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.