Spinner strobing as a "Bird Strike Countermeasure"

"Roger (K8RI)" wrote in message
...
On Sun, 02 Dec 2007 22:09:30 -0000, Jim Logajan
wrote:

At cruise RPM that effect would be completely lost. There's not a
bird or human alive that can discern stroboscopic effects of more than
a couple hundred cycles let alone over a 1000. Most of us can't even
discern 60 cps.



"Mike Noel" wrote in message
...
True, but aren't we talking about 40 cps when the prop RPM is 2400?


Seems I have heard the 16 cps is all that is required for movies to appear
continuous. I think the human eye loosed it around 12 or 13. However, we
don't seen consciously either. Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

I can say I worked in the engine shop at American for 15 years, and we were
always told it was a very cost effective bird strike tool. But that is no
guarantee. We always did say if you hadn't heard a good rumor my 10:00 am,
then start one.

But then again, it shouldn't be needed by ground personnel. If someone can
look at a high bypass engine and tell if it's turning fast enough to be
dangerous, the need to be teaching English in France or something.

In article ,
Maxwell wrote:

"Roger (K8RI)" wrote in message
...
On Sun, 02 Dec 2007 22:09:30 -0000, Jim Logajan
wrote:

At cruise RPM that effect would be completely lost. There's not a
bird or human alive that can discern stroboscopic effects of more than
a couple hundred cycles let alone over a 1000. Most of us can't even
discern 60 cps.



"Mike Noel" wrote in message
...
True, but aren't we talking about 40 cps when the prop RPM is 2400?


Seems I have heard the 16 cps is all that is required for movies to appear
continuous. I think the human eye loosed it around 12 or 13. However, we
don't seen consciously either. Hence the reason an aircraft propeller will
appear to be revolving slowly backwards at times.

Visual perception is funny and complex.

black & white films were 16 frames/second.
Color films are 24 frames/second

U.S. TV is 60 fields/second, European is 50/second.
This is driven more by the need for phospors that 'decay' rapidly enough
to not produce 'blurred' motion than perception issues.

OTOH, A significant number of people can perceive 'flicker' in conventional-
tube fluorescent lamps. which is at 120 flickers/second.

Also, the eye -- and brain -- 'notices' things that are too fleeting for
conscious identification. Google 'subliminal' advertizing -- IIRC, lab
tests showed that injected imagery with a duration of only a few milliseconds
had 'measurable' effects.

In article ,
says...


Visual perception is funny and complex.

black & white films were 16 frames/second.
Color films are 24 frames/second


The frame-rate was increased from 16 to 24 at the introduction of sound (not
color). The increased linear speed was desirable to improve fidelity of the
analog optical soundtrack on the film. In either case, 24 or 16 FPS, each image
is projected three or two times (respectively) to produce an effective rate of
48 - this was done to avoid perception of flicker.



Also, the eye -- and brain -- 'notices' things that are too fleeting for
conscious identification. Google 'subliminal' advertizing -- IIRC, lab
tests showed that injected imagery with a duration of only a few milliseconds
had 'measurable' effects.



Oh NO! Not Vance Packard and the "Hidden Persuaders"!!

"Airbus" wrote in message
...
In article ,


The frame-rate was increased from 16 to 24 at the introduction of sound
(not
color). The increased linear speed was desirable to improve fidelity of
the
analog optical soundtrack on the film. In either case, 24 or 16 FPS, each
image
is projected three or two times (respectively) to produce an effective
rate of
48 - this was done to avoid perception of flicker.


Anyone know off hand what the frame rate was for home movies (8mm)?

In article twV4j.1755$QS.57@trndny03,
"Yes - I have a name" wrote:

"Airbus" wrote in message
...
In article ,


The frame-rate was increased from 16 to 24 at the introduction of sound
(not
color). The increased linear speed was desirable to improve fidelity of
the
analog optical soundtrack on the film. In either case, 24 or 16 FPS, each
image
is projected three or two times (respectively) to produce an effective
rate of
48 - this was done to avoid perception of flicker.


Anyone know off hand what the frame rate was for home movies (8mm)?

It was supposed to project at 16fps, which makes for a bit of adjustment
when converting old home movies to DVD.

U.S. TV is 60 fields/second, European is 50/second.

And it takes two interlaced fields to make a frame, therefore US
broadcast TV standard (NTSC) is actually only 30 frames per second.
Europe's PAL and SECAM standards are both 50 interlaced fields per
second, yielding 25 actual frames per second.

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

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

Mxsmanic wrote:
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

Wrong, exactly backwards wrong. Rutger was correct.

Gig 601XL Builder writes:

Wrong, exactly backwards wrong. Rutger was correct.

The frame is a painted raster. The image is the complete set of visual data
for simultaneous assimilation.