Considering such rare aircraft as the Beechcraft Starship, the Saab Draken, the F4 Phantom, or three F7F Tigercats flying together, the video I captured of the Piaggio Avanti has been the most sought after. I was enjoying a beautiful spring day at the airport when I heard that distinctive sound of an Avanti approaching so I swung up my camera and was able to finally capture a landing. Looks like it zips right along in landing too!
Another possible reason for their unique sound: low and high pressure air meeting at the trailing edge of the wing that is then being chopped up by the five-bladed propellors.
For more information on the Piaggio Avanti, see their web site at: http://www.piaggioaero.com/en/