This is why China’s J-20 can’t dogfight US stealth fighters

China's J-20 stealth fighter jet represents a massive milestone for Beijing's armed forces and the first stealth aircraft ever fielded outside the US, but the impressive effort still falls noticeably short in some areas.

The J-20 doesn't have a cannon and represents the only entry into the world of fifth-generation fighters that skips the gun, which has seen 100 years of aerial combat.

Enemy aircraft can't jam a fighter jet's gun. Flares and chaff will never fool a gun, which needs no radar. Bullets rip out of the gun already above the speed of sound and need not wait for rocket boosters to kick in.

While the F-22, the US's fifth-generation stealth superiority fighter, can hold just eight missiles, its 20mm rotary cannon holds 480 rounds it can expend in about five seconds of nonstop firing.

The US's other fifth-generation stealth jet, the F-35, has already used its cannon in combat missions in Afghanistan.

But not every jet needs a gun, and not every jet needs to dogfight.

The F-35B firing its gun pod in the air for the first time.

(Lockheed Martin photo by Dane Wiedmann)

The J-20 doesn't even consider dogfights

The J-20's lack of a gun shows that the "Chinese recognize that being in a dogfight is not a mission that they're building for," retired US Marine Corps Lt. Col. David Berke, a former F-22 pilot and F-35B squadron commander, told Business Insider.

"They probably want to avoid a dogfight at all costs," he continued.

Air-combat experts previously told Business Insider that the J-20 most likely couldn't compete with even older US jets like the F-15 in head-on dogfights, but that it most likely didn't need to.

The Chinese jet — with powerful sensors, long-range missiles, and a stealth design — poses a serious threat to US Air Force refueling, early warning, and other support planes. Tactically, beating back these logistical planes with J-20s could allow China to keep the US operating at an arm's length in a conflict.

But it increasingly looks as if the J-20 would lose handily to US fighter jets in outright combat, and that may be the point.

According to Berke, guns only work to about 800 feet to score aerial kills.

"I'd rather have a missile that's good to 800 feet that goes out to 20 miles than a gun that goes to 800 feet and closer but nothing else," Berke said, adding, "Once you start getting outside of 1,000 feet, you can start using missiles."

Because the J-20 wasn't meant to be a close-in brawler, the Chinese ditched it, saving room and weight aboard the jet to allow for other technologies.

Also, the mission of the gun in air-to-air combat may be disappearing.

The last US air-to-air-guns kill wasn't exactly done by a fifth-gen.

(DVIDS)

The US started building the F-22 in the 1990s with a hangover from combat losses to air-to-air guns in Vietnam after fielding jets without guns and relying solely on missiles. The F-35 includes a gun because it has a broad set of missions that include close air support and air-to-ground fires.

"In air-to-air, the cannon serves one very specific and limited purpose only useful in a very predictable phase of flight, which is a dogfight," Berke said.

"The Chinese probably recognize that [dogfights are] not where they want the airframe to be and that's not the investment they want to make," he continued.

"Utilizing a gun against a highly maneuverable platform is an incredibly challenging task," Berke said. In World War II, propeller-driven planes frequently engaged in turning fights where they attempted to get behind one another and let the guns rip, and bombers flew with turret gunners covering the whole compass.

But today's F-22s, J-20s, Su-35s, and other highly maneuverable jets give the guns an "extremely limited use" in combat, according to Berke.

Berke said the US most likely hadn't scored an air-to-air-guns kill in decades.

A Business Insider review found that the last time a US plane shot down an enemy aircraft with guns was most likely the Cold War-era tank buster A-10 downing an Iraqi helicopter in 1991— hardly applicable to the world of fifth-generation fighter aircraft.

This article originally appeared on Business Insider. Follow @BusinessInsider on Twitter.