Mt. Saint Helens

"G.R. Patterson III" wrote in message
...


NW_PILOT wrote:

I know if it dose go I will be up taking photos.

You can get the best shots from directly overhead.

Briefly


George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to
have
been looking for it.

"Philip Sondericker" wrote in message
...
in article fT27d.3595$mS1.2578@fed1read05, BTIZ at

wrote on 9/30/04 7:00 PM:

that would be one heck of a thermal ride... if it weren't for the
rocks...
and "cough cough" the ash..

BT

I was thinking about this recently, and I was trying to determine exactly
what the effects would be on a small plane flying into an ash cloud. How
long would it take for the air filter to become completely clogged? And at
that point, assuming the plane had a carburetor, what would be the effect
on
the engine? Would the plugs become fouled? Would they fire at all?

Volcanic ash is very fine, like talcum powder. It is the same abrasive stuff
that they sell in pumice soap that removes anything, including your skin,
from your hands. It gets into everything. Worst case scenario if you flew
into a cloud of it your air filter would become clogged almost instantly. A
lot of the ash might work its way through the filter and into the engine,
where it is going to start abrading all the moving parts very quickly. Using
unfiltered air will just suck huge quantities of ash into the engine. The
cylinders will quickly overheat and the engine will quit. Odds are, though,
it would not be that bad. There are plenty of films of people driving around
in the ash cloud. It isn't smart and most of them suffered engine damage,
but their cars kept running. You might be able to keep a piston airplane
engine running long enough to make it to a safe landing area, but it will
probably suffer some damage.

Perversely, just when you would like to enrichen the mixture in order to
cool the engine and maybe wash some ash out of it, the ash is displacing air
and causing the mixture to be too rich already. As you set up for approach
and landing, you will find brakes, flaps, landing gear, propellers, and
every other moving part clogged with ash, even if you are no longer inside
the cloud. Your alternator may be ground to a pulp and your battery dead, so
you will not have any electrical system anyway. Your prop governor will also
be damaged, as will the oil cooler and anything else that moves. Control
surfaces and cables will be coated with abrasive, sticky ash.

The ash will also simultaneously reduce lift and increase drag. Stall speed
will increase as significant amounts of ash accumulate on and in the
airplane.

You also will be IMC and the cabin will also fill with ash to the point that
you will have difficulty breathing. All surfaces will be sand blasted and
you won't be able to see out the windows once you leave the cloud. It is
very dark inside a volcanic cloud, even darker than night. You cannot see
your hand in front of your face. The whole effect is one of driving around
at night in a very heavy snowstorm and dense fog.

Did I mention the poisonous gases? They aren't concentrated enough to hurt
most people, but asthmatics and others with impaired breathing can be
killed. There will be unhealthy concentrations of CO2, various sulfur
compounds, and acids. They can also damage the airplane. Fortunately they
are pretty well dispersed except in the immediate vicinity of the volcano.

"Rich Lemert" wrote in message
k.net...
Philip Sondericker wrote:

in article fT27d.3595$mS1.2578@fed1read05, BTIZ at

wrote on 9/30/04 7:00 PM:


that would be one heck of a thermal ride... if it weren't for the
rocks...
and "cough cough" the ash..

BT


I was thinking about this recently, and I was trying to determine
exactly
what the effects would be on a small plane flying into an ash cloud. How
long would it take for the air filter to become completely clogged? And
at
that point, assuming the plane had a carburetor, what would be the
effect on
the engine? Would the plugs become fouled? Would they fire at all?

Considering that a volcano almost brought down a 747 once, I don't
think a small plane is going to last long at all. Of course, the pilot
is going to have been broiled long before he has to worry about his
engine.

Depends on how close you are to the volcano. If you are more than a couple
miles away it won't be that hot inside the ash cloud.

I forgot to mention one other effect of dense ash clouds:

They are warm, unstable, moist (volcanos have a lot of steam), and have a
lot of friction going on inside them. They can generate lightning and
turbulence and just about anything else that goes on inside a severe
thunderstorm, including hail.

One other thing about my previous posts. They assume a small to moderate
eruption, where the ash cloud will not extend more than 100 miles downwind.
Even there, flying through the ash cloud will be like flying through a Texas
sandstorm, not something you would want to do every day.

