Example:
15 TW = 2.011533e+10 horsepower (550 ft·lbf/s)
1 TW = 1.341022e+9 horsepower (550 ft·lbf/s) | 1 horsepower (550 ft·lbf/s) = 7.456999e-10 TW
Conversion Steps:
15 × (1e+12 / 745.699871582) = 2.011533e+10