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Re: [PSUBS-MAILIST] Free Surfaces solution!



Added thought: should design constraints limit the VBT to anything but a sphere, remember to baffle the tank.
 
M.Child's VBT will be along the centreline of the boat, about a foot longitudinally and two feet high.
 
Yeah, being a pilot can just confuse things.  A little like having to unlearn previous bad habits  :-)
 
Rick L
 
----- Original Message -----
 
for smaller subs with minimum consumables HP air  the best way to deal with this is to keep the stores as close to the center of buoyancy as possible. the biggest item for change is in the hard ballast tanks. a spherical tank place at the center of buoyancy on the longitudinal axis will minimize the free surface effect . as the bow goes down. the water in the tank shifts fwd but the tank shifts aft in respect to the center of buoyancy canceling the shift. an 18 sphere at the center will give you up to 110 lbs buoyancy without having a free surface problem. 
 
go to link to see drawing of this http://www.frappr.com/?a=myfrappr&id=386116
 
spherical tanks will self level. square tanks will go 45 degress down 45 degress up or level these are the equalibrium states. cylinder tanks will have  equalibrium points  farther off as then square tanks.
 
    fianl conclusion any tank exposed to free surface effect should be spherical.
 
Rick m