TTailedTiger
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Are there any noise requirements for military aircraft?

Tue Oct 01, 2019 11:57 pm

Having just heard three combat jets roar over my friend's house (no idea what for), it made me wonder why there hasn't been any progress in making new combat jets quieter. If we are going to burden commercial and private aircraft with noise requirements then the same should be required of military aircraft. I would imagine it is especially annoying for those living near training bases.

The GE F404 turbofan produces 17,700 lbs of thrust and is a real screamer. The GE90 is capable of producing 115,540 lbs of thrust but is whisper quiet in comparison. So are noise factors just not a requirement of military aircraft? Can some of our propulsion engineers explain why small turbofans like the F404 can't be fitted with some kind of sound suppression?
 
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kanban
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Re: Are there any noise requirements for military aircraft?

Wed Oct 02, 2019 12:14 am

military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:
 
GalaxyFlyer
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Re: Are there any noise requirements for military aircraft?

Wed Oct 02, 2019 1:09 am

Jet noise—the sound of freedom.

Afterburning engines are inherently noisy as they have to accelerate the mass flow to much higher speeds than the turbofans on civil aircraft. And, no, state aircraft are exempt from certification rules including noise standards.
 
HAWKXP
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Re: Are there any noise requirements for military aircraft?

Wed Oct 02, 2019 2:56 am

making it quiet ,makes lt slower. Not a good compromise in a fighter
 
JayinKitsap
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Re: Are there any noise requirements for military aircraft?

Wed Oct 02, 2019 3:18 am

kanban wrote:
military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:


A sample is needed. Death Valley Days is a good one.

https://www.youtube.com/watch?v=SiAW6u4Yt1w
 
Ozair
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Re: Are there any noise requirements for military aircraft?

Wed Oct 02, 2019 4:57 am

JayinKitsap wrote:
kanban wrote:
military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:


A sample is needed. Death Valley Days is a good one.

https://www.youtube.com/watch?v=SiAW6u4Yt1w


Some examples of noise levels. Noise of course is subjective based on distance and aspect.

Image

Image
 
Armadillo1
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Re: Are there any noise requirements for military aircraft?

Wed Oct 02, 2019 7:41 am

topicstarted never heard afterburner sound ?
 
RetiredWeasel
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Re: Are there any noise requirements for military aircraft?

Thu Oct 03, 2019 5:02 pm

Noise complaints around USAF bases are a common place occurrence and the brass have taken steps to try and tone it down at certain bases. Changing approach and departure paths, limiting use of afterburner, modifying traffic patterns, and changing flying schedules are some of the steps that have taken place around bases as urban encroachment has grown.

But as others have stated, anything done to the jets that would limit performance will not be done. 'Quieting' aircraft was done on certain turboprop recon aircraft in the Vietnam/80s era, but that was a very narrow application to avoid detection and wouldn't apply to high performance fighters.
 
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kc135topboom
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Re: Are there any noise requirements for military aircraft?

Sun Oct 06, 2019 10:38 pm

The F-35 is the current loudest aircraft in the US Military Inventory. But it couldn't hold a candle to J-57 equipped aircraft of the past when water injection was used for take-off like the KC-135A/Q and the B-52B/C/D/E/F/G. They had dB levels at 135+. They were louder than any afterburning (reheat) engine at the time. The Solar or Air Research APUs on the KC-135s were the worst, the APU was inside the cargo compartment. They produced over 145 dB and the old headsets we had offered only little protection.
 
zanl188
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Re: Are there any noise requirements for military aircraft?

Mon Oct 07, 2019 12:34 am

kanban wrote:
military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:


This is no joke. Mere presence of a high performance military aircraft can coerce opposing ground forces into picking another day/target.
Legal considerations provided by: Dewey, Cheatum, and Howe
 
Nicoeddf
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Re: Are there any noise requirements for military aircraft?

Mon Oct 07, 2019 11:50 am

zanl188 wrote:
kanban wrote:
military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:


This is no joke. Mere presence of a high performance military aircraft can coerce opposing ground forces into picking another day/target.


The Ju-87 StuKa "siren" comes to mind.
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SheikhDjibouti
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Re: Are there any noise requirements for military aircraft?

Mon Oct 07, 2019 3:23 pm

Nicoeddf wrote:
zanl188 wrote:
kanban wrote:
military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:

This is no joke. Mere presence of a high performance military aircraft can coerce opposing ground forces into picking another day/target.

The Ju-87 StuKa "siren" comes to mind.

And the Turkish AF pilot(s) who boasted about flying their F-100 supersonic + low level over Cyprus, to break windows and intimidate the Greek-Cypriot population (1974). Whether the F-100 was actually capable of exceeding the speed of sound at low-level is something to consider.

To some extent, when used in limited quantities, military engine noise (and sonic booms) can also serve to demonstrate to your own public where their tax dollars have been spent.
For instance in recent years RAF Typhoons have been scrambled and cleared for supersonic speeds over Norfolk (UK) when they were only moments away from reaching the North Sea anyway, en-route to escorting a Ryanair flight with a suspicious passenger on board. IMO the sonic booms were totally unnecessary.
Nothing to see here; move along please.
 
GalaxyFlyer
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Re: Are there any noise requirements for military aircraft?

Mon Oct 07, 2019 3:46 pm

SheikhDjibouti wrote:
Nicoeddf wrote:
zanl188 wrote:
This is no joke. Mere presence of a high performance military aircraft can coerce opposing ground forces into picking another day/target.

The Ju-87 StuKa "siren" comes to mind.

And the Turkish AF pilot(s) who boasted about flying their F-100 supersonic + low level over Cyprus, to break windows and intimidate the Greek-Cypriot population (1974). Whether the F-100 was actually capable of exceeding the speed of sound at low-level is something to consider.

To some extent, when used in limited quantities, military engine noise (and sonic booms) can also serve to demonstrate to your own public where their tax dollars have been spent.
For instance in recent years RAF Typhoons have been scrambled and cleared for supersonic speeds over Norfolk (UK) when they were only moments away from reaching the North Sea anyway, en-route to escorting a Ryanair flight with a suspicious passenger on board. IMO the sonic booms were totally unnecessary.



I only had 500 hours in the Hun but rather doubt it would go super on the deck. But, a 480 knot pass at a 100’ would certainly be attention getting, if not damaging.

Off QRA, speed at pilot’s discretion and an intercept must be done ASAP.

GF
 
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flyingturtle
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Re: Are there any noise requirements for military aircraft?

Mon Oct 07, 2019 10:01 pm

There are no noise regulations, but pollution requirements.

The Eurofighter does not produce any pollution. The jet boasts a 100% fuel-to-noise conversion ratio. :crazy:
Reading accident reports is what calms me down
 
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kc135topboom
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Re: Are there any noise requirements for military aircraft?

Mon Oct 07, 2019 11:04 pm

flyingturtle wrote:
There are no noise regulations, but pollution requirements.

The Eurofighter does not produce any pollution. The jet boasts a 100% fuel-to-noise conversion ratio. :crazy:


:rotfl: :rotfl: :rotfl: :rotfl: :rotfl: :bigthumbsup:
 
Pentaprism
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Re: Are there any noise requirements for military aircraft?

Wed Oct 09, 2019 3:49 pm

Interesting to know how they calculated the Bedroom Noise!
 
aumaverick
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Re: Are there any noise requirements for military aircraft?

Wed Oct 09, 2019 7:20 pm

kanban wrote:
military aircraft are loud because they want to scare the enemy into surrendering without using precious munitions. :duck:


And if this were true, the most lethal of all potential military aircraft would have been the XF-84H Thunderscreech!
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