Russia's new stealth fighter made an eyebrow-raising surprise appearance on June 5 - soaring over the Crimean Peninsula, which Moscow ripped from Ukraine in early 2014. The T-50 - Russia's answer to the U.S. Air Force's F-22 - is far from war-ready. Indeed, the twin-engine, radar-evading warplane is suffering such serious design, quality-control and financing problems that it might never enter frontline service in large numbers.