Co-axial rotor systems... a couple of Qs
To anyone who has flown, or has professional knowledge of, the co-axial rotor design found on Kamov helos, perhaps you can answer a couple of Qs coming from a PPL(H) with time only in the R-22, Bell-206 and Hughes 500?
1) What are the ball park rotor stall speeds (percent RRPM) for co-axial helos? Perhaps a very generic question, but feel free to answer with specifics for the types you have flown
2) If a co-axial rotor system fully stalls, can it be recovered by flaring and inducing airflow through the disk, or do the blades simply fold up (as I was taught is the case with the R-22 and Bell 206 teetering head systems)
3) Autos: I understand that yaw control becomes an issue during the flare, and am also informed that standard auto for something like the Ka-50 is a 120 knot descent with a late flare and a 3g bounce/rolling touchdown. Does this sound about correct? Is there any way to auto a co-axial to the ground with zero forward velocity following the flare?
4) Flight envelope-wise, what conditions must exist for the two separate rotor disks to be at risk of collision? Low RRPM and high forward velocity, for example? Similarly, are the typical danger areas for tail boom strike (low-RRPM and low forward velocity) to other types also applicable to co-axial types?
5) Does the co-axial design lend itself particularly to performance in terms of manouverability?
6) Are there any additional complications from entering VRS in a co-axial type, or are entry criteria and recovery procedures the same as normal?
Any help much appreciated!