It is estimated and the only way to find out these things is to use a device that mesures the rpm. now the rpm on the engine will drop a bit and the slip on the pro will encrese a bit.Įstimated: 70 x 1,6 x 12.000 x 60 - 15% : 1000000 = 68,5 KM/T or 43 mph. 15% (less on a small pitch and more on a high pitch) divided by 1000000 (estimated or sured) x minutes in an hour (60) - prop slip aprx.
If you calculate the speed in km/t it is done this way: diameter on prop x pitch x engines rpm. I think that the x470 or x 472 will work better than the x 670
