water balast?

I have only flown as a passenger once in a sailplane, and thus, will ask the
obvious question. Is water blast used in temperatures where it is likely to
freeze? If so, what is done to prevent this?

Thanks ...john

Not a good idea to have it freeze you could blow the wing up.

Fly with out water.

More likely to freeze in winter.

Flight level 235 in August was -30oC
http://www.mals.net/bunyan04/pages/Picture%20013.htm the grease starts to
freeze.

Mal

www.mals.net


"JohnWN in Burke, VA" wrote in message
news:41FSd.689$2s.199@lakeread06...
I have only flown as a passenger once in a sailplane, and thus, will ask
the obvious question. Is water blast used in temperatures where it is
likely to freeze? If so, what is done to prevent this?

Thanks ...john

Ridge flights in the spring can expose the sailplane to near freezing
conditions at ridge height ... or definitely during periods when you
have to climb as the temp drops quickly as altitude gained.

Many pilots add some anti-freeze if they expect to be in sub-freezing
conditions for any lenght of time. This is not as extreme as
automotive protection ... a light amount of antifreze (I add windshield
washer fluid to wing water and use 100% in the tail tank as the volume
is smaller and will freeze more quickly.) to depresses the freezing
point by 10 degress or so ... let say down to 20F. Sailplanes have no
heat ... so these temps can get pretty uncomfortable quickly ... i.e.
we don't stay there. :-) BTW, we have thermometers to measure outside
air temp.

So, we typically don't fly in extended freezing conditions with H20 ...
but may be in sub 32F conditions for a short time anticipatieng we will
be out quickly ... and will often add antifreeze if we expect some type
of possible longer exposure ... even if not extended.


KK

JohnWN in Burke, VA wrote:
I have only flown as a passenger once in a sailplane, and thus, will
ask the
obvious question. Is water blast used in temperatures where it is
likely to
freeze? If so, what is done to prevent this?

Thanks ...john

Most manufactures recommend dumping once the temperature lowers to 4
degrees C. As noted by Ken, we have strategies for using water in
sub-freezing conditions, but there is some risk associated. These
include accumulation of ice on the tail due to leaks or freeezing shut
of the dump valves.

Using the 4C mark guarantees avoiding both problems. But as in all
things, good judgement and forethought can expand the envelope a
little. One simply has to understand and effectively manage the
increased risk.