Unfortunately the effect is nullified a few seconds later by the closing of the throttle as part of the identification phase. With closed throttle very little air gets into the cylinders. Centaurus,
Whilst that's true consider the s'down drill when the student is practising failures.......
Case 1. Use mixture....If you use the mixture to 'simulate' the s'down then the student will have to retard the identified failed throttle to check they have correctly identified the failed engine (because both throttles will still be forward) and you keep the mixtures hidden so the student HAS to use dead foot/leg = dead engine to identify the failed engine and if they get it wrong and retard the live throttle then there is a significant yaw change. However
Case 2. Use throttle........ if the throttle is pulled back by the instructor to simulate the failure and he/she hides the throttles behind paper/map etc until the stude correctly idents the failed engine and they get it wrong, what can you do? Just say try again or show them the throttle quadrant and say 'wrong'? Not a satisfactory demo IMHO or a satisfactory learning point for them.
With Case 1, they get a much closer drill to real life ie they actually get to retard the throttle as it is still forward and aligned with the other and get an actual and real result on the controls if they get it wrong.....for this reason I would much prefer to use the mixture for demos airborne. That said my schools SOP is to use the throttle
so I use the throttle (Mostly)!
Regards...