Originally Posted by
treadigraph
I recall being in the Friends of Fighter Collection area at Duxford's Flying Legends once - two guys were running trailer mounted Griffon and Merlin nearby, both beautiful sounding engines yet with those particular short props or the RPM chosen or whatever there was an unpleasant resonance; no idea if we were in the focal point or if it was more widespread. Noticed that the A400 also produces a similar unpleasant noise sometimes when flying overhead outbound Brize, quite painful on the lugs.
I was there that day (if there was only one) as well, and thought the engines being run on trailers was a fascination. Got a photo somewhere.
Big prop aircraft noise coming right through into the house from altitude has made a reappearance with the A400. Have had them go over at 30,000ft and heard them inside two closed doors. Used to live long ago close to the Wallasey VOR, and although you could hear the Vanguards at altitude on London to Belfast etc from the garden, I don't remember ever it being inside. The only other thing I pick up here is the An-12 from various operators, they seem to be a quite bit lower at about 23,000ft, which is possibly the limit of their pressurisation.