age , ▁a ▁press ur ized ▁double ▁gla zed ▁co ck pit ▁of ▁nearly ▁identical ▁external ▁appearance ▁to ▁the ▁ 1 7 7 A ' s ▁standard ▁" C ab in ▁ 3 " ▁nose , ▁a ▁longer ▁wings pan , ▁and ▁a ▁more ▁conventional , ▁single ▁o le o ▁str ut - per - side ▁set ▁of ▁tw inned - w heel ▁main ▁under car riage , ▁abandon ing ▁the ▁cum bers ome ▁four - str ut ▁main ▁g ear ▁system ▁of ▁the ▁He ▁ 1 7 7 A , ▁needed ▁for ▁the ▁earlier ▁design ' s ▁pair ▁of ▁larger - d iam eter , ▁four - bla de ▁prop ellers . ▁ ▁The ▁He ▁ 2 7 4 ' s ▁advanced , ▁high - alt itude ▁co ck pit , ▁despite ▁its ▁a for ement ioned ▁He ▁ 1 7 7 A - like ▁res embl ance ▁from ▁an ▁external ▁view , ▁compr ised ▁a ▁press ur ized ▁compart ment ▁for ▁a ▁crew ▁of ▁four , ▁this ▁employ ing ▁double ▁walls ▁of ▁heavy - g au ge ▁al loy , ▁h ollow ▁sand wich - type ▁gla zing ▁and ▁infl atable ▁rub ber ▁se als , ▁a ▁pressure ▁equivalent ▁to ▁that ▁at ▁ 2 , 5 0 0   m ▁( 8 , 2 0 0   ft ) ▁being ▁maintained ▁at ▁high ▁alt itude . ▁L arg ely ▁unnecessary ▁def ensive ▁arm ament ▁was ▁restricted ▁to ▁a ▁single ▁forward - f iring ▁ 1 3   mm ▁(. 5 1