public DropHead_Symmetrical()
 {
     model               = new Model();
     _spacingTop         = inputValues.CreateDoubleCalcValue("Spacing at top", "L_1", "m", 0.8);
     _spacingBottom      = inputValues.CreateDoubleCalcValue("Spacing at bottom", "L_2", "m", 0.8);
     _spacingVertical    = inputValues.CreateDoubleCalcValue("Vertical spacing", "h", "m", 1);
     _loadA              = inputValues.CreateDoubleCalcValue("Force A", "F_A", "kN", 1);
     _reactionA          = outputValues.CreateDoubleCalcValue("Reactions", "", "", 0);
     _reactionB          = outputValues.CreateDoubleCalcValue("Reactions", "", "", 0);
     _strutResolvedForce = outputValues.CreateDoubleCalcValue("Resolved strut force", "F_{strut}", "kN", 0);
     _tieForce           = outputValues.CreateDoubleCalcValue("Bottom tie force", "F_{tie}", "kN", 0);
 }