In school, our teachers would pull that trick all the time, and I think it usually worked. And let’s be honest, we would probably have made fun of our teachers if they confessed their ignorance about a certain subject. Kids can be jerks sometimes, especially when they’re in a pack. I know we were!
But the older you get, the more you respect the answer “I don’t know, I have to look that up first”. I guess that doesn’t come with age per se, but with the experience of how much you can’t remember yourself!
“Precession” is when the axis of a rotating body (gyroscope, in this case) – either due to outside force or due to inherent instability (the latter due to imbalance or insufficient rotational speed) begins to “wander” from its original orientation.
If the gyrocompass weren’t constantly being impelled by either pressurised air on the vanes of the rotor (or air flowing over the vanes due to suction,) the gyroscope rotor would lose speed and become unstable.
Also, if the external force capacity of the gyroscope were exceeded (typically due to lateral G forces,) it would also become unstable. Different method, same result.
Precession is a cyclic motion of the gyroscope axis that was originally caused by the instability – instead of, say, rotating with the axis dead vertical; the gyroscope’s “free axis” (whichever one is most allowed to move) would describe a circle about its original running point (this can be seen with a child’s “pull-the-string” gyroscope toy.) In the event of a gimbal-mounted gyroscope (as in a gyrocompass,) /both/ endpoints of the axle would describe smaller circles about their original running points.
Typically, the only real correction for precession is to brake the gyroscope rotor and realign it (this is typically described using the phrase “gyro’s tumbled.”)
Precession is also seen in astronomy. The Earth’s axis runs several degrees off from normal to the orbital ecliptic plane; thus, it tends to precess (since it’s running “off-axis.”) This is responsible for the “Pole Star” shifting back and forth between, as I recall, Polaris and Vega on a cycle of something like 20,000 years.
(Never ask an engineer how something works!)
“I don’t know” is an insufficient answer to a question. It should ALWAYS be followed with “But let me find out!” I haven’t answered a question with simply “I don’t know” in the last thirty years…
“Gyro Scopic” is when someone is scoping out your kebab, i.e. “I was in the middle of eating a gyro and dude was scoping it out with an eye to swiping some.” Allegedly.
Heheheheheheheheh!!
“Can’t find it under ‘J’”
That Chuck! XD
If you just can´t afford the real thing, here is a nice way to learn about gyroscopic precession:
Get yourself a decent fllight sim (I recommend X-Plane, has got a free demo to download!) and in addition a freeware Spitfire, Bf109 or similar high-powered taildragger with a very narrow track for it.
Get yourself in the cockpit, open the throttle wide and try to do a straight take-off with it!