This is a real video of a helicopter in flight. I’m sure most readers will immediately pick up on how it stays aloft, but it initially caught me off guard. Click play, or go to the Link [metacafe] to see the video.
Miss Cellania
Neat video! I wonder if the camera operator was trying to do this, or if it just came out that way.
Chris
I'm baffled. I have no idea.
Shograt
... This -isn't- a video effect.
Rather, it's a helicopter slowly descending, with rotors stopped. The rotors are lift surfaces, after all.
IE, this is analagous to a 747 'flying' with its engines off. It can't, neither can this helo, they're just both in descents affected by control surfaces.
Andrew32
Shograt, hahahaha, tell that to my Blade CP Pro (Rc Heli) that ran out of batteries at 40'!
I do, literally have in front of me the Official Rotorcraft Fying Handbook. Although it's made 7 years ago, physics doesn't change. In section 11-10, it says, under Low Rotor RPM and Blade Stall, "...However, if you let rotor r.p.m. decay to the point where all the rotor blades stall, the results is usually FATAL, especially when it occurs at altitude. The danger of low r.p.m. and balde stall is greatest in SMALL helicopters..."
Now, there is something called "autogyro" or Autorotation, in which there is limited power to the rotors, but in which they KEEP SPINNING.
So, me being the RC heli geek that I am, have seen MANY crashes to gear slipping and shaft failures, I can safely say that there is now way this is a real video. Although it may be a camera trick. But what you explained is impossible, and I'm sure millions of high school physics text books agree with me.
P.S. I actually do own the Rotorcraft Flying Handbook... I don't know why... (FAA-H-8083-21)
Ari
i was fooled by this neat camera trick when i began training as a chopper pilot! The trick is with the camera recording every 5 or 6 frames, which is the same time as the blades making a full rotation, therefore it only looks like they are staying still, the rear rotor spins at a higher speed to provide stability so thats why you can see it spinning and changing speed. Good trick and very clear shots, kudos!
Dan Smith
I was going to say...I'm fairly familiar with the phenomenon of helicopter blades appearing to stand still, or more commonly move backwards, due to their high speeds and the limitations of the human eye. (or camera in this case)
Chris
Oh..... That is tricky!
Anita
Shograt - the blades are definitely moving ... this is happening because the frame rate and rotor spin rate are exact multiples of each other.
For example, the frame rate might be 30fps, and the rotor might be spinning at 6 rotations per second. Since there are 5 blades, if the alignment were exact it would appear that the blades weren't moving.
Alex
frame rate shframe rate - it's magic, I tell you. Magic!
Dan
Yeah, while you can't see the blades moving, you can definitely hear them. If you can't believe your eyes, pay attention to your ears.
On another note, that is an old, Soviet Hind helicopter. I've always had a thing for them because they looked like they were created by aliens.
FFFish
I have some doubts as to it being the result of video framerate matching: it seems to me the maneuvers being performed would require the pilot to continuously adjust the rotor speed.
andrew
It's vectored thrust! like on those old harrier jets. It's meant to improve maneuverability, but it's also useful for wowing press and neatorama devotees. check out the thrust ports on the sides of the rotor stack.
andrew
nope, it's frame rate synchro...oops
Johnny Cat
It's obviously a streetlight.
TubbyCat
Haha, oh I get it, it's on a string! =D
cardoso
Good Old stroboscopic effect.
brian
I think the frame rate of the video is matching the rotation of the blades. I saw this posted before, and my favorite comment was
"Stupid Russians, can't even afford spinning blades!"
Mossel
Nice short shuttertimes... hardly any motionblur..
I want that camera! =]
And boy, do I love those Mi24 Hinds, fav chopper all times!
And Shograt... man you made me laugh =]
Niel Smith
Well but why can you see a shadow of the blade?
It must be fake
Mossel
Er... why would you NOT see the shadow?
Kris
Haha, Niel Smith - you lose.
B
I'm pretty sure Jesus is the co-pilot.
Andrew32
The Russians finally perfected their anti-gravity helicopter, but too late, the cold war is over...
teaBagger
Definitely vectored thrust
The blades are standing still and there is no way that the frame rate of the camera would perfectly match a multiple of the rpm of the blades for suck a long time.
Slappy
It's not just vectored thrust, look at the blades, they are angled upwards. If they were stopped they'd be drooping big time.
biltmore
@ B
"I’m pretty sure Jesus is the co-pilot."
That makes no freaking sense whatsoever, and isn't even funny. Talk about delusional.
