|
|
Post by clifftop on May 19, 2019 17:21:46 GMT 1
I live close to Liverpool airport and as I'm sure many of you do, I have Manchester arrivals going overhead my house at around 5000 ft.
I have noticed that at some point there is a really weird sound, almost like the engines are struggling, it's a bit like a very slow ambulance siren, only lasts a couple of seconds. What law of physics is causing it?
|
|
|
|
Post by viscount on May 19, 2019 17:31:59 GMT 1
Both Airbus and Boeing have put much research into reducing airframe noise in the past decade or more. One result is the engineered shape of the engine rear cowling on Boeing's newer products The Boeing 757 makes a very audible extended 'whoop' as the flaps are further extended and airflow over the wings disrupted. I've heard this frequently over South Liverpool from aircraft on descent to Manchester, although Airbus products and the '737 flaps extension are nothing like as audible. In the descent airframe noise is greater than that of engine thrust created sound. Undercarriage doors opening and extension of the legs leads to another set of sounds closer to finals.
Nothing beats the F-104 Starfighter opening the speed brakes at the end of an airshow fast and low pass though!
|
|
|
|
Post by clifftop on May 20, 2019 13:47:34 GMT 1
Thanks Brian. A very good explanation, cheers.
|
|
