T - 9 ▁design ation ▁during ▁W W II ▁to ▁design ate ▁Tor ped o ▁Squadron ▁N ine . ▁ ▁V X : ▁Dis est ab lished ▁and ▁De activ ated ▁Ex perimental ▁and ▁Development ▁squad rons ▁The ▁V X ▁design ation ▁first ▁appeared ▁in ▁ 1 9 2 7 ▁to ▁design ate ▁" Ex perimental ▁Squadron " ▁and ▁was ▁used ▁until ▁ 1 9 4 3 . ▁It ▁was ▁again ▁used ▁beginning ▁in ▁ 1 9 4 6 ▁when ▁four ▁" Ex perimental ▁and ▁Development " ▁squad rons ▁( V X - 1 ▁( st ill ▁exists ▁today ), ▁ 2 , ▁ 3 ▁and ▁ 4 ) ▁were ▁established ▁to ▁develop ▁and ▁evaluate ▁new ▁equipment ▁and ▁methods . ▁From ▁ 1 9 4 6 ▁to ▁ 1 9 6 8 ▁the ▁design ation ▁was ▁various ly ▁" Ex perimental ▁and ▁Development " ▁squad ron , ▁" Oper ational ▁Development " ▁squad ron , ▁" A ir ▁Oper ational ▁Development " ▁squad ron ▁and ▁" A ir ▁Development " ▁squad ron . ▁In ▁ 1 9 6 9 ▁the ▁design ation ▁changed ▁to ▁" A ir ▁Test ▁and ▁E valu ation " ▁squad ron ▁and ▁it ▁remains ▁as ▁such ▁today . ▁ ▁Dis est ab lished ▁or ▁de activ ated ▁hel ic opter ▁squad rons ▁See : ▁List ▁of ▁in active ▁United ▁States ▁Navy ▁hel ic opter ▁squad rons . ▁ ▁Dis est ab lished ▁B limp ▁Pat rol ▁Squad rons ▁( Z P ) ▁ ▁See ▁also ▁ ▁List ▁of ▁military