Sound radar most definately exists with canopy open, which I always do coz I can see better. I only fly red, just in case anyone doesn't know.
Last night I would've been blown out of the sky by Little_D were it not for hearing him coming. I checked my 6 and there he was, easily 100yds away.
I avoided his first pass with a steep turn and we swung around for a couple of more or less head on passes, and on the third pass he stopped my engine. I got a shot off at him even with a dead engine but missed, then dived down to Hawkinge for an emergency landing.
I survived, but really I shouldn't have.