 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
nuckolls.bob(at)cox.net
Guest
|
 Posted: Sat Feb 16, 2008 10:57 am Post subject: Lights . . . how big do they really need to be? |
 |
|
At 11:01 AM 2/16/2008 -0600, you wrote:
| Quote: |
<ceengland(at)bellsouth.net>
rampil wrote:
>
>
>OK Bob,
>
>Just remember that the human optical receiver system uses a log-sensitive
>scale, so even a doubling of intensity (double the number of photons)
>would be imperceptible. It would probably be easier to just measure the
>voltage spike on scope with the appropriate probe (admittedly not as much
>fun)
>
>--------
>Ira N224XS
And if you can't see the difference, why not go 'lighter'?
It would be advisable for builders to remember the same thing when they
get all over stimulated by the thought of going from a 50W halogen to a
75W halogen for their landing lights, etc etc etc.
|
Absolutely! I once took a guy for a ride after dark in
the 1K1 J-3 using only a hand-held fisherman's lantern
(6v, .5A 3 watts) as an aid to landing. I let him sit in
the front seat and operate the manually retracting landing
light. We stuck it out the open door and found that it
provided plenty of light to effect graceful arrival with
the earth.
We had an adjacent lighted runway just in case but
the lantern allowed us to use the grass with no
problems.
Years ago, we had a discussion on the 'net about
landing lights for a Rotax powered Kitfox. From the
time you throttle back for approach to landing to
the time you apply full throttle for the next takeoff,
your electrical system is essentially battery-only.
A builder who was wanting to operate occasionally
from a lighted field was considering a 100W landing/
taxi light installation. I was remembering my first
night dual where the instructor never let me turn
the landing light on. After a half dozen or so touch
and goes, I began to realize that my ability to sense
height above the ground was enhanced a great deal by
the perception of texture in the surface under the
airplane that I could see every time the strobes flashed.
This brought forth the idea of mounting small 12v
halogen store spots on each wing tip and pointed
mostly down but a bit forward and outboard. The
goal was to increase the accuracy of height perception
by illuminating the surface under the wing tips and
visible in peripheral vision during the flare.
See:
http://www.aeroelectric.com/Pictures/Lighting/20W_Halogen_Spot_2.JPG
The builder installed the lights and operated them
with a push-button on the stick grip. A second set
of lights in tips pointed forward for taxi assist.
By pushing the right button only when the light was
needed reduced his energy consumption to a tiny
fraction of that needed to power up more conventional
lighting products.
Here's the cowl installation of a 55w miniature reflector
spot in a Quickie. The owner reports very satisfactory
performance after more than 5 years of service and
frequent night flights.
http://www.aeroelectric.com/Pictures/Lighting/MVC-007W.JPG
Bottom line is that the quest for klieg-light
performance in our landing/taxi/warning systems
has a diminishing return on investment after a
certain useful threshold has been reached.
Bob . . .
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
 |
aerobubba(at)earthlink.ne
Guest
|
| Posted: Sun Feb 17, 2008 3:18 pm Post subject: Lights . . . how big do they really need to be? |
|
|
| Quote: | > Just remember that the human optical receiver system uses a
log-sensitive
|
| Quote: | > scale, so even a doubling of intensity (double the number of photons)
> would be imperceptible. It would probably be easier to just measure
the voltage
|
| Quote: | spike on scope with the appropriate probe (admittedly not as much
> fun)
|
This is all true, but we also need to not confuse the lab with the real
world. If you are in a dark room with two point sources of light that are
of a whole order of magnitude of brightness different, and they are
illuminated individually and alternately, you would likely have a hard time
telling which was which. This is due to the adaptability of your eye. If
you had a constantly lit background and did the same test, one source could
well be distinguishable while the other was lost in the background.
Now consider flying near dusk and it's right about 3 miles vis in haze. A
more powerful strobe will be visible while the weaker may not, although
there may be zero practical difference at midnight in a cold, clear, winter
sky.
I used the most powerful strobes I could.
FWIW-
glen matejcek
aerobubba(at)earthlink.net
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?AeroElectric-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
