Boeing XB-59 Martin XB-51 Convair XB-46 Douglas XB-43 Jetmaster Convair XB-53 Lockheed XB-30 Fokker XB-8 Boeing XB-55 Boeing XB-15 Douglas XB-42 Mixmaster Douglas XB-22 Douglas XB-19 Douglas XB-31 Boeing XB-38 Flying Fortress North American XB-70 Valkyrie Boeing XB-39 Superfortress 1979 XB 2002 XB 1991 XB 2012 XB 2008 XB 2006 XB 2010 XB (7753) 1988 XB (96590) 1998 XB (3757) 1982 XB Boeing XB-56