So the early 707s had no artificial feel unit (no powered rudder) but the rudder pedals moved with the parallel yaw damper.
And the more recent 707s had a Q-feel system, but the yaw damper was in series and so the rudder pedals did not move with the yaw damper.
So again, I think my proposition that, "Yaw damper rudder inputs are not an input to the rudder artificial feel units on any aircraft I know about." stands.
The RAAF OIC was trying to give the trainees a challenging scenario to deal with for training purposes. I guess he succeeded in that regard, but the trainees never got the chance to use their new found knowledge.
It is interesting that in both the RAAF and the TWA accidents it seems that the OIC and the FAA PIC were on the jump seat and therefore had no way of either :
(1) Knowing what control inputs and with what force were being applied to the rudder pedals; or,
(2) Making their own rudder pedal inputs to correct the rapidly deteriorating situation (and therefore quickly realising that it was not able to be sorted out), but rather were only able to shout words of encouragement from the jump seat.
It also seems that in both cases no crew member chose to switch the rudder boost back on when they realised that things were not going according to plan. Interesting CRM lesson about assertiveness and mindset perhaps?
But oh what a terrible waste all round.