Vapour trails

[Michael Calwell]

Hello,

Question from a complete landlubber.

I work outdoors beneath the flightpath to Edinburgh Airport.

I take it that vapour trails are the condensed water contained in the
air ingested by the engines. My question is, how much air does an engine
ingest at cruise? How would you visualise that amount of air?

Yours in amazement at how you stay aloft,

Michael

[Orval Fairbairn]

In article >,
Michael Calwell > wrote:

> Hello,
>
> Question from a complete landlubber.
>
> I work outdoors beneath the flightpath to Edinburgh Airport.
>
> I take it that vapour trails are the condensed water contained in the
> air ingested by the engines. My question is, how much air does an engine
> ingest at cruise? How would you visualise that amount of air?
>
> Yours in amazement at how you stay aloft,
>
> Michael


Vapor trails are also the condensed ice crystals resulting from just the
movement of the plane through the air. On a humid day, I can pull
contrails off my prop tips.

[Morgans]

"Michael Calwell" > wrote in message
...
> Hello,
>
> Question from a complete landlubber.
>
> I work outdoors beneath the flightpath to Edinburgh Airport.
>
> I take it that vapour trails are the condensed water contained in the
> air ingested by the engines. My question is, how much air does an engine
> ingest at cruise? How would you visualise that amount of air?
>
> Yours in amazement at how you stay aloft,
>
> Michael

It is not the vapor from the air you are seeing, it is the water that is
produced as a byproduct of burning hydrocarbons.

Ever see water dripping from your car tailpipe, especially in the morning
when you start it up? Water is being produced, and being condensed on the
cold sides of the tailpipe, then it drips out. When the tailpipe gets
warm, the water stays invisible, so you don't see clouds unless the outside
temperature gets very very cold, then you get clouds coming from the back of
the car, as the result of the exhaust cooling rapidly, and the vapor in
exhaust condenses to become visible.

This is similar to what is happening when you see contrails. They almost
always are very high, so the water vapor condenses and then freezes into ice
crystals almost instantly, so then it is harder for the water to
re-evaporate into the surrounding air. This is the reason con trails are
visible for a long time after the aircraft passes by.

The vapor that you see off the tips of props, or from the topside of fighter
jet wings when they are pulling high G-forces are from the pressure in the
air being reduced very quickly, which causes the water vapor to become
visible for an instant, then disappearing just as quickly when the pressure
is returned back to normal.

As far as the amount of air being passed through an engine, for a
reciprocating engine, the amount is much smaller than a jet engine. Gallons
per second for a piston engine, and hundreds of gallons for a jet engine?
Something like that.

I hope this has helped.
--
Jim in NC

[Larry Dighera]

On Sat, 11 Dec 2004 20:42:05 +0000, Michael Calwell
> wrote in
>::

>I work outdoors beneath the flightpath to Edinburgh Airport.
>
>I take it that vapour trails are the condensed water contained in the
>air ingested by the engines. My question is, how much air does an engine
>ingest at cruise? How would you visualise that amount of air?

If I recall correctly, as a result of the ban on flight over the US
following the 9/11 terrorist attack, there was a measurable
temperature rise attributed to the reduction in airliner contrails.

Yahoo yielded this:
http://p211.ezboard.com/fchemtrailsstratosphericandtroposphericozoneresear ch.showMessage?topicID=75.topic

[Morgans]

"Larry Dighera" > wrote

> If I recall correctly, as a result of the ban on flight over the US
> following the 9/11 terrorist attack, there was a measurable
> temperature rise attributed to the reduction in airliner contrails.
>
> Yahoo yielded this:
>
http://p211.ezboard.com/fchemtrailsstratosphericandtroposphericozoneresear ch.showMessage?topicID=75.topic

I was unable to find where the link talked about that in a reasonable amount
of time, but I gotta say.....

Yeah, right!!! :-)
--
Jim in NC

[vincent p. norris]

>As far as the amount of air being passed through an engine, for a
>reciprocating engine, the amount is much smaller than a jet engine. Gallons
>per second for a piston engine, and hundreds of gallons for a jet engine?
>Something like that.

Let me see..... The fuel-air mixture for a piston engine is about 14
pounds of air per pound of avgas, is it not? Would it be about the
same for jet fuel?

How "big" a pound of air is depends on pressure and temperature
(Boyles' and Charles' Laws, if I recall correctly), but I can't even
guess how big a box it would take to hold a pound of air at STP.
Perhaps someone else can. I guess any good chemist could do it.

vince norris

[Capt.Doug]

>"vincent p. norris" wrote in message >
>The fuel-air mixture for a piston engine is about 14
> pounds of air per pound of avgas, is it not? Would it be about the
> same for jet fuel?

Jet fuel averages 6.7 pounds per gallon with more BTUs, so the
stoichiometric ratio is slightly different. Much of the air ingested by a
jet engine is used for cooling, not for burning. Do we include this air as
being ingested? Do we include the fan's cold stream as being ingested?

D.

[Capt.Doug]

>"Michael Calwell" wrote in message >
> My question is, how much air does an engine
> ingest at cruise? How would you visualise that amount of air?

The smaller jet engines are rated for 2000 pounds of thrust. The largest are
rated around 100,000 pounds of thrust. For every action (forcing air through
a jet engine), there is a reaction (thrust). The best visual I know of for
this is to watch, hear, and feel a B-777 do a full-power engine run. It's
awesome.

D.

[Rod Madsen]

Jets use something like 100% "excess air" in their combustion process,
unlike piston engines. Much of this air is used for internal engine cooling
and some is used as "bleed air" for cabin pressurization, de-icing, etc.

