rrrrrrrrrr-sound of airbus/boeing engines
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rrrrrrrrrr-sound of airbus/boeing engines
Hello,
aircraft like the A320, A319 etc. produce a metallic "rrrrrrrrrrrrrrrrrr"-sound
when the engines are running at full thrust. B757 and B767 (depends on engine type) also have this sound sometimes, and if you listen carefully, you will also hear it in a 737 or 747, but not that loud as in the airbus family.
I have a few questions concerning the "rrrrrrrrrrrrrrrrr"-sound:
1) Why does it exist, what are the technical reasons for it? This is most interesting for me.
2) Why is it only at high thrust levels?
3) Why is it stronger in some aircraft (i.e. A320) und weaker in other aircraft (i.e. B767)
4) Does an ordinary airline pilot
know why the engine produces such a sound?
Thanks!
Malte
EDDH
aircraft like the A320, A319 etc. produce a metallic "rrrrrrrrrrrrrrrrrr"-sound
when the engines are running at full thrust. B757 and B767 (depends on engine type) also have this sound sometimes, and if you listen carefully, you will also hear it in a 737 or 747, but not that loud as in the airbus family.I have a few questions concerning the "rrrrrrrrrrrrrrrrr"-sound:
1) Why does it exist, what are the technical reasons for it? This is most interesting for me.
2) Why is it only at high thrust levels?
3) Why is it stronger in some aircraft (i.e. A320) und weaker in other aircraft (i.e. B767)
4) Does an ordinary airline pilot
know why the engine produces such a sound? Thanks!
Malte
EDDH
Originally Posted by Malte
Hello,
aircraft like the A320, A319 etc. produce a metallic "rrrrrrrrrrrrrrrrrr"-sound when the engines are running at full thrust. B757 and B767 (depends on engine type) also have this sound sometimes, and if you listen carefully, you will also hear it in a 737 or 747, but not that loud as in the airbus family.
I have a few questions concerning the "rrrrrrrrrrrrrrrrr"-sound:
1) Why does it exist, what are the technical reasons for it? This is most interesting for me.
2) Why is it only at high thrust levels?
3) Why is it stronger in some aircraft (i.e. A320) und weaker in other aircraft (i.e. B767)
4) Does an ordinary airline pilot know why the engine produces such a sound?
Thanks!
Malte
EDDH
aircraft like the A320, A319 etc. produce a metallic "rrrrrrrrrrrrrrrrrr"-sound
when the engines are running at full thrust. B757 and B767 (depends on engine type) also have this sound sometimes, and if you listen carefully, you will also hear it in a 737 or 747, but not that loud as in the airbus family.I have a few questions concerning the "rrrrrrrrrrrrrrrrr"-sound:
1) Why does it exist, what are the technical reasons for it? This is most interesting for me.
2) Why is it only at high thrust levels?
3) Why is it stronger in some aircraft (i.e. A320) und weaker in other aircraft (i.e. B767)
4) Does an ordinary airline pilot
know why the engine produces such a sound? Thanks!
Malte
EDDH
I have never met an ordinary airline pilot so I have no idea what he knows.
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I know what you mean about the 'rrrrrrrrrrr' noise. My sister lives in Langley (close to Heathrow) and you can always tell whether it's a Boeing or an Airbus just by listening to it's engines! 
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How would you explain the fact that the Airbus engines produce this noise and the Boeings not (or not much). Do they have the same cowles? I have also noticed this when the aircraft are at low altitude. I generally have two aircraft fly over my house at around 10pm from Heathrow. One is a 747 and the other is an A340.
Do they have the same engines?
Do they have the same engines?
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Originally Posted by paulkinm
How would you explain the fact that the Airbus engines produce this noise and the Boeings not (or not much). Do they have the same cowles? I have also noticed this when the aircraft are at low altitude. I generally have two aircraft fly over my house at around 10pm from Heathrow. One is a 747 and the other is an A340.
Do they have the same engines?
Do they have the same engines?
But when they pass your house, that may partly be a matter of configuration difference between the types, thus different power setting. But the sound it self is no mistery, simple shockwave.
Except the sound is known to be a bit odd at 10 PM.
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It's actually the engine manufacturer. For example, an IAC powered Airbus sounds a lot different than a CFM powered one. The Rour is in the CFM engine. The IAC just sort of hushes.
A more interesting thread would be to discuss lomapaseo's comment,
Cheers /cj
A more interesting thread would be to discuss lomapaseo's comment,
"...I have never met an ordinary airline pilot so I have no idea what he knows..."
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Buzz Saw?
There have been quite a few threads on "buzz saw" noise (if this is the noise that you refer to) from high bypass (mostly RR?) engines on this section. Did a search but couldn't find the one I was looking for, but several others.
