A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Piloting
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Spinner strobing as a "Bird Strike Countermeasure"



 
 
Thread Tools Display Modes
  #71  
Old December 4th 07, 03:32 PM posted to rec.aviation.piloting
Bertie the Bunyip[_19_]
external usenet poster
 
Posts: 3,851
Default Spinner strobing as a "Bird Strike Countermeasure"

"Gig 601XL Builder" wrDOTgiaconaATsuddenlink.net wrote in
:

cavelamb himself wrote:
STANDARD FLAME POST version 3.432 (c) 1996-1997. Check all that apply.


I hadn't seen that in a long time. You need to update though to the
4.0(rec.aviation) version.

It replaces all of that with.

Shut the **** up, MX.




Bwawhahwhahhwahwh!


Bertie
  #72  
Old December 4th 07, 03:52 PM posted to rec.aviation.piloting,rec.aviation.homebuilt
Paul Tomblin
external usenet poster
 
Posts: 690
Default Spinner strobing as a "Bird Strike Countermeasure"

In a previous article, "Yes - I have a name" said:
I'm sure I've seen wheels on cars that appear to be moving backwards. Are

my
eyes defective?


That's due to something else strobing the light, such as the reflection
off other wheels or off the lugnuts. It's also reported that a steady
vibration of your eyes can cause the effect, such as when humming (or
probably while sitting in a noisy airplane).

http://findarticles.com/p/articles/m...17/ai_18471030


The discrete vision theory has been discredited.

Kline K, Holcombe A, Eagleman D (2004). "Illusory motion reversal is
caused by rivalry, not by perceptual snapshots of the visual field.".
Vision Res 44 (23): 2653-8. PMID 15358060.

Kline K, Holcombe A, Eagleman D (2006). "Illusory motion reversal does not
imply discrete processing: Reply to Rojas et al.". Vision Res 46 (6-7):
1158-9. PMID 16199075

--
Paul Tomblin http://blog.xcski.com/
C is *supposed* to be dangerous, damnit!
-- Anonymous, on "Safer C"
  #73  
Old December 4th 07, 04:16 PM posted to rec.aviation.piloting,rec.aviation.homebuilt
Yes - I have a name[_2_]
external usenet poster
 
Posts: 44
Default Spinner strobing as a "Bird Strike Countermeasure"

"Paul Tomblin" wrote in message
...

That's due to something else strobing the light, such as the reflection
off other wheels or off the lugnuts.


So Anthony's statement IS wrong :

"it never appears to move backwards."

Refer to MX rule #1


  #74  
Old December 4th 07, 04:37 PM posted to rec.aviation.piloting,rec.aviation.homebuilt
cavelamb himself[_4_]
external usenet poster
 
Posts: 474
Default Spinner strobing as a "Bird Strike Countermeasure"

Gig 601XL Builder wrote:
cavelamb himself wrote:

STANDARD FLAME POST version 3.432 (c) 1996-1997. Check all that apply.



I hadn't seen that in a long time. You need to update though to the
4.0(rec.aviation) version.

It replaces all of that with.

Shut the **** up, MX.



Dude!
That's sweet.

Direct, to the point, and saves considerable bandwidth.

Wish this idiot could do the same.
But Noooooo.... Not this one.

Ah well.


Richard
  #77  
Old December 4th 07, 05:15 PM posted to rec.aviation.piloting,rec.aviation.homebuilt
[email protected]
external usenet poster
 
Posts: 2,892
Default Spinner strobing as a "Bird Strike Countermeasure"

In rec.aviation.piloting Mxsmanic wrote:
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.


The Non Sequitur Kid puts in a surprise appearance.

Yet he fails to state that at any given moment there are thousands of
phonographs in use.

--
Jim Pennino

Remove .spam.sux to reply.
  #78  
Old December 4th 07, 05:17 PM posted to rec.aviation.piloting, rec.aviation.homebuilt
Harry K
external usenet poster
 
Posts: 153
Default Spinner strobing as a "Bird Strike Countermeasure"

On Dec 3, 7:21 pm, Harry K wrote:
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- Hide quoted text -

- Show quoted text -


After thinking that over...

It gets worse. There will be multiple rpm that will show the effect
under strobe conditions. With a 2 blade prop it can be sychronizing
every 1/2 rev. 3-blade prop every 1/3 or 2/3 rev, etc. in addition to
synching on the harmonics.

Harry K
  #79  
Old December 4th 07, 06:33 PM posted to rec.aviation.piloting, rec.aviation.homebuilt
Tina
external usenet poster
 
Posts: 500
Default Spinner strobing as a "Bird Strike Countermeasure"

If any of you have tried to use a strobe light to determine rotational
speed, you'll remember harmonics are a serious problem.

If there's a single mark on a shaft, it will appear stationary if the
flash rate is equal to the time it takes the shaft to turn once. It
will also appear stationary if its rate is half of that time, (it will
blink on the spot every other time) a quarter of that time, and so on.
It gets worse. If the blink rate is twice that of the shaft speed, the
spot will appear stationary, but only half as intense, since one flash
will 'lock' the spot, and the next will illuminate the opposite side
of the shaft at an unmarked place.

To make this relevant to aviation, replace spot with prop blade.


On Dec 4, 11:17 am, Harry K wrote:
On Dec 3, 7:21 pm, Harry K wrote:





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- Hide quoted text -


- Show quoted text -


After thinking that over...

It gets worse. There will be multiple rpm that will show the effect
under strobe conditions. With a 2 blade prop it can be sychronizing
every 1/2 rev. 3-blade prop every 1/3 or 2/3 rev, etc. in addition to
synching on the harmonics.

Harry K- Hide quoted text -

- Show quoted text -


  #80  
Old December 4th 07, 06:55 PM posted to rec.aviation.piloting,rec.aviation.homebuilt
[email protected]
external usenet poster
 
Posts: 2,892
Default Spinner strobing as a "Bird Strike Countermeasure"

In rec.aviation.piloting Harry K wrote:
On Dec 3, 7:21 pm, Harry K wrote:
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- Hide quoted text -

- Show quoted text -


After thinking that over...


It gets worse. There will be multiple rpm that will show the effect
under strobe conditions. With a 2 blade prop it can be sychronizing
every 1/2 rev. 3-blade prop every 1/3 or 2/3 rev, etc. in addition to
synching on the harmonics.


It isn't that bad.

Synchronization only occurs on integral fractions and engine RPM is
usually 1000 and about 2700 RPM so the possibilities are limited.

For a 2 bladed prop:

7200/2= 3600 - 1800 RPM

7200/3= 2400 - 2400 RPM and 1200 RPM

7200/4= 1800 - 1800 RPM and 900 RPM

etc.

I leave it to someone else to show how many blades you see at each RPM.


--
Jim Pennino

Remove .spam.sux to reply.
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Saturday 072807 in Oshkosh Pt 6 - Warbird show pix I forgot to post earlier [10/33] - "Bird Dog.jpg" yEnc (1/1) Just Plane Noise[_2_] Aviation Photos 0 July 31st 07 10:48 PM
"British trace missile in copter strike to Iran" Mike[_7_] Naval Aviation 8 March 10th 07 09:20 PM
Bird strike(s) Jay Honeck Piloting 45 November 30th 05 05:39 AM
Bird strike Jase Vanover Piloting 16 May 17th 05 11:44 AM


All times are GMT +1. The time now is 04:42 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.