Re: [Telecom] Cell-phone generation increasingly disconnected

According to Spider Robinson ("The Crazy Years"), the airlines got

> smoking banned aboard aircraft for a completely different reason: it > meant they could slow down the air circulation systems in aircraft > cabins by a factor of two or three (to save energy and money for the > airline) without the fact being visible. The stagnant air that > passengers now have to breathe as a result is almost certainly more > of a health hazard than the slightly smoky air it replaces.

Probably not more so much as different. I really didn't like the smoke...

***** Moderator's Note ***** > > Sorry, that doesn't make sense. Jet aircraft have so much spare > power that air circulation is never a problem: the engines provide > pressurized air for free,

It was almost free on older engine designs but I believe newer high bypass ratio fan engines take a non-trivial performance hit when you extract pressurized air.

so moving air through the cabin is very easy to do.

Regardless of the engine design the pressurized air is hot - too hot, I suspect, to drop to cabin temperature by passive cooling alone. That's more energy spent on active cooling.

In any case, it doesn't pass the common-sense test: why risk offending > passengers when the aircraft has all the ventilation anyone could ever > want?

Why pressurize the cabin to only 8000ft? Why pack seats so close together? It's all a balancing act to keep costs down without driving off too many passengers.

Dan Lanciani ddl@danlan.*com

Reply to
Dan Lanciani
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I flew 707s, 727s, DC-9s, 767s, and L1011s.

Pressurization, heating and air conditioning uses bleed air off the engines drive air cycle machines (turbo compressors in 707).

Any time you bleed a significant amount of air off the engines it reduces engine performance. Often you can recover the lost performance by increasing the power setting, which means more fuel burn.

In some of the earlier airlines like the first 707s, there was no spare power so you had to take off unpressurized to have the required takeoff performance. Then, pressurization started at 1,000 feet, or so. In the winter engine anti ice and especially wing anti ice take away performance by using bleed air.

No free lunch.

What's this have to do with telephony? ;-)

***** Moderator's Note *****

Good question. Pick any answer:

  1. The thread got airborne after someone commented about the effect of tobacco smoke on CO equipment, and I was nostalgic for good old days when you could smoke anywhere except on the flight line. I no longer indulge, but I've always felt that the Thought Police went overboard on the public smoling thing.

  1. I was a pilot once. It's summer, I'm bored, it was a slow day.

  2. I was going to call you about that.
Reply to
Sam Spade

Salon's Ask the Pilot, who is a real commercial pilot, also says that the air circulation is set to make people comfortable, not to minimize the trivial costs.

Stress on the metal hull from pressure/depressure cycles. The 787 will be pressurized to 6000 ft because the plastic hull is stronger.

Oh, because Americans will without exception pick the lowest price, then act suprised when the product is cruddy.

I hear that when they banned smoking and cleaned all of the accumulated tar and gunk out of the cabins, the planes were appreciably lighter.

R's, John

Reply to
John Levine

He's blowing smoke. They turn off one air conditioning pack to save on using bleed air, thus saving a "trivial" amounnt of fuel (when mutiplied by a couple thousand flights a day adds up to some real cash savings).

I was an airline pilot for 27 years and still do consulting in the industry.

***** Moderator's Note *****

This _has_ veered too far away from telecom, so this will be the last post in this thread.

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