The test took place Oct. 30, 2015 in California, Pentagon officials described.

“This milestone was the first in a series of test flights to functionally evaluate the in-flight operation of the F-35A’s internal 25mm gun throughout its employment envelope,” a Pentagon statement said.

The Gatling gun will bring a substantial technology to the multi-role fighter platform, as it will better enable the aircraft to perform air-to-air attacks and close-air support missions to troops on the ground – a task of growing consequence given the Air Force plan to retire the A-10.

Called the Gun Airborne Unit, or GAU-22/A, the weapon is engineered into the aircraft in such a manner as to maintain the platform’s stealth configuration.

The four-barrel 25mm gun is designed for rapid fire in order to quickly blanket an enemy with gunfire and destroy targets quickly. The weapon is able to fire 3,300 rounds per minute, according to a statement from General Dynamics.

“Three bursts of one 30 rounds and two 60 rounds each were fired from the aircraft’s four-barrel, 25-millimeter Gatling gun. In integrating the weapon into the stealthy F-35A airframe, the gun must be kept hidden behind closed doors to reduce its radar cross section until the trigger is pulled,” a statement from the Pentagon’s Joint Strike Fighter said.

The first phase of test execution consisted of 13 ground gunfire events over the course of three months to verify the integration of the gun into the F-35A, the JSF office said.

“Once verified, the team was cleared to begin this second phase of testing, with the goal of evaluating the gun’s performance and integration with the airframe during airborne gunfire in various flight conditions and aircraft configurations,” the statement added.

The new gun will also be integrated with the F-35’s software so as to enable the pilot to see and destroy targets using a helmet-mounted display.

The gun is slated to be operational by 2017.

Small Diameter Bomb II: 

A key part of the SDB II is a technology called a “tri-mode” seeker — a guidance system which can direct the weapon using millimeter wave radar, uncooled imaging infrared guidance and semi-active laser technology.

A tri-mode seeker provides a range of guidance and targeting options typically not used together in one system. Millimeter wave radar gives the weapon an ability to navigate through adverse weather, conditions in which other guidance systems might encounter problems reaching or pinpointing targets.

Imagining infrared guidance allows the weapon to track and hone in on heat signatures such as the temperature of an enemy vehicle. With semi-active laser technology, the weapon can be guided to an exact point using a laser designator or laser illuminator coming from the air or the ground.

Also, the SBD II brings a new ability to track targets in flight through use of a two-way Link 16 and UHF data link, Raytheon officials said.

The millimeter wave radar turns on first. Then the data link gives it a cue and tells the seeker where to open up and look. Then, the weapon can turn on its IR (infrared) which uses heat seeking technology, Raytheon officials said.

The SBD II is engineered to weigh only 208 pounds, a lighter weight than most other air dropped bombs, so that eight of them can fit on the inside of an F-35 Joint Strike Fighter, Raytheon officials explained.

Attack Missions in the A-10 - A Pilot's View

Known for an ability to keep flying after taking multiple rounds of enemy machine gun fire, land and operate in rugged terrain, destroy groups of enemy fighters with a 30mm cannon and unleash a wide arsenal of attack weapons, the A-10 is described by pilots as a “flying tank” in the sky -- able to hover over ground war and provide life-saving close air support in high-threat combat environments.

“It is built to withstand more damage than any other frame that I know of. It’s known for its ruggedness,” A-10 pilot Lt. Col. Ryan Haden, 23rd Fighter Group Deputy, Moody AFB, told Scout Warrior in an interview.

The pilot of the A-10 is surrounded by multiple plates of titanium armor, designed to enable the aircraft to withstand small-arms fire and keep flying its attack missions.

“The A-10 is not agile, nimble, fast or quick,” Haden said.  “It’s deliberate, measured, hefty, impactful calculated and sound. There’s nothing flimsy or fragile about the way it is constructed or about the way that it flies.”

A-10 Thunderbolt II, affectionately known as the Warthog, has been in service since the late 1970s and served as a close air support combat aircraft in conflicts such as the Gulf War, Operation Enduring Freedom, Operation Iraqi Freedom and Operation Allied Force in Kosovo, among others.

Having flown combat missions in the A-10, Haden explained how the aircraft is specially designed to survive enemy ground attacks.

“There are things built in for redundancy. If one hydraulic system fails, another one kicks in,” he said.

If the aircraft loses all of its electronics including its digital displays and targeting systems, the pilot of an A-10 can still fly, drop general purpose bombs and shoot the 30mm cannon, Haden explained.

“So when I lose all the computers and the calculations, the targeting pod and the heads up display, you can still point the aircraft using a degraded system at the target and shoot. We are actually trained for that,” he said.

Unlike other air platforms built for speed, maneuverability, air-to-air dogfighting and air-to-air weapons, the A-10 is specifically engineered around its gun, a 30mm cannon aligned directly beneath the fuselage. The gun is also called a GAU-8/A Gatling gun.

“The 30mm cannon has 7 barrels. They are centered the way the aircraft fires. The firing barrel goes right down the center line. You can point the aircraft and shoot at the ground. It is designed for air to ground attack,” Haden explained.

Armed with 1,150 rounds, the 30mm cannon is able to fire 70-rounds a second.

Haden explained the gun alignment as being straight along the fuselage line without an upward “cant” like many other aircraft have. Also, the windows in the A-10 are also wider to allow pilots a larger field of view with which to see and attack targets.

The engines of the A-10 are mounted high so that the aircraft can land in austere environments such as rugged, dirty or sandy terrain, Haden said. The engines on the A-10 are General Electric TF34-GE-100 turbofans.

 “I’ve seen this airplane land on a desert strip with the main gear buried in a foot of sand. On most planes, this would have ripped the gear up, but the A-10 turned right around and took off,” he added.

There have been many instances where A-10 engines were shot up and the pilots did not know until the returned from a mission, Haden said.

These aerodynamic configurations and engine technology allow the A-10 to fly slower and lower, in closer proximity to ground forces and enemy targets.

“The wings are straight and broadened. The engines are turbofan. They were selected and designed for their efficiency, not because of an enormous thrust. We have a very efficient engine that allows me to loiter with a much more efficient gas-burn rate,” Haden said.

Close Air Support: 

By virtue of being able to fly at slower speeds of 300, the A-10 can fly beneath the weather at altitudes of 100 feet. This gives pilots and ability to see enemy targets with the naked eye, giving them the ability to drop bombs, fire rockets and open fire with the 30mm cannon in close proximity to friendly forces.

“We shoot really close to people. We do it 50-meters away from people. I can sometimes see hands and people waving. If I get close enough and low enough I can see the difference between good guys and bad guys and shoot,” Haden explained.

The aircraft’s bombs, rockets and cannon attack enemies up close or from miles sway, depending on the target and slant range of the aircraft, Haden added.