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"Wang" Noise On Take-off From Jet Engines  
User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Posted (6 years 1 week 3 hours ago) and read 10714 times:

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.


What gets measured gets done.
25 replies: All unread, showing first 25:
 
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (6 years 1 week 2 hours ago) and read 10698 times:



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.


User currently offlineSkoker From United States of America, joined Apr 2006, 439 posts, RR: 1
Reply 2, posted (6 years 1 week 2 hours ago) and read 10696 times:

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:



User currently offlineLowrider From United States of America, joined Jun 2004, 3220 posts, RR: 10
Reply 3, posted (6 years 1 week 1 hour ago) and read 10663 times:



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.



Proud OOTSK member
User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 4, posted (6 years 6 days 11 hours ago) and read 10496 times:



Quoting Lowrider (Reply 3):

Yes sir. This is why I love tech ops.



What gets measured gets done.
User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 5, posted (6 years 6 days 8 hours ago) and read 10428 times:



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?



Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (6 years 6 days 3 hours ago) and read 10374 times:



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.


User currently offlineSpeedracer1407 From United States of America, joined Dec 2004, 333 posts, RR: 0
Reply 7, posted (6 years 6 days 2 hours ago) and read 10353 times:



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.



Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
User currently offlineMir From United States of America, joined Jan 2004, 21642 posts, RR: 55
Reply 8, posted (6 years 6 days 1 hour ago) and read 10330 times:



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



7 billion, one nation, imagination...it's a beautiful day
User currently offlineHangarRat From United States of America, joined Jul 2005, 633 posts, RR: 0
Reply 9, posted (6 years 5 days 15 hours ago) and read 10225 times:



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.



Spell check is a false dog
User currently offlineSPREE34 From United States of America, joined Jun 2004, 2248 posts, RR: 9
Reply 10, posted (6 years 5 days 14 hours ago) and read 10204 times:



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!



I don't understand everything I don't know about this.
User currently offlineUSAIRWAYS321 From United States of America, joined Jul 2001, 1848 posts, RR: 9
Reply 11, posted (6 years 5 days 13 hours ago) and read 10163 times:

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.

User currently offlineKimberlyrj From United Kingdom, joined Mar 2008, 385 posts, RR: 1
Reply 12, posted (6 years 5 days 12 hours ago) and read 10150 times:

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.


User currently offlineAccess-Air From United States of America, joined Sep 2000, 1939 posts, RR: 13
Reply 13, posted (6 years 4 days 13 hours ago) and read 9961 times:

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



Remember, Wherever you go, there you are!!!!
User currently offlineAA737-823 From United States of America, joined Mar 2000, 5831 posts, RR: 11
Reply 14, posted (6 years 2 days 18 hours ago) and read 9775 times:



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.


User currently offline747fan From United States of America, joined Jun 2007, 1187 posts, RR: 1
Reply 15, posted (6 years 2 days 16 hours ago) and read 9765 times:

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:



User currently offlinePhxplanes From United States of America, joined Feb 2005, 436 posts, RR: 0
Reply 16, posted (6 years 2 days 10 hours ago) and read 9707 times:

I thought the blades could not go supersonic because they would loose a lot of efficiency from the turbulent air flow.

User currently offlineSovietjet From Bulgaria, joined Mar 2003, 2612 posts, RR: 17
Reply 17, posted (6 years 2 days 9 hours ago) and read 9705 times:
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Is there a video anywhere of an early 747 with the JT9D and blow-in doors?

User currently offline71Zulu From United States of America, joined Aug 2006, 3082 posts, RR: 0
Reply 18, posted (6 years 2 days 8 hours ago) and read 9681 times:

Good sound on this one

 bigthumbsup 




The good old days: Delta L-1011s at MSY
User currently offlineEGNR From United Kingdom, joined Feb 2004, 510 posts, RR: 0
Reply 19, posted (6 years 2 days 7 hours ago) and read 9672 times:

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!





7late7, A3latey, Sukhoi Superlate... what's going on?
User currently offlineSPREE34 From United States of America, joined Jun 2004, 2248 posts, RR: 9
Reply 20, posted (6 years 2 days 6 hours ago) and read 9657 times:



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.



I don't understand everything I don't know about this.
User currently offlineFlyASAGuy2005 From United States of America, joined Sep 2007, 7004 posts, RR: 11
Reply 21, posted (6 years 2 days 3 hours ago) and read 9629 times:



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...



What gets measured gets done.
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 22, posted (6 years 2 days 1 hour ago) and read 9607 times:



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.


User currently offlineBartonsayswhat From Canada, joined Oct 2007, 434 posts, RR: 0
Reply 23, posted (5 years 12 months 4 days ago) and read 9408 times:



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.


User currently offlineCc2314 From Ireland, joined Jan 2008, 159 posts, RR: 0
Reply 24, posted (5 years 12 months 3 days 16 hours ago) and read 9366 times:

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!!!

User currently offlineLuv2cattlecall From United States of America, joined Sep 2007, 1650 posts, RR: 2
Reply 25, posted (5 years 11 months 4 weeks 5 hours ago) and read 9094 times:
Support Airliners.net - become a First Class Member!



Quoting SPREE34 (Reply 10):
Depends on accent.

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



When you have to breaststroke to your connecting flight...it's a crash!
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