But suppose the big one hits, like 1980. It will become dark as night as far
east as Idaho. People will be killed by heat and poisonous gases up to 20
miles away. The shock wave will be felt for hundreds of miles. All trees and
structures will be leveled for 20 miles. The ash cloud will travel around
the world several times. The explosive power will exceed that of all the
earth's nuclear weapons combined. You would not want to be anywhere near
such an explosion, in an airplane or anything else.

Mt. Rainier is similar in structure to St. Helens, only bigger and even more
powerful. It has thousands of years of glaciated water built up on its
slopes. It is located in a much more densely populated area. Should it
explode (and it might), loss of life could reach into the hundreds of
thousands and it could well be the worst and most devasting natural disaster
in history. There is some evidence of a prehistoric volcanic explosion at
Yellowstone that reduced the worldwide human population to fewer than a
dozen individuals, but that event has yet to be proven.

On Fri, 01 Oct 2004 02:20:25 GMT, Philip Sondericker
wrote:


I was thinking about this recently, and I was trying to determine exactly
what the effects would be on a small plane flying into an ash cloud. How
long would it take for the air filter to become completely clogged? And at
that point, assuming the plane had a carburetor, what would be the effect on
the engine? Would the plugs become fouled? Would they fire at all?

I'm a new pilot and relatively ignorant of engine operations, so I'm curious
to hear the answers.

I recall reading a first hand experience of exactly what you are
describing. Not positive but I think the pilot was flying an early
Cessna or perhaps a Luscombe or something similar. He was with his
wife and was flying downwind of Mt St Helens and unaware of the
explosion. He was either overtaken by the plume, or flew into it
thinking it was something else and was in immediate and serious
trouble.

He could not see hardly anything and ended up luckily overflying an
airfield on which he had to circle to land, in the otherworldly
darkness and lack of vision. His engine was barely running by this
time and he managed to bump it down and it quit instantly as he
touched down.

My recollection is that the airplane looked like it had been
sandblasted. The paint was gone from the leading edges of the wing
and anything facing into the wind. The windshield was opaque. The
prop was abraided, the air filter was clogged to the point where it
would not pass any air and I seem to remember engine damage.

I also recall him saying that he burst into tears upon getting out of
the airplane as he realised just how close things had been for him and
his wife.

Corky Scott

"C J Campbell" wrote in message
...
[...] There is some evidence of a prehistoric volcanic explosion at
Yellowstone

Yellowstone is one huge caldera, almost certainly the remains of a large
erupted volcano. This is well-established geological fact.

that reduced the worldwide human population to fewer than a
dozen individuals

Never heard that one before. Fewer than 12 people remaining, around the
entire globe you say? Yeah, right. I doubt any scientist with an actual
clue believes that.

but that event has yet to be proven.

No kidding? I'm shocked.

Pete

I was in the St. Helens ash fallout in 1980. I was in a hanger in Wenachee WA
repairing the landing gear of a Steen Skybolt. The ash got into everything.
My car was inside the hanger with the doors & windows closed. The ash got
inside anyway.
In mid morning when the volcano blew, I heard the eruption. I wasn't near any
radio/TV, thus I thought I heard a sonic boom from a passing fighter. A few
hours later the ash came, preceeded by dark clouds like a midwestern fast
moving cold front....little did I know.
VL

In article ,
Peter Duniho wrote:
"C J Campbell" wrote in message
...
[...] There is some evidence of a prehistoric volcanic explosion at
Yellowstone

Yellowstone is one huge caldera, almost certainly the remains of a large
erupted volcano. This is well-established geological fact.

that reduced the worldwide human population to fewer than a
dozen individuals

Never heard that one before. Fewer than 12 people remaining, around the
entire globe you say? Yeah, right. I doubt any scientist with an actual
clue believes that.

but that event has yet to be proven.

No kidding? I'm shocked.

I've never heard the less then a dozen people left, but one of
those Discovery Channel type shows awhile back was on using DNA
markers to trace how humans have moved around and interbred over
the years. One of the things they found was that at one point,
the human population was drastically reduced to ~10,000 people.

John
--
John Clear - http://www.panix.com/~jac

"G.R. Patterson III" wrote:


NW_PILOT wrote:

I know if it dose go I will be up taking photos.

You can get the best shots from directly overhead.

Now *that's* what I call real, he-man killfiling.
--
Dan
C-172RG at BFM