Hmm, a few interesting ones there!
The vortex ring state is generally written to include the 'worst state'. What this means is that rotor downwash recirculation, leading to the incipient vortex ring state, can occur below the expected value due to a variety of environmental effects. How many of us have flown a vortex ring demo perfectly? If you take this 'worst case' teaching with an aircraft on a still wind day with a perfect 0 groundspeed descent the rotor tip vortex recirculation will occur at a lower ROD due to the vortex state not being removed from above the rotor by wind/forward airspeed etc... This serves as a warning, especially in cases of photographic flights etc. where the aircraft may be doing 30/40 kts downwind with 30 kts wind and hey presto you are in still air, add in a gentle rate of descent and theres your problem.
It has been seen where rapidly rising air over, for example. a very hot concrete surface can cause a reduction in the required OBSERVED ROD.
Watch out for environmental factors that can bite.
As for the turns, the decision to turn the aircraft is based upon which pedal you use to arrest the turn as not to over torque upon stopping. (be it a US or European Helo)
Gas turbine engines work upon the principle of mass airflow and are optimised to perform at a specific mass throughput. Therefore changing the density of the incoming air will have a dramatic effect upon the engines power/performance. Why do you think we calculate density altitdue calculations for helo ops. Don't expect your Jet Ranger to leap off the pad in Dubai with the same performance as in the UK. It ain't gonna happen. OAT is a performance killer for Jet Helos!!
And Finally, coz thats all I came remember from da points, VFR places the flight visibility, conditions and maintenance therefore, terrain and aircraft collision avoidance with the aircraft captain. The weather gets too cr%^py then don't fly, Land, go home whatever. The captaincy decision is yours alone, if you go for it and screw it up then the decision was yours alone, noting to do with what the rules state. A poor decision will always come from poor information.
Pheew, sit back, don steel helmet and wait for flak!!
