A320 vortex generator retrofit
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Soundsamples:
https://www.lufthansagroup.com/en/re...abatement.html
https://www.lufthansagroup.com/en/re...abatement.html
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Soundsamples:
https://www.lufthansagroup.com/en/re...abatement.html
https://www.lufthansagroup.com/en/re...abatement.html
yes, thank you very much - oder, Vielen dank!
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We (Lufthansa-group airline) have installed them on all our A320 and as someone who lives directly under the approach path of a nearby airport I can tell you that these vortex generators really make a difference. The whisteling noise is completely gone after the modification.
Oh yes, the noise relief is now 6dB at least, that means that the noise energy produced is now divided by 4.
In other words, proviously the silly A320's FOPs emitted 3 times more noise than all the rest of the plane!
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The landing gears can be retracted.
Pilots can however remember that outputting the landing gears too early costs fuel and increases the residential noise.
Regards.
Laszlo
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On the original pure turbojet and low bypass turbofan jets, the engine noise so dominated the noise generation that nobody paid much attention to the aerodynamic noise generation. But as the engines have gotten progressively quieter, the airframe contribution has become increasingly important. Years ago Boeing did a noise test of the 747 (I forget which model but is was long enough ago that I suspect it was a -200). They flew over the microphone array at max takeoff power, then repeated the tests - same speed, altitude, etc. but with the engines at idle. It only made 3 db difference - basically meaning that at takeoff power the airframe contribution to the noise was roughly equal to the engines
On the new, quieter aircraft (787, 747-8, A350, etc) the noise engineers spend as much time working things like the flaps and landing gear as they do the engines.
On the new, quieter aircraft (787, 747-8, A350, etc) the noise engineers spend as much time working things like the flaps and landing gear as they do the engines.
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On the original pure turbojet and low bypass turbofan jets, the engine noise so dominated the noise generation that nobody paid much attention to the aerodynamic noise generation. But as the engines have gotten progressively quieter, the airframe contribution has become increasingly important. Years ago Boeing did a noise test of the 747 (I forget which model but is was long enough ago that I suspect it was a -200). They flew over the microphone array at max takeoff power, then repeated the tests - same speed, altitude, etc. but with the engines at idle. It only made 3 db difference - basically meaning that at takeoff power the airframe contribution to the noise was roughly equal to the engines
On the new, quieter aircraft (787, 747-8, A350, etc) the noise engineers spend as much time working things like the flaps and landing gear as they do the engines.
On the new, quieter aircraft (787, 747-8, A350, etc) the noise engineers spend as much time working things like the flaps and landing gear as they do the engines.
One frequently forget, that landings harms more people than starts. Landing is flat and aircrafts follow the ILS as on rails. The starts are steeper and the routes diverge soon.
And yes some trivial improvements like castellated bolts on the wheels make a significant difference on the landing noise.
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The landing gears can be retracted.
Gatwick will be charging more airbus aircraft not fitted with the FOPP mod. That factors into the business case.
https://www.gatwickairport.com/globa...nt-30jan17.pdf
https://www.gatwickairport.com/globa...nt-30jan17.pdf
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I think the unmodified A320 family sums it up
As part of the wake turbulence measurement, we are measuring the sound frequency of the passing ac, not just the noise level. This helps in the mitigation of noise, as a blanket insulation is overkill, but if you target frequencies, the mitigation can be very effective.
As part of the wake turbulence measurement, we are measuring the sound frequency of the passing ac, not just the noise level. This helps in the mitigation of noise, as a blanket insulation is overkill, but if you target frequencies, the mitigation can be very effective.
Last edited by underfire; 23rd Nov 2018 at 18:38.
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I think the unmodified A320 family sums it up<br />As part of the wake turbulence measurement, we are measuring the sound frequency of the passing ac, not just the noise level. This helps in the mitigation of noise, as a blanket insulation is overkill, but if you target frequencies, the mitigation can be very effective.
I have a detailed frequency diagram for you: The frequency analysis there (Sonogramm) reveals a lot: the whine sound (the pair of Z shaped dark traces) is perceived far before and long after the main aircraft noise.<br />The unmodified A320 is an acoustical catastrophe in the begin of the ILS landing.<br />
Since i can't post an image yet, I invite you to go to cjoint.com and append /doc/18_11/HKxvmhuM0d1_Akustische-Analyse.jpg to that address.
Maybe someone can post the image for me?
Regards
Laszlo
Never found the reason until now. The ugly disgraceful whine sound of A320 family. Only at landing. But not anymore before touchdown. Thanks a bunch they found a solution. Unfortunately still some aren't fixed.
The poster above mentioned diagrams. I share them. The frequencies of those different sized openings are stated as 530Hz and 580Hz. Absolutely disharmonic and annoying, See here the recording of an A320 overfly. Sonogram: Left to right is approaching over leaving the microphone position. More black means higher noise level. See the 2 strong curves, that's the dominating whine sound. And it is the first noise one hears and the last before the noise disappears. Due to doppler effect the frequency lowers during overpass.
The poster above mentioned diagrams. I share them. The frequencies of those different sized openings are stated as 530Hz and 580Hz. Absolutely disharmonic and annoying, See here the recording of an A320 overfly. Sonogram: Left to right is approaching over leaving the microphone position. More black means higher noise level. See the 2 strong curves, that's the dominating whine sound. And it is the first noise one hears and the last before the noise disappears. Due to doppler effect the frequency lowers during overpass.
Oh, this is a good overview
Presentation re EasyJet (gatwickairport.com; PDF)
Presentation re EasyJet (gatwickairport.com; PDF)
Only half a speed-brake
Further search in the old threads reveals your annoyance well share around the globe. At one point, probably even still, Gatwick Airport would charge what, 900 GBP if you'd brought in aircraft without the MOD? Per movement! The answer probably in the AIP.
Only half a speed-brake
Sorry for the grammar of the previous post. More soothing reading here: https://www.gatwickairport.com/globa...19-2024-lr.pdf Slide 45 shows a daytime turn-around with an A320 without the generators incurs a penalty of 1400 GBP. That's actually more of a political statement than a fee, not joking.
