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Enthusiast Joined: Sep 22, 2008 Posts: 40 Status: Offline

http://www.airforcetimes.com/news/2008/ ... ng_102608/

The Air Force is very quiet about a noisy fighter.

At military housing areas and base schools on Eglin Air Force Base, Fla., noise from F-35 Lightning II operations will be twice as loud as current Eglin F-15 flights, reaching 83 decibels.

Off base, F-35 noise will be even louder, reaching up to 90 decibels in civilian neighborhoods under an Eglin flight path.

All that is revealed in an environmental impact study prompted by plans to set up the joint F-35 pilot and maintenance training school at Eglin.

But the impact of the study goes beyond Eglin, as the Air Force looks to stand up F-35 units at bases across the country. The service has not yet decided where that would be, but is looking at Eielson Air Force Base, Alaska; Luke Air Force Base, Ariz.; Moody Air Force Base, Ga.; Mountain Home Air Force Base, Idaho; and Shaw Air Force Base, S.C.

Air Force officials declined to discuss the report other than to say its findings have their attention.

“The Air Force is committed to being a good neighbor to the communities which surround Eglin and the future installations selected for F-35 basing,” Kathleen Ferguson, deputy assistant secretary of Air Force for installations, said in a written statement.

“We are diligently exploring methods to mitigate the impact.”

Around Eglin, much of the public’s environmental concerns center on jet noise.

People living near the base are accustomed to the roaring jets at the base and don’t look twice when a fighter circles for a landing or takes off at full military power.

In fact, the seal for Okaloosa County, where Eglin is located, pictures two airborne F-15s.

But when the Air Force issued a preliminary environmental study in June showing an F-35’s single engine would generate more noise than the two engines of an F-15, people started paying attention.

In the city of Valparaiso, along the north side of Eglin, civic leaders bristled at suggestions the residents and businesses under the F-35’s flight path should move to quieter areas.

The preliminary findings were confirmed in the environmental assessment released by the Air Force on Oct. 10.

“At military takeoff power, noise from the F-35 is about 9 decibels higher — or twice as loud — than an F-15C at military takeoff power,” the report said.

The F-35 is even louder coming in for a landing. “During approach, noise from the F-35 is about 19 decibels higher than noise from an F-15C,” the report said. “This corresponds to the F-35 being about four times as loud as the F-15C” when it lands.

There should be plenty of opportunities at Eglin to hear just how loud an F-35 is. On training days, about 125 F-35s will take off and land at Eglin, the study said.

Overall, the combination of louder engines and different flight patterns drastically expands the areas where engine roar will reach 75 decibels and higher.

The number of people living near Eglin exposed frequently to sound levels of 75 decibels or more would rise by more than 1,500 percent, jumping from 142 people to 2,174 people, the report said.

The study calmly noted that once sound levels exceed 75 decibels, more than one third of the people are “high annoyed.”

Still, the new center might bring some good news: jobs.

Overall, 2,146 airmen, sailors and Marines would be assigned to the training wing, including 109 student pilots and 436 student maintainers. In addition, 180 civilians would work for the wing.

The training wing replaces the operational 33rd Fighter Wing, now phasing out as its two squadrons of F-15s are retired or sent to other units.

Regardless of the F-35 basing, Eglin would continue to be home to several Materiel Command units, including the 46th Test Wing and Air Armament Center, and Air Combat Command’s 53rd Wing.

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There was an extensive and informative debate on the subject here (read the article AND the comments):
http://www.aviationweek.com/aw/blogs/de ... 659a5be8d8

Elite 1K Joined: Dec 19, 2005 Posts: 1195 Status: Offline

Sorry, for the dumb question but does engine noise have at relationship to power out put????

Until these greedy Walmart trampling, Toys”R”us shooting non-citizens realize that these noises are from aircraft that protect the Nations #1 issue (National Security)

... AND ...

Until they “realize” what is important in life! Then and only then, you won’t hear a “Peep” out of them! Until then … **** them if they can’t take a joke!

In the meantime God bless the folks on active duty and civilized citizens around the world that understand this.

Too many people embarres this country over greed!! Evil or Very Mad

Elite 3K Joined: May 11, 2004 Posts: 3243 Status: Offline

Finally a jet that I consider loud other than the Raptor Thumb

I don't know about the rest of you or the rest of the population, but I love jet noise Twisted Evil

I kid you not, it's relaxing for me Cool

Elite 1K Joined: Dec 14, 2005 Posts: 1131 Status: Offline

Corsair1963 wrote:

Sorry, for the dumb question but does engine noise have at relationship to power out put????

As noted before this "news" has been covered months before...

But as for your question Corsair; jet engine noise has a relationship to the engine's exhaust gas velocity, and it's surface area. Turbofans have a lower total exhaust velocity, so are typically quieter than a Low-Bypass Turbofan, or Turbojet.

Now I'll point out we're talking about the "roar" you hear from an engine at a distance when taking off... which is what the media/press seem to concentrate on.

