Well, I would like to hear it, if you have time. TIA
Fair enough.
Any control system has a natural frequency - a sort of sine wave behaviour at which it responds to sudden inputs. You can see this in a car or bike - make a sudden (small !!!!!) input to the steering wheel, and you'll see it make a few small swerves back and forth before re-establishing a straight track, or in flight do the same on the stick or rudder in any of the three axes, and you'll see something similar. Whilst it's not likely to help your instructors blood pressure, assuming that your aeroplane has self centring steering (virtually all do) the same will work with the ground steering.
The frequency of that sine wave response, in the vast majority of cases, is very fast - around 1Hz would be normal for a light aeroplane's nosewheel steering, or pitch control, maybe 0.5 Hz in yaw and roll.
Because the control circuit uses that frequency, you have problems with any input that is at the same frequency or a lot faster. So (
DO NOT DO THIS - test pilots do this sort of thing, because they've trained for it, it is possible to pull the aeroplane apart if you do it wrong) if you waggle the stick for-and-aft very fast in flight, the aeroplane does virtually nothing. If you slow down to the frequency of the control system (say 1 Hz, it'll be about that) then the aeroplane operates in anti-phase to the stick input. So, as you push the stick forward the aircraft pitches nose-up, and as you pull the stick back the aircraft pitches nose-down - it's also possible to amplify the response very quickly and possibly pull the wings off (I'd certainly not do it in a T67 for example, which has a very poorly damped short period pitch mode). This is arguably confusing and unhelpful behaviour, and not to be encouraged. If you move the stick much slower than this (which is what we all normally do) then the input is sufficiently slower than the aircraft response that you see nothing odd, and the aeroplane simply does what it's told.
Now, coming back to the issue of the nosewheel steering. That steering circuit will also, as I said, have a frequency around the 1Hz mark. If you make rapid inputs, then you are getting around this frequency, and as a result the aeroplane does not steer in the direction that you expected, because you are putting inputs in at the wrong point in the cycle. The result will be an aeroplane that swerves all over the place and appears to be uncontrollable. The technical term for this is a "PIO" or "Pilot Induced Oscillation", and it can be prevented by gradual control inputs, or if it is really all getting to much, just clamping the offending control in the middle until the aeroplane sorts itself out, then trying again.
I hope that was reasonably clear - it's much easier with diagrams!
G