Hello jcomm,
as a retired airline ops engineering guy and with 40+ years of glider and (TMG) power experience I am happy to confess to not just using sideslip techniques on final, but also at other times. Even climbing, during a (short) pull-up over the beginning of the airfield, to kill airspeed in and then land halfway near the hangars.
Already before flying for many years from a coastal airfield, I have always been keen on knowing how cross-controlled one can fly during crosswind operations. Because some gliders and TMGs are rather restricted in the slip angle that can be maintained in a straight line with full rudder and appropriate aileron input.
The German Schleicher Ka-8 from the 1960’s (now a vintage glider) is at the limit of rudder authority in a really effective sideslip.
The original Grob 109 TMG, often named the 109A, is worse, and will maintain only a small slip angle. It is very challenging to handle in a right-crosswind take-off.
I once had the joy of flying one of the few remaining Reinhardt Cumulus IIIf gliders. A kind of Grunau Baby, but with only a very narrow tail boom and hardly any fin surface, but a very large rudder. It seemed to want to rotate freely around the centre of pressures when I gave it some sideslip input!
The rather more modern Dimona and Super Dimona TMGs seem tot be happy in any cross-controlled situation. I guess the Katana and other Diamond types may well behave similarly.
So I have always been curious how far a particular airframe can be steered to withstand the normal weathervaning tendencies. Because you don’t want an invisible but powerful hand turning the landing strip away from you when practicing sideslips on short final.
To correct for wind variations and turbulence, and to point the flight path to exactly where you want to touch down, it may be necessary to diminish the bank angle in a slipping approach while maintaining full rudder. This then commences a form of rudder turn that you are curious about.
If planes can be made to fly straight in a steady sideslip, and pilots shall show proficiency in that technique, it follows that gradual turning flight in such a cross-controlled attitude must be feasible as well, and not just towards the low wing!
So I found out that my Standard Cirrus glider could be lazily turned, wings level, to kill altitude when it was time for my mate to fly. This turned out to be a fairly stable manoeuvre at low speed, with the advantage that nobody around you would be fooled to think that you were in a thermal, as happens when you circle down with airbrakes out.
Having experienced the slow rate of turn together with the considerable sink rate that comes with it, I would expect a real all-engines-out 747 (I can’t really say ‘dead stick’ when supposing the use of full rudder!) to require more than 6000 feet to complete one 360!