P power in Watts
F force in Newtons
v velocity in meters per second.
So a prop fighter having 4000 N of drag (say L/D 10 and 40000 N weight) at a speed of 200 m/s would need 4000 N * 200 m/s = 800,000 W = 800 kW of power. With prop inefficiency perhaps 1 MW. In obsolete units, that's about 1500 HP.
Instructions for converting stuff from other units to SI ones are above, Google does it.