ORIGINAL: rmh
For those with nothing else to do - try this
setup a motor and propeller FIXED to a mount
directly behind it , tether and suspend a nice flat foam model ( these do give very good simple results) positioned as if the motor was attached.
Now -when the prop is spinning -producing thrust - you can see if the resultant airstream is indead a spiral flow or simply pressurized air.
In doing the many foamie tests with my own stuff - I have noticed the deflection of the surfaces caused by the prop blast -
It appears that the flow is assymetrical (has some spiralling) but the torque is obvious
the gyro reaction is also easily felt in my fingertips as aI move the control surfaces and change the original spinning prop track-
P factor is not possible to feel .
Tho it obviously occurs with a moving model - fling these little models in calm air reveals all these factors
This beats the heck out of digging thru various textbooks
Plus, it's fun
lol.... now there is a great experiment. Simple.... to the point..... any idiot ought to be able to see and feel the results.
I'd like to suggest and even simpler takeoff of the same setup.
I have a box fan in my shop that runs 24/7. I've held little foamies in front of it many a time. Fans are perfect substitutes for RMH's clever experiment. Except of course

their blades aren't usually airfoiled, so if you're one of the crowd that fears flat surfaces.......

you've got a detail to use to in your argument the experiment isn't appropriate.
So far, this discussion has been heartwarming in that nobody has tried to argue that our models don't hook a left on takeoff, that it's just theory that they do. But there's still time.......