Originally Posted by
double_barrel
At around 6'30" to 6'40" what sounds like a 'beat' is audible. ie a low frequency due to the interaction of 2 high frequencies. Is it possible that this is due to sound bouncing back from the ground? If so, is that a 'thing' and can it ever convey useful information?
sounds like blade slap to me, due to loading the rotor (pulling g) as the pilot starts to lose control.