Rod
"vincent p. norris" > wrote in message
...
> >As far as the amount of air being passed through an engine, for a
> >reciprocating engine, the amount is much smaller than a jet engine.
Gallons
> >per second for a piston engine, and hundreds of gallons for a jet engine?
> >Something like that.
>
> Let me see..... The fuel-air mixture for a piston engine is about 14
> pounds of air per pound of avgas, is it not? Would it be about the
> same for jet fuel?
>
> How "big" a pound of air is depends on pressure and temperature
> (Boyles' and Charles' Laws, if I recall correctly), but I can't even
> guess how big a box it would take to hold a pound of air at STP.
> Perhaps someone else can. I guess any good chemist could do it.
>
> vince norris

[Larry Dighera]

On Sat, 11 Dec 2004 19:01:04 -0500, "Morgans"
> wrote in >::

>I was unable to find where the link talked about that...


Absence of contrails increases diurnal temperature range

Clouds formed by the water vapor in the exhaust from jet planes have a
small but significant effect on daily temperatures, a new study
confirms. The grounding of commercial flights for three days after
last September's terrorist attacks in the United States gave David
Travis at the University of Wisconsin-Whitewater and colleagues a
chance they never thought they'd have: to study the true impact that
contrails from jet engines have on our climate1

Despite a wealth of experiments, it had been virtually impossible to
gauge the effect of contrails because air traffic, particularly over
regions such as Europe and North America, never stopped. Until 11
September 2001, that is. Contrails left high in the atmosphere spread
out into cirrus-like clouds under the right atmospheric conditions.
Natural cirrus clouds - thin layers of wispy water vapor that often
resemble fish scales - trap heat being reflected from the ground and,
to a lesser extent, reflect some of the Sun's rays.

Travis's team compared the average daily high and low temperatures
over North America from 11 to 14 September 2001, with climatic records
from 1977 to 2000, matching the weather over those three days with
similar weather in September from historical records.
They found that the difference between daily high and nightly low
temperatures in the absence of contrails was more than 1 oC greater
than in the presence of contrails. Comparing the three-day grounding
period with the three days immediately before and after, the impact
was even larger - about 1.8 oC.

The researchers suggest that in regions with crowded skies, contrails
work just like artificial cirrus clouds, preventing days from getting
too hot by reflecting the Sun's rays, and keeping nights warmer by
trapping the Earth's heat. Averaged over the globe, which is largely
free of air traffic, the effect is negligible. "But locally, contrails
are equally as significant as greenhouse gases," says Carleton.

The discovery is important, "especially when you consider that air
traffic is expected to increase at about five per cent a year". But
making use of the information by incorporating it into climate models,
for example, will be difficult. Little is known about what conditions
lead to contrail formation, how long they last, and whether they
affect more than just temperature.

References

1Travis, D. J., Carleton, A. M & Lauritsen, R. G. Contrails reduce
daily temperature range. Nature, 418, 601, (2002).

[Morgans]

"Capt.Doug" > wrote

> Jet fuel averages 6.7 pounds per gallon with more BTUs, so the
> stoichiometric ratio is slightly different.

More air, to take advantage of the BTU's, right? Plus jets are more
efficient at altitude, so more air again, right?.

>Much of the air ingested by a
> jet engine is used for cooling, not for burning. Do we include this air as
> being ingested?

For what we were talking about, which is how much air is being used to make
con trails, (my take on it) it would seem to me we are talking about the air
that is being used to burn fuel.

> Do we include the fan's cold stream as being ingested?

I wouldn't. It's just a big fancy prop, and props are not making any con
trails.

Another thing that is being overlooked, is the HP rating of the engine. In
talking about the air being injested, we have to remember that piston
engines are at most making a couple thousand HP (most lots less than that)
and the turbine engines on large jetliners are making multiples more power,
burning more fuel, using more air, and making more water vapor, and making
bigger contrails.

I'm no expert on this stuff, but I think my thinking (and guestimates) are
about right. After all, the original question was not a highly defined,
quanitative question, and neither is the answer. <g>
--
Jim in NC

[Stefan]

Larry Dighera wrote:

> If I recall correctly, as a result of the ban on flight over the US
> following the 9/11 terrorist attack, there was a measurable
> temperature rise attributed to the reduction in airliner contrails.

The source you menion says quite the opposite:

"Locally, contrails are equally as significant as greenhouse gases."

(Copied from your later post.)

Stefan

[Larry Dighera]

On Sun, 12 Dec 2004 13:07:18 +0100, Stefan >
wrote in >::

>Larry Dighera wrote:
>
>> If I recall correctly, as a result of the ban on flight over the US
>> following the 9/11 terrorist attack, there was a measurable
>> temperature rise attributed to the reduction in airliner contrails.
>
>The source you menion says quite the opposite:
>
>"Locally, contrails are equally as significant as greenhouse gases."
>

Would that "opposite" be during the day or night? It also says: "...
nights warmer by trapping the Earth's heat."

So while my 3 year old memory may have been incomplete, it was about
as accurate as your interpretation of the article I posted yesterday.

What seems infinitely more significant is the awesome magnitude of
exhaust spewing from airliners as a result of burning 18,536,000,000
(that's 18-1/2 trillion) gallons of kerosene annually*; one would
expect some environmental impact.

* http://www.aopa.org/whatsnew/factcard.pdf

[Newps]

Larry Dighera wrote:


>
> What seems infinitely more significant is the awesome magnitude of
> exhaust spewing from airliners as a result of burning 18,536,000,000
> (that's 18-1/2 trillion) gallons of kerosene annually*; one would
> expect some environmental impact.
>

Baloney. If we had as a goal to raise or lower the temp of the earth by
a few degrees we couldn't do it. 30 years ago the sceintific community
was scared to death about global cooling. That didn't get anybody
revved up so they switched to global warming. Cover story in a 1975
issue of Time magazine, quoting all the great sceintists of the day,
said by the year 2000 there would be widespread famine due to the
reduced growing season because it was getting too cold. Now a mere 30
years later we're worrying about global warming. The globe is certainly
warming or cooling, it always has. But you cannot prove anything with
the 100 or so years of data that we have much less the last 30 years.
There used to be glaciers covering the northern 5th of the US, they came
and went dozens of times in the history of the earth. Did the caveman
worry about global warming as he watched the glaciers recede? Did the
caveman have anything to do with it? To think that man could change the
temp of the earth one way or the other is the height of arrogance.

