# Spinner of Boeing 777-300ER

Hello pilots, what’s up?

In real life does the 77W motor spinner change the direction of rotation when N1 at 66%, equal to the infinte?

Thanks! ✌🏼

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The rotational direction remains the same. It only appears to go backwards because we can’t process those speeds with our eyes. It’s an optical illusion.

Look at a helicopter and it will appear that the blades are hardly spinning when at a certain speed. There are rotating at a high revolution but our eyes/mind cannot process it giving the illusion that the blades are in slow motion or they look like they are rotating backwards.

https://www.scientificamerican.com/article/why-is-it-that-when-you-l/

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This kind of stuff happens because of how FPS and rotation rate interacts.

uh no? @Levet explained it fairly well. If you look at anything that spins really fast, IRL or in a game, if it has a design like a wheel, if it spins really fast it’ll appear like it’s not moving. or moving extremely slow… In game or not. As stated our eyes/brains can’t process such fast speeds.

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Roger! Thanks

Well if you are watching a recording it’s gonna be the FPS vs rotation thing.

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Picture it like this, once it reaches a certain speed, the part of the spinner is like 95% of the way around by the time your eyes can detect it, so the frame rate of the video in this case. So every 30th of a second it is just behind whare it was last which gives it the illusion of backwards movement…

He’s not wrong in his point either. This is validated in the link I provided as well. Same theories and principles apply.

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I mean, i notice the illusion no matter what, if i focus on something spinning that’s fast in game or irl, it appears backwards or slow… I mean i guess it could be because of FPS but it’d still be like the same phenomenon per say

Actually I think in the case of looking at anything through a screen it’s most likely FPS related.

If your screen is 30 fps, and something spins 29 times a second, it’s gonna look like it’s spinning backwards once a second.

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Yes, but it is the same idea. Just here it is limited by the FPS instead of how fast your brain can figure it out…

Both statements are valid 👍 I think our brains can process 1000 fps. So when the phenomenon happens things are spinning well extremely extremely fast

That’s the quick cut and dry answer. But that is based mostly on reaction time. Our mind doesn’t quite work in chucks like a computer does. It is much more of a constant flow. Our mind can still be tricked into seeing this sort of thing, but not nearly as easy as video.

The 1,000 frames per second comes from the fact that our neurons can fire roughly 300-1000 times per second, so the buttons in our eyes can theoretically get data to our brains about a thousand times per second. But there is a lot of diminishing return here. Pretty much no one would notice any sort of difference what so ever seeing something at 1,000 FPS…

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Here’s a video on what way jet engines spin and explains it in detail.

Here’s a video showing the no spinning engine helicopter taking off due to the frame rate.

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