- to - weight ▁ratio ▁of ▁ 0 . 3 ▁and ▁an ▁augment ation ▁ratio ▁of ▁ 1 . 6 – 2 . 0 . ▁The ▁nose - up ▁pitch ing ▁moment ▁can ▁also ▁be ▁minim ized ▁by ▁increasing ▁the ▁area ▁of ▁the ▁fus el age ▁and ▁decre asing ▁the ▁area ▁of ▁the ▁outer ▁wing . ▁ ▁Cru ise ▁▁ ▁After ▁the ▁aircraft ▁reaches ▁the ▁speed ▁of ▁aer od ynamic ▁flight , ▁the ▁ann ular ▁du ct ▁is ▁closed ▁off ▁by ▁shut ters ▁mounted ▁at ▁the ▁top ▁and ▁bottom ▁of ▁the ▁du ct ▁to ▁form ▁a ▁smooth ▁disc ▁wing . ▁The ▁lift ▁fans ▁stop ▁working ▁and ▁are ▁en closed ▁in ▁the ▁ann ular ▁du ct ▁during ▁cru ise ▁flight . ▁The ▁traditional ▁a iler ons ▁and ▁elev ators ▁located ▁at ▁the ▁rear ▁edge ▁of ▁the ▁outer ▁wing ▁are ▁needed ▁for ▁roll ▁and ▁pitch ▁control , ▁but ▁the ▁rud der ▁probably ▁is ▁not ▁necessary . ▁ ▁  Acc ording ▁to ▁the ▁CF D ▁simulations , ▁tur bo f ans ▁with ▁a ▁thrust - to - weight ▁ratio ▁of ▁ 0 . 3 ▁can ▁enable ▁a ▁top ▁forward ▁speed ▁of ▁Mach ▁ 0 . 6 2 ▁( 7 5 9   km / h ) ▁based ▁on ▁aer od ynamic ▁drag ▁predictions , ▁much ▁faster ▁than ▁hel ic op ters ▁and ▁t ilt rot ors . ▁ ▁Dead ▁weight ▁ ▁Because ▁the ▁lift ▁fan ▁system ▁does ▁not ▁work ▁in ▁cru ise , ▁it ▁is ▁dead ▁weight ▁in ▁flight . ▁However , ▁this ▁problem ▁can ▁be