The high velocity exhaust stream exiting the engine "rubs" against the slower moving air around it, as this happens noise is created. When the stream is concentrated it takes longer for the air to mix and loose the "rub"

If you increase the surface area of the "rub" by using mixers, (giving a star or pedal pattern for example versus a simple round shape) the noise will be reduced as the exhaust stream will mix with and match the speed of the surrounding air quicker. (See the photo below for a "mixer")

Augmentors (Afterburners) also have a great impact on noise, and the F135 will be no exception. The design of the augmentor can affect it's noise signature too. The liners inside the augmentors are shaped and tailored to reduce noise as much as possible. Noise translates into vibration; even more so in long objects (tubes, wiring harnesses, ducts, nozzles, etc) and if vibration is bad, it can damage parts. If vibration reaches a resonance point in a specific part or area they can fail in a very short period of time.

So yes and no to the basic question. More yes in military engines than civilian.

Keep 'em flyin' Thumb

TEG

Raptors aren’t too bad?

15E’s with 229’s back-to- back take-off, and from multiple bases during Red Flag is deafening.

Can't wait until they put 40 plus 35's in the air during the "Flag" within a 60 minute window. The valley will rock.

Thumb

Elite 1K Joined: Dec 14, 2005 Posts: 1131 Status: Offline

I love the crackle of a PW-229 AB launch on a cold-crisp-dry morning....

Ahhh Jet Noise; the sound of freedom!

Cheers

Elite 1K Joined: Dec 14, 2005 Posts: 1131 Status: Offline

http://www.f-16.net/index.php?name=PNph ... f135+noise

TEG, welcome back Bro.

The only jet that I know that makes a lot of noise and no power is what is in the T-37

AAAAHHHHHHH what a horrible sound Shocked

Elite 1K Joined: Dec 14, 2005 Posts: 1131 Status: Offline

VarkVet wrote:

TEG, welcome back Bro.

The only jet that I know that makes a lot of noise and no power is what is in the T-37

AAAAHHHHHHH what a horrible sound Shocked

Oh, I'm always around.... Life happens...

Agreed, the T-37's compressor noise was horrible!?! Shocked

The T-37/J69 sounded like a dog whistle tuned for human hearing then pumped through an amplifier directly to your ears.

One of the "old engine guys" at my base called the Tweet a "kerosene powered siren." Laughing

Whenever one pulled onto our ramp, everyone would scatter... Then the lowest ranking guy we could find would have to park the offending Tweet. Rolling Eyes

TEG

Elite 1K Joined: Dec 19, 2005 Posts: 1195 Status: Offline

That_Engine_Guy wrote:

Corsair1963 wrote:

Sorry, for the dumb question but does engine noise have at relationship to power out put????

As noted before this "news" has been covered months before...

But as for your question Corsair; jet engine noise has a relationship to the engine's exhaust gas velocity, and it's surface area. Turbofans have a lower total exhaust velocity, so are typically quieter than a Low-Bypass Turbofan, or Turbojet.

Now I'll point out we're talking about the "roar" you hear from an engine at a distance when taking off... which is what the media/press seem to concentrate on.

The high velocity exhaust stream exiting the engine "rubs" against the slower moving air around it, as this happens noise is created. When the stream is concentrated it takes longer for the air to mix and loose the "rub"

If you increase the surface area of the "rub" by using mixers, (giving a star or pedal pattern for example versus a simple round shape) the noise will be reduced as the exhaust stream will mix with and match the speed of the surrounding air quicker. (See the photo below for a "mixer")

Augmentors (Afterburners) also have a great impact on noise, and the F135 will be no exception. The design of the augmentor can affect it's noise signature too. The liners inside the augmentors are shaped and tailored to reduce noise as much as possible. Noise translates into vibration; even more so in long objects (tubes, wiring harnesses, ducts, nozzles, etc) and if vibration is bad, it can damage parts. If vibration reaches a resonance point in a specific part or area they can fail in a very short period of time.

So yes and no to the basic question. More yes in military engines than civilian.

Keep 'em flyin' Thumb

TEG

That was very informative..............and thanks! Wink

VarkVet wrote:

Until these greedy Walmart trampling, Toys”R”us shooting non-citizens realize that these noises are from aircraft that protect the Nations #1 issue (National Security)

... AND ...

Until they “realize” what is important in life! Then and only then, you won’t hear a “Peep” out of them! Until then … **** them if they can’t take a joke!

In the meantime God bless the folks on active duty and civilized citizens around the world that understand this.

Too many people embarres this country over greed!! Evil or Very Mad

Amen to that!!
When fighter jets come into town, if they do anything other than a low approach the airport always gets complaints from people including one lady who was sure her house was being bombed. Rolling Eyes

They even had to put [more] restrictions on football pre-game flyovers for noise abatement! To me that defeats the purpose!

Bring 'em all to Eielson. There's nothing around there worth getting bothered about, and besides, most people would simply think there were more mosquitos in the air.

I miss the sound of 229 F-15Es here in Anchorage. At my old job when they would take off the picture my boss had of her little dog "Fluffy" would always fall off the wall and crack. She never learned to just leave it on her desk instead of the wall, so "Fluffy" was the most cracked and chipped picture in the building.

Elite 1K Joined: Dec 19, 2005 Posts: 1195 Status: Offline

Personally, I always enjoyed watching big twin tubro fan fighters like the F-14 and F-15 at airshows! Man, when the F-4 flew with the Thunderbirds and Blue Angles. Must have been quite a show...............

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Forum: F-35 Lightning II

F-35 twice as loud as the F-15!