For all the government conspiracy militia nuts out there, I’ve got some good news and some bad news. The good news is that there is no such thing as silent, stealth black helicopters. The bad news is that, thanks to Eurocopter’s noise-canceling Blue Edge rotor blades, there soon will be.
The extremely loud noise made by helicopter blades results primarily from the blades chopping through eddies in their own wakes, a phenomenon known as blade-vortex interaction. By changing the shape of the rotor blades, Eurocopter manages to pair down the blade-vortex interaction so thoroughly that the sound only reaches the whisper volume of 3 or 4 decibels.
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3-4 decibals? No way. That is still extremely loud.They’ve cut ear splitting noise in half…. good for passengers and observers, but if you can’t still hear one of those suckers coming then you’re half deaf anyway.
The PopSci article got the noise level wrong. It should have said a 3-4 dB reduction in noise, not overall noise level. Somebody misread the PR.
#3 Nate is correct. 3db noise is less than running water in a sink.
Great! Please make sure that all of the National Guard heli’s get these first so I can get some sleep instead of hearing them practice from 3/4 of a mile away and when they fly over my house and rattle all of the glass and art work.
When I was In Viet Nam, The Huey’s would fly over..the V.C.(Viet Cong)would scatter like crazy. You could one coming 10 miles away. It was a give away what was to come.
Um, we had a group of unmarked black helicopters buzz the local campus one day, and they were -real- quiet even though they were very, very low. The only perceptible noise was a visceral bassy throbbing, and you felt that more than heard it.
Talking with other people on the oval, we thought it had some sort of active noise cancelation tech, like Bose headphones except projected downward. The fact that a bunch of engineering students figured this out within seconds suggests that such a technology is really not that exotic.
It strikes me as odd that believing corporations or government would use decades old active noise cancelation technology in their helicopters is characterized as loony. If they aren’t using technology in such obvious ways to improve their tactical efficacy, then where is all of our R&D money going?
Laughter may be allied to truth, but ridicule is allied with falsehood.
Whats that joke about Italians that goes “Whop,whop,whop?”
There was a documentary a few years back about
the A-10 ground attack plane. They claimed that
during Desert Storm the enemy called it “silent
ghost” it was so quite. A year later 2 flew over
my house. Except for thunder it was the loudest
thing I’ve ever heard. Guess everything is
relative.
#9 – As was the A-111 ‘Aardvark’ Viet Nam; if they approach at just less than the speed of sound you cannot hear them coming. Going is another story, those sucker were *LOUD*.
#8 – and the little rotor went ‘ginny, ginny, ginny’ 🙂
“Black Helicopters”??? I’m gonna have to pull the race card on this one.
OK so the blades are quieter, but I’m guessing the loudspeakers blasting out “Ride of the Valkyrie” will still give you away …
#1 pedro alluded to it, but I remember in the film ‘Blue Thunder’ a claim that such technology existed when the film was produced. The movie was released in 1983.
odd i always thought the thut thut of the helicopter was the rotor blades breaking the sound barrier……
hhhmmmm
Very impressive. Clever little Europanians!
Awesome! Does it work in Harley’s?
I am a private pilot and I saw a ‘Black Helicopter’ flying into Pendleton Marine Air Station in 1990 accompanied by an F117 stealth fighter. Neither aircraft had any navigation lights on even though it was an hour after sunset and although I was walking in a quiet neighborhood and the chopper was only about 150 feet above ground I could not hear any rotor noise at all and could barely hear the whine of the 2 turbine engines. Being a pilot who grew up around Edward’s Air Force Base I have seen many strange aircraft before they were made public and this is one of those as yet unexplained sightings.
The point is: this technology is decades old and people should understand anything made public is not leading edge science or aircraft technology. Some details are always withheld from the public.
#12 LOL!
cue the horned helmets!
The old noisy police helicopters had a psyops quality about them.
I lived for a long time in the inner-city of one of the more crime ridden cities in America and helicopter chases of gang members was pretty-much a constant affair.
It was nerve wracking! I wondered if it made the gangsters panic and bolt and that was part of the anti-gang strategy.
They finally replaced them with newer, much quieter models and it just wasn’t as threatening.
Apache Longbows are pretty quiet.
KABOOM!
Too late for you.
At least some of the noise associated with helicopters comes from the rotor blades changing pitch twice per rotation. This is a big part of how helicopters fly and isn’t going away any time soon. The 3-4 db lessening of the sound seems much more likely than that the sound is reduced _to_ 3-4 db.
3db is a halving of the noise, which would be really great for people in helicopter intense areas.
Another issue with noise is that the mechanical energy of the noise is quite damaging to the helicopter structure… less noise means longer life and reduced costs.
Of course, the real question is retrofit to Bell and other non-Eurocopter birds.
Statistically speaking rotor blades are harder to find than most elements on the periodic table. That’s just what I heard on MTV.
This is an old thread and I’m not sure that anyone will read this, if you do, please reply because I’d love to hear your opinion.
Let me be quite clear: I have seen a so-called ‘black helicopter’ and no, I was not mistaken or hallucinating. Here’s what happened: I was laying on a sofa in my attic office here in the UK one evening at dusk. I was dozing for short periods in and out of shallow sleep when suddenly I ‘heard’ an explosion ‘in my head’. I awoke with a start thinking something had gone bang in the house somewhere, yet as I opened my eyes I could see through the window set into the roof above my feet a helicopter, sillhouetted against the dark blue sky, approaching my house at a height of no more than a 200ft or so. I could clearly see the skids underneath it and one red light on it’s port side (my right). I instantly thought it was the local police heli, which often clatters about over our town, however, this one was totally silent. It was also unlit, except for the one red light I mentioned, completely unlike the police heli, which is usually lit up with all the usual aviation lights plus a search light.
It slid out of view over my roof in the space of about three seconds while I lay there wondering what I had seen. Let me make this quite clear: it was SILENT and at that height it would have been very loud indeed. To prove this point a couple of days later the police heli flew over at about the same height and I could feel the vibrations through my floor as well as hear it above everything else.
This was without doubt a classic ‘silent black helicopter’. There was not a single sound coming from it AT ALL and to this day I am a little disturbed by what I saw. I have my pilot’s licence and fly from the same airfield that the police fly from and have been held on the taxiway by ATC on numerous occasions while the police have been given clearance to take off in a hurry – so I know what I’m talking about. Take it from me, this was not a normal helicopter.
I live in a large town (although my street is very quiet) and this thing would have been very obvious to everyone but it slid past silently, which in my opinion would have been impossible at that height. Even at normal altitudes the helis round here make a racket. It was very eerie.
Btw, I am not lying, I have no agenda. I saw what I saw. You can believe it or you can disbelieve it. I don’t care!
I have also seen a silent black helicopter. I didn’t know they weren’t real. I had never researched them, but had heard them in conspiracy theories on the internet. One morning I was walking to the bank, from the store that I worked at, to do a bank deposit. I looked up because I heard a very, very, very faint fluttering sound. It was a fluttering sound, not a “chop chop” sound. I looked up and there was a large black helicopter just hovering over me, about 500 feet high. It was close, close enough that it should have been very loud. I didn’t know they weren’t real, because I saw one, and they are real.