In message , Don Klipstein
writes
Runways have so many lights that I surely doubt failure of one or
even a few of them or even half of them could make a plane crash. For
that matter, jetliners have instruments that can guide them onto
runways, good enough for any weather short of bad gale force
crosswinds, downbursts, especially dense fog or blizzards or icing of
the runway or height of a full-blown thunderstorm.
(Planes do get scheduled to land at Orlando around 3 or 3:15 PM in
Orlando in the summer, peak time of day and year in the "thunderstorm
capital" of the USA, and how often do we hear news of plane crashes
there?)

One I was on almost crashed as it landed in Orlando. It was tornado
season and the air was very turbulent. As the tyres were just about to
touch the Tarmac the plane suddenly tipped sideways and I saw the tip of
the wing just barely miss hitting the runway by about a foot. The pilot
pulled it back over, the plane swivelled round at about 45 degrees to
the runway, pulled back and slammed down.

There was no applause for the pilot as often happens with difficult
landings. Everyone was gripping the arm rests of their seats with white
knuckles.

Scary, but exhilarating.

--
Clive Mitchell
http:/www.bigclive.com

On Sun, 06 Nov 2005 13:00:53 -0500, w_tom
wrote:

[snip]

As LED lumens output increases, then LED's efficiency
decreases - which is why LED replacement for incandescent
bulbs in the tens of watts range are so expensive and require
heatsinks.

I don't disagree that there is some decrease in LED efficacy
as the output is increased, but this is not the major reason
why LED replacements for incandescent lamps are so
expensive. To stay within the same operating range for power
per unit chip area, you need to use either larger LED chips
or more smaller chips to get more light. The cost of the LED
system increases approximately linearly with chip area. In
contrast, the cost of incandescent, fluorescent and HID
lamps is almost independent of wattage. So, while LEDs can
compete with flashlight bulbs, they are a long way from
being about to compete with any of the much higher lumen
output lamps we use to light our homes and offices.

Do not assume efficiencies of a conventional LED also apply
to LEDs designed to replace a room light incandescents. As
lumens increase, so does inefficiency and heat dissipation.
This was discussed even in IEEE Spectrum sometime in maybe
2001.

Actually high brightness LEDs, the ones that some day might
be used to light rooms, have some of the highest efficacies.
The high cost per lumen is the major factor holding these
back from replacing incandescent lamps and smaller
fluorescent lamps.
--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
replace xxx with vdr in the Reply to: address
or use e-mail address listed at the Web site.

This information is provided for educational purposes only.
It may not be used in any publication or posted on any Web
site without written permission.

On 6 Nov 2005 14:30:58 -0800, scribbled this
interesting note:

I agree with you that old technologoly has its merits - some of it is
even superior to its newer counterpart - and I myself enjoy using it on
many occasions. But like everything else, it has its place and time.
Let us assume that the advice you gave me is good enough for you to
take it yourself. If so, I am amused with the idea that every time when
you turn your computer on, you also light your kerosene lamp and keep
it burning beside the keyboard until it is time to turn your computer
off.


Only when there is a power outage does the kerosene lamp get lit!~
And then, not having a UPS, the computer stays off!:~(


As a byproduct to my disappointment, I still got a pay off in two ways.
First, a lot of laughter, and laughter, so they say, is good for
health. Second, I found here a fellow, namely yourself, who, like me,
enjoys classical music. It is nice to meet people with something in
common to share.


Happy to have been of service!:~)


All the best,

Aharon

--
John Willis

(Remove the Primes before e-mailing me)