Explain "gyroscopic effect"?

Answer 1

Combined rotation in three mutually perpendicular directions is gyroscopic effect. The instrument in which this is made possible is called gyroscope.

Answer 2

A spinning wheel has angular momentum. This is the rotational equivalent of translational momentum, and there is a similar conservation law called conservation of angular momentum. What this means is that a spinning wheel will keep spinning about the same rotation axis at the same speed unless a torque is applied.
Angular momentum is a vector. It points along the wheel's rotation axis. If you have a spinning wheel whose axle is connected through bearings to a rigid frame (i.e., a gyroscope), you can pick up the frame with its spinning wheel and apply a torque to the system. If the torque you apply (which is also a vector) is in the direction of (or directly opposite to) the wheel's rotation, you won't be trying to change the angular momentum direction, and because no torque in that direction is transmitted through the bearings you won't change its magnitude either. But if you apply a torque at right angles to the rotation, you are changing its direction. If you visualize your torque vector being added to the wheel rotation vector, you will see that you are actually doing is adding the wheel rotation vector and the torque vector, thus rotating the wheel rotation vector about a third axis, which is perpendicular to both your torque and the wheel rotation vector! So the torque you apply produces a tendency to rotate the system about a different axis.
This is the basis of gyroscopic precession. To keep this answer from becoming a treatise, I suggest you now google "gyro precession" to learn more about the effects of this rather surprising phenomenon.

Answer 3

Gyroscopes can be very perplexing objects because they move in peculiar ways and even seem to defy gravity. These special properties make gyroscopes extremely important in everything from your bicycle to the advanced navigation system on the space shuttle. A typical airplane uses about a dozen gyroscopes in everything from its compass to its autopilot. The Russian Mir space station used 11 gyroscopes to keep its orientation to the sun, and the Hubble Space Telescope has a batch of navigational gyros as well. Gyroscopic effects are also central to things like yo-yos and Frisbees!