t ▁in ▁Paris ▁and ▁attempt ▁to ▁conv ince ▁them ▁to ▁join ▁a ▁new ▁effort ▁in ▁the ▁Soviet ▁Union . ▁S änger ▁and ▁B red t ▁turned ▁down ▁the ▁inv itation . ▁ ▁In ▁November ▁ 1 9 4 6 , ▁the ▁S ovi ets ▁formed ▁the ▁N II - 1 ▁design ▁b ureau ▁under ▁M st is lav ▁K eld y sh ▁to ▁develop ▁their ▁own ▁version ▁without ▁S änger ▁and ▁B red t . ▁Their ▁early ▁work ▁convinced ▁them ▁to ▁convert ▁from ▁a ▁ro cket ▁power ed ▁hyp erson ic ▁skip - g lide ▁concept ▁to ▁a ▁ram jet ▁power ed ▁su person ic ▁cru ise ▁miss ile , ▁not ▁unlike ▁the ▁Nav aho ▁being ▁developed ▁in ▁the ▁United ▁States ▁during ▁the ▁same ▁period . ▁Development ▁continued ▁for ▁a ▁time ▁as ▁the ▁K eld y sh ▁bom ber , ▁but ▁improvements ▁in ▁conventional ▁ball istic ▁miss iles ▁ultimately ▁rendered ▁the ▁project ▁unnecessary . ▁ ▁In ▁the ▁United ▁States , ▁the ▁skip - g lide ▁concept ▁was ▁advoc ated ▁by ▁many ▁of ▁the ▁German ▁scient ists ▁who ▁moved ▁there , ▁primarily ▁Walter ▁D orn berger ▁and ▁Kra ff t ▁Ehr ic ke ▁at ▁Bell ▁A ircraft . ▁In ▁ 1 9 5 2 , ▁Bell ▁proposed ▁a ▁bom ber ▁concept ▁that ▁was ▁essentially ▁a ▁vertical ▁launch ▁version ▁of ▁Sil ber v og el ▁known ▁as ▁B omi . ▁This ▁led ▁to ▁a ▁number ▁of ▁follow - on ▁concepts ▁during ▁the ▁ 1 9 5 0 s , ▁including ▁Rob o , ▁Hy wards