Twin Northrop YF-23 Grey and BlackTwin Northrop YF-23 Grey and Black. The twin YF-23 nick named black widow of Northrop Company captured while in flight. There are two livery, grey and black. The 'Y' stands for concept jet aircraft since these were developed and competed with F-22 Raptor of Lockheed Martin in terms to built fifth generation jet fighter. At the end this model defeated and the official fifth generation jet of USA went to the Raptor. However, some people said that the YF-23 should won the competition, and the winning of Lockheed was more to political issue.