F ▁tur b op rop ▁engines ▁which ▁allowed ▁raising ▁the ▁gross ▁weight ▁to ▁ 7 2 0 0   l bs ▁( 3 2 6 5   kg ). ▁The ▁new ▁aircraft ▁car ries ▁the ▁military ▁design ation ▁of ▁R U - 3 8 B . ▁ ▁The ▁R U - 3 8 B ▁has ▁ 1 4 0 ▁cub ic ▁feet ▁( 4 . 0 ▁cu ▁m ) ▁of ▁payload ▁space ▁ ▁with ▁a ▁payload ▁weight ▁of ▁ 8 0 0   l bs ▁( 3 6 3   kg ) ▁available . ▁The ▁payload ▁b ays ▁all ▁have ▁large ▁access ▁doors ▁and ▁are ▁located ▁both ▁in ▁the ▁tail bo oms ▁and ▁also ▁behind ▁the ▁pilot ▁and ▁co - p il ot ▁seats ▁in ▁the ▁fus el age . ▁The ▁latter ▁space ▁can ▁also ▁accommod ate ▁a ▁third ▁crew ▁member , ▁if ▁required . ▁Using ▁pal let - mount ed ▁sensor ▁packages ▁the ▁aircraft ▁can ▁be ▁quickly ▁changed ▁from ▁one ▁mission ▁to ▁another . ▁ ▁The ▁R U - 3 8 B ▁is ▁able ▁to ▁achieve ▁quiet ▁operation ▁while ▁lo iter ing ▁by ▁using ▁a ▁prop eller ▁speed ▁as ▁low ▁as ▁ 1 0 0 0 ▁r pm . ▁This ▁is ▁possible ▁because ▁the ▁sail plane - der ived ▁wing ▁is ▁efficient ▁and ▁flight ▁at ▁low ▁air speed ▁can ▁be ▁sust ained ▁with ▁low ▁power . ▁Ex ha ust ▁from ▁the ▁front ▁engine ▁is ▁rout ed ▁over wing , ▁reducing ▁the ▁noise ▁foot print . ▁ ▁Two ▁R U - 3 8