[Larry Dighera]

On Sun, 12 Dec 2004 09:04:18 -0700, Newps > wrote
in >::

>Larry Dighera wrote:
>
>>
>> What seems infinitely more significant is the awesome magnitude of
>> exhaust spewing from airliners as a result of burning 18,536,000,000
>> (that's 18-1/2 trillion) gallons of kerosene annually*; one would
>> expect some environmental impact.
>>
>
>Baloney.

[Temperature related diatribe snipped]

Stand down wind of an airliner and inhale, then tell me there's no
significant air pollution emanating from turbine engines. When I
worked at LAX I was nearly overcome with the fumes from these fire
breathers as they taxied by.

[Stefan]

Larry Dighera wrote:

> Would that "opposite" be during the day or night? It also says: "...
> nights warmer by trapping the Earth's heat."

Clouds reflect radiation wich results in cooler days and warmer nights.
The question is, what is the total effect (i.e. integrated over 24
hours). The article you cited says, the total effect will be a warmer
climate.

This said, and not having read the original paper, the weak point of
that paper is that it is the result of a singular event and as such, the
results cannot be reproduced. (Actually, they could...)

In general, the impact of clouds to the climate is mathematically very
difficult to model and is one of the last unresolved factors in climatology.

Stefan

[Mike Beede]

In article >, Newps > wrote:

> Larry Dighera wrote:
>
>
> >
> > What seems infinitely more significant is the awesome magnitude of
> > exhaust spewing from airliners as a result of burning 18,536,000,000
> > (that's 18-1/2 trillion) gallons of kerosene annually*; one would
> > expect some environmental impact.

Where I come from, 18e9 is 18 billion. I'm amused in sort of an odd way
that everyone keeps saying things like "assuming people can affect the
climate of the earth is the height of arrogance." This usually comes just
before or after they say there isn't enough evidence to decide one way
or the other. Pick a position and stick with it--using both arguments
is a hint that you've made up your mind and you're just spraying a
blinding cloud of rhetoric. My position is that the evidence probably
isn't conclusive, but the consequences are pretty severe, so we'd better
be damned sure we aren't boning ourselves. Perhaps everyone that's
convinced there's nothing to global warming should move to Florida
as a show of faith?

By the way, sorry for the double-quoting. If I weren't such a bad man
I'd have posted once on Newps's and once on Larry's comments....

Mike Beede

[Larry Dighera]

On Sun, 12 Dec 2004 17:32:20 +0100, Stefan >
wrote in >::

>Larry Dighera wrote:
>
>> Would that "opposite" be during the day or night? It also says: "...
>> nights warmer by trapping the Earth's heat."
>
>Clouds reflect radiation wich results in cooler days and warmer nights.
>The question is, what is the total effect (i.e. integrated over 24
>hours). The article you cited says, the total effect will be a warmer
>climate.

That's reasonable. The point is, airline traffic is of such great
magnitude that it is conceivable that it affects earth's environment.

[Dan Luke]

"Newps" wrote:
> To think that man could change the temp of the earth one way or the
> other is the height of arrogance.

You've pulled statements to this effect out of your nether regions and
posted them before, but you've never cited any backup for them. What
are your qualifications as a climatologist?

[Newps]

Larry Dighera wrote:


>
>
> [Temperature related diatribe snipped]
>
> Stand down wind of an airliner and inhale, then tell me there's no
> significant air pollution emanating from turbine engines. When I
> worked at LAX I was nearly overcome with the fumes from these fire
> breathers as they taxied by.

A bad smell doesn't equate to pollution.

[Larry Dighera]

On Sun, 12 Dec 2004 13:30:36 -0700, Newps > wrote
in >::

>Larry Dighera wrote:
>
>>
>> [Temperature related diatribe snipped]
>>
>> Stand down wind of an airliner and inhale, then tell me there's no
>> significant air pollution emanating from turbine engines. When I
>> worked at LAX I was nearly overcome with the fumes from these fire
>> breathers as they taxied by.
>
>A bad smell doesn't equate to pollution.

I would expect, that inhaling raw hydrocarbons can be hazardous to
your health. But I could be wrong. :-)

Perhaps the situation is different at altitude, and the turbine
exhaust only produces water and CO2, but I have no way of obtaining
first hand knowledge of that.

[Larry Dighera]

On Sun, 12 Dec 2004 11:10:47 -0600, Mike Beede > wrote
in >::

>In article >, Newps > wrote:
>
>> Larry Dighera wrote:
>>
>> >
>> > What seems infinitely more significant is the awesome magnitude of
>> > exhaust spewing from airliners as a result of burning 18,536,000,000
>> > (that's 18-1/2 trillion) gallons of kerosene annually*; one would
>> > expect some environmental impact.
>
>Where I come from, 18e9 is 18 billion.

I can't argue with that. Thanks. (I'll blame the virus from which
I'm trying to recuperate.)

It's still 98%* of all the aviation fuel consumed in US operations.
And that figure appears to fail to account for military and foreign
operations.

* http://www.aopa.org/whatsnew/factcard.pdf

[Capt.Doug]

>"Morgans" wrote in message > Plus jets are more
> efficient at altitude, so more air again, right?.

No, less air, because the density of the ambient air is less as altitude
rises. Less air in the front means less air out the back (though the
pressure ratio can be the same). Jet engines produce less thrust at
altitude. There is less cooling air which means that maximum exhaust
temperature is reached at a lower thrust. The efficiency gains come from the
forward speed of the engine (sort of a ram effect) and the lower aerodynamic
drag at altitude (higher true airspeed).

> Another thing that is being overlooked, is the HP rating of the engine.

Turbojets have no torque and therefore have no horsepower. There is an
equation for 'equivalent horsepower' which involves an airspeed of around
375 mph.

> I'm no expert on this stuff, but I think my thinking (and guestimates) are
> about right.

If you are more confused now than before, you get an A+!

D.

