Boeing B-17 Flying Fortress PB-1W

After the war the US Navy acquired 31 more B-17Gs, renamed PB-1W, and fitted them with AN/APS-20 radar to develop the airborne-early-warning concept (an AWACS forerunner). The conversion sealed the bomb bay doors, added 300-US-gallon drop tanks under each wing — on top of the existing "Tokyo tank" wing cells, for up to 3,400 gallons total — and mounted the radar's bulbous ventral radome, along with modernized IFF, radio direction finder, ILS and LORAN. The chin turret, Norden bombsight, forward dorsal turret, cockpit armor, waist guns, ball turret and tail armament were all removed. With the extra fuel it could stay airborne over 22 hours. It entered service with Patrol Bombing Squadron 101 in spring 1946.