another consern is the weight will add mass to the crank.. and it will smooth out your throttle responce... ie it will slow it down as it will take the engine longer to get it spooled up... the reverse is also true.. once it is going it will be harder to stop. if you spin a pencil in your hand it spins easy and fast.. now put a big blob of playdough on the end and spin it.. it is harder to get it to go.. .same for your plane