Winter Water Ballast

On Nov 25, 10:45*am, Scott Alexander
wrote:
If there is a concern of water freezing when dumping it out over the
rudder, flaps or ailerons, then consider this.

The CRJ-200 has a limitation during certain icing parameters to move
the ailerons (wiggle them) every 5,000 feet during climbout. *There's
been a few CRJ's that had the ailerons freeze up due to ice.

Seems like if we were to dump ballast, then during the dumping move
the control surfaces back and forth that are going to get wet until
the water is all dumped out.

Hmmm this whole discussion got me to thinking. What if you changed the
ballast tanks to handle something like extremely fine silica sand.
This would be denser, and if kept sufficiently dry would flow quite
well. IIRC balloonists have been using and dumping sand bags for
years, why not in a sailplane?

Pete

On Nov 25, 11:45*am, Scott Alexander
wrote:
If there is a concern of water freezing when dumping it out over the
rudder, flaps or ailerons, then consider this.

The CRJ-200 has a limitation during certain icing parameters to move
the ailerons (wiggle them) every 5,000 feet during climbout. *There's
been a few CRJ's that had the ailerons freeze up due to ice.

Seems like if we were to dump ballast, then during the dumping move
the control surfaces back and forth that are going to get wet until
the water is all dumped out.

It's not so much about the control surfaces (though the rudder in the
example I gave actually was fairly limited in travel as a rsult of the
icing). It's the assymetric dumping and other stuff. For example:

On the LS8, the wing dumps orifices are about 1" give or take. The
tail dump is maybe 0.25". Which one is more likely to ice-up if you
get something wrong? Now, depending on the empty CG, dumping all
the wing ballast and not being able to dump the tail may (or may not)
be a big deal. In other ships with fiddly valves (pretty much any
Schleicher OEM system), what if one wing dumps and the other doesn't?
Big dieal? Sometimes yes, sometimes no. Obviously, these same risks
exist in warm weather, but they are clearly greater in cold weather.
So again, what are the real percentages in carrying water ballast in
our neck of the woods in winter? Most of the big records are done in
April/May or September/October when the days are long enough to get
started early and fly late.

Not to mention the fact that it's just damned uncomfortable messing
with water when it's cold outside :-)

On Wed, 25 Nov 2009 08:50:13 -0800 (PST), vontresc
wrote:

Hmmm this whole discussion got me to thinking. What if you changed the
ballast tanks to handle something like extremely fine silica sand.
This would be denser, and if kept sufficiently dry would flow quite
well. IIRC balloonists have been using and dumping sand bags for
years, why not in a sailplane?

It's been tested decades ago in a Morelli sailplane, which had a sand
tank inside the fuselage and a huge dumping duct.
It worked fine on the ground; in the air, after repeated altituted
change, the igroscopic sand became almost solid and would not flow
through the large ducts.

Aldo Cernezzi

On Wed, 25 Nov 2009 08:59:08 -0800 (PST), Papa3
wrote:


In other ships with fiddly valves (pretty much any
Schleicher OEM system), what if one wing dumps and the other doesn't?
Big dieal? Sometimes yes, sometimes no.

Inflight it's no problem at all - you don't even feel the asymmetric
loading.
On the ground you are going to drop a wing sooner or later (I'd
estimate at about 25 kts, far below touchdown speed), but with braking
you'll have at maximum 100 ft of ground run with one wing on the
gound. No big deal on grass, maybe a little problematic on a hard
surface.
I had the pleasure to test this with an ASW-27 and the AS-22, both
times with full water ballast in one wing and the other one completely
empty.

On Nov 25, 11:24*pm, Andreas Maurer wrote:
On Wed, 25 Nov 2009 08:59:08 -0800 (PST), Papa3
wrote:

In other ships with fiddly valves (pretty much any
Schleicher OEM system), what if one wing dumps and the other doesn't?
Big dieal? Sometimes yes, sometimes no. *

Inflight it's no problem at all - you don't even feel the asymmetric
loading.
On the ground you are going to drop a wing sooner or later (I'd
estimate at about 25 kts, far below touchdown speed), but with braking
you'll have at maximum 100 ft of ground run with one wing on the
gound. No big deal on grass, maybe a little problematic on a hard
surface.
I had the pleasure to test this with an ASW-27 and the AS-22, both
times with full water ballast in one wing and the other one completely
empty.

You obviously never flew LS gliders :-) I've had 2 or 3 instances
of asymmetric dumping over the years, and an LS8 with one outboard
tank empty and one full will head off at 90 degrees once you hit about
35kts even with full aileron deflected. With the weak to non-
existent wheel brake, you're heading for the weeds or the trailers or
the staged gliders with very little you can do about it. If it's a
hard surface runway, especially one with runway lights, you're
probably looking at some (hopefully) minor damage as a wing or
fuselage takes out a light.