Since a .61weighs more than a .46 and if you increase the size of the fuel tank thereby increasing fuel weight, your wing loading will increase. As the fuel burns off, that weight will decrease. IMOH, a good flying model should have a wing loading not greater than 23-25 oz/sqin. You can calculate wing loading by dividing the gross weight (wet or dry) in ounces by the wing area. As in full scale aircraft, the ambient temperature will affect performance also, although not an issue in Ohio this time of year.