kwcarolma
Posts: 40
Joined: Mon Jun 26, 2006 3:57 pm

Engine Sound Onboard A Supersonic Flight

Sun Nov 12, 2006 3:01 pm

I was browsing some aviation related forum and found an interesting question, that whether we're able to hear any sound generated by the aircraft we're onboard when it's flying supersonic. So far I ain't lucky enough to ride a supersonic flight so I don't know the answer. But my guest is we're able to hear that as we're in motion with the aircraft itself so we can catch any sound generated by the aircraft because we're moving in the same speed as it's.
 
Cessna057
Posts: 417
Joined: Tue Sep 26, 2006 10:24 am

RE: Engine Sound Onboard A Supersonic Flight

Sun Nov 12, 2006 3:22 pm

I have never been on a supersonic, but i would think the answer would be this: When you are accelerating to M1.0+, yes you could hear it, but after that, the sound would be behind you and it would be rather quiet. I've heard that the concord was very noisy because of the air passing around the body, not necessarily the engines.

Again, I have never been on a supersonic flight, please correct me if i am wrong
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ptcflyer
Posts: 88
Joined: Fri Apr 13, 2001 12:03 pm

RE: Engine Sound Onboard A Supersonic Flight

Sun Nov 12, 2006 3:26 pm

Flying on Concorde... the sound is like a normal subsonic flight... perhaps the engines are a bit louder.

You are correct, you do not hear any super-sonic booms or any other unusual sounds as you pass through the speed of sound.

The only way of knowing how fast you are going is by:

1) Looking at the Mach Meter at the front of the cabin.
2) Noticing your approach into Paris after only 3 1/2 hours after leaving JFK.

I recall a slight "puff" of acceleration as we passed through Mach 1...but the sound was not very noticeable.

The most noticeable effect of flying supersonic is that the skin of the plane continued to "heat up". Standing near the door... or leaning toward the window, I could feel the heat.

Otherwise, The Concorde had the feeling of a regional jet with domestic first class seats. But the coolest part of the flight is when we were invited to the cockpit! Even post 9/11!
 
vikkyvik
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Joined: Thu Jul 31, 2003 1:58 pm

RE: Engine Sound Onboard A Supersonic Flight

Sun Nov 12, 2006 3:28 pm

Quoting Kwcarolma (Thread starter):
But my guest is we're able to hear that as we're in motion with the aircraft itself so we can catch any sound generated by the aircraft because we're moving in the same speed as it's.

Any sound that is transmitted through the aircraft frame will be heard. The air inside the cabin is not moving with respect to you, so any sounds that reach the cabin air will reach you.

I'd imagine there's quite a bit of noise transmitted through the aircraft, from both the engines and the air friction.

At least, that's the way it seems to me. Correct me if I'm wrong.

"I recall a slight "puff" of acceleration as we passed through Mach 1...but the sound was not very noticeable."

Believe that the bumps you feel are the afterburners (reheats) being lit. If I remember correctly, they're lit at around M0.8, and turned off around M1.6.

[Edited 2006-11-12 07:30:41]
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HAL
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Joined: Tue Jan 15, 2002 1:38 am

RE: Engine Sound Onboard A Supersonic Flight

Sun Nov 12, 2006 4:07 pm

Quoting Vikkyvik (Reply 3):
Any sound that is transmitted through the aircraft frame will be heard. The air inside the cabin is not moving with respect to you, so any sounds that reach the cabin air will reach you.

Vikkyvik is correct. Even in a subsonic jetliner, almost all the engine noise you hear is what is conducted through the airframe, and not across the air into the fuselage. Most of the air moving through the engine is doing so a nearly the speed of sound when the engine is producing high (takeoff, climb, & cruise) power settings, so the sound from inside the engine is hard to hear. The roar from the exhaust can be heard in the aft portions of a subsonic aircraft with wing mounted engines, as is noticeable when you walk from one end of the plane to the other.

With supersonic aircraft of course, you can't hear the noise through the air, but the airframe does conduct that noise, and with higher airspeeds comes more air noise around the fuselage. The concorde was actually a fairly noisy aircraft because of that.

HAL
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Tristarsteve
Posts: 3359
Joined: Tue Nov 22, 2005 11:04 pm

RE: Engine Sound Onboard A Supersonic Flight

Mon Nov 13, 2006 3:39 am

Because the Concorde fuselage heats up in flight it needs more cabin air conditioning to keep it cool.
On my one and only Concorde flight I thought it was quite noisy inside, but it was explained to me later by a Concorde engineer that it was the air conditioning noise.
Also remember the Concorde was always an old aircraft. Technology in cabin noise has come a long way since the early sixties.
 
rtfm
Posts: 421
Joined: Sat Oct 09, 2004 5:35 pm

RE: Engine Sound Onboard A Supersonic Flight

Mon Nov 13, 2006 4:12 am

Believe me - you could hear the engines when you accelerated on take off!

Much louder than a subsonic jet. But in the cruise I can't remember it being any noisier than a subsonic.... And as previously stated, apart from the mach reading in the cabin, there is no other sensation of going supersonic; didn't even cause a ripple in the champagne!

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