The F-35 is twice as loud as the F-15 Eagle.

F-15 Eagle

New Member
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.

http://www.airforcetimes.com/news/2008/10/airforce_f35_basing_102608/
 

Haavarla

Active Member
There was a debate in Norway about the Noise from the aircaft JAS vs JSF!
Due to the location of the fighter wings here.
If you look at Bodø Airbase, currently housing a F-16 skvd.
The base itself is half engulfed by the city(Bodø).
They may have to build a New Air field all together, cause of the new fighters!
The JAS has also a higher noise factor than our F-16s.

Its not very "stealthy" with all that noise coming from the F-35?






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.

http://www.airforcetimes.com/news/2008/10/airforce_f35_basing_102608/
 

cobzz

New Member
When an aircraft is travelling at Mach .9 at 40,000 feet, I doubt sound is going to relevant, at all.
 

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
Before this goes on too much longer.

Those countries that are getting JSF's and don't have F-22's (and that's potentially 10 x airforces) - will be operating at full spectrum. There is no such thing as limited to 40k feet - in fact that operational ceiling cap is rubbish.

Also the russians and italians developed acoustic trackers - they were extensively used in the cold war. The russians intent was to use them to track high altitude bombers in predetermined corridors of interest. They weren't that useful, but the basic tech and capability as developed and operational.

At a combat level, arguing about acoustic transmission and amplification is a moot point. - It's borderline ridiculous.

At a civilian level its resolveable - and I seriously doubt some of the guff used to make claims as warfighting demands override these concerns when the "manure hits the mistral"
 

Haavarla

Active Member
I don't think noise has anything to do it stealth. Stealth is just not showing up on radar, since radar does not pick up noise.


Let's say a F-35 in a low-medium level mission, in the night. At some point it has to pass over several places that the enemy is located on the ground.
If the enemy have a pre-knowledge that no frendly is in the airspace. They would for sure alert the Air command.
Now this is hypotetical, but in essence the enemy will know hostile aircraft is in the air and try to track the source of heat/noise.
They would try to calculate the route of the enemy and intercept with all the recources available.

The noise is part of the stealth regime?
 

F-15 Eagle

New Member
  • Thread Starter Thread Starter
  • #10
I don't know about you guys but I like the noise from jets its so cool and I can't wait to see a F-35 at an airshow man what a sight that has to be.

Now back on topic I just want to ask how many AA systems and SAMs in the world lock onto noise of a fighter jet? None thats my point since the F-35 will be almost invisible to radar and as long it is not in full AB no missile should be able to touch it.

And whats with all the crap about the F-35 only flying at below 40,000 ft? The F-16 can go past 50,000ft so why not the F-35?
 

stigmata

New Member
F-15 Eagle said:
And whats with all the crap about the F-35 only flying at below 40,000 ft? The F-16 can go past 50,000ft so why not the F-35?
The F-35 is optimized for low level flights. Whether that suck or not is debatable, but you just can't have it both ways. Whether it sucks or not, -it's vise to optimize an aircraft for what it is intended to do IMHO.
 

StingrayOZ

Super Moderator
Staff member
Accoustic sensors could track movements of aircraft. While not instantly useful to guide missiles, tracking aircraft this way may allow the opposition to establish flight corridors used after the fact.

This information could be used to determin where it is best to place defences etc.

F-117 showed one of the potential problems when using stealth aircraft if its movements are frequently tracked, even by a fairly primative and small force.

However I don't see it as a massive issue. I don't think at this stage noise would be number 1 priority for the F-35 development.

I do wonder about the F-35B perhaps creating even more noise and possible OH&S issues for on deck handling.
 

tphuang

Super Moderator
I have a problem with this considering that part of being a stealth fighter is that it should have a LO accoustic signature also.
 

stigmata

New Member
The F-117 incident over Jugoslavia is a shining example on how Accoustic sensors would be best deployed. Track it with Accoustic sensors and Keep the radar silent until the aircraft is close enough to engage. What countries deploy Accoustic sensors for this purpose today ? and are they cheap enough to make it worthwile to cover needed area ?

Could it possible to track it with enough accuracy to zoom in with ground based IRST, and engage with ground based AMRAAM or the south african Yakhonto? IR, thus making the entire engagement concealed ?
 
Last edited:

Lopex

New Member
I live in Salisbury UK and only two miles from the Boscombe Down Air base. I can say that the loudest aircraft they have ever had is the the Harrier GR9A (engine upgrades and sniper pod upgrade).

Is this because of the thrust vectoring or just because its a low flying aircraft?
 

gf0012-aust

Grumpy Old Man
Staff member
Verified Defense Pro
pulled from another loc.

