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Silencing Stealth Technology ?

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posted on Aug, 22 2017 @ 06:41 PM
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A few nights ago I was outside and observed a very very fast aircraft passing close overhead. I know it wasn't commercial as we get heaps of them and I also know it wasn't a satellite as it had 1 continuous white light on and one flashing white light forward of that, there were no red or green lights. And I know it was close as there was an easily discernible gap between both the continuous and flashing lights.

Anyway, the thing that struck me the most about the "sighting" was the complete lack of noise. It was a still and clear night, the trees were calm and there was next to no sound coming from this aircraft. In fact the only sound that I actually heard was when it had disappeared from view. At best it sounded like an extremely distant jet and to be honest, had I not seen the lights I would have no evidence to know that it had actually been there at all, seriously this thing was whisper quiet.

Having never experienced anything like this before it got me to thinking about stealth technology and specifically silencing technology. There surely must be such a thing, so I thought I'd put this up to get a bit of education.




posted on Aug, 22 2017 @ 06:58 PM
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a reply to: myselfaswell

The B-2 is far quieter than people think. One of the ways they do that is a series of baffles in the exhaust. It also helps reduce the IR signature. Putting the exhaust on the back of the aircraft is another trick they use. The fuselage blocks some of the sound.

You also have to take into account the altitude they operate at. A commercial aircraft at 35,000 feet isn't the loudest thing as it goes over. Now put an F-22 at 50,000+ feet and fly it over and the odds are you won't hear a thing unless they're supersonic. .
edit on 8/22/2017 by Zaphod58 because: (no reason given)



posted on Aug, 22 2017 @ 06:59 PM
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Altitude guess? Sometimes if the wind is right on a dead quiet night I can watch an A380 pass overhead at 30000ft without hearing it. On calm nights I can just barely hear it though.



posted on Aug, 22 2017 @ 07:05 PM
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a reply to: E92M3

If I was having a punt at altitude I'd say barely more than a few thousand feet.

I say this because of the clear and obvious gap between the lights as well as the fact that it cleared about 120° of sky in less than 10 seconds probably.



posted on Aug, 22 2017 @ 07:27 PM
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a reply to: myselfaswell

I'm not sure what exactly your asking. Yes we discovered things that reduce noise such as beveling exhaust ports. Vary the shape of chevrons has also been shown to reduce noise. Basic trick their is reducing turbulence behind the aircraft.

The reason military craft tend to be louder then commercial aircraft is simple they move faster. This causes more turbulence and thus a louder noise. Anything g you do to decrease turbulence will mean a quiter air craft.



posted on Aug, 22 2017 @ 09:21 PM
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a reply to: dragonridr



I'm not sure what exactly your asking


In a nutshell, has there been any whisperings or suggestions of new fandangled noise reduction technology beyond tweeking exhaust pipes.



posted on Aug, 22 2017 @ 09:22 PM
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Brisbane airport is just across Moreton bay from us.Some nights you can hear them land.Other times its a deep rumble and things shake a little bit.All depends on wind flightpath as well as some go straight over the top or along the passage.



posted on Aug, 22 2017 @ 09:25 PM
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a reply to: myselfaswell

Why though? What they've used to date works and works really well.



posted on Aug, 22 2017 @ 09:31 PM
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a reply to: Zaphod58

Oh zaph...



Hey blackfinger ill be in Brisbane in december. Then cairns. Then back down by towoomba for a few months.

Myselfaswell,

I know just what you mean about really fast, really low and dead quiet. Seen it myself. Hard to believe unless youve seen it too. Ill be following this thread.



posted on Aug, 22 2017 @ 09:37 PM
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originally posted by: myselfaswell
a reply to: dragonridr



I'm not sure what exactly your asking


In a nutshell, has there been any whisperings or suggestions of new fandangled noise reduction technology beyond tweeking exhaust pipes.


Well nothing new because the noise isn't from the aircraft. The noise is from the turbulence to remove all noise you need to removal all turbulance. Problem is anything that travels through the atmosphere at high speed will cause turbulance. The only other method is to hide the turbulance behind the body of the craft. Meaning from the front very quite from the rear not so much. Helecopters attempt to lower the turbulence from blades couple of ways is spacing and using carbon fibers to lower turbulance. Problem becomes you can never make any aircraft silent as long as it has to move through atmosphere. The best you can hope for is to make it quiet enough so other noises could overpower it. But every aircraft wI'll have some area where the noise is easy to detect. Any way you use to destroy turbulance other than say changes to the exhaust will have severe effects on performance.



posted on Aug, 22 2017 @ 09:40 PM
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a reply to: Zaphod58



Why though?


