▁trouble ▁several ▁times . ▁ ▁The ▁wings ▁had ▁a ▁ 4 5 ° ▁swe pt ▁N AC A ▁ 0 0 1 2 - 0 , 5 5 - 1 , 2 5 ▁profile ▁of ▁ 1 2 % ▁thick ness . ▁The ▁continu ously ▁varying ▁profile ▁shape ▁caused ▁a ▁st all ▁in ▁certain ▁flight ▁conditions , ▁which ▁caused ▁complete ▁loss ▁of ▁control . ▁This ▁was ▁later ▁corrected ▁by ▁use ▁of ▁f ences ▁on ▁the ▁top ▁of ▁the ▁wings . ▁ ▁Development ▁ ▁Con cept ▁ ▁The ▁D FS ▁ 3 4 6 ▁was ▁a ▁parallel ▁project ▁to ▁the ▁D FS ▁ 2 2 8 ▁high - alt itude ▁reconna issance ▁aircraft , ▁designed ▁under ▁the ▁direction ▁of ▁Felix ▁K racht ▁and ▁his ▁team ▁at ▁D FS . ▁While ▁the ▁D FS ▁ 2 2 8 ▁was ▁essentially ▁of ▁conventional ▁sail plane ▁design , ▁the ▁D FS ▁ 3 4 6 ▁had ▁highly - s we pt ▁wings ▁and ▁a ▁highly ▁stream lined ▁fus el age ▁that ▁its ▁design ers ▁hoped ▁would ▁enable ▁it ▁to ▁break ▁the ▁sound ▁bar rier . ▁ ▁Like ▁its ▁stable mate , ▁it ▁also ▁featured ▁a ▁self - cont ained ▁escape ▁module ▁for ▁the ▁pilot , ▁a ▁feature ▁originally ▁designed ▁for ▁the ▁D FS ▁ 5 4 ▁prior ▁to ▁the ▁war . ▁The ▁pilot ▁was ▁to ▁fly ▁the ▁machine ▁from ▁a ▁pr one ▁position , ▁a ▁feature ▁decided ▁from ▁experience ▁with ▁the ▁first ▁D FS ▁ 2 2 8 ▁prototype . ▁This ▁was ▁mainly ▁because ▁of ▁the ▁smaller