An improved version of China's FC-31 Gyrfalcon stealth fighter jet has conducted its maiden flight in Shenyang, capital of Liaoning province, according to aviation industry sources.

Previously known as the J-31, the twin engine, radar evading aircraft is still under development by Shenyang Aircraft Corp, part of the Aviation Industry Corp of China.

The first test flight of the FC-31's second prototype took place on Friday morning at Shenyang Aircraft Corp, four years after the first prototype took to the skies, sources said.

Aviation enthusiasts posted pictures on Chinese websites, showing what they said was the second prototype in flight.

A publicity officer at AVIC who declined to be named confirmed the flight test but said he was not authorized to disclose details.

The FC-31 was unveiled in October 2012, when the first prototype made its maiden flight, becoming the country's second fifth-generation fighter jet following the J-20, which conducted its first flight in January 2011. Deliveries of the J-20 to the People's Liberation Army Air Force have started. Fifth-generation fighters are the most advanced available.

The new FC-31 seems to have better stealth capabilities, improved electronic equipment and a larger payload capacity, said Wu Peixin, an aviation industry observer in Beijing.

"Compared with the first FC-31, there are a lot of improvements on the second prototype. Changes were made to the airframe, wings and vertical tails, which make it leaner, lighter and more maneuverable," he said.

Fu Qianshao, an aircraft expert with the PLA Air Force, said that the new FC-31 has state-of-the-art instruments such as its electro-optical targeting system and helmet-mounted display and sight system.

He said AVIC wants to use the FC-31 to capture market share at home and abroad, but the company is making a big push to attract foreign buyers with its medium-sized stealth combat planes.

"I believe the aircraft will have bright prospects in the market. Based on my experience and knowledge, I presume its price will be around $70 million, about half that of the United States' Lockheed Martin F-35 Lightning II," he said. "Moreover, the fourth-generation Eurofighter Typhoon and Dassault Rafale fighter jets are priced at about $100 million. All of these mean you can spend a lot less money to get an advanced, fifth-generation stealth combat plane."

Li Yuhai, deputy general manager of AVIC, has previously said AVIC plans to use the FC-31 to "put an end to some nations' monopolies on the fifth-generation fighter jet" and this plane "is able to compete with any other aircraft of its kind".

The only fifth-generation fighter jet currently available in the market is the US' F-35 Lightning II, but the US sells it only to allies.

AVIC displayed a large-scale model of the FC-31 at the 14th Dubai Airshow in the United Arab Emirates in November 2015.

Specifications supplied by AVIC show the FC-31 has a maximum takeoff weight of 28 metric tons, a flight radius of 1,250 kilometers and a top speed of Mach 1.8, or 1.8 times the speed of sound. It can carry 8 tons of weapons. The plane can hold six missiles in its internal weapons bay and another six under its wings, according to the company.