Question

A helicopter moves horizontally in the x direction at a speed of 120 mi/h. Knowing that the main blades rotate clockwise when viewed from above with an angular velocity of 220 rpm, determine the instantaneous axis of rotation of the main blades.

Answer 1

Answer:

The instantaneous axis of rotation=

x = 0 ; z = 8.4 ft

Explanation:

Given:

Speed of helicopter, Vo= 120 mi/h, converting to ft/sec, we have:

$\frac{5280 * 120}{60*60}$

= 176 ft/s

Angular velociyy, w = 220 rpm, converting to rad/sec, we have: $\frac{200*2*pi}{60} =20.95 rad/s$

The helicopter moves horizontally in the x direction at a speed of 120 mi/h, this means that the helicopter moves in the positive x direction at 120mi/h

To find the instantaneous axis of rotation of the main blades, we have:

Where Vc = 20.95 rad/s

Vo = 176 ft/s

$z = \frac{V_0}{V_c} = \frac{176ft/s}{20.95rad/s}$

= 8.4 ft

Therefore the axis of rotation=

x = 0 ; z = 8.4 ft