▁in ▁their ▁protection . ▁For ▁the ▁following ▁North am pton ▁class , ▁the ▁arm or ▁protection ▁was ▁increased ▁to ▁ ▁with ▁ ▁of ▁arm or ▁along ▁the ▁main ▁bel t . ▁Still , ▁these ▁ships ▁only ▁disp la ced ▁between ▁ ▁and ▁ ▁While ▁the ▁Port land - class ▁cru is ers ▁were ▁more ▁heavily ▁arm ored ▁than ▁the ▁preceding ▁classes , ▁this ▁problem ▁was ▁found ▁to ▁be ▁so ▁significant ▁that ▁in ▁fis cal ▁year ▁ 1 9 2 9 , ▁an ▁entirely ▁different ▁design ▁was ▁form ulated ▁for ▁a ▁new ▁class ▁of ▁cru is ers , ▁the ▁New ▁Orleans ▁class . ▁Several ▁of ▁the ▁Port land ▁h ull s ▁were ▁then ▁converted ▁to ▁New ▁Orleans ▁h ull s ▁during ▁construction . ▁ ▁The ▁Port land ▁class ▁were ▁also ▁designed ▁with ▁more ▁advanced ▁arm ament ▁in ▁mind . ▁Their ▁main ▁guns ▁were ▁the ▁first ▁to ▁be ▁spe cially ▁designed ▁to ▁fire ▁long - point ▁project iles ▁with ▁a ▁stream lined ▁shape , ▁which ▁increased ▁the ▁guns ' ▁range ▁when ▁compared ▁with ▁older ▁cru iser ▁guns . ▁Such ▁project iles ▁were ▁in ▁use ▁by ▁ships ▁of ▁the ▁Imperial ▁Japanese ▁Navy , ▁which ▁until ▁that ▁point ▁out - r anged ▁U . S . ▁cru is ers ▁with ▁their ▁fire power . ▁The ▁New ▁Orleans ▁class ▁was ▁designed ▁with ▁these ▁less ons ▁in ▁mind , ▁intended ▁to ▁create ▁a ▁better ▁balance ▁between ▁protection , ▁arm ament ▁and ▁speed . ▁ ▁Const ruction ▁ ▁Five ▁ships ▁were ▁ordered ▁in ▁fis cal ▁year ▁ 1 9 3