Nikitin-Shevchenko IS Polymorphic Fighter. Designed with a retractable lower wing to change from biplane to monoplane in flight https://www.destinationsjourney.com/historical-military-photographs/nikitin-shevchenko-is-polymorphic-fighter/ #aeroplane #Aircraft #airplane #aviation #fighter #NikitinShevchenkoIS #polymorphic #polymorphicfighter