[[email protected]]

Another visualization for this...I visited the GE factory last year and
was able to stand inside the inlet of a 777's GE90 engine. That
particular model had a mass flow rate of about 3,000 lb/s. That's as
much air in one second as there was in the building we were in (a large
warehouse). Pretty impressive.

[[email protected]]

Be afraid. Be very, very afraid :-)

http://www.stop-chemtrails.com/

[[email protected]]

Michael Calwell wrote :
> take it that vapour trails are the condensed water contained in the
>air ingested by the engines.

I can't believe this thread has gone on for 3 days without mention of
the true nature of these "vapor trails".

See the Chemtrails site :
http://www.rense.com/politics6/chemdatapage.html

:-)))))))))))))))))))))))))))))))))))))))))))))))))) ))))))))))))))))))))))))
John Galban=====>N4BQ (PA28-180)

[Robert M. Gary]

Hey, don't make fun. These Chemtrails contain large amount of
Dihydrogen Monoxide. Dihydrogen Monoxide is responsible for untold
number of deaths every year!!
Check out http://www.dhmo.org


-Robert (hiding in fear of everything)

[mike regish]

Actually, if that number's written right, it's 18 1/2 BILLION.

mike regish

"Larry Dighera" > wrote in message
...
>
> What seems infinitely more significant is the awesome magnitude of
> exhaust spewing from airliners as a result of burning 18,536,000,000
> (that's 18-1/2 trillion) gallons of kerosene annually*; one would
> expect some environmental impact.
>
> * http://www.aopa.org/whatsnew/factcard.pdf

[mike regish]

I've gradually built up a tolerance to that stuff so that now I can drink it
by the quart and it doesn't even hurt me.

mike regish

"Robert M. Gary" > wrote in message
oups.com...
> Hey, don't make fun. These Chemtrails contain large amount of
> Dihydrogen Monoxide. Dihydrogen Monoxide is responsible for untold
> number of deaths every year!!
> Check out http://www.dhmo.org
>
>
> -Robert (hiding in fear of everything)
>

[G.R. Patterson III]

mike regish wrote:
>
> I've gradually built up a tolerance to that stuff so that now I can drink it
> by the quart and it doesn't even hurt me.

That's nothin'! I *bathe* in it every day!

George Patterson
The desire for safety stands against every great and noble enterprise.

[Jay Beckman]

"Robert M. Gary" > wrote in message
oups.com...
> Hey, don't make fun. These Chemtrails contain large amount of
> Dihydrogen Monoxide. Dihydrogen Monoxide is responsible for untold
> number of deaths every year!!
> Check out http://www.dhmo.org
>
>
> -Robert (hiding in fear of everything)
>

OhMyGawd...

That's one of the scariest (funniest) sites I've ever seen...classic!

Jay Beckman
PP-ASEL
Chandler, AZ
(A Low DHMO Zone)

[Peter Duniho]

"G.R. Patterson III" > wrote in message
...
>> I've gradually built up a tolerance to that stuff so that now I can drink
>> it
>> by the quart and it doesn't even hurt me.
>
> That's nothin'! I *bathe* in it every day!

You both are amateurs. Not only do I inhale the stuff with EVERY SINGLE
BREATH, I often go out of my way to "enhance" the air around with me with
it, just so I can breathe MORE of it.

[Stefan]

Robert M. Gary wrote:

> Hey, don't make fun. These Chemtrails contain large amount of
> Dihydrogen Monoxide.

I understand the joke. This said, water vapour is a powerful green house
gas, and an increase of water vapour in the athmosphere *does* cause
problems.

Stefan

[Ash Wyllie]

mike regish opined

>I've gradually built up a tolerance to that stuff so that now I can drink it
>by the quart and it doesn't even hurt me.

I find that adding large amounts of ethonal to DMHO reduces its toxicity.

>mike regish

>"Robert M. Gary" > wrote in message
oups.com...
>> Hey, don't make fun. These Chemtrails contain large amount of
>> Dihydrogen Monoxide. Dihydrogen Monoxide is responsible for untold
>> number of deaths every year!!
>> Check out http://www.dhmo.org
>>
>>
>> -Robert (hiding in fear of everything)
>>




-ash
Cthulhu in 2005!
Why wait for nature?

[Newps]

Stefan wrote:

>
> I understand the joke. This said, water vapour is a powerful green house
> gas, and an increase of water vapour in the athmosphere *does* cause
> problems.

Bull****.

[Casey Wilson]

"Ash Wyllie" > wrote in message
...
> mike regish opined
>
>>I've gradually built up a tolerance to that stuff so that now I can drink
>>it
>>by the quart and it doesn't even hurt me.
>
> I find that adding large amounts of ethonal to DMHO reduces its toxicity.
>
Yah, but one of the severe side affects of excess ethanol additive is
losing the ability to spell, amongst other things.
Pressurizing DHMO with CO2 has yeilded some interesting results.

[Matt Barrow]

"Casey Wilson" > wrote in message
news:03Evd.5728$Qp.5422@trnddc01...
>
> "Ash Wyllie" > wrote in message
> ...
> > mike regish opined
> >
> >>I've gradually built up a tolerance to that stuff so that now I can
drink
> >>it
> >>by the quart and it doesn't even hurt me.
> >
> > I find that adding large amounts of ethonal to DMHO reduces its
toxicity.
> >
> Yah, but one of the severe side affects of excess ethanol additive
is
> losing the ability to spell, amongst other things.
> Pressurizing DHMO with CO2 has yeilded some interesting results.
>
At frat parties.

[Larry Dighera]

On Tue, 14 Dec 2004 08:22:51 -0700, Newps > wrote
in >::

>Stefan wrote:
>
>>
>> I understand the joke. This said, water vapour is a powerful green house
>> gas, and an increase of water vapour in the athmosphere *does* cause
>> problems.
>
>Bull****.

