▁( T WA ) ▁on ▁ 3 0 ▁September ▁ 1 9 5 4 ▁the ▁L - 1 4 4 9 ▁would ▁use ▁the ▁same ▁fus el age ▁as ▁the ▁ 1 0 4 9 ▁series ; ▁Hugh es ▁Tool ▁Company ▁ordered ▁ 2 5 ▁in ▁December , ▁though ▁T WA ▁estimated ▁the ▁L - 1 4 4 9 ▁would ▁lose ▁money , ▁even ▁with ▁every ▁seat ▁occupied . ▁When ▁P & W ▁dropped ▁their ▁engine , ▁Lock he ed ▁proposed ▁an ▁L - 1 5 4 9 ▁with ▁All ison ▁tur b opro ps , ▁but ▁T WA ▁and ▁Lock he ed ▁agreed ▁on ▁the ▁p ist on - engine ▁L - 1 6 4 9 ▁instead , ▁and ▁so ▁am ended ▁the ▁L - 1 4 4 9 ▁contract . ▁In ▁April ▁ 1 9 5 5 ▁Lock he ed ▁told ▁T WA ▁that ▁they ▁wanted ▁to ▁drop ▁the ▁ 1 6 4 9 , ▁but ▁Hugh es ▁refused ▁to ▁agree . ▁ ▁Though ▁the ▁L - 1 4 4 9 ▁and ▁L - 1 5 4 9 ▁were ▁never ▁built , ▁all ▁Const ell ations ▁from ▁ 1 9 5 4 ▁on wards ▁were ▁strength ened ▁to ▁take ▁the ▁thrust ▁generated ▁by ▁the ▁T 3 4 / PT - 2 ▁tur b opro ps , ▁which ▁were ▁fitted ▁to ▁several ▁R 7 V - 2 ▁Const ell ations ▁for ▁the ▁United ▁States ▁Navy ▁( US N ). ▁ ▁With ▁the ▁abandon ment ▁of ▁the ▁L - 1 5 4 9