▁their ▁first ▁aer ial ▁tests ▁from ▁at op ▁the ▁pair ▁of ▁surv iving ▁He ▁ 2 7 4 ▁pro tot ypes . ▁The ▁slightly ▁less ▁powerful , ▁French ▁designed ▁four - eng ined ▁SN CASE ▁SE . 1 6 1 ▁L angu ed oc ▁air lin er ▁design ▁took ▁over ▁this ▁" m other ▁ship " ▁role ▁later ▁in ▁the ▁ 1 9 5 0 s , ▁for ▁further ▁air ▁launch ▁duties ▁with ▁French ▁high - speed ▁aer od ynamic ▁research ▁pro tot ypes . ▁ ▁Oper ators ▁▁▁ ▁French ▁Air ▁Force ▁ ▁Spec ifications ▁( He ▁ 2 7 4 ▁V 1 ) ▁ ▁See ▁also ▁ ▁References ▁ ▁S ources ▁▁ ▁Jane ' s ▁fighting ▁aircraft ▁of ▁World ▁War ▁II . ▁Studio ▁Books , ▁ 1 9 8 9 . ▁ ▁Green , ▁William . ▁War plan es ▁of ▁the ▁Third ▁Reich . ▁London : ▁Mac don ald ▁and ▁Jane ' s ▁Publish ers ▁Ltd ., ▁ 1 9 7 0 ▁( 4 th ▁Im pression ▁ 1 9 7 9 ). ▁. ▁ ▁Gr ie hl , ▁Man fred ▁and ▁D ress el , ▁Jo achim . ▁He inkel ▁He ▁ 1 7 7 - 2 7 7 - 2 7 4 , ▁Airl ife ▁Publishing , ▁Sh rew s bury , ▁England ▁ 1 9 9 8 . ▁. ▁ ▁G unst on , ▁Bill ▁& ▁Wood , ▁Tony . ▁Hitler ' s ▁Luft wa ffe . ▁London : ▁Sal am ander ▁Books ▁Ltd ., ▁ 1 9 7