March 27, 2015: Strategy Page

U.S. SOCOM (Special Operations Command) has decided to install a 105mm cannon in its new AC-130J gunship. In the last decade SOCOM had been replacing the 40mm and 20mm autocannon and 105mm cannon with missiles but combat experienced showed that that cannon were still needed in many situations. Before that SOCOM decided to bring back autocannon and install 30mm cannon (to replace the rather elderly 40mm and 20mm models). Thus the latest C-130 gunship model, the AC-130J has a 105mm cannon fired out the back of the aircraft via a modified rear ramp. Meanwhile SOCOM has standardized on the Griffin missile and GPS guided SDB (small diameter bomb).

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 rate of fire used. Each 30mm round weighs about 714 g (25 ounces, depending on 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.

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 11 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 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.

 SOCOM is expanding its existing AC-130 gunship fleet to 37 new AC-130J models. These 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.

March 18, 2015: Strategy Page

The U.S. Air Force recently revealed that a new (JMMBRU) bomb rack for the F-35 will not work in the bomb bay of the vertical takeoff version (F-35B) of the F-35 until the bomb bay is modified to move a hydraulic line and a bracket. These two items did not interfere with the original bomb racks that were to go into the bomb bay. The JMMBRU is a new development that was not really planned for when F-35 development began. Sort of an “unknown, unknown.” 

In late 2014 the air force had successfully tested the new JMMBRU bomb rack for the 225 kg SDB (Small Diameter Bomb) in an F-35A. JMMBRU allows the F-35 to carry eight SDBs internally (instead of four), plus (in a less stealthy configuration) another 16 externally. This makes the F-35 a much more effective bomber, especially since the SDB has been upgraded to glide farther and hit moving targets, as well as still penetrate the ground to destroy bunkers. The new SDB II has three different guidance systems: radar, heat seeker, and homing on laser light bounced off the target. That means no matter what the weather or time of day there is a guidance system that will find the target.

A frequent user of JMMBRU will be the vertical takeoff version, which the U.S. Marine Corps needs to provide ground support. The marines are buying 533 F-35Bs and the B version had to be heavily modified internally to handle the vertical takeoff capability. Changes to the bomb bay (including making it a bit smaller) were considered acceptable until the JMMBRU was designed and apparently did not take into account these differences in the F-35B

Meanwhile a lot of controversy surrounds the F-35. The U.S. Air Force still expects to get production models of its 31 ton F-35A in late 2016. This is the cheapest version, costing about $159 million each. The U.S. Navy version (the F-35C) will arrive in late 2019 and cost about $264 million each. This version has a stronger landing gear to handle carrier landings and components that are more resistant to corrosion from constant exposure to salt water. The vertical take-off version for the marines, the F-35B, will cost $214 million each. All of these prices are expected to be much higher (20 percent or more) in reality. This is happening despite more and more delays as well as questions about reliability and cost. At the moment the F-35 costs 60 percent more (than the F-16, per flight hour) to operate.

The F-35 is armed with an internal 25mm cannon and, before the SDB, four internal air-to-air missiles (or two missiles and two smart bombs) plus four external smart bombs and two missiles. All sensors are carried internally and max weapon load is 6.8 tons. The aircraft is very stealthy when just carrying internal weapons. The more compact (it looks like a missile) SDB was designed with the internal bomb bays of the F-22 and F-35 in mind.

Like the F-22 fighter, the F-35 is stealthy and stuffed with a lot of new technology. Most (about 60 percent) of the F-35s built will be used by foreign nations. The rising cost of the F-35 brings with it reluctance to buy as many aircraft as currently planned. The success of smart bombs in Iraq and Afghanistan has also made it clear that fewer aircraft will be needed in the future. In any event, it's likely that F-35s will end up costing close to $200 million each. But with SBDs F-35s become a very potent bomber that can get at well protected targets.