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Why are the cabin chimes one semitone lower on the Boeing 747-400 than on other aircraft? [closed]

I noticed that the cabin chimes on the Boeing 747-400 overall sound one semitone lower than on other aircraft, including the 737, 777, Airbus A320, and even the 747-8. The same semitone-lower chimes ...
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0answers
45 views

What is the importance of Mach number (M) on shock waves?

My primary question is: what is the importance of Mach number (M) on shock waves? Although I believe confirming and/or answering the below will help clarify my misconceptions. When a wave moves ...
27
votes
3answers
4k views

Why would a turboprop rev down just before going full throttle during takeoff?

The only turbprop I've travelled is the ATR 72. I've noticed that the props' rev go down (for like a second, the sound also goes down) just before engaging full throttle in order to takeoff. I've ...
9
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1answer
2k views

What did the “gear warning horn” on the North American P-51 sound like?

I'm working on a sound project for a P51 simulation and I'm having real trouble trying to find a reference on how the P51 gear warning horn sounded like. What mechanisms were used in the '40s to make ...
4
votes
2answers
477 views

What causes the “growl” of some large turbofans at takeoff thrust?

There are some (all?) large turbofans which emit a distinct "growl" (some people call it a "buzzsaw" sound) at takeoff thrust. What causes it? I've seen it explained (as in this question) as the fan ...
2
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0answers
481 views

Why Planes Don't Fly Faster? [duplicate]

I recently Stumbled on this Why Planes Don't Fly Faster on youtube and it talked about how less speed is more economical for airlines and he also said something that plane above and below speed of ...
9
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4answers
1k views

Can an experienced airplane spotter identify planes only by sound?

I come from a background in railroad watching, and often times one can identify the maker of a railroad locomotive purely by sound. Maybe not the exact model of locomotive, but at least what type of ...
3
votes
1answer
776 views

What do we hear, on the ground, from a helicopter in flight?

Last week I heard a helicopter approaching from a distance. The sound it made was a very distinct and deep wop wop wop at a remarkably slow two beats per second, more or less. As it came closer, the ...