Adam Stanhope
This is the same thing as the old wagonwheel effect on film - or a saw blade in a factory appearing to be stationary under non-phased fluorescent light.
If the blades really weren't spinning the craft would drop from the sky like a stone immediately.
Gordon
That's a Soviet-era Mi 24 Hind gunship, if anyone is interested. I spent my youth getting chased around by those ugly buggers off Simushir Island in the Kuriles.
BTW, its not called an "autogyro" (which is a combination of aircraft / rotorcraft), its an autorotation, defined as "a method of keeping a pilot's hands and feet occupied as he plunges to his death."
v/r Gordon
Lefty
I'm surprised that TubbyCat was the only one who was smart enough to get it.
It's a toy helicopter on a string.
Saul Wall
The tail rotor is also very slow because while it is strobing too, its speed does not match the frame rate.
MisterTrilby
I'm 101% sure that Jesus must be holding it up.
Andrew32
...I thought jesus was the co-pilot was funny.
And Gordon, wow, I checked out the history of the Kuriles, so are you Japanese?
miki
It is aliasing that is caused by a low sampling frequency.
Mossel
I spend alot of time flying these on Desert Combat, Its actually the reason I started playing that old game again =]
My snot-nosed guess is that its a Czech Hind, judging by the paintjob and nose gun layout, which would make it a "Mil Mi-24V Hind-E" (Mi-35 for export.. want one?)
Couldnt find it's rotorspeed though...
Mossel
oh, and.. er...
did someone say Muybridge?
I still want that camera btw =]
Gordon
No, not Japanese - I am former Navy; we used to fly in the Sea of Ohkotsk and between Vladivostok & Sakhalin Island, which was within range of shore-based Hinds. Lots of Hinds, Badgers, Su-15s, and the occasional MiG 23 would come out to play with us. Do a search on Seasnake and Gordon and it will take you to a page where I have ~60 photos posted of our encounters with Soviet warplanes. Fun times, fun times...
Jason McIntire
Anyone who watches this and does not figure out that it is an illusion resulting from a synch between the camera's sampling/frame rate and the RPM of the heli's main rotor within the first3 1/2 seconds is a complete and utter moron. Vectored Thrust? Are you f*ck!ing kidding me? I don't know if any heli's actually do utilize vectored thrust, but if a heli had an engine which utilized vectored thrust strong enough to keep it airborne, it would no longer be a heli, it'd be a freaking plane! A slowing descending heli? Horse Patties!!! You can not compare a no-where-close-to-aerodynamic helicopter to a built-as-aerodynamic-as-possible-to-create-lift airplane. The helicopter gets all of it's lift from the main rotor and stabilizes itself with the rear/tail rotor. If that rotor stopped spinning while the heli was still airborne, it would drop like a rock. An airplane uses forward thrust to create lift with its wings. The stabilizers, trims, and rudder all also use the plane's forward for operation. If the engines go out, the planes momentum will continue to produce forward thrust for the plane to create lift. It will slowly die off, the less aerodynamic the plane, the more air friction will slow the the plane, the quicker the thrust dies off, and the quicker the plane will loss control. The less thrust, the less lift the wings can produce, and the less the trims, stabs, and rudder respond. Make a paper airplane and throw it, see what happens? Now ball up a piece of paper and throw it. See the difference? Shadow of the blade? No way, you are a whole new kind of stupid. Do you believe the the blade of this machine move faster than the speed of light, or do you actually believe someone has invented a strong metal that reflects light so we can see it, but at the same time allows light to pass through it, thus not casting a shadow. Anything in the path of sunlight reflects of most of the rays of that light (it absorbs some, and other things like water and glass which we consider transparent let quite a bit of light though themselves, but not steel), thus removing the light from it would be path, hence the shadow. Toy on a string? Damn good looking toy, and loud. Whoever it was that pointed out that this SOUNDS like a real heli, and that you can actually HEAR the blade spinning thank you. I'm not much of a Christian, but leave Jesus out. I doubt he has much interest in modern war weaponry and machinery. It's not even funny. I hardly ever post on these, but I have not seen so much stupidity gathered in one place before, couldn't passed the chance to rant and rave at random stupidity of a bunch idiots I don't know and don't know. I can sleep happy tonight whether you feel insulted or not. I'm not trying to insult everyone one this page, only the ones making the moronic points I just discussed. People like them will ensure I always have a good job. Good Night. Oh... and the bit about "Stupid Russian, can't even afford rotating blades", that's f&ck!ng hilarious!! -Jason
erikpurne
Haha, Shograt is a funny guy.
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