Will Ellis
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Senior Boarder
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Re:water Ballast - 2008/05/29 06:43
You are correct to think about those sorts of issues. I spent a long time weighing up the pros and cons of the various options.
-max landing weight of my 15 is 898lbs which would permit landing with some water on board
-if my batteries went flat so that I was unable to dump my water, an early decision must be made to choose a larger/firmer field
-conveniently the valves I am using make a loud clunk sound as they open so it is obvious if they have failed (very unlikely) or the battery is not supplying voltage
-I have twin batteries and can select which instruments and valves use which, depending on the voltmeter reading
-I chose a separate valve for each bag although two shared valves for both bags was an option, but this was discarded due to potential cross feed in a partially filled state
-the flow rate available from ‘normal’ sized valves is poor, so very large 20mm orifice sized valves were used, and these draw 1 amp each (x2)
In practice the system works very well and even after long 6 hour plus flights with all the instruments and a pda/logger, I have not had any problem dumping (although there is always about 4-5 litres left in each bag which dribble out after landing).
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