Two J-20s, China's most advanced fighter jet. perform at the Chinese Air Force's open day event in Changchun, NE China's Jilin on Thursday. Photo: VCG

China's J-20 fighter jet has been spotted equipped with pylon adapters under its wings, indicating the stealth aircraft may also be able to enter a "beast mode" like the US' F-35 fighter jet if needed by giving up some stealth capability in exchange for larger weapons loads, reports said.

A J-20 prototype taking a test flight had two external pylon adapters, one under each side of its wings, and could carry a total of four extra missiles, Shanghai-based news website eastday.com reported on Monday, citing a recent photo widely circulated on Chinese social media.

Judging by a performance flight at Airshow China 2018, a single J-20 can carry at least four PL-15 missiles in its main weapon bay and two PL-10 short-range combat missiles in its side weapon bays, when not using external adapters.

Usually, stealth aircraft hide their weapons in bays to keep a low radar profile, making them difficult to be detected, and using external pylons to carry weapons will make them less stealthy but more powerful, a Chinese military expert who asked for anonymity told the Global Times on Wednesday.

The warplanes can choose different types of loadouts according to different mission requirements, the expert said.

This is similar to the US' F-35 fighter jet, which has a "stealth mode" that can only carry a small amount of internal ordnance and a "beast mode" that can carry a lot more internal and external ordnance, the eastday.com report said.

Stealth aircraft can use "stealth mode" to seize aerial superiority, and once the sky is clear and safe, they can ditch stealth and switch to "beast mode" by carrying more munitions via external adapters and launch extended attacks, the report said.

The photo indicates that the J-20 could enter a "beast mode" like the F-35 when engaged in low-risk and low-threat missions, eastday.com reported, noting that the J-20 could also carry external fuel tanks for extended range.