Super Size Me

[miked10270 0]

AS far as the "SMOKING" issue went, there was a 'Quite Interesting' thing on an old edition of QI (it's a British TV show) which dealt with the whole Non-Smoking Flights issue.

When smoking was allowed on aircraft, the cabin air was changed using bleed engine air, so that you had a complete change of cabin air every 15 minutes. Now that smoking is forbidden, the cabin air is continually recirculated with Co2 levels being far higher and viruses, airborne bacteria, etc... circulated throughout the cabin.

In effect... the air yo breath in a commercial aircraft is now far less healthy than it was when folk smoked on planes - BUT - Airlines save around 6% on fuel by recycling cabin air!

"For your safety AND OUR PROFIT!!!"

Mike.

Taking the piss out of the FrenchAmericans since before it was fashionable.

Prenait la pisse hors du FrançaisCanadiens méridionaux puisqu'avant lui à la mode.

[billvon 3,132]

>the cabin air was changed using bleed engine air, so that you had a
> complete change of cabin air every 15 minutes. Now that smoking is
> forbidden, the cabin air is continually recirculated . . .

Airplanes leak like sieves (at least compared to, say, spacecraft.) But it doesn't matter much, because they are constantly being pressurized by bleed air. Indeed, most aircraft pressurization systems don't control the exact cabin pressure by regulating how much bleed air enters - they regulate pressure by how much air _leaves_ through an outlflow valve. Bleed air is pretty warm, but it's under pressure, so if you compress it a bit more, cool it and _then_ allow it to expand it gets very cold, which is a cheap way to provide air conditioning on the ground. That's what the 'air packs' do. (At 30,000 feet, of course, you want that heat, so you skip the cooling part.)

The APU also provides bleed air, and thus can run the air packs on the ground when needed.

Since the outside air has very little humidity, fans generally mix internal cabin air with bleed air so you're getting something like half cabin air (which is humid from people breathing, coffeepots etc) and half outside air. 100% outside air would be really, really dry (although sometimes they use that air in the flight deck, to go easy on the avionics.) 100% recirc air would result in a pretty rapid depressurization, since the door seals (and some of the cable/hose/seam seals) aren't perfect. So a mix is good.

>In effect... the air yo breath in a commercial aircraft is now far less
> healthy than it was when folk smoked on planes - BUT - Airlines
> save around 6% on fuel by recycling cabin air!

See above. You'd pass out pretty fast if they shut down the pressurization system on an airliner and relied on 'recycled' air.

[ln311 0]

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Based on your invocation of Bill Hicks you 'must be cool' according to LN311.

Is that a compliment? I'm not entirely sure what this LM311 that you speak of is?

heheh he was talking about me...i was reading your post over his shoulder at the time. i love Bill Hicks

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[dropoutdave 0]

Hahaha, well that clears that one up! Good man!

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