Lockheed F-117A Nighthawk
F-117A alama ce ta fifikon fasahar Amurka a lokacin yakin cacar baki.
F-117A Nighthawk Lockheed ne ya gina shi don mayar da martani ga buƙatar Sojan Sama na Amurka (USAF) don wani dandamali mai iya latsawa cikin tsarin tsaron iska na abokan gaba. An halicci jirgin sama na musamman, wanda, godiya ga siffarsa da ba a saba da shi ba da kuma tasirin yaki na almara, ya shiga tarihin jirgin sama na soja har abada. F-117A ya tabbatar da cewa shi ne jirgin farko mai ƙarancin gani (VLO), wanda aka fi sani da "stealth".
Kwarewar yakin Yom Kippur (yakin da ke tsakanin Isra'ila da hadin gwiwar Larabawa a 1973) ya nuna cewa jirgin sama ya fara rasa kishiyarsa ta "madawwami" tare da tsarin tsaro na iska. Tsarin tarkace na lantarki da tsarin garkuwa da tashoshin radar ta hanyar “naɗewa” dipoles na lantarki suna da iyakokin su kuma ba su samar da isasshiyar murfin jirgin sama ba. Hukumar Tsaro ta Advanced Research Projects Agency (DARPA) ta fara yin la'akari da yiwuwar cikakken "ketare tsarin." Sabuwar manufar ta ƙunshi haɓaka fasahar da za ta rage tasirin radar giciye (RCS) na jirgin sama zuwa matakin da zai hana tashoshin radar gano shi yadda ya kamata.
Ginin #82 na Lockheed shuka a Burbank, California. An lullube jirgin da abin rufe fuska mai ɗaukar microwave da fentin launin toka mai haske.
A cikin 1974, DARPA ta ƙaddamar da wani shiri wanda aka fi sani da Project Harvey. Sunansa ba na bazata ba - yana nufin fim din 1950 Harvey, babban halayensa shine zomo marar ganuwa kusan mita biyu. A cewar wasu rahotanni, aikin ba shi da suna a hukumance kafin a fara matakin "Have Blue". Daya daga cikin shirye-shiryen Pentagon a lokacin ana kiransa Harvey, amma dabara ce. Mai yiyuwa ne yaduwar sunan "Project Harvey" yana da alaƙa da ayyukan ɓarna a kusa da ayyukan wancan lokacin. A matsayin wani ɓangare na shirin DARPA, ya nemi mafita na fasaha don taimakawa rage RCS na yuwuwar jirgin sama na yaƙi. An gayyaci kamfanoni masu zuwa don shiga cikin shirin: Northrop, McDonnell Douglas, General Dynamics, Fairchild da Grumman. Mahalarta shirin kuma dole ne su tantance ko suna da isassun kayan aiki da kayan aiki don kera yuwuwar jirgin RCS mara nauyi.
Lockheed baya cikin jerin DARPA saboda kamfanin bai yi wani jirgin yaki ba a cikin shekaru 10 kuma an yanke shawarar ba zai iya samun gogewar ba. Fairchild da Grumman sun fice daga wasan kwaikwayon. Janar Dynamics a zahiri yayi tayin don gina sabbin matakan lantarki, wanda, duk da haka, ya gaza ga tsammanin DARPA. McDonnell Douglas da Northrop ne kawai suka gabatar da ra'ayoyi masu alaƙa da rage tasirin tasirin radar mai inganci kuma sun nuna yuwuwar haɓakawa da ƙima. A ƙarshen 1974, kamfanonin biyu sun karɓi PLN 100 kowannensu. Kwangilar USD don ci gaba da aiki. A wannan mataki ne rundunar sojin sama ta shiga cikin shirin. Kamfanin kera radar, Hughes Aircraft Company, shi ma ya shiga cikin kimanta ingancin hanyoyin magance kowane mutum.
A tsakiyar 1975, McDonnell Douglas ya gabatar da kididdigar da ke nuna yadda ƙananan radar giciye na jirgin sama zai zama abin da zai sa ya zama "marasa gani" ga radars na rana. DARPA da USAF ne suka ɗauki waɗannan ƙididdiga a matsayin ginshiƙi don kimanta ayyukan gaba.
Lockheed ya shigo cikin wasa
A lokacin, jagorancin Lockheed ya fahimci ayyukan DARPA. Ben Rich, wanda tun daga watan Janairun 1975 ya kasance shugaban sashin ƙira na ci gaba da ake kira Skunk Works, ya yanke shawarar shiga cikin shirin. Tsohon shugaban Skunks Works Clarence L. "Kelly" Johnson ya goyi bayansa, wanda ya ci gaba da zama babban injiniyan tuntuɓar sashen. Johnson ya nemi izini na musamman daga Hukumar Leken Asiri ta Tsakiya (CIA) don bayyana sakamakon binciken da ke da alaƙa da ma'aunin radar giciye na Lockheed A-12 da SR-71 jiragen bincike da jiragen sama na D-21. DARPA ne ya samar da waɗannan kayan a matsayin tabbacin ƙwarewar kamfani tare da RCS. DARPA ya yarda ya haɗa da Lockheed a cikin shirin, amma a wannan matakin ba zai iya shiga kwangilar kuɗi tare da shi ba. Kamfanin ya shiga shirin ne ta hanyar zuba jarin kansa. Wannan wani nau'i ne na cikas ga Lockheed, saboda, ba a ɗaure shi da kwangila ba, bai bar haƙƙin kowane ɗayan hanyoyinsa na fasaha ba.
Injiniyoyin Lockheed sun daɗe suna taƙama tare da ra'ayin gaba ɗaya na rage tasirin tasirin radar na ɗan lokaci. Injiniya Denis Overholser da masanin ilmin lissafi Bill Schroeder sun zo ga ƙarshe cewa za a iya samun ingantaccen tunani na radar radar ta hanyar amfani da ƙananan filaye masu yawa kamar yadda zai yiwu a kusurwoyi daban-daban. Za su jagoranci na'urorin lantarki masu haske don kada su koma tushen, wato, ga radar. Schroeder ya ƙirƙiri ma'auni na lissafi don ƙididdige matakin hasashe daga filaye mai kusurwa uku. Dangane da wannan binciken, darektan bincike na Lockheed, Dick Scherrer, ya ƙera ainihin siffar jirgin, tare da babban fikafi mai kaifi da fuselage na jirgin sama da yawa.
