FAA Instrument Flight Instructor (FII)Instruments and SystemsEasy
A CFII is teaching gyroscopic principles and asks a student what property allows a gyroscope to maintain its plane of rotation in space, unaffected by movement of its mounting base, until acted upon by an outside force?
- AAngular momentum decay
- BPrecession
- CGyroscopic drift
- DRigidity in space
Show answer & explanationAnswer & explanation
Correct answer: D. Rigidity in space
Rigidity in space is the fundamental gyroscopic property that allows the attitude and heading indicators to maintain a fixed orientation while the aircraft maneuvers around them. Precession is the reaction to an applied force, not the property of resisting movement itself.
Why the other options are wrong
- A. Gyros don't lose momentum this way; friction/vacuum loss causes drift, not 'decay' as a principle.
- B. Precession is the tilting reaction caused by an applied force, not resistance to it.
- C. Not a recognized gyroscopic principle term.
Rigidity in Space
The property of a spinning gyroscope that causes it to maintain its plane of rotation in space unless acted upon by an outside force.
- Basis for attitude and heading indicators
- Resists, rather than causes, orientation change
- Force applied 90° ahead in rotation causes precession
Memory trick: Rigid gyro stays put — Precession makes it scoot 90° away.