Well, consider this scenario;

Combat situation, the aircraft is enemy, flying low with a full suite of radar avoidance tech, obviously no lights and virtually noiseless. Here am I on the lookout for enemy aircraft what do I perceive, absolutely bugger all so no alarms are raised from my end. How far does the enemy aircraft with that capability penetrate........



posted on Aug, 22 2017 @ 09:48 PM
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a reply to: myselfaswell

You wouldn't be flying low if you have radar avoidance technology though. You'd be flying high, where the noise levels would be virtually undetectable with the existing technology you have on board. But they already have ways to reduce the noise levels that work. Which was my point. The existing methods work well, and have for years.



posted on Aug, 22 2017 @ 09:51 PM
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a reply to: Zaphod58



You wouldn't be flying low if you have radar avoidance technology though. You'd be flying high


Ok, so tweeking the scenario,the aircraft has no radar avoidance technology, everything else remains the same.



posted on Aug, 22 2017 @ 10:11 PM
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a reply to: myselfaswell

Same situation though. They currently have ways to reduce the sound levels for aircraft, although they don't use them on non-stealth aircraft. Noise reduction is another tool to reduce detection range, and a conventional aircraft can already be detected at long range by radar. They didn't use noise reduction because it can affect the engine performance, depending on the engine in question. So they went with other tools.



posted on Aug, 23 2017 @ 04:58 AM
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I believe there was a project (or perhaps more correctly, a proposal to fund a project) back in the late 1990s that involved active cancellation technology for sound in helicopters, possibly also fixed wing. The principle is solid: a wavelength with a certain amplitude and frequency is met by another of identical amplitude and frequency, but half a wavelength out of phase - thus cancelling each other out. This technique is rumoured to be used by the Rafale and possibly the B-2 for radar waves, though in practice it is nowhere near as easy as I just described it. But it can be used for sound, as it is for many headphones and some higher end cars via the internal speakers, to make for a quieter interior. I am not 100% sure, but I think the idea was from Textron/Bell, but in conjunction with at least one other organization?

Anyone else can add to this?
edit on 23/8/2017 by Borys because: Typo and addition of Bell Textron reference.



posted on Aug, 23 2017 @ 06:22 AM
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a reply to: Borys

Now we might be getting somewhere.



posted on Aug, 23 2017 @ 07:08 AM
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a reply to: myselfaswell

And afraid that is as much as I can remember...well almost. Will give a bit of context...

Around 1997 I was spending some time with friends in Seattle. At the time I was a consultant in transport, working for a major multinational. And my friends were PhDs and Masters in Engineering, degrees from CalTech, Carnegie Mellon i.e. top schools....and unemployed, or at best severely underemployed: they used to work for MD/Boeing, Lockheed, Raytheon etc etc. This was during the worst part of the "Peace Dividend": the end of the Cold War a few years earlier had seen vast swathes of the US Defense sector - military, contractors and support - suffer huge cutbacks and as a result, you had many very smart people out of work and struggling badly to transition to the civilian arena. A few caught the first internet wave, but not all (it was bad in the US and often worse in other countries). We were just chilling, and I remember one of my friends talking about his friends setting up companies to try and commercialize certain projects, or ideas. This idea for helicopters being made silent was one among many. My memory is a bit hazy (the Jack Daniels bottles were emptying fast), but I think the project was being shopped around to some VC guys, to banks, to foreign government agencies...basically, anyone who had some money and wanted to take a chance.

That's all I can recall. Hopefully this may trigger someone else who knows more...



posted on Aug, 23 2017 @ 08:58 AM
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a reply to: myselfaswell

The famed "black triangles" and assorted craft using the same exotic physics are not aerodynamic, no wings, tails or jet engines. They do not actually fly but simply move through the air under a field effect. They may have an astounding shapes (much reported) compared to any true aircraft must have. The field effect probably bounces off any radar.

Don't expect any aviation expert here or elsewhere to take any of those points seriously. But if you see one up close and personal as many of us have, you gotta say, "Well, I see it. Is it ours or ET?"



posted on Aug, 23 2017 @ 09:34 AM
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When I was five, before starting school, I was in the back yard playing when all of a sudden a jet broke the sound barrier overhead creating a sonic boom and hit afterburners. All this at what I would now guess was 5-600 feet. It must of come from Vandenberg and was doing low altitude runs. Where I lived was just outside of the Santa Anna Canyon, a place called Coronita Ca. Pretty much the most awesome thing I would see for some years. At night we could lay on the grass on a blanket and see Sputnic orbit overhead. Stealth in those days was unknown.
edit on 23-8-2017 by Plotus because: a day without editing is like ...... oh, a day without editing



posted on Aug, 23 2017 @ 10:34 AM
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a reply to: Borys

Submarines do that trick with their active sonar. They also broadcast sounds so that their boats sound like enemy subs to be disregarded by enemy SOSUS like networks




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