Forum: F-35 Lightning II

But think about the importance of noise reduction for a stealth multi-role fighter like the F-35 Lightning II. They're gonna need a reduced noise turbofan. If they can't develop one, why not use the Raptor's F119-PW-100. That'll give the Lightning II the same supercruise and TVC capability.

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Any "small" high thrust engine will be loud. It has to do with exhaust gas velocity and the size of the exhaust plume.

A reduced noise turbofan isn't something that would work well in a military aircraft due to size, and performance loss. So while you could design such an engine, the loss of thrust from the slower exhaust, or reduced thrust from exhaust mixing would give you poor performance.

Slapping the F119 into the F-35 would not instantly guarantee super-cruise. The F119 was designed/tuned for the Raptor. It's inlets, it's weight/drag, envelope ect. If it would have been that simple you would have seen the F-35 fitted with the F119-PW-200, or the F119-PW-400 for the Navy. It would have been much cheaper than designing the F135 saving the program BILLIONS of dollars.

As for the TV, the F-35 is all about being cheap to maintain/fly, and lightweight. Both of which are in the 'cons' list for a TV nozzle.

Keep 'em flyin' Thumb

TEG

TEG is right, a single F119 would be nowhere near a match for an F135.

Forum Veteran Joined: Jul 01, 2007 - 07:22 PM Posts: 605

Not as much fun at airshows either.

Well we all know that jet noise is the sound of freedom... right?

So wouldn't louder mean better for freedom? Shrug

TEG

Forum Veteran Joined: Jul 01, 2007 - 07:22 PM Posts: 605

It does to me.

"I LOVE the sound of 'burner in the morning...." Cheers

Oh no, not jet noise!!! What about civilians "quality of life"? Heard that crap in the debate about NAS Cecil Field. Funny, no one wants jet noise near a military base, but the airshow is frickin packed full of people EVERY YEAR. Go figure.

It's much quieter and chic to slap a "Support Our Troops" sticker on your car than to let our troops hone their skills.

How about the "don't close our base during a BRAC, or take away our local jobs" but then "don't base those noisy jets in our city..." WTF

The communities who DON'T complain about noise or inconvenience should be the first in line for the F-35s and the one's who DO complain the most should be the last and/or on the top of the next BRAC list. Two Cents

TEG

f14_forever wrote:

Oh no, not jet noise!!! What about civilians "quality of life"? Heard that crap in the debate about NAS Cecil Field. Funny, no one wants jet noise near a military base, but the airshow is frickin packed full of people EVERY YEAR. Go figure.

It's much quieter and chic to slap a "Support Our Troops" sticker on your car than to let our troops hone their skills.

Howdy F14,

Well when Cecil closed there was very little, if any discussion about noise. The city fought tooth and nail to keep it open. I worked the F18s, S3s,and occasional F14s in and out of it on a daily bases and there was absolutely NO flight profile restrictions in or out of the base for noise. It never made any sense to me or most that knew what went on with the military jets as to why this base would be closed. It was the master jet base for every F18 on the east coast, had room to grow substantially, pilots had every SUA there was (MOAs, Warning Areas and Restricted airspace) and got direct routes to every one of them 99.9% of the time.

The cities they moved these jets to all complained non stop about the noise and they don't have anywhere close to the freedom to do as they want. New base houseing and hangar space had to built all over the place to accommodate them and to top it off, they still fly back down to the Jacksonville area routinely to work the practice areas. Not to mention Whitehouse which was only 7 miles north of Cecil and where all the carrier pilots do their carrier quals is still there and now they all have to come back down to Navy Jax and then fly out of there to get the quals in. Another brilliant move by our brain dead politicians.

After a decade of it being closed when there was talk of getting it back, then there was the noise complaint issue. By this time the city had changed a lot in that area of town and many folks living there now did not want the noise. But before that it was practically all militaRY familys in the area and all the businesses were geared towards them and there was no complaining from them Wink

. I still think though if the Navy would have said they wanted back they would have got their wish. It's still the best place on the entire east coast for military jets to actually do their thing uncontested for the most part.

I'll be sure to ask the senator and congressman why so long getting a new carrier at Mayport. But I can tell ya from past dealings with them, they both have been at it so long all they can do is give ya a politically correct answer which is most always a line of BS. They are incapable of actually speaking their mind and telling the truth or actually even telling you what their exact position is on any given matter. Every time I get an answer from either, it's all I can do not to puke!!

Beazz

It does seem like the BRAC Commission always recommends closure on some of the oddest bases.

I know at one point even Tinker AFB showed up on the list; go figure the vast majority of the USAF's 'depot level' jet engine repair is done there!?! Doh

I think Wright Patterson AFB was on a BRAC list at one time too.... Shrug

Who's running these things? Oh yeah - Civilians and Politicians!?! WTF

I wonder when the NEW administration will call for the next round of BRAC?

Keep 'em flyin' Thumb

TEG

Someone mentioned how exhaust velocity is related to noise. If you want the scientific explanation, the noise is proportional to exit velocity to the eighth. So small increases in exhaust velocity can dramatically change the volumbe, but remember Db is a logarithimic scale (so going from 70 Db to 80 Db is in fact 10x as loud).

I believe TEG was talking about mixing earlier and having the lobed mixer. Those mix things very quickly (~1-3 diameters) but I believe the differences in velocity can create some very large turbulence so they become very loud. So a well mixed jet stream can be very loud.

That doesn't sound right. 10 Db increase corresponds to 2x as loud.

daemonllama wrote:

That doesn't sound right. 10 Db increase corresponds to 2x as loud.

Oh that's right, I forgot there's a factor of 20 in there somewhere. You're right.

I didn't really pay attention in my controls classes (where we actually talked about Db).

daemonllama wrote:

That doesn't sound right. 10 Db increase corresponds to 2x as loud.

10db is more than 2x as loud.

Forum: F-35 Lightning II

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