i undersand these things!
free hinge
weight equal
falling at the same rate...
horizontally...
but, like you say you are weighting both of the TWO sections equal AND horizontally! this is not working when you say, do not use ballast in the tailsection, i don´t mean dierctly in the tail^^
i cant weight them equal and horizontally WITHOUT any ballast in the tailsection, because if i don´t, it sitting in the water nose down!
the first section will be horizontally that way and the tailsection is forcing to the surface....
hope you understand what i´m trying to explain^^