Ah, Geoffers, the thought of all that delicious Italian pasta for supper! Though I prefer the suppers after a trip in a French sim
Only ever saw "Vortex Ring" once - in a Whirlwind on the climb to 10,000ft sortie when in was demoed on the way back down - decided I would avoid it at all costs - at that height I couldn't tell if we had a head or tail wind - neither could the old Whirly 10
HF
Crab - I am surprised at your answer - head and tail winds are only with reference to the earth not the the mass of air the helicopter is flying in!!