aged ▁and ▁bol ted ▁dur al umin ▁t ube ▁structure , ▁which ▁had ▁been ▁developed ▁by ▁Sydney ▁C amm ▁and ▁Fred ▁Sig rist ▁in ▁ 1 9 2 5 . ▁The ▁new ▁design ▁featured ▁autom obile - like ▁side - open ing ▁doors ▁for ▁entry , ▁and ▁used ▁a ▁large ▁ 4 0   ft ▁( 1 2   m ) ▁wing ▁that ▁was ▁much ▁th icker ▁in ▁cross - section ▁than ▁those ▁on ▁aircraft ▁like ▁the ▁Sp it fire . ▁The ▁rear ▁fus el age , ▁from ▁behind ▁the ▁co ck pit , ▁differ ed ▁from ▁that ▁of ▁the ▁H urr icane ▁in ▁that ▁it ▁was ▁a ▁dur al umin , ▁semi - mon oco que , ▁flush - riv et ed ▁structure . ▁The ▁all - met al ▁wings ▁incorpor ated ▁the ▁legs ▁and ▁wheel - b ays ▁of ▁the ▁wide - track , ▁in ward - ret ract ing ▁main ▁under car riage . ▁The ▁two ▁models ▁were ▁also ▁very ▁similar ▁to ▁each ▁other ; ▁the ▁R ▁plane ▁had ▁a ▁round er ▁nose ▁profile ▁and ▁a ▁vent ral ▁radi ator , ▁whereas ▁the ▁N ▁had ▁a ▁fl atter ▁deck ▁and ▁a ▁ch in - mount ed ▁radi ator . ▁The ▁fus el age ▁of ▁the ▁T orn ado ▁ahead ▁of ▁the ▁wings ▁was ▁ 1 2   in ▁( 3 0   cm ) ▁longer ▁than ▁that ▁of ▁the ▁Ty ph oon , ▁the ▁wings ▁were ▁fitted ▁ 3   in ▁( 7 6   mm ) ▁lower ▁on ▁the