Physics 220  Class exercise October 23

Here's the plot:

The maximum excess power occurs at 85 Kt.  At this point the total power available is approximately 180 hp. Since the force is parallel to the velocity, then

P = Fv
and so
F = P/v = 180 hp / 85 kt.
Changing the units, 180 hp = 180x746 W = 1.34E+05 W and 85 kt = 85 x .5145 m/s = 43.7 m/s and so the thrust is
F = 1.34E05 W / 43.7 m/s = 3100 N

The excess power is approximately 120 hp.  This power is used to lift the airplane.  Thus:

excess P = mg dh/dt
So
dh/dt = 120 hp / 3000 lb =  8.95E+04 W / 1.33E+04 N = 6.7 m/s
Finally we compute the angle of climb.  We have the total speed and the vertical component (rate of climb).
Thus:
sin (angle) = 6.7 m/s / 43.7 m/s = 0.153
and thus the angle is
8.8 degrees.