if your couples are correct the aircraft must roll right as the TR passes the height of the MR
Yes, that's the crux of my argument, Crab. Whether it really happens that way I've never tested, and in the end it's not a biggie. I still don't see why the force diagrams aren't correct, but perhaps I'll never know...
The placement of the T/R relative to the M/R head has nothing to with the rolling force generated by the T/R.
That doesn't affect the magnitude of the force generated by the TR, but the separation of the forces in the couple does affect the torque generated (increasing separation, or moment arm, providing more torque), which again is a crucial point in my (perhaps misguided!) argument.
Cheers all, we must look a bit like a bunch of old bearded blokes arguing about verses in the Koran or something.