Soundsamples:
https://www.lufthansagroup.com/en/re...abatement.html

Nice! Thank you!

It was the concern of FlightDetent that the small vortex gens could have a negative impact on the fuel consumption.
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

Yes. Unfortunately many planes from Eurowings taken over from Air Berlin are still not retrofitted. Their managers seem to be unable to calculate.

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 :eek:
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.

I m not surprised. The engines ususally radiate noise behind the aircraft.The noise intensity with hen engines on might make only 3dB difference, the duration is however longer. But for the certification tests the duration was not relevant.
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.

I was referring to the variants where, when retracted, the landing gear is not covered. I would think that castellated bolts would make more noise?
https://cimg5.ibsrv.net/gimg/pprune....c39c0693eb.jpg


https://cimg8.ibsrv.net/gimg/pprune....8ac7637c88.jpg

Charges seem not insignificant. Page 27 (as printed on bottom of page). I don't know what "chapter" the A320 is in. Text is all legible here if page full screen.

https://cimg1.ibsrv.net/gimg/pprune....e76d8289ea.png

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.

Chapter 4.

<br /><br />

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.

https://cimg6.ibsrv.net/gimg/pprune....9f6228c712.jpg
https://cimg9.ibsrv.net/gimg/pprune....f351dcfbe6.jpg

Oh, this is a good overview
Presentation re EasyJet (gatwickairport.com; PDF)

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.

Obviously such was necessary to force the airlines into action. Well done, Gatwick! If some other relevant airports follow, healing is ahead. I mean, the A320 family, compared to recent other traffic on approach, was outstanding in noise and how it bothers your brain.

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.