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If in a helicopter, you have an altitude and you maintain that altitude without any motion will you revolve around earth in 24 hours due to coriolis effect as helicopter unlike airplanes is not affected by wind speeds when it is stationary in air?

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    $\begingroup$ Related: physics.stackexchange.com/q/58154/2451 and links therein. $\endgroup$ – Qmechanic Jul 23 '15 at 15:03
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    $\begingroup$ What do you mean by "stationary in air"? Does that mean airspeed is zero? Does that mean groundspeed is zero? If airspeed is zero, you move with winds. If the groundspeed is zero, you won't go around Earth, obviously. I can't think of any other definition that a respectable pilot would call "stationary in air" $\endgroup$ – Jim Jul 23 '15 at 15:04
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No, because you forgot to take into account the W-->E motion the helicopter had upon takeoff. What matters (ignoring winds and such) is the relative linear speed and the altitude. Calculate the circumference at the ground, compare with the circumference at altitude, and you'll see that since both the Earth and the helo have the same linear W-->E speed that you'll basically travel the difference in the two circumferences.

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The coriolis effect only applies to objects in relative motion -- specifically, motion that changes the distance from the rotational axis (of the earth in this case). A hovering helicopter cannot feel this force. You seem to be confusing the coriolis effect with wind: the coriolis effect is the consequence of us pretending the earth is not rotating: under this assumption, we interpret the effect of rotation of the coordinate system that we pretend to be stationary, as extra forces (coriolis and centrifugal).

However, the wind itself is influenced by the coriolis forces so the winds felt by the helicopter are indirectly connected to the rotation of the earth (just look at the rotation of the cyclones).

A minor side remark: the rotor itself does spin, so there are systemic torques acting on it due to rotation of the earth. This would (in ideal conditions - a spinning top suspended in perfect vacuum) lead to precession.

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  • $\begingroup$ Not entirely true: the Coriolus effect depends on the total time a (ballistic) object is airborne. The object's W-->E speed is set at launch time, and the total offset depends on the total time before falling to ground. The difficulty with a real-world helicopter is in avoiding any horizontal acceleration. $\endgroup$ – Carl Witthoft Mar 19 '15 at 14:10
  • $\begingroup$ Well if it hovers (no vertical or horizontal motion with respect to the ground), there is no velocity in the local coordinate frame. If there is no falling and no W->E motion, there is no Coriolis force. So if the air is not moving with respect to the earth (no wind) and you started stationary, you will remain stationary (OP says maintaining the altitude). However, as you said, upon takeof, things are different. $\endgroup$ – orion Mar 19 '15 at 14:12
  • $\begingroup$ True, since "without any motion" is an ambiguous phrase. $\endgroup$ – Carl Witthoft Mar 19 '15 at 14:14