Question

A model of a helicopter rotor has four blades, each 3.4 m in length from the central shaft to the tip of the blade. The model is rotated in a wind tunnel at 550 rev/min. What is the radial acceleration of the blade tip, expressed as a multiple of the acceleration g due to gravity?

A. (5.72 × 104)g
B. (6.23 × 102)g
C. (1.15 × 103)g
D. (2.25 × 103)g

Answer 1

Answer:
a) v = 198 m/s
b) α = 11201 m/s² = 1143 g
Step-by-step explanation:
a) v = rw
r = 3.50 m, w = 2πf
f = 540 rev/min = 9 rev/s
w = 2πf = 2π × 9 = 56.57 rad/s
v = 3.50 × 56.57 = 198 m/S
b) Radial acceleration, α = v²/r = 198²/3.5 = 11201 m/s²
Dividing by g = 9.8 m/s²,
α = 1143 g