T Nation

Explain This Helicopter

As the caption says… WTF?

http://www.filecabi.net/video/ufochopper.html

I don’t know, I watched it a bunch of times and can’t figure it out, first I was going to say that the tail rotor shouldn’t be spinning unless the main rotor is, because they are linked, but the main rotor does spin slightly, which takes that out…

…then I noticed the main rotor blades flexed upward as the aircraft rose, almost as if there was an extremely strong wind lifting the aircraft. I don’t know, looks crazy though!

The resolution of the camera is set so it appears the main rotors arent spinning.

It’s a model suspended by clear fishing line. The helicopter sound is either due to a real helicopter in the area, dubbed over, or a recording. It’s a very simple special effect utilized by UFO pranksters back in the day.

DB

Uuuhhh… no, the FPS on the video camera are exactly in sync with the rotation of the blades so it appears that they are not moving. But I like the fishing line idea.

[quote]dollarbill44 wrote:
It’s a model suspended by clear fishing line. The helicopter sound is either due to a real helicopter in the area, dubbed over, or a recording. It’s a very simple special effect utilized by UFO pranksters back in the day.

DB[/quote]

[quote]Amsterdam Animal wrote:
Uuuhhh… no, the FPS on the video camera are exactly in sync with the rotation of the blades so it appears that they are not moving. But I like the fishing line idea.
[/quote]

Correct.

In old westerns, the wheels on wagons would often appear to be turning backwards.

[quote]Amsterdam Animal wrote:
Uuuhhh… no, the FPS on the video camera are exactly in sync with the rotation of the blades so it appears that they are not moving. But I like the fishing line idea. [/quote]

Best explanation.

Note also that when the chopper drops or climbs, the rotor seems to move slightly. You’d get that effect from the slight slowing or speeding up that the rotor would experience during those manoeuvres.

Cool result though.

Anyone wanna bet it ends up on a UFO site with doofuses (doofi?) claiming that it’s the US government testing alien technology?

If only my Linux machine could play the video…

[quote]pookie wrote:
Anyone wanna bet it ends up on a UFO site with doofuses (doofi?) claiming that it’s the US government testing alien technology?
[/quote]

It most likely already has. Looks like a Russian copter, though.

I can’t believe you guys that think it has to do with the camera. It’s obviously a sweet-ass hood ornament on a new type of airplane. blinging through the sky too.

You’re all wrong. There is a person with advanced telekinesis on the ground controlling it, and they have the rear propeller spinning to train the guy on how to control moving objects.

I’ve been studying the art for a while, and typed this whole post without physically touching my keyboard or mouse.

[quote]Miserere wrote:
If only my Linux machine could play the video…[/quote]

sounds like somebody needs to get feisty fawn

[quote]SWR wrote:
I’ve been studying the art for a while, and typed this whole post without physically touching my keyboard or mouse. [/quote]

I once had a job as an intern where the project was over and there was absolutely nothing to do.

I actually got to the end of the internet.

So I figured I’d see if I could make a pencil move with my brain. For hours at a time. Once, I thought I saw it move, but nope, it was just the insanity.

[quote]nephorm wrote:
So I figured I’d see if I could make a pencil move with my brain. For hours at a time. Once, I thought I saw it move, but nope, it was just the insanity.[/quote]

No, it actually did move. But it was just SWR fucking with you.

[quote]Amsterdam Animal wrote:
Uuuhhh… no, the FPS on the video camera are exactly in sync with the rotation of the blades so it appears that they are not moving. But I like the fishing line idea.
[/quote]

Just to expand on the topic further, a technique similar to this is used in engineering labs. If you have something that is vibrating at a high frequency, or something like a fan blade turning at a high speed (heli blade in this case), they use a strobe light that’s tuned to the vibration frequency to “freeze” motion so they can troubleshoot or take measurements they need.

Just in case someone out there was curious!

If you look at the helicopter, there are shadows on the side from the blades. Would the frames per second still give the same shadow on the fuselage?

I still think we are missing out on the K.I.S.S. explanation…it’s a great photoshop. Otherwise I think the FPS of the camera is the best idea.

[quote]ratherbelifting wrote:
If you look at the helicopter, there are shadows on the side from the blades. Would the frames per second still give the same shadow on the fuselage?
[/quote]

The shadows would be in the same place.

[quote]
I still think we are missing out on the K.I.S.S. explanation…it’s a great photoshop. Otherwise I think the FPS of the camera is the best idea.[/quote]

Well, there are two things that are necessary for this effect to happen:

  1. The blades have an angular velocity that is near a multiple of the reciprocal FPS of the camera. So if the camera captures 30 FPS, then every 1/30th of a second, the same blade has to return to about the same place. If the apparatus is otherwise symmetrical, of course, that isn’t necessarily the case.

  2. The camera has to have a shutter and film speed high enough to stop the motion, otherwise the blade will travel too much while the frame is being captured, thus creating a motion blur. A strobe could also be used, as another poster pointed out - but not in daylight.

Or it could be a model. The world may never know!