Special Operations: New Generation Gunship

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December 13, 2019: The U.S. Air Force finally got its new AC-130J gunship into combat. This occurred in Afghanistan during mid-2019. The AC-130J spent 1,380 hours in the air during its first 130 days. This air time was spent carrying out 218 sorties. The AC-130J is called Ghostrider for short and it proved to be popular with the SOCOM (Special Operations Command) special operations troops it spent most of its time supporting. SOCOM actually controls the AC-130s and makes major decisions on what weapons and related electronics the gunships will carry as well as when and how they will be used. Although designed to support SOCOM personnel the gunships are popular with ground troops in general. Thus the gunships will support any troops who need it if local SOCOM personnel do not.

Compared to previous AC-130s, the AC-130J has improved sensors and fire control as well as a new assortment of weapons. This is the result of testing various weapons combinations on older AC-130 models to find out what combination works best. This, combined with the improved sensors, fire control and communications provides more accurate fire support with a larger array of weapons. Most of the weapons are now laser-guided missiles of various sizes. These laser-guided missiles are ideal for gunships, which were never about massive firepower. Instead, gunships are essential because they can provide lots of precision firepower and have the ability to circle the target area for hours. SOCOM operators on the ground found that the AC-130J did all that better than earlier models of AC-130.

While late getting the first AC-130Js into combat, all 32 of them will be in service by 2021 and all 37 of the older AC-130 models will be retired. In 2015 SOCOM received the first AC-130J gunship for acceptance tests. It was expected to enter service in early 2016 but there were delays as the equipment and weapons configurations were tweaked and perfected. By 2016 sixteen AC-130Js had been built but these had to undergo several modifications to get from the initial Block 10 version to the Block 30 that entered combat in 2019. A “Block” designation indicates a specific configuration of an aircraft.

Since 2010 the design of the AC-130J has gone through several major changes. A very visible one was bringing back the 105mm cannon. This was part of a retreat from an earlier decision. Since 2005 SOCOM had been replacing the long-used 40mm and 20mm autocannon and 105mm cannon with missiles but combat experience showed that that cannon were still needed in many situations. SOCOM also decided to bring back autocannon and installed one 30mm cannon to replace the rather elderly 40mm and 20mm cannon. A 2015 change brought back the 105mm cannon, fired out the back of the aircraft via a modified rear ramp.

Meanwhile, SOCOM has standardized on which guided missiles are used on gunships. The smaller one was the Griffin missile and the larger one the GPS guided SDB (small diameter bomb). The AGM-176 Griffin weighs 15 Kg (33 pounds, or 20.5 kg/45 pounds with the launch tube) and has a 5.9 kg (13 pound) warhead. Griffin was first used in Afghanistan. Griffin has a greater range (20 kilometers from aircraft for the B and C versions) than Hellfire because of pop-out wings that allow it to glide after launch. The latest version (Griffin C) uses laser, GPS, inertial guidance and two-way communications. Griffin is launched from launch cells in the C-130 and these launch cells can be reloaded in flight by the crew. Ghostrider can also carry and use the larger (49 kg) Hellfire missile which is similar to Griffin but larger and faster. Hellfire is rocket-propelled and also laser-guided.

The 129 kg (285 pound) Small Diameter Bomb (SDB) is a GPS guided smart bomb designed for urban warfare and targets very close to friendly troops. The smaller blast (17kg/38 pounds of explosives, compared to 127 kg/280 pounds for the 500 pound bomb) from an SDB results in fewer civilian casualties. Friendly troops can be closer to the target when an SDB explodes. Hellfire and SDB hang from the wings of the AC-130J.

The Mk44 30mm Bushmaster cannon weighs 157 kg (344 pounds) and fires at 200 or 400 rounds per minute (up to 7 per second). The cannon has 160 rounds available before needing a reload. That means the gunner has 25-50 seconds worth of ammo, depending on the rate of fire used. Each 30mm round weighs about 714 g (25 ounces, depending on the type). Explosive anti-personnel rounds are fired when used in gunships. The fire control system, and night vision sensors enable the 30mm gunners to accurately hit targets with high explosive shells. After several tweaks to the 30mm ammo and the fire control system, the 30mm autocannon can now reliably provide very precise firepower. Or as the 30mm operators and the troops down below put it, it’s almost like a sniper rifle. The 30mm gun is used it you need pretty accurate fire right now. If you can wait a minute or so you can use a Hellfire. If you can wait a few minutes more you can use the smaller Griffin laser-guided missile. If you need a bigger bang you can call for the less accurate (than laser-guided) SDB. There is a new SDB available that can also use laser-guidance. The 105mm cannon is less accurate than the 30mm autocannon but delivers a bigger bang and does so quickly. If this sounds complicated, it is. But so is what SOCOM operators on the ground, or operating the AC-130J sensors and weapons, prefer because they are all highly trained and have lots of combat experience. That means they can quickly select and use the right weapon for the right situation. The guys on the ground have first call on what but when a specific weapon is not mentioned the gunship crew can be relied on to deliver appropriate firepower quickly.

