Spinner strobing as a "Bird Strike Countermeasure"

On Dec 3, 2:45 pm, Just go look it up! wrote:
On Mon, 03 Dec 2007 21:52:04 -0800, Airbus wrote:
In article , says...

When observed directly under artifical light that "flickers", the most
obvious being a strobe light, but there are other types of artificial
lights that have flicker.

--

Fine - but which ones cause you to see the propellers turning in
apparent reverse? Do you frequently operate your airplane indoors?
Propellers are usually observed in natural light, which does not flicker. At
night, on the rare occasions where you actually see the props clearly, it is
from the aircraft's own lighting, which is DC. I have nbever seen the props
turning backwards on a real plane - see it frequently in movies though. . .

Night, near one of those big off-amber ramp lights, run the RPM up and
down, there's a range where it will look like it's going backwards. I
thought it was kind of interesting.

It's something similar to the poor-man's "is my RPM somewhat right"
test, it'll appear stopped at (I forget what RPM now) RPM and if your
tach is somewhat near, viola.- Hide quoted text -

- Show quoted text -

Been a long, long time but my rusty math skills says it would be about
3600 unless I am wrong (per wife that is my normal state). That is
the 1/2 harmonic of the rpm/flicker rate. 60 X 120 = 7200. The
phenomenon should appear at 1/2, 1/4, double rate etc intervals.

Harry K

writes:

And it takes two interlaced fields to make a frame, therefore US
broadcast TV standard (NTSC) is actually only 30 frames per second.

30 images, 60 frames

writes:

When observed directly under artifical light that "flickers", the most
obvious being a strobe light, but there are other types of artificial
lights that have flicker.

That is an artifact of the lighting, not of human vision.

Additionally, natural light (e.g., sunlight) does not flicker.

Mxsmanic wrote in
:

writes:

And it takes two interlaced fields to make a frame, therefore US
broadcast TV standard (NTSC) is actually only 30 frames per second.

30 images, 60 frames


You're an idiot


Berie

writes:

Any light that flickers at an appropriate rate will cause the prop to
appear to turn in reverse.

The likelyhood of being somewhere with lights that flicker is irrelevant.

It's highly relevant in aviation, where exposure to flickering lights is
essentially unknown.

The original statement was that it -ONLY- happens in movies and video, and
that absolute statement is false as are most of MX's absolute statements.

The original assertion was that it was an artifact of human vision, which is
never true.

Maxwell writes:

Do you really think you see and visualize motion constantly. Perhaps you
should spend a little more time around and airport yourself. Many
propellers, especially the large diameter props found on radial engines,
will appear at times to be rotating slower, or backwards. It's a fainter
image than recorded on film, but the partnership of the human eye and brain
does not realize fluid motion.

This is completely incorrect. Human vision produces no such artifact.
Anything moving beyond a certain speed is simply a blur; it never appears to
move backwards.

Motion pictures captured on film greatly exaggerates the phenomenon.

No, motion pictures PRODUCE the phenomenon. It's an artifact of the motion
picture, not human vision.

Some of the new video equipment will seem to even stop a prop to the
extent it's distracting to the quality of the recording.

That is a function of shutter speed.

But the human visual system well do so as well, just to a much lesser extent.

No, the human visual system will not do it at all.

Maxwell writes:

Guess again.

It wasn't a guess.

Yes - I have a name writes:

My phonograph turns at either 33-1/3 or 45 RPM, which is just as relevant to
this conversation as your mention of turbofans.

At any given moment there are thousands of aircraft powered by turbofans in
flight.

Mxsmanic wrote in
:

writes:

When observed directly under artifical light that "flickers", the most
obvious being a strobe light, but there are other types of artificial
lights that have flicker.

That is an artifact of the lighting, not of human vision.

Additionally, natural light (e.g., sunlight) does not flicker.


How would you know, ever seen sunlight?


Bertie

Mxsmanic wrote in
:

writes:

Any light that flickers at an appropriate rate will cause the prop to
appear to turn in reverse.

The likelyhood of being somewhere with lights that flicker is
irrelevant.

It's highly relevant in aviation, where exposure to flickering lights
is essentially unknown.



Bwawhahwahwhahwhahhwhahwhahwhahhwhahwhahwha!

Another gem from the master.


Bertie