Allow me to strongly disagree.
Nick,
The point that I am making is that the MR downwash creates a 'benificiary' flow in the plane paralell to the TR. This benificiary flow has a positive effect on reducing the chance of a TR-VRS.
In the case of a light american style heli (I am referring to calculations of induced flows we made in a thread quite a long time ago) VRS will happen in the 10-15 knts wind from the left range, certainly if -as Prouty states- the disk is far away from the main rotor so that we get no interference and hence a 'clean' vortex.
The Mean Rotor down wash, washes that vortex away just in the same way as forward speed washes a MR vortex ring away. As you stated over and over again, even with small forward speed in case of the MR VRS the danger zone goes away. Well similarly even small components of beneficial MR downwash make the TR-VRS danger zone go away.
My point has -as far as I am concerned- no bearing on the question of sizing the B-206 tail rotor. Just as a MR-VRS has no bearing on lack or not of MR and engine power, the TR-VRS has no bearing on the power capability, it just depends on induced velocities. TR-power of course is needed in other TR-operating regimes.
delta3
Last edited by delta3; 31st Oct 2007 at 15:29.