F-35C Needs New Outer Wings To Carry AIM-9X

Feb 17, 2017 James Drew and Lara Seligman | Aerospace Daily & Defense Report

The head of the F-35 Joint Program Office (JPO) says the outer wