If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
|
#1
|
|||
|
|||
Winter Water Ballast
Anyone have any bright ideas on how to keep the water from freezing?
Salt? Antifreeze? Anything? |
#2
|
|||
|
|||
Winter Water Ballast
On Nov 23, 9:20*pm, Scott Alexander
wrote: Anyone have any bright ideas on how to keep the water from freezing? Salt? Antifreeze? Anything? Yes antifreeze, but the type of antifreeze that is made for winterizing RV drinking water tanks. (not toxic when dumped) -Paul |
#3
|
|||
|
|||
Winter Water Ballast
On Nov 23, 10:20*pm, Scott Alexander
wrote: Anyone have any bright ideas on how to keep the water from freezing? Salt? Antifreeze? Anything? The two best solutions are Methanol and Propylene glycol. Salt absolutely not! Cost wise it will depend on how much of a freezing point depression you need. Freezing Point Propylene Glycol Solution (% by mass) F 0 32 10 26 20 18 30 7 Methanol Concentration (% by mass) F 0 32 10 20 20 0 30 -15 Methanol will cost about $3 to $4 per gallon, Propylene Glycol can be purchased as RV antifreeze in either -50 or -100 solutions. These are 25% and 50% solutions so you will need to to dilute accordingly. Price for the -50 runs about $4 a gallon. Lets do a back of the envelope calculation of what you need for a day where you want to protect down to about 15 F. Propylene Glycol you will need a 22% solution by mass or about 27% by volume so you for a 40 gallon total load in your glider you will need about 35 gallons of off the self -50 antifreeze. Cost of about $140 per flight. Methanol you will need about 13% by mass or 16.5% by volume. So you will need about 6.6 gallons of menthanol at a cost of about $25 USD per flight. |
#4
|
|||
|
|||
Winter Water Ballast
On Nov 24, 12:20*am, Scott Alexander
wrote: Anyone have any bright ideas on how to keep the water from freezing? Salt? Antifreeze? Anything? You mentioned Dan & Dave Cole in another thread in the context of getting good, conservative advice. Ask them. I predict you'll get some more good, conservative advice :-). Temptation to fly with ballast in extremely cold weather is sometimes an indicator of an excessive BCS ratio. -Evan Ludeman / T8 |
#5
|
|||
|
|||
Winter Water Ballast
On Nov 24, 12:26*pm, T8 wrote:
You mentioned Dan & Dave Cole in another thread in the context of getting good, conservative advice. *Ask them. *I predict you'll get some more good, conservative advice :-). Temptation to fly with ballast in extremely cold weather is sometimes an indicator of an excessive BCS ratio. -Evan Ludeman / T8 Ditto on that. We at Blairstown fly ridge all year round, and over the years folks have fiddled with this stuff. There are just too many things to go wrong. I have a great photo somewhere of Dave Michaud (UM) with like 8 lbs of ice (okay, probably not 8) hanging off his tail boom. Some combination of leaking dump valve in the wing and getting the mixing ratio of anti-freeze wrong. Frankly, the days are too short for record flights, so the only reason to carry ballast is to smooth out the ride a bit or go a little faster. I submit that it's just not worth it. P3 |
#6
|
|||
|
|||
Winter Water Ballast
On Nov 24, 2:38*pm, Papa3 wrote:
On Nov 24, 12:26*pm, T8 wrote: You mentioned Dan & Dave Cole in another thread in the context of getting good, conservative advice. *Ask them. *I predict you'll get some more good, conservative advice :-). Temptation to fly with ballast in extremely cold weather is sometimes an indicator of an excessive BCS ratio. -Evan Ludeman / T8 Ditto on that. *We at Blairstown fly ridge all year round, and over the years folks have fiddled with this stuff. *There are just too many things to go wrong. * I have a great photo somewhere of Dave Michaud (UM) with like 8 lbs of ice (okay, probably not 8) hanging off his tail boom. * Some combination of leaking dump valve in the wing and getting the mixing ratio of anti-freeze wrong. *Frankly, the days are too short for record flights, so the only reason to carry ballast is to smooth out the ride a bit or go a little faster. * I submit that it's just not worth it. P3 The concern over ballast freezing in the wing is not the issue. Forget about all antifreeze additives, particularly alcohols and salt. As pointed out, leaking valves is the issue. Water cools slowly to zero and then it has to jump 80 calories per gram to freeze (heat of fusion). Starting with relatively warm water gives you many hours of sloshing; I have contest experience in New Zealand with flights of many hours in the wave (-20 degrees) without ballast freezing. The wing's foam cores serve as insulation and freezing is not a problem in all but the most extreme circumstances of time and temperature. Warm water can extend the hours significantly. Carry water all year if you like, just make sure you have water tight valves. Freezing the valves shut is more of a concern than dangling ice for wing-mounted dumps; fuselage dumps are another matter due to possible CG shift from accumulation on the tail boom. Overall, it is not a big concern. ron tabery |
#7
|
|||
|
|||
Winter Water Ballast
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. |
#8
|
|||
|
|||
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 |
#9
|
|||
|
|||
Winter Water Ballast
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 :-) |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Who first used water ballast and when? | John McCullagh | Soaring | 9 | October 18th 06 09:36 AM |
water ballast leak | Robert Harvey | Soaring | 2 | May 27th 05 03:49 PM |
water ballast leak | Robert Harvey | Soaring | 0 | May 26th 05 10:33 PM |
Std 102 water ballast plug | Tom Dukerich | Soaring | 3 | April 12th 05 05:10 PM |
astir cs-77 water ballast | pete83 | Soaring | 4 | May 27th 04 05:21 AM |