I was set up to record a Mark IX Spitfire at the Imperial War Museum, Duxford, near Cambridge when an announcement came over the PA system that a couple of Chinook helicopters would be carrying out a "Tactical Landing"... Well, why am I telling you this? You can hear for yourselves: the PA announcement comes mainly from the left and slightly to the rear with a lot of excellent bounce-back from assorted hangars. Some kids run up to watch the fun and the two Chinooks duly arrive from the left and depart to the right, with more bounce from the rear. Rather nice, I think.