Newps, the logic of your argument reveals the mind of an astute
scientist. Thanks for your contribution of astute analysis. :-)

There's little question that you are eminently qualified for the
position of Vice President of the US. :-)

http://www.washingtonpost.com/wp-dyn/articles/A3699-2004Jun24.html

[Ash Wyllie]

Casey Wilson opined

>"Ash Wyllie" > wrote in message
...
>> mike regish opined
>>
>>>I've gradually built up a tolerance to that stuff so that now I can drink
>>>it
>>>by the quart and it doesn't even hurt me.
>>
>> I find that adding large amounts of ethonal to DMHO reduces its toxicity.
>>
> Yah, but one of the severe side affects of excess ethanol additive is
>losing the ability to spell, amongst other things.
> Pressurizing DHMO with CO2 has yeilded some interesting results.

Add a touch of quinine to your CO2 + DHMO + ethanol mix, and you have a good
anti-malarial compound. Now, what did I do with that mosquito...


-ash
Cthulhu in 2005!
Why wait for nature?

[Ash Wyllie]

Newps opined

>Stefan wrote:

>>
>> I understand the joke. This said, water vapour is a powerful green house
>> gas, and an increase of water vapour in the athmosphere *does* cause
>> problems.

>Bull****.

CO2 alone does not explain global warming. It is the increase of DHMO in the
that cause problems. DHMO is a much more potent, and much more commen
greenhouse gas.

-ash
Cthulhu in 2005!
Why wait for nature?

[Casey Wilson]

"Ash Wyllie" > wrote in message
...

> Add a touch of quinine to your CO2 + DHMO + ethanol mix, and you have a
> good
> anti-malarial compound. Now, what did I do with that mosquito...

Hmmmm, first I think you need to compound a small amount of liquidus DHMO
and ethanol with the steam distillate of Dipterocarpus cornutus. The result
is less volatile and enhances the effect of the quinine. The result, when
ingested after having been passed over "en solidus" DHMO will cause
impairment of vision in persons with low tolerance. Supporting your claim
above, I have not found one case history of malaria involved with this
treatment. Hyperingestion, on the other hand, has led to nausea and
vomiting, combined with disorentation and cardiovascular depression.

[Dean Wilkinson]

So, lets look at this factually...

In recent history, atmospheric CO2 levels have been at their lowest levels
in the entire history of the planet. It has been as low as about 150 ppm.
In recent history, it has been steadily climbing toward 300 ppm, presumably
due to human activity, but there has been a fair amount of volcanic activity
in recent years which also contributes large amounts of CO2.

Given the fact that during the age of the dinosaurs, CO2 levels were up
around 1,000 to 2,000 ppm, this recent CO2 rise is rather insignificant by
comparison.

Also, historical global temperature data shows that the earth has a
bi-stable average temperature (bouncing between 12C and 22C). The average
temperature of the earth is currently at the low bi-stable point, but
throughout most of the earths history, the temperature was at the high
bistable point. The last time that the earth had the current combination of
low CO2 and low average temperature was about 300 million years ago.

There is a nice historical summary graph that shows both atmospheric CO2
levels and average temperature that is available at
http://www.clearlight.com/~mhieb/WVFossils/PageMill_Images/image277.gif

Dean

[Newps]

Dean Wilkinson wrote:
> So, lets look at this factually...
>
> In recent history, atmospheric CO2 levels have been at their lowest levels
> in the entire history of the planet.

You have no way of knowing that. I can just see the caveman out there
with his CO2 test kit.....


It has been as low as about 150 ppm.
> In recent history, it has been steadily climbing toward 300 ppm, presumably
> due to human activity, but there has been a fair amount of volcanic activity
> in recent years which also contributes large amounts of CO2.

It's a guess. We only have maybe 150 years of temp data and much less
years of other data. In the history of the planet that is zip.


>
> Also, historical global temperature data shows that the earth has a
> bi-stable average temperature (bouncing between 12C and 22C). The average
> temperature of the earth is currently at the low bi-stable point, but
> throughout most of the earths history, the temperature was at the high
> bistable point. The last time that the earth had the current combination of
> low CO2 and low average temperature was about 300 million years ago.

The earth has cooled and warmed constantly. Glaciers come and go.
Humans couldn't change that if they wanted.

[Dean Wilkinson]

"Newps" > wrote in message
...
>
>
> Dean Wilkinson wrote:
> > So, lets look at this factually...
> >
> > In recent history, atmospheric CO2 levels have been at their lowest
levels
> > in the entire history of the planet.
>
> You have no way of knowing that. I can just see the caveman out there
> with his CO2 test kit.....
>
>
Actually, we do know this with a fair degree of confidence. Antarctica has
trapped bubbles of air going way back in its ice that has been core sampled.
There are other geologic indicators that they use to determine the levels as
well for prehistoric data.

> It has been as low as about 150 ppm.
> > In recent history, it has been steadily climbing toward 300 ppm,
presumably
> > due to human activity, but there has been a fair amount of volcanic
activity
> > in recent years which also contributes large amounts of CO2.
>
> It's a guess. We only have maybe 150 years of temp data and much less
> years of other data. In the history of the planet that is zip.
>
There are other geological records that are used to determine temperature
besides direct measurements.

>
> >
> > Also, historical global temperature data shows that the earth has a
> > bi-stable average temperature (bouncing between 12C and 22C). The
average
> > temperature of the earth is currently at the low bi-stable point, but
> > throughout most of the earths history, the temperature was at the high
> > bistable point. The last time that the earth had the current
combination of
> > low CO2 and low average temperature was about 300 million years ago.
>
> The earth has cooled and warmed constantly. Glaciers come and go.
> Humans couldn't change that if they wanted.

[David CL Francis]

On Mon, 13 Dec 2004 at 03:20:38 in message
>, Capt.Doug
> wrote:

>No, less air, because the density of the ambient air is less as altitude
>rises. Less air in the front means less air out the back (though the
>pressure ratio can be the same). Jet engines produce less thrust at
>altitude. There is less cooling air which means that maximum exhaust
>temperature is reached at a lower thrust. The efficiency gains come from the
>forward speed of the engine (sort of a ram effect) and the lower aerodynamic
>drag at altitude (higher true airspeed).

