Assuming that the curve of KT versus J is a straight line over the working range, show that, for a given forward speed, the thrust (T) developed by a propeller varies with its rpm. (N) as follows. T = AN2 - BN Where A and B are constants for a given propeller and a given ground speed.
For a particular propeller model of 50.8 cm, operating at 1?8 m/min, the constants have the following values: A 75.?; B 289, when N is measured in hundredths of r.p.m., and T is measured in newtons. Calculate the thrust of a geometrically similar propeller of 3.05 m diameter at 200 r.p.m. and a forward speed of 12 knots in seawater.