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.
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!