This interests me as it is often said, the idea of less drag at
altitude presumably comes from the idea that drag depends on air
density? Which of course it does. However if you fly for maximum range
than you fly close to maximum lift/drag ratio which depends only on
getting the correct alpha (ignoring compressibility effects).

So since lift = weight, drag depends on weight and it reduces as fuel is
burned. The aircraft flies faster to create the lift at altitude but the
drag is presumably almost the same?

Am I wrong?
--
David CL Francis

[Newps]

Dean Wilkinson wrote:


>>You have no way of knowing that. I can just see the caveman out there
>>with his CO2 test kit.....
>>
>>
>
> Actually, we do know this with a fair degree of confidence. Antarctica has
> trapped bubbles of air going way back in its ice that has been core sampled.

Would that be before, during or after the volcanic eruption? While
interesting, trapped air doesn't tell us much of anything. We can't
even affix a date to within a reasonable amount of time.


>>
>
> There are other geological records that are used to determine temperature
> besides direct measurements.
>

Yes, but today we know what the temp is every hour of every day.
Looking at rocks we only have generalities. It was hot during this
period of years, cold during this period, etc. Now we're trying to say
that because the temp has gone up 1 degree in the last 50 years we have
a problem.

[Peter Duniho]

"David CL Francis" > wrote in message
...
> [...]
> So since lift = weight, drag depends on weight and it reduces as fuel is
> burned. The aircraft flies faster to create the lift at altitude but the
> drag is presumably almost the same?
>
> Am I wrong?

Yes. :)

The drag is actually less. The indicated airspeed is a good way of seeing
how the airframe is currently being affected by the ambient air at whatever
density it is. Regardless of the air's actual density, the 1G stall speed
is always the same, and for constant engine power, cruise speed remains
remarkably constant (I'm not sure whether it is actually constant, but
having flown a turbocharged engine at altitudes up to 18,000' and noting an
airspeed drop only higher than 16,000', the turbocharger's "critical
altitude", I am confident in saying that, when measured by indicated
airspeed, there's practically no change as long as power is kept constant).

As altitude goes up and indicated airspeed remains constant, TRUE airspeed,
on the other hand, goes up. Same lift (equal to weight, as you note), but
you're going faster for the same power. Obviously thrust didn't increase
(and in fact, decreased, since you get less thrust from the prop due to the
less dense air...though with a constant speed prop, much if not all of the
lost thrust can be regained using coarser prop pitch), so the only way to go
faster is for drag to have decreased.

Since lift is constant, maximum lift/drag ratio still occurs at the
particular angle of attack where drag is minimized. But the ratio is
higher, because drag is lower. It's the angle of attack that's constant,
not the ratio itself.

Pete

[[email protected]]

Air is pretty heavy, which is why we can fly. It weighs .078
lb/cubic foot at standard sea level pressure and temperature. What's
that, about 13 cubic feet for a pound? The air in a room can easily
outweigh the occupants.

Dan

[Orval Fairbairn]

In article . com>,
wrote:

> Air is pretty heavy, which is why we can fly. It weighs .078
> lb/cubic foot at standard sea level pressure and temperature. What's
> that, about 13 cubic feet for a pound? The air in a room can easily
> outweigh the occupants.
>
> Dan

I seem to recall .002378 #m/ft3 as air density at STP.

[Jose]

Air is mostly (70%) Nitrogen, most of the rest is Oxygen.

The atomic mass of Nitrogen is 14, of Oxygen is 16. Both occur as
molecules (N2, O2) so the mass of each molecule is twice the above
figures.

Now, at STP, there are 22.4 liters in a mole, and a mole is the amount
of stuff that would weigh (in grams) what its molecular mass is. So,
22.4 liters of nitrogen would weigh 28 grams. Of Oxygen, it would be
32 grams. So we have a little over a gram per liter. Ok, more than
just a little, but less than a gram and a half per, and it's in the
ballpark. Lets use one gram per liter.

A liter is 1000 cubic centimeters, which is the volume of a cube 10
centimeters on a side. (or equivealently, 1/10 meter on a side).
1000 liters would be a cube one meter on a side, and air would weigh
"a little" over one Kg per cubic meter. A meter is "a little" over
three feet, so a cubic meter is "a little more" over 27 cubic feet.
One Kg is "a little" over two pounds, divide by 27, or even 30, and I
get something less than a tenth of a pound per cubic foot.

> Air is pretty heavy, which is why we can fly. It weighs .078
> lb/cubic foot at standard sea level pressure and temperature. What's
> that, about 13 cubic feet for a pound?

Yep. That's just about right.

Now, take a typical room that's three meters tall, three meters wide,
and four meters deep. Not a very big room, but it has a high ceiling.
This gives us 36 cubic meters, and the air would weigh "a little"
over 36 Kg. Well, I weigh more than a little over 36 Kg, but it's
close enough to show that a smallish room will hold less than a
person's mass in air, but a largish roomfull of air can easily
outweigh a person.

> The air in a room can easily
> outweigh the occupants.

Yep again.

Now, how big is the White House?

Jose
--
Freedom. It seemed like a good idea at the time.
for Email, make the obvious change in the address.

[Larry Dighera]

On Thu, 16 Dec 2004 04:59:41 GMT, Jose >
wrote in >::

>Now, how big is the White House?


Hot air weighs a lot less. :-)

[Corky Scott]

On Wed, 15 Dec 2004 17:48:10 -0700, Newps > wrote:

>Yes, but today we know what the temp is every hour of every day.
>Looking at rocks we only have generalities. It was hot during this
>period of years, cold during this period, etc. Now we're trying to say
>that because the temp has gone up 1 degree in the last 50 years we have
>a problem.

You don't think we have a problem?

Corky Scott

[[email protected]]

Orval Fairbairn wrote:
> In article . com>,
> wrote:
>
> > Air is pretty heavy, which is why we can fly. It weighs .078
> > lb/cubic foot at standard sea level pressure and temperature.
What's
> > that, about 13 cubic feet for a pound? The air in a room can easily
> > outweigh the occupants.
> >
> > Dan
>
> I seem to recall .002378 #m/ft3 as air density at STP.

http://www.engineeringtoolbox.com/24_600.html lists it at 60
degrees F. as 7.636 x 10-2 lbs/cu.ft., or .07636 lbs, a bit less than I
had quoted. STP is at 59 degrees, but the one degree difference doesn't
change the density much.

