  in ) ▁cal iber ▁M G ▁ 1 3 1 ▁machine ▁gun ▁and ▁rem ot ely ▁controlled ▁d ors al ▁and ▁vent ral ▁Fern bed ien bare ▁D reh la f ette ▁F DL ▁ 1 3 1 Z ▁gun ▁tur rets ▁each ▁containing ▁a ▁pair ▁of ▁M G ▁ 1 3 1 s ▁and ▁with ▁the ▁d ors al ▁tur ret ▁operated ▁from ▁a ▁slightly ▁offset ▁P lex ig las ▁dom ed ▁rot ating ▁sight ing ▁station ▁in ▁the ▁roof ▁of ▁the ▁flight ▁deck ▁as ▁most ▁A - series ▁He ▁ 1 7 7 s ▁were , ▁with ▁the ▁vent ral ▁unit ▁aim ed ▁from ▁the ▁rear ▁of ▁the ▁vent ral ▁B ola ▁g ond ola . ▁The ▁power pl ants ▁selected ▁were ▁the ▁same ▁type ▁of ▁ ▁Da im ler - B enz ▁DB ▁ 6 0 3 A ▁K raf tei ▁" power - eg g " ▁unit ized ▁engine ▁install ations , ▁complete ▁with ▁their ▁He ▁ 2 1 9 - style ▁ann ular ▁radi ators ▁that ▁were ▁placed ▁on ▁the ▁wings ▁of ▁the ▁quart et ▁of ▁ordered ▁He ▁ 1 7 7 B ▁pro tot ypes , ▁but ▁for ▁the ▁He ▁ 2 7 4 ' s ▁use , ▁added ▁D V L - des igned ▁T K ▁ 1 1 ▁tur bo charg ers , ▁one ▁per ▁engine , ▁for ▁better ▁power ▁output ▁at ▁high ▁alt itude . ▁ ▁Ab andon ed ▁pro tot ypes ▁ ▁Const ruction ▁of ▁the ▁two ▁pro tot ypes , ▁the