Just make sure the tank centreline is in line with the carb spray bar and tune the engine by ear with the tank half full & held vertical. Remember, this airplane does not need to go forward to fly (sounds dumb but you will see) and cannot be flown like a rocket