Question: 3 question 560 the thrust f of a free propeller...
3. (Question 5.60.) The thrust F of a free propeller depends on density r, rotation rate n (rev/sec), diameter D, and forward velocity V. Ignore viscous effects. Tests on a 0.25m diameter propeller, in a sea level wind tunnel, give the following data at V = 20 m/s: (n = 4800 rpm, F = 6.1 N), (n=6000 rpm, F = 19 N), (n=8000 rpm, F = 47 N). The relevant dimensionless quantities are Cf = F/(r n2 D4) and J = V/(nD).
a) Plot Cf vs. J
b) Determine the expected thrust from a 1.6M diameter propeller at 3800 rpm flying at 225 mi/hr at 4000m altitude ( r = .8191 kg/m3).