A decibel is defined as 10*log(P1/P0), which means "twice as loud" will add 10*log(2) = 3.01 decibels to the noise level.


So, "Twice as loud" only means another 3 decibels and, since the power of sound decreases with the square of distance, 3 decibels is barely noticeable from far away. If the media stays out of it, I doubt anyone will notice.


quite frankly, some of the arguments getting thrown into the debate are borderline hysterical - the anti-JSF pro-Gripen argument is starting to remind me of the australian anti-JSF pro-Super F111 debate.

ie lots of volume from people outside of those actually involved and contemptuous silence from those who actually have access to the real datasets.
 

StingrayOZ

Super Moderator
Staff member
Accoustic sensors would be pretty cheap to setup. But I don't know of any systems that are designed to detect aircraft out of the box. Certainly very accurate setups are avalible for marine applications, I would imagine adapting one of these to be pretty easy.

Development would be fairly easy and cheap. PC or low powered industrial computer, networking (GSM,3G,Radio, fiber or copper etc) and some high quality microphones. Scatter them across the hills, buildings in town etc. The more you have, the more accurate the information is going to be.

It could report heading, position and speed. However this data would obviously be lagged by the speed of sound. The slower the aircraft the more useful the information would be. For helicopters it proberly could provide targeting information. For an F-35, maybe if it was travelling real slow, performing some slow airshow tricks, possibly. Depends really on the situation. Landing and take offs might be doable. (but then again why not just blow up the hanger).

These same sensors could also provide data such as when and where and by who is shooting/large machinery moving on the ground.

I belive western forces are seriously developing accoustics for land warfare in combination with automated firing systems. But I don't know if the other sides have simular systems in development. (GF??)

As a passive system I think its highly worthwhile. Unlike radar systems, I would imagine the accoustic sensors would last more than 10 minutes in a war situation. The cost

Lopex, the harrier has a massive oversized turbofan so it can move the air to do what it does. Combined with the fact it can point that noise/air I would imagine it would be pretty noisey. I hope the F-35B seperate fan, results in less noise.
 

karan583

New Member
“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.
pulled from another loc.
A decibel is defined as 10*log(P1/P0), which means "twice as loud" will add 10*log(2) = 3.01 decibels to the noise level.


So, "Twice as loud" only means another 3 decibels and, since the power of sound decreases with the square of distance, 3 decibels is barely noticeable from far away. If the media stays out of it, I doubt anyone will notice.
Hmmm... lets get this straight and separate the apples and oranges. One must be careful when using dB, especially when it isn't clearly stated if they're talking about sound intensity or sound pressure level. 9 time out of 10, it's sound pressure level.

Sound intensity in dB is defined as I = log(I1/I0), I0 = 10^-12
Sound pressure level in dB is defined as SPL=10*log((P1/P0)^2) = 20*log(P1/P0), P0 = 20µPa
Double I1, Intensity increases 3 dB
Double P1 and the SPL increases 6dB.
Increase the SPL 10dB and it is perceived as twice as loud. A 3dB increase (SPL) is believed to be the smallest increase noticeable to the human ear.

Regarding decrease in sound with increased distance:
Sound intensity decreases as 1/r^2, where r is the distance to the source.
Sound pressure decreases as 1/r => Double distance, half the SPL (although not perceived as half as loud).

Confusing? I hope a managed to bring something to the table.
 

stigmata

New Member
karan583 said:
Sound pressure decreases as 1/r => Double distance, half the SPL (although not perceived as half as loud).
Is it perceived less or more then half as loud ?
And, i take it a microphone does not perceive anything, just react to sound pressure ?

stingrayOZ said:
It could report heading, position and speed. However this data would obviously be lagged by the speed of sound. The slower the aircraft the more useful the information would be. For helicopters it proberly could provide targeting information. For an F-35, maybe if it was travelling real slow, performing some slow airshow tricks, possibly.
Agree, in the case of aircraft, it should be coupled with an IRST to provide accurate enough data to launch
 

karan583

New Member
Is it perceived less or more then half as loud ?
And, i take it a microphone does not perceive anything, just react to sound pressure ?
Given that an increase is of 10dB sounds twice as loud, a decrease by 10dB sounds half as loud. I.e. double the distance, it's perceived as louder than half the sound level. This is tricky since it's a subjective matter, a matter of peoples opinions and the perception will vary among the population. Microphones, as you said, only senses the pressure.

But when talking about moving homes because of increased noise sources, this is the way to argue. A different argument, IMO, applies when talking about tracking sensors.
 
Top