If you can relate your calculations to pounds of thrust, figure about
1 hp for every 30 pounds thrust, e.g., 300 pounds of thrust is roughly
equal to 10 hp.


ah, no. thrust times rpm / 60 / 550 = hp. (IIRC) 30# of thrust at 4,500 rpm
is 3x the hp of 30# of thrust at 1,500 rpm.