Sukhoi's fifth-generation T-50 PAK-FA fighter was one of the highlights of the MAKS Moscow air show, as three of the company's prototype aircraft were displayed flying in formation for the first time.
Speaking to journalists at the show, Russian air force commander Lt Gen Victor Bondarev said the PAK-FA project is at the experimental phase of its development.
"Operable specimens continue to undergo tests by the manufacturer, in preparation for submission to the defence ministry for state acceptance trials," he says. These will last for three years, he adds, and will assess the PAK-FA's compliance with the air force's technical and tactical specifications.
Several of the flight test aircraft will be moved from the third quarter of 2013 to a Russian air force base, for tests to be conducted by service personnel.
Four flying examples of the PAK-FA have so far been produced, with another four to follow by the end of the 2013.
Crowds also saw a flying display by one PAK-FA flown by Sukhoi chief test pilot Sergey Bodgan, which included a number of aerobatic manoeuvres never previously performed in public with the type.