, ▁the ▁layout ▁required ▁separate ▁c rank sh aft s ▁on ▁each ▁end ▁of ▁the ▁engine ▁that ▁must ▁be ▁couple d ▁through ▁g ear ing ▁or ▁sh aft s . ▁The ▁primary ▁advantages ▁of ▁the ▁design ▁were ▁un if low ▁breath ing ▁and ▁a ▁rather ▁" flat " ▁engine , ▁originally ▁intended ▁to ▁be ▁buried ▁in ▁the ▁wings ▁of ▁large ▁aircraft . ▁ ▁The ▁Admir alty ▁required ▁a ▁much ▁more ▁powerful ▁engine , ▁and ▁knew ▁about ▁J unk ers ' ▁designs ▁for ▁multi - c rank sh aft ▁engines ▁of ▁straight ▁six ▁and ▁diam ond - form . ▁The ▁Admir alty ▁felt ▁that ▁these ▁would ▁be ▁a ▁reasonable ▁starting ▁point ▁for ▁the ▁larger ▁design ▁which ▁it ▁required . ▁The ▁result ▁was ▁a ▁triangle , ▁the ▁cyl inder ▁banks ▁forming ▁the ▁sides , ▁with ▁c rank sh aft s ▁at ▁each ▁corner ▁connected ▁via ▁ph asing ▁g ears ▁to ▁a ▁single ▁output ▁sh aft — effect ively ▁three ▁separate ▁V - 1 2 ▁engines . ▁The ▁D elt ic ▁could ▁be ▁produced ▁with ▁varying ▁numbers ▁of ▁cyl ind ers — n ine ▁and ▁eigh teen ▁were ▁the ▁most ▁common , ▁having ▁either ▁three ▁or ▁six ▁cyl ind ers ▁per ▁bank ▁respectively . ▁In ▁ 1 9 4 6 , ▁the ▁Admir alty ▁placed ▁a ▁contract ▁with ▁the ▁English ▁Electric ▁Company , ▁parent ▁of ▁Nap ier , ▁to ▁develop ▁this ▁engine . ▁ ▁One ▁feature ▁of ▁the ▁engine ▁was ▁the ▁way ▁that ▁c rank sh aft - ph asing ▁was ▁arranged ▁to ▁allow ▁for ▁exhaust