Dan

[Morgans]

"Newps" > wrote
>
> It's a guess. We only have maybe 150 years of temp data and much less
> years of other data. In the history of the planet that is zip.
>

Not really. By drilling into the glacial ice, they measure the air coming
from the teeny little bubbles trapped in the ice, and are very good at
measuring the makeup of the atmosphere, for a LONG way back.
--
Jim in NC

[Newps]

Corky Scott wrote:
> On Wed, 15 Dec 2004 17:48:10 -0700, Newps > wrote:
>
>
>>Yes, but today we know what the temp is every hour of every day.
>>Looking at rocks we only have generalities. It was hot during this
>>period of years, cold during this period, etc. Now we're trying to say
>>that because the temp has gone up 1 degree in the last 50 years we have
>>a problem.
>
>
> You don't think we have a problem?

Of course not. Why would you think we do? Why would you think that we
could change it one way or another?

[Newps]

Morgans wrote:

> "Newps" > wrote
>
>>It's a guess. We only have maybe 150 years of temp data and much less
>>years of other data. In the history of the planet that is zip.
>>
>
>
> Not really. By drilling into the glacial ice, they measure the air coming
> from the teeny little bubbles trapped in the ice, and are very good at
> measuring the makeup of the atmosphere, for a LONG way back.

That doesn't tell us hardly anything. You can't even nail down within a
100 year period when that air was trapped, much less what the temp was
on July 24th that year. Or the year before. Or after.

[[email protected]]

Newps wrote:
> Morgans wrote:
>
> > "Newps" > wrote
> >
> >>It's a guess. We only have maybe 150 years of temp data and much
less
> >>years of other data. In the history of the planet that is zip.
> >>
> >
> >
> > Not really. By drilling into the glacial ice, they measure the air
coming
> > from the teeny little bubbles trapped in the ice, and are very good
at
> > measuring the makeup of the atmosphere, for a LONG way back.
>
> That doesn't tell us hardly anything. You can't even nail down
within a
> 100 year period when that air was trapped, much less what the temp
was
> on July 24th that year. Or the year before. Or after.

Actually, they can tell exactly which year the bubbles were trapped...
it doesn't tell you the temperature, but it does tell you how much CO2
was present.

How do they know the year? Because the ice in Antarctica builds up a
new layer ever year as the snow falls. The layers look like the rings
in a tree. I saw a good documentary recently where a climbing party
was digging down into the snow pack in Antarctica to measure the annual
snowfall. The snowpack gets compressed into ice layers as more falls
on top. I have also seen programs showing the core samples, and the
scientists pointing out each layer and noting which year it was formed.

Global warming is alarmist bunk. Even if the earth's average
temperature goes up, the earth will still be OK. It will simply mean
that climates may shift around a bit, but life will not be
extinguished. In fact, the Gaia theory asserts that the temperature
range of the earth is not an accident, it is controlled by the presence
of life. Without life, the earth would have become overheated a long
time ago by all the CO2 coming out of volcanoes. Life regulates the
balance of atmospheric CO2, O2, and H20 which controls the temperature.
The oceanic lifeforms are primarily responsible for this and provide a
natural feedback loop that keeps the earth's climate balanced...

Dean

[Larry Dighera]

On 16 Dec 2004 21:00:13 -0800, wrote in
. com>::

>Even if the earth's average
>temperature goes up, the earth will still be OK.

It's apparent you don't own any ocean front property.

[Corky Scott]

On Thu, 16 Dec 2004 16:02:55 -0700, Newps > wrote:

>> You don't think we have a problem?
>
>Of course not. Why would you think we do? Why would you think that we
>could change it one way or another?

I didn't say we could change it, but that doesn't mean we don't have a
problem.

In another message, Dean says:

On 16 Dec 2004 21:00:13 -0800, wrote:

>Global warming is alarmist bunk. Even if the earth's average
>temperature goes up, the earth will still be OK. It will simply mean
>that climates may shift around a bit, but life will not be
>extinguished. In fact, the Gaia theory asserts that the temperature
>range of the earth is not an accident, it is controlled by the presence
>of life. Without life, the earth would have become overheated a long
>time ago by all the CO2 coming out of volcanoes. Life regulates the
>balance of atmospheric CO2, O2, and H20 which controls the temperature.
>The oceanic lifeforms are primarily responsible for this and provide a
>natural feedback loop that keeps the earth's climate balanced...
>
>Dean

The fact that the world is getting warmer, and that the polar icecaps
are shrinking isn't bunk, it's scientific fact, something that can be
measured and has been for some time now.

Some things are not difficult to predict: Since the polar ice caps and
glaciers are melting, the water being added to the oceans is causing
them to rise, this is really not difficult to measure and compare to
years past. If the warming continues, more water will be added to the
oceans, and they will rise higher yet. That should be obvious to
anyone. Many of the worlds cities are located along coastlines, if
the oceans continue to rise, these cities will be at considerable
risk. Again, blindingly obvious.

It's the intangibles that are difficult to foresee. For instance,
it's been noticed that there is a huge reduction in the population of
Krill in the Antarctic. Scientists aren't absolutely positive, but it
appears this is a direct correlation with the reduction of the ice
shelf. The ice shelf is shrinking of course due to the slightly
higher global temperatures. There are a lot of creatures that depend
on Krill for their food. Obviously, a diminishing food source will
cause a reduction in the population of the animals that feed on it.
What will the world be like if the sea animal population is reduced is
another intangible.

The predictions of super storms, created by warming oceans are yet to
be scientifically verified, it's basically an educated guess.

