Sukhoi says it has started testing an active electronically scanned array (AESA) radar on its fifth-generation T-50 PAK-FA fighter in a statement issued on 8 August.

The company says that the radar is showing "considerable progress" in ground and flight testing. The performance demonstrated so far "corresponds to the existing level of best aviation systems available elsewhere", Sukhoi says. There are currently three flying T-50 prototypes, but only one is equipped with an AESA.

The Tikhomirov NIIP-developed AESA employs "advanced technologies of electronic control over the radar beam", Sukhoi says, which is a first for a Russian-built set.

The new radar will not only afford the PAK-FA the ability to detect targets from greater ranges, it will also enable the simultaneous use of air-to-air and air-to-surface modes. The radar can also engage several targets at a time using precision-guided munitions. Additionally, it features built-in target recognition and classification capabilities as well as secure communications and electronic countermeasures.

Sukhoi says that there is a growth path to integrating additional capabilities to the new AESA radar. But, because the system is designed to be modular, there could be other potential applications for the new system including retrofits to older aircraft types or even air defence systems, the company says.

Sukhoi also is continuing to wring-out other systems onboard the PAK-FA. For example, testing of the jet's "optical channels" has started, the company says. Additionally, a fourth PAK-FA prototype could soon be joining the test fleet.

Mikhail Pogosyan, president of Russia's United Aircraft Corporation (UAC), told reporters at the Farnborough airshow in July that a fourth PAK-FA prototype would start flying "shortly". He added that by start of the show, the three current prototypes had flown 120 test sorties.

Pogosyan said that Russia will continue to build fourth-generation fighters for the export market alongside the PAK-FA. That would offer customers a choice between relatively inexpensive conventional warplanes and the high-priced fifth-generation machines.

Meanwhile, Sukhoi continues to test its other new fighter. The new Su-35 variant of the venerable Flanker has accumulated more than 600 flights, Pogosyan said. Later this year, UAC must deliver six such aircraft to the Russian air force, he added.

Sukhoi says that volume production of the Su-35 "starts in 2013". Currently, the aircraft is undergoing weapons firing trials.

In the future, the Su-35 could be fitted with the PAK-FA's new AESA, replacing its current passive electronically scanned array RLPK-35 "Irbis" radar, Sukhoi says.

Source: Flight International