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Questions tagged [noise-reduction]

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6
votes
2answers
725 views

Is engine sync to avoid beat frequencies also a concern for jet engines?

Is synchronization of rpm to avoid beat frequencies also a concern on jet engine aircraft like it is on propeller driven airplanes? Context: This question on SE-Aviation discusses prop sync for ...
16
votes
2answers
7k views

What is the loud noise of a helicopter when the rotors are not yet moving?

What is the loud noise when a helicopter is ready to start flying, but the rotor is not yet rotating? For example at Trump's "chopper talk", when he is intercepted by reporters on the way to Marine ...
31
votes
2answers
4k views

Why don't modern jet engines use forced exhaust mixing?

Jet engines are noisy[citation needed] - even a modern high-bypass turbofan is still deafeningly loud compared to pretty much anything except the even-louder low-bypass turbofans or a turbojet (much ...
11
votes
6answers
3k views

Is ear protection necessary for General Aviation aircraft?

What would happen if someone flew a brand new Cessna Skylane/Caravan or a Robinson R22 without using earplugs or headphones? Would they get hearing damage or it would be just a little bit loud where ...
4
votes
1answer
294 views

What is the cabin noise hertz in typical commercial aircrafts?

In cabin, we hear noises in commercial aircrafts. Wondering if it is in general over or under 100 hz. There should be a band width. Thanks!
1
vote
2answers
197 views

Using ANR aviation headset with a PC

I just started my studies towards PPL, and am looking into buying a good ANR aviation headset for flying on Cessna 172. I have an office job, and I'm dealing with a lot of noise, hence ideally I'd ...
4
votes
2answers
142 views

How (and when) does Heathrow alternate arrival paths?

I've noticed that flights over Richmond (particularly arrivals) seem to have significantly reduced over the last few weeks. This is based on looking at Flightradar, as well as listening to the noise ...
4
votes
0answers
130 views

Aerospike nose cones for supersonic jets?

Not to be confused with aerospike nozzles. This is about the big pin-like rod in front of ICBM nose cones. This answer (from Space) about aerospike nose cones notes that one of the potential ...
3
votes
1answer
564 views

Why does Schiphol airport have such a long taxi way? [duplicate]

I heard that from runway 18R-36L the taxi time is around 20 minutes, I heard that this runway was built and is used mainly to reduce noise pollution, but what reasons are there for the length of the ...
2
votes
2answers
491 views

What are ways to reduce drag and noise generated by the landing gear?

Apart from using fairings, what ways are there, or have been studied, but not necessarily implemented in reducing drag and noise produced by the landing gear, mainly for commercial aircraft with ...
7
votes
1answer
161 views

Do noise abatement procedures have an impact on aircraft emissions?

The ICAO has imposed Noise Abatement Departure Procedures (NADP1 and NADP2) in order to limit the noise impact of departing aircraft on communities living nearby airports. Could noise reduction lead ...
3
votes
1answer
583 views

Is hypersonic flight possible with a Busemann's Biplane?

The modifications to the Busemann's Biplane design reported in this article have proven that it is possible to design a modified Busemann's Biplane wing design that actually produces lift at ...
5
votes
2answers
968 views

What noise reduction measures were taken in the time between hush kits and chevrons?

In older jets such as 727 hush kits are used in the engines to reduce noise. In very modern jets such as 787 or 747-8F, chevrons are used for the same purpose. What happened in between? The switch to ...
2
votes
1answer
459 views

Which type of chevrons is applied on the B787?

Which type of chevron nozzle was applied on the B787? I'm really confused about whether if it's sawtooth or sine wave.
9
votes
3answers
4k views

Why are light aircraft engines so noisy?

I live near an airport where students spend a lot of time flying circuits. During the base leg, pilots can be heard reducing engine revs prior to the final left/right turn to line up with the runway. ...
7
votes
1answer
657 views

In what way(s) will making an airplane electric help to make it “quiet”?

In this blog I read about the Quiet Flight Initiative, which - if I understand correctly - will be quieter than a comparable carbon fueled plane at least in part because it is electric. It's an ...
4
votes
1answer
156 views

What factors come into play when reducing the total noise generated by a helicopter?

I simply cannot understand how a helicopter can be made quieter. What are the things that would considerably affect the noise signature of a helicopter ?
2
votes
0answers
302 views

Can quadcopter-like UAVs ever get significantly quieter? Any candidate technology?

The light weight quadcopter and hexacopter UAVs that can cary say 2kg to 20kg payloads for "delivery" produce enough noise that a steady stream of pizza and book deliveries might not be so welcome in ...
5
votes
1answer
793 views

What are the relative internal noise levels in various aircraft?

What are the relative noise levels in various aviation scenarios for observers seated inside an aircraft? I'm sure the specifics depend on model but I'm curious if any general trends can be drawn that ...
12
votes
2answers
1k views

Can noise from contra-rotating propellers be reduced by having a different number of blades on each propeller?

Heads up: This came from Wikipedia's page on contra-rotating propellers and it explicitly says citation needed: However they can be very noisy ... It is also helpful if the two propellers have a ...
4
votes
1answer
145 views

Which UK airport uses different approaches for noise reduction?

I remember hearing about a British airport that had two approaches that were used on alternating weeks. They implemented this pilot project (no pun intended) so that different houses would be ...