It's not just the size but the airfoil, too. Don't expect much thrust from an APC. I would try a MAS wood if you're on a budget, or a top flight wood. Stay away from scimitar and pro zinger, They are more for speed and don't have as much thrust as the wide blade props. People will say " that prop runs slower or bogs my engine down" it's not just more drag that is loading the engine, it's grabbing more air and pushing a higher volume of air. The 120 may be too small to hover. When you can, go for an OS 160 and pump it and run a Mezjlik 18x8. You'll have a rocket.