When we started building 747 sims, we had to add this to our "standard" sound sim system, and I think it was related to the high-bypass, large-diameter, fans. (although I don't remember it on the "Peggy 6" in the Harrier - maybe because the Pegasus, although 5:1, was a smaller diameter?)
Only really noticable at high power settings, and I hear it clearly these days when flying (in the back of) A330s, especially during the climb.
When we started building 747 sims, we had to add this to our "standard" sound sim system, and I think it was related to the high-bypass, large-diameter, fans. (although I don't remember it on the "Peggy 6" in the Harrier - maybe because the Pegasus, although 5:1, was a smaller diameter?)
Only really noticable at high power settings, and I hear it clearly these days when flying (in the back of) A330s, especially during the climb.
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You can compare a few here, unfortunately no Airbus sounds or engine identification, however, for the nostalgic Concorde is included:
http://www.caa.co.uk/default.aspx?ca...=90&pageid=321
http://www.caa.co.uk/default.aspx?ca...=90&pageid=321
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I would describe the noise as a "buzz-saw moan".
On the L-1011 (RB-211) it was most pronounced in early climb, and reduced in intensity as speed increased, suggesting that it might be resonance that was N1/airspeed sensitive.
It was quite reassuring to hear after a heavy takeoff, you could now relax and enjoy the rest of the flight.
On the L-1011 (RB-211) it was most pronounced in early climb, and reduced in intensity as speed increased, suggesting that it might be resonance that was N1/airspeed sensitive.
It was quite reassuring to hear after a heavy takeoff, you could now relax and enjoy the rest of the flight.
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My favourite jetnoise
B777-200 in a rolling takeoff.
http://www.flightlevel350.com/Aircra...ideo-4435.html
B777-200 in a rolling takeoff.
http://www.flightlevel350.com/Aircra...ideo-4435.html
Oops pardon me
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Airbus v Boeing
If u take an A319 or 320 with CFM 56 you will notice although the core is basically the same as a 737, the fan is bigger. Quite a lot bigger in fact so you get quite a different harmonic note from it. Coupled with the fact that the nose cone is different and the jet pipe it could almost be regarded as a completely different engine as far as the rrrrrrrrrr sound is concerned!
Coop & whats that nois
e Bear
Coop & whats that nois
e Bear
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Are you fella's the guys I see at the airport lookout with a dozen antennas hanging off your car, standing on the roof with some binoculars and a handheld radio?
I heard they sell tapes of jet noises on the same stand as "sounds of the rainforest" and "songs of the whales" in the airport news agent.
I heard they sell tapes of jet noises on the same stand as "sounds of the rainforest" and "songs of the whales" in the airport news agent.
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I am with Chopper
Its a noise that is caused by the different design of fan blades. BFD !
It allows me to sit at my desk without having to get off my ass and see if it is my next aircraft arriving on bay so my coffee or conversation is not disturbed.
Wide cord fan blades V long thin (high aspect) are going to make a different sound. The engine manufacturer has to keep their engine under a certain decibel rating not a tone.
If tone were in the equation perhaps there would be a need for engine run trimming to the sound to the Doh Ray Mee song..
Pilots could make tech log write ups.
At take off thrust engine 2 made more of a "Doh" sound rather than a "Ray" sound during takeoff power as confirmed by all Tech crew and cabin crew singing in chorus.
Now every one after me....MEE MEE MEE MEEEEEE
This thread deserves to be in the spotters forum!!!
Its a noise that is caused by the different design of fan blades. BFD !
It allows me to sit at my desk without having to get off my ass and see if it is my next aircraft arriving on bay so my coffee or conversation is not disturbed.
Wide cord fan blades V long thin (high aspect) are going to make a different sound. The engine manufacturer has to keep their engine under a certain decibel rating not a tone.
If tone were in the equation perhaps there would be a need for engine run trimming to the sound to the Doh Ray Mee song..
Pilots could make tech log write ups.
At take off thrust engine 2 made more of a "Doh" sound rather than a "Ray" sound during takeoff power as confirmed by all Tech crew and cabin crew singing in chorus.
Now every one after me....MEE MEE MEE MEEEEEE
This thread deserves to be in the spotters forum!!!
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Hmm, thinking about it now actually I'd probably be trying to name what engine type/aircraft the noise is coming from so sleep would be improbable.
Never mind.
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rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr sound is typical of high bypass turbo fan engines. the rrrrrrrrrrrrrrrrrrrrrrrrr is the sound from the compressors and fan. by-passing causes less shear at the rear end hence less jet noise; compare the modern aircraft 767 etc to a 727 or 732. the latter has very little by-pass so the jet noise becomes the dominant noise.
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An example of an RB211 producing the same effect here:
http://www.flightlevel350.com/Aircra...ideo-3611.html
http://www.flightlevel350.com/Aircra...ideo-3611.html