tail ballast antifreeze

Try this experiment.
Put your full 6 liter MSR Dromedary Bag (a great way to carry
drinking water of a decent quantity) in the freezer at home.
Take it out every couple of hours, and see how much of it is frozen.
That much water is pretty stable. ...And that experiment was in the
freezer, not barely below freezing in a sun-bathed glider!

By the way, the Dromedary Bag is built rather like ye olde Smiley
water ballast bags, nearly bulletproof.
Jim

What a silly bugger.
That post sat in my computer for hours, then I posted it directly after
an identical one.
Go to jail, do not collect $200
Jim

Francisco De Almeida wrote:
The German manufacturers would rather have their customers release the =
tail ballast at +2=BAC. I suspect solar radiation is the reason why =
people can keep their water at lower air temperatures without =
immediately being awarded a split tailplane.
So if you have both outside temperatures below 2=BAC and no sunlight ... =
beware!







What's +2=BAC and 2=BAC for the clueless?

What can happen though is that the small water content in the valve does
freeze, nad then you'll have a bloody leaking valve.

"Marc Ramsey" wrote in message
...
Francisco De Almeida wrote:
The German manufacturers would rather have their customers release the =
tail ballast at +2=BAC. I suspect solar radiation is the reason why =
people can keep their water at lower air temperatures without =
immediately being awarded a split tailplane.
So if you have both outside temperatures below 2=BAC and no sunlight ...
=
beware!

I've been assuming that solar heating is the reason that the tail ballast
doesn't end up freezing during these summer flights. At a few degrees
below 0C in shadow, it should still take something more than an hour for a
few liters of water to freeze to the extent that it would cause structural
damage. Lack of lift and cold toes would cause me to seek warmer environs
long before that point...

Hi,

I am not an expert on high altitude flying as I've done very little of it.
However, I do believe I would take the possibility of water freezing in the
wing and/or tail very seriously if I were flying above 10,000 feet for more
than a few minutes. The reason is that a while back I saw a photo of a
glider with the leading edge of the wing split open due to water freezing
and expanding in the wing. It was a dramatic photo taken in flight with the
leading edge open 4 inches or more over a split that was perhaps 3 feet
long. This is all from memory so I may not be remembering correctly. It
think it was a photo in Soaring magazine.

Good Soaring,

Paul Remde

"Bert Willing" wrote in message
...
What can happen though is that the small water content in the valve does
freeze, nad then you'll have a bloody leaking valve.

"Marc Ramsey" wrote in message
...
Francisco De Almeida wrote:
The German manufacturers would rather have their customers release the =
tail ballast at +2=BAC. I suspect solar radiation is the reason why =
people can keep their water at lower air temperatures without =
immediately being awarded a split tailplane.
So if you have both outside temperatures below 2=BAC and no sunlight ...
=
beware!

I've been assuming that solar heating is the reason that the tail ballast
doesn't end up freezing during these summer flights. At a few degrees
below 0C in shadow, it should still take something more than an hour for
a few liters of water to freeze to the extent that it would cause
structural damage. Lack of lift and cold toes would cause me to seek
warmer environs long before that point...

Take this with a grain of salt since the consequences of being wrong are
huge.

There are a lot of pilots flying out of Boulder, CO who routinely fly above
the freezing level with ballast in the wings and fin tanks. I fly a Duo
Discus with water in the fin tank. I don't know of any problems although
pilots worry about it. Foam core sandwich construction is a pretty good
thermal insulator which probably helps a lot. For sure if the tank is cold
enough long enough it WILL freeze.

I speculate that since the water gets a lot of sloshing from turbulence,
while that doesn't reduce the heat required to freeze, it does keep the
temperature of the whole tank uniform and that helps insure that all the
water will freeze at once or not at all. Sloshing may also add a tiny
amount of heat. Getting the water down to the freezing temperature is one
thing. Removing the heat of crystalization is the other - that takes a
while. Most flights don't stay above the freezing level that long.

One thing I know is that it's important never dump ballast above the
freezing level. That would almost certainly result in a l;arge amount of
ice on the rear fuselage, possibly freezing the rudder.

