jettstarblue,the props i have been running are a trainer props,three bladed,except the 12X6 wooden prop however the one i cut down to 11X4,still three bladed, is at the bottom of the scale but would work but if were talking about two pladed props the 12X6 is pretty near the top.One reason for the 12X4 props that come with the plane is to keep the speed down so the flyer will get used to the plane,it's slow flying,then i will try others.Thanks again for the chart.