That's not torque. It's caused by the spiralling slipstream striking one side of the fin. Torque swing is the airframe's reaction to the propeller's being driven and it places more weight on the wheel opposite the downgoing blade and increases the rolling friction on it.Contra-rotating propellers are most valuable in tractor configuration because they reduce torque swing on take-off by reducing the amount of airframe exposed to prop-wash.
One of my former colleagues, years ago, contemplated a speed demon based on the German RFB Fantrainer:What is the definition of a propeller for these purposes? When does a ducted propeller become a jet...?
But how much jet thrust is each making?Yes curious thing it is actually flying 950 km/h ( 590 mph ) at same power to weight ratio as Dh Mosquito does 415 mph. So the ( relative ) reduced drag is enermous with swept wings and adequate huge propellers ( and flying very high in the thin air ).
Don't uderestimate the FORCE !Add solar panels and pedals.
=not exactly=torque (reaction momentum) is equal to engine or reductor momentum...Contra-rotating propellers are most valuable in tractor configuration because they reduce torque swing on take-off by reducing the amount of airframe exposed to prop-wash.