I'd like to hear of a suitable 'anti-freeze'. That would remove the worry.

Bill Daniels


"Paul Remde" wrote in message
news:LpRog.805639$084.97636@attbi_s22...
Hi,

I am not an expert on high altitude flying as I've done very little of it.
However, I do believe I would take the possibility of water freezing in
the wing and/or tail very seriously if I were flying above 10,000 feet for
more than a few minutes. The reason is that a while back I saw a photo of
a glider with the leading edge of the wing split open due to water
freezing and expanding in the wing. It was a dramatic photo taken in
flight with the leading edge open 4 inches or more over a split that was
perhaps 3 feet long. This is all from memory so I may not be remembering
correctly. It think it was a photo in Soaring magazine.

Good Soaring,

Paul Remde

"Bert Willing" wrote in
message ...
What can happen though is that the small water content in the valve does
freeze, nad then you'll have a bloody leaking valve.

"Marc Ramsey" wrote in message
...
Francisco De Almeida wrote:
The German manufacturers would rather have their customers release the
=
tail ballast at +2=BAC. I suspect solar radiation is the reason why =
people can keep their water at lower air temperatures without =
immediately being awarded a split tailplane.
So if you have both outside temperatures below 2=BAC and no sunlight
... =
beware!

I've been assuming that solar heating is the reason that the tail
ballast doesn't end up freezing during these summer flights. At a few
degrees below 0C in shadow, it should still take something more than an
hour for a few liters of water to freeze to the extent that it would
cause structural damage. Lack of lift and cold toes would cause me to
seek warmer environs long before that point...

Paul Remde wrote:
The reason is that a while back I saw a photo of a
glider with the leading edge of the wing split open due to water freezing
and expanding in the wing. It was a dramatic photo taken in flight with the
leading edge open 4 inches or more over a split that was perhaps 3 feet
long. This is all from memory so I may not be remembering correctly. It
think it was a photo in Soaring magazine.

Think about how long it would take 10 or 15 gallons of water to freeze.
I suppose it might freeze if it left overnight in sub-freezing weather,
but I doubt it would do so during a 5 hour flight. The more likely
explanation is that someone ignored the manufacturers warnings about the
maximum amount of "head" allowed during filling. The water pressure
from the typical garden hose or even an SUV top mounted water bag is
sufficient to split a wing open.

A tail tank (and fin) freezing and splitting open is a worry, in
practice it doesn't seem to happen with any noticeable frequency during
summer flights to 18K feet in the western US...

Marc

My take is that freezing level in the summer months out west is around
15,000 feet and that at 18,000 feet it is rarely below 20 degrees F
(about -6 C). If you take the average temperature between 15,000 and
18,000 as around 26 F (-3 C), it will take a long time to extract
enough heat out of water to freeze it.

If you're really worried, you could paint your fin black!

Definition: BTU (British Thermal Unit) is that 1 BTU,
is equal to the amount of heat required to raise 1
pound of water 1 degree farenheight. This refers diredtly
to raising or lowering temps in water (sensible heat).
When removing latent heat (the heat contained in changing
state ie from water to ice) it takes 140 BTU's per
pound as compared to 1. In other words it will take
140 times the exposure to change the water to ice as
it took to lower it 1 degree in the tank. There fore
if you could measure the temps in you tank you could
then do the math to figure out when you tail or wings
are going to explode Any way have been flying for
3500 hours with many 0-15 degree hours with water and
not had a problem yet. But then again I don't have
a tail tank



At 17:42 29 June 2006, Mike The Strike wrote:
My take is that freezing level in the summer months
out west is around
15,000 feet and that at 18,000 feet it is rarely below
20 degrees F
(about -6 C). If you take the average temperature
between 15,000 and
18,000 as around 26 F (-3 C), it will take a long time
to extract
enough heat out of water to freeze it.

If you're really worried, you could paint your fin
black!

Gary Emerson wrote:

What's +2=3DBAC and 2=3DBAC for the clueless?

Sorry, it is the degree symbol, adulterated by some mismatch in the =
character sets along the way from my computer to the r.a.s. server.
Please read "+2 degree Celsius".