The 105mm cannon used is a modified (to weigh about 1.4 tons) version of the M102 howitzer that was used by light infantry units from the 1960s to the 1990s. The M102 fires a 15 kg (33 pound) shell. The complete round (with casing and propellant) weighs about 19 kg (42 pounds). On the ground the 105mm fires at distant targets it cannot see, with the shell following a curved trajectory to hit something up to eleven kilometers away. On the gunship it fires directly at targets the gunship sensors can see and that shortens the range to about 1,100 meters. On the gunship, the 105mm can fire up to one round every ten seconds. Usually, only one round per target is needed. In the older AC-130s, 96 105mm rounds were carried. The larger AC-130J can carry twice as many, if not more.

One of the many issues that delayed the AC-130Js use in combat was problems getting enough of the right 30mm ammunition. In late 2017, the air force put in a rush order for new 30mm ammo for its AC-130W and U model gunships. This came about because recent fighting in Iraq and Syria showed that the existing PGU-13D/B 30mm rounds were less accurate than expected at max range and also had a high dud rate. The newer PG-46/B 30mm round was designed specifically for the AC-130W/Us 30mm cannon, is more accurate at long range and has fewer duds. SOCOM had people on the ground, as well as 30mm gun operators on the AC-130s agreeing that the accuracy and reliability problem of the older shells was real.

This sort of thing had not been a problem before but after 2010 two Mk44 30mm cannon replaced the 25mm and 40mm cannon on the older (130J) AC-130s. Testing had shown that at longer ranges the 40mm autocannon shells would be accurate and reliable while the 30mm round was less accurate but it was believed this would not be a problem in combat. That belief turned out to be wrong and that meant a switch to the improved PG-46/B 30mm round.

There were still a lot of the older PGU-13D/B rounds available because the Mk44 30mm Bushmaster autocannon used in the AC-130 and the 30mm autocannon used on the A-10 aircraft, while quite different in many ways, both use the same size ammo. A lot of A-10 30mm ammo was repackaged as PGU-13D/B for use on AC-130s. There were large stocks of 30mm A-10 ammo, but the A-10s were not using their 30mm cannon as much now that they could use smart bombs and laser-guided missiles while the AC-130, now armed with two 30mm cannon were using a lot of it. The PGU-13D/B worked well enough initially at shorter ranges and in situations where the dud rate was not critical. But as AC-130 crews and troops on the ground got more accustomed to the 30mm autocannon, and began to depend on it as a last-ditch weapon for supporting troops in close proximity to the enemy and nearby civilians. That was when accuracy and dud rates became an issue. This was especially the case when the Bushmaster was firing at extreme ranges.

A 30mm round weighs about 715 g (25 ounces), depending on the type. Explosive anti-personnel rounds are the most common round used in the Mk44. From higher altitudes (up to 6,100 meters/20,000 feet), the AC-130 fire control system and night vision sensors, enable the 30mm gunners to accurately hit targets with the high explosive shells. The 30mm round is widely used in ground weapons as well and new 30mm rounds are usually developed for those weapons.

The existing 25mm and 40mm guns on the AC-130 were finally phased out of military service as the older AC-130s were replaced by the AC-130J. The 40mm gun is something of a museum piece. None have been manufactured since the 1990s and parts have to be custom made. Ammo is hard to get, and expensive, as well. The new 30mm Bushmaster is easier to operate and maintain. For example, many repairs can be made while in the air, and it's easier to reload. The older AC-130s were converted to use the 30mm guns until the accuracy and dud rate problems with the 30mm ammo were discovered. That problem has been fixed and with the AC-130J model, 30mm autocannon are standard.

AC-130J will replace 37 older models (eight AC-130Hs, 12 AC-130Ws and 17 AC-130Us). When using the SDB and missiles, the AC-130J can fly high enough to stay out of range of ground fire and this enables it to operate in daylight. But with the cannon, the gunship must fly much lower, where the sensors and all weapons are more effective if only because the missiles and bombs arrive on target more quickly and the 30mm and 105mm cannon can add their firepower. When using the cannon, the AC-130J only operates at night. But with so many missiles and the SDB. Ghostrider can safely operate in combat during daylight and now regularly does so as needed.

 


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