EntityQ2001199· pop 17· linked from 127 articlesNorthrop X-21Sign in to savemilitary aircraftConnectionsNASAConceptlist of X-planesEntityDouglas B-66 DestroyerEntityInternational Standard Book NumberEntityNorthrop B-2 SpiritConceptMcDonnell Douglas F/A-18 HornetEntitydragEntitylaminar flowEntityX-15EntityEdwards Air Force BaseEntityturbojetEntityX-1EntityNorthrop F-5EntityDouglasCompanyBoeing X-37EntityNorthrop P-61 Black WidowEntityboundary layerEntityNorthrop YF-23EntityNASA X-43EntityNorthropEntityCategories1960s United States experimental aircraftAircraft first flown in 1963Aircraft with retractable tricycle landing gearEdwards Air Force BaseHigh-wing aircraftNorthrop aircraftTwinjets