There is one lone positive regarding global warming that I heard on
"the Daily Show" with John Stewart. They showed a clip of some VIP,
who's name I did not catch, who was pontificating on how global
warming would open up northern shipping routes to Russia because the
Arctic icecap is shrinking, something they've desired for hundreds of
years. Stewarts' reaction to this news was to quip: "Great, now we
can have unlimited access to Russian nesting dolls."

That the world is getting warmer is not the question, what's causing
it is the question and can it, should it be stopped.

Corky Scott

[Newps]

Larry Dighera wrote:
> On 16 Dec 2004 21:00:13 -0800, wrote in
> . com>::
>
>
>>Even if the earth's average
>>temperature goes up, the earth will still be OK.
>
>
> It's apparent you don't own any ocean front property.

He said the earth will be OK. The fact that your life may be slightly
inconvenienced is irrelavant.

[Newps]

Corky Scott wrote:

> On Thu, 16 Dec 2004 16:02:55 -0700, Newps > wrote:
>
>
>>>You don't think we have a problem?
>>
>>Of course not. Why would you think we do? Why would you think that we
>>could change it one way or another?
>
>
> I didn't say we could change it, but that doesn't mean we don't have a
> problem.

Then you are not part of the global warming crowd. They believe we have
directly affected the earths temp.

[David CL Francis]

On Wed, 15 Dec 2004 at 16:52:25 in message
>, Peter Duniho
> wrote:
>As altitude goes up and indicated airspeed remains constant, TRUE airspeed,
>on the other hand, goes up. Same lift (equal to weight, as you note), but
>you're going faster for the same power. Obviously thrust didn't increase
>(and in fact, decreased, since you get less thrust from the prop due to the
>less dense air...though with a constant speed prop, much if not all of the
>lost thrust can be regained using coarser prop pitch), so the only way to go
>faster is for drag to have decreased.
>
That is true I agree but lift and drag both depend on TAS. Do you claim
that that lift does, but drag does not depend on TAS?

>Since lift is constant, maximum lift/drag ratio still occurs at the
>particular angle of attack where drag is minimized. But the ratio is
>higher, because drag is lower. It's the angle of attack that's constant,
>not the ratio itself.

But if drag is lower then lift should also be lower.

Interesting Peter but you have not yet convinced me. If you do a test on
an airfoil you will determine its lift and drag coefficients. Apart from
effects due to Reynolds number and compressibility those figures apply
to all conditions. The plot of CL against CD remains the same - why
should it change? You are effectively saying that an aircraft with an
L/D of say 12 has a much higher maximum lift drag ratio at high altitude
- how much 25 or more?

Does a high performance glider with a normal Lift/drag max of 50 have an
even higher one at high altitude?

Since lift and drag both depend directly on indicated airspeed (which
is merely a correction due to air density) for given IAS the ratio of
lift and drag will be produced at the same AoA at all altitudes. There
is a substantial difference in kinematic viscosity from sea level to
high altitude and that will change the Reynolds Number characteristics
although the higher true speeds also change the Reynolds number at least
partly in compensation - how much I am not sure but it will not change
lift and drag separately AFAIK.

Don't forget that both lift and drag depend on true airspeed and on air
density. It is the concept of dynamic pressure (0.5 *density *
velocity^2) which gives us the convenience of IAS.

I would like to get this a bit straighter in my mind. My theoretical
studies are so long ago that things may have changed and so may I!
--
David CL Francis

[David CL Francis]

On Thu, 16 Dec 2004 at 03:36:14 in message
>, Orval
Fairbairn > wrote:

>I seem to recall .002378 #m/ft3 as air density at STP.

That is in slugs per cubic foot. Both figures are correct. One in pounds
mass and the other in slugs which is a mass unit. Is the slug still
used? I used it a lot in my early days.

My old standard atmosphere data gives sea level at 0.07675 lb/cubic
foot.

Divide that by g (32.17 ft per second per second) gives 0.0023857 slugs
per cubic foot.
--
David CL Francis

[Capt.Doug]

>"David CL Francis" wrote in message> However if you fly for maximum range
> than you fly close to maximum lift/drag ratio which depends only on
> getting the correct alpha (ignoring compressibility effects).

If the correlation between thrust and fuel burn is fairly linear, this is
correct. A piston powered airplane with a constant speed propeller will
achieve max range at any altitude it can sustain the correct alpha angle.
Jets do not have a linear correlation. The jet I fly gets the same fuel burn
at 5000' and 250 KIAS as it does at FL350 and 440KTAS.

> So since lift = weight, drag depends on weight and it reduces as fuel is
> burned.

Remember that there are 2 kinds of drag- Parasite and Induced. Parasite drag
is dependent on speed. Induced drag is dependent on alpha angle (among other
things).

I suggest a book called 'Aerodynamics for Naval Aviators'. Most good pilot
shops have it.

D.

[David CL Francis]

On Sat, 18 Dec 2004 at 03:35:40 in message
>, Capt.Doug
> wrote:
>Remember that there are 2 kinds of drag- Parasite and Induced. Parasite drag
>is dependent on speed. Induced drag is dependent on alpha angle (among other
>things).

Yes but induced drag depends on Lift coefficient (the square of it
approximately) so if you fly at maximum Lift Drag the alpha and the
contribution of induced drag remain the same.

I have certainly not forgotten induced drag.
--
David CL Francis

[Stefan]

Newps wrote:

> You have no way of knowing that. I can just see the caveman out there
> with his CO2 test kit.....

Actually, we know quite precisely how the climate was *way* before
cavemen appeared on earth.

Obviously you don't have the slightest clue of recent scientific
methods. There's nothing wrong with this, I'm sure you know lots of
other things which I don't have a clue of. Just don't make any
statements about climatology.

Stefan

[Stefan]

wrote:

> Global warming is alarmist bunk. Even if the earth's average
> temperature goes up, the earth will still be OK.

Certainly, the earth will still be ok. It's just us will have some problems.

Stefan

[G.R. Patterson III]

Stefan wrote:
>
> Certainly, the earth will still be ok. It's just us will have some problems.

Along with most of what we call lifeforms.

George Patterson
The desire for safety stands against every great and noble enterprise.