Page 1 of 1

"Wang" Noise On Take-off From Jet Engines

Posted: Wed Sep 17, 2008 3:16 am
by FlyASAGuy2005
To hear what I am talking about, you must be sitting either right next to the engine opening or forward of it all together (low wing engines).

I've always noticed on take-off as the throttles are advanced, you hear the scream of the engine but then it is overtaken by a low pitched "wang" noise. A good example is in the bellow video, or any video shot in the front of coach or first class. The engine "scream" as I call it starts at about 00:32 and the "wang" noise takes over pretty quickly at around 00:34 - 00:35.

http://www.youtube.com/watch?v=ETD_q8swEfk (sorry, I don't know how to make the vid show in the thread Big grin )

I've been told by enthusiasts that the sound i'm hearing is the blades moving faster than the speed of sound. Sounded pretty crazy to me but more than one person has given me this explanation.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Wed Sep 17, 2008 4:12 am
by tdscanuck


Quoting FlyASAGuy2005 (Thread starter):
The engine "scream" as I call it starts at about 00:32 and the "wang" noise takes over pretty quickly at around 00:34 - 00:35.



Quoting FlyASAGuy2005 (Thread starter):
I've been told by enthusiasts that the sound i'm hearing is the blades moving faster than the speed of sound. Sounded pretty crazy to me but more than one person has given me this explanation.

Correct. The fan blade tips are going locally supersonic.

Tom.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Wed Sep 17, 2008 4:26 am
by skoker
Wow, 1 hour and change and nobody's ripped on your use of "wang" in the thread topic yet. A gleam of hope from the A.net population?

For the lazy clickers in said population:


RE: "Wang" Noise On Take-off From Jet Engines

Posted: Wed Sep 17, 2008 5:34 am
by lowrider


Quoting Skoker (Reply 2):
A gleam of hope from the A.net population?

Hey, this is Tech/Ops, not to be confused with some of the Cretins in (Un)Civil Av.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Wed Sep 17, 2008 7:52 pm
by FlyASAGuy2005


Quoting Lowrider (Reply 3):

Yes sir. This is why I love tech ops.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Wed Sep 17, 2008 10:49 pm
by speedracer1407


Quoting Skoker (Reply 2):
Wow, 1 hour and change and nobody's ripped on your use of "wang" in the thread topic yet. A gleam of hope from the A.net population?

I was gonna comment on that, but not for the obvious reasons. I'm not sure why anyone would describe a deep buzz-saw sound as "wang." Does wang sound like brap? Or quack? Or kapow?

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 3:36 am
by tdscanuck


Quoting Speedracer1407 (Reply 5):
I'm not sure why anyone would describe a deep buzz-saw sound as "wang."

Among other things, I think of "wang" as the sound you get when one piece of metal bounces off another and vibrates. On some aircraft/engine combinations, if you fudge it a little bit, the "buzz saw" effect does sound kind of metallic.

Tom.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 4:22 am
by speedracer1407


Quoting Tdscanuck (Reply 6):
Among other things, I think of "wang" as the sound you get when one piece of metal bounces off another and vibrates. On some aircraft/engine combinations, if you fudge it a little bit, the "buzz saw" effect does sound kind of metallic

Quite. I thought of the sound a saw makes when you bend it and let it flick back into shape. Thus, I was hoping for a long thread trying to diagnose such an unusual sound coming from a plane on takeoff.

As long as we're talking about the "buzz saw" effect, it seems that most enthusiasts assume that the world was introduced to that unique sound with the first big fan engines, like the JT9D. But I swear I hear it quite clearly on small-fan JT8Ds in any seat forward of the intakes on an MD-80 at takeoff. And in a recent cockpit video of a KC-135 with JT3Ds, the buzz saw sound could be heard loud and clear.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 5:40 am
by Mir


Quoting Speedracer1407 (Reply 7):
As long as we're talking about the "buzz saw" effect, it seems that most enthusiasts assume that the world was introduced to that unique sound with the first big fan engines, like the JT9D.

I first heard it on a 767 with GE engines.

-Mir

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 3:41 pm
by hangarrat


Quoting Speedracer1407 (Reply 7):
It seems that most enthusiasts assume that the world was introduced to that unique sound with the first big fan engines, like the JT9D.

I think they were the first engines from which you could hear the fan sound on the ground. I remember summers as a kid playing in my grandmother's garden off the departure end of one of the runways at LHR wondering what made the big jets sound different.

Quoting Speedracer1407 (Reply 7):
But I swear I hear it quite clearly on small-fan JT8Ds in any seat forward of the intakes on an MD-80 at takeoff.

I remember being surprised to hear it the first time I flew on a DC-9. Most of the flying I did until I was 20 or so was on 747s across the pond. Can't say I ever noticed the sound on 727s.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 4:27 pm
by SPREE34


Quoting Skoker (Reply 2):
Wow, 1 hour and change and nobody's ripped on your use of "wang" in the thread topic yet. A gleam of hope from the A.net population?

The song is Wang Chung. Done by the Rolls Royces some time back. I think the had a few other hits in the 80s.

Quoting Speedracer1407 (Reply 5):
I was gonna comment on that, but not for the obvious reasons. I'm not sure why anyone would describe a deep buzz-saw sound as "wang." Does wang sound like brap? Or quack? Or kapow?

Depends on accent.


It's a beautiful noise!

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 6:01 pm
by USAIRWAYS321
The buzzsaw is one of my favorite sounds. I first noticed it on the A320 family, and perhaps it's in my head, but I tend to notice it more on those aircraft than any other.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 18, 2008 6:35 pm
by kimberlyRJ
Hi there

Quoting USAIRWAYS321 (Reply 11):
The buzzsaw is one of my favorite sounds. I first noticed it on the A320 family, and perhaps it's in my head, but I tend to notice it more on those aircraft than any other

I love it to, sounds great. I also noticed a very odd sound while working on a B772 GE version. On approach it makes so great buzzsaw / lawnmower. The RR version does not seem to do this, but makes a great growl sound on take off, its GREAT!

Kimberly.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Fri Sep 19, 2008 6:10 pm
by access-air
I have heard this Buzz Saw sound on many jets too and including the BAC OneEleven!! I have audio recorded a couple BAC fligts in the area of the engine inlet and you could definately hear it. Also a few flights on DC9s of all sizes and engine marks. Too and including 737-200s and 727-100/200.....Taped the sounds of a flight on an TWA 7272-231 back in 1987 from KCMO to STL and I was in seat 29F with an engine outside my window..Talk about a nice Pratt And Whitney song....You can also hear that buzz in a tape I made taking off in an AA DC10 out of Las Vegas....Some engines you cannot detect it because of all the sound suppression on the inlet. The Fokker 70/100 can be heard loud and clear.
The Buzz Saw sound would probably be much louder if it was not shrouded...Can you imagine the noise of one of those high bypass engines if the front fan was exposed? If you shrouded a prop on a prop plane and ducted it I can gurantee itd sound different just the same.

Have any of you heard the shriek made by the Good Ole C-5 Galaxy? Correct me if I am wrong, but back in the day, wasnt that just about how loud the first 747 engines used to be? Especially with their blow in doors?

Okay, I just thought Id throw in my 2 cents worth...

Access-Air

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Sun Sep 21, 2008 12:50 pm
by AA737-823


Quoting USAIRWAYS321 (Reply 11):
I first noticed it on the A320 family

Indeed, the A320 is a great wang aircraft.

Sorry, couldn't resist.

But it's true- the IAE V2500 engine is known for its very unique noise. And the CFM on the Airbus sounds strange, too. Sounds quite different from the similar engine on the 737s.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Sun Sep 21, 2008 2:49 pm
by 747fan
I love that sound, its noticeable on almost all turbofan-powered aircraft, even low-bypass ones such as the PW JT8D and RR Spey (and even the PW JT15 on the Cessna Citation).
One of the best examples of this buzzsaw sound is that made by the RB211's on the 757:


RE: "Wang" Noise On Take-off From Jet Engines

Posted: Sun Sep 21, 2008 9:10 pm
by phxplanes
I thought the blades could not go supersonic because they would loose a lot of efficiency from the turbulent air flow.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Sun Sep 21, 2008 9:27 pm
by sovietjet
Is there a video anywhere of an early 747 with the JT9D and blow-in doors?

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Sun Sep 21, 2008 10:54 pm
by 71Zulu
Good sound on this one

 bigthumbsup 


RE: "Wang" Noise On Take-off From Jet Engines

Posted: Sun Sep 21, 2008 11:31 pm
by egnr
From spotting at MAN, my perception is that the best aircraft for this buzzsaw noise is the RR-powered B757.

It seems to be particularly prevalent on the more elderly B757s - when Air 2000 was re-branding to First Choice, a number of their older B752s were cycled out of the fleet for newer models. The older ones had a more obvious buzzsaw sound than the newer ones. Or at least that's my perception. Jet2 have at least one B752 with a very vocal buzzsaw sound!



RE: "Wang" Noise On Take-off From Jet Engines

Posted: Mon Sep 22, 2008 12:35 am
by SPREE34


Quoting Phxplanes (Reply 16):
I thought the blades could not go supersonic because they would loose a lot of efficiency from the turbulent air flow.

The flow only goes supersonic at the blade tips.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Mon Sep 22, 2008 3:24 am
by FlyASAGuy2005


Quoting 747fan (Reply 15):
One of the best examples of this buzzsaw sound is that made by the RB211's on the 757:

I'm a little biass to PW Big grin .

Quoting 71Zulu (Reply 18):

Agreed! Thanks for the addition!

Quoting EGNR (Reply 19):
It seems to be particularly prevalent on the more elderly B757s - when Air 2000 was re-branding to First Choice, a number of their older B752s were cycled out of the fleet for newer models. The older ones had a more obvious buzzsaw sound than the newer ones. Or at least that's my perception. Jet2 have at least one B752 with a very vocal buzzsaw sound!

I dn't know that it is with the 757. I've heard it on the T7 and 767 but it always sounded even "sweeter" on the 75.

Side note that kind of has nothing to do with this, but has anyone ever stood on the ramp or atleast near a CRJ and hear those engines scream (I hope this is a better example than wang  crossfingers  )when they are spooled up for taxi or on take-off? It's the best sounding engine during that time IMO...

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Mon Sep 22, 2008 6:11 am
by tdscanuck


Quoting Phxplanes (Reply 16):
I thought the blades could not go supersonic because they would loose a lot of efficiency from the turbulent air flow.

Turbulence isn't the problem (I suspect most blades have turbulent boundary layers most of the time), it's shock waves that are the issue when you go supersonic. However, as previously noted, it's a local phenomenon that isn't affecting most of the fan.

Going locally supersonic isn't a death sentence or anything...the airflow on the upper side of the wing is also locally supersonic at cruise conditions for most commercial jets.

Tom.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 25, 2008 7:11 am
by Bartonsayswhat


Quoting FlyASAGuy2005 (Reply 21):
stood on the ramp or atleast near a CRJ

the CRJ spool up is a very nice sound, esp the UAX (skywest) taxiing out on one engine. in my station the rest of the CRJ is 200s and the pilots seem to just nudge off the stand, very little spooling.

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Thu Sep 25, 2008 2:32 pm
by cc2314
I was crew onboard a L1011 (euro atlantic airways) i had a cockpit seat on a leg fron snn -dub,instead of staying in the cockpit i opted to go sit in the seat that was closest to the engine,,the growl from them RR on take off is unreal!!!

RE: "Wang" Noise On Take-off From Jet Engines

Posted: Wed Oct 01, 2008 2:10 am
by luv2cattlecall


Quoting SPREE34 (Reply 10):
Depends on accent.

The BA aircraft sing through crooked fan blades that've never seen an Ortho  duck