
http://spotters.net.ua/search/?aircraft=Antonov+Mk.181&
Project target was create and test channel-wing, (invented by american Custer in 1920's) for short take off, and mostly completed, but not finished and closed after end of USSR.
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About Custer Channelwing design:
http://en.wikipedia.org/wiki/Channel_wing
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Single developed prototype now can be seen in National Aviation Museum of Ukraine (use googletranslate):
http://aviamuseum.com.ua/ua/exposition/ ... 2-virb-181

Info from:
Product 181 - Wikipedia (translated)
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Here also is a list of ASTC Antonov Backpack projects like ZK-4,which based on An-181,and a VTOL airliner design
http://cafefoundation.org/v2/pdf_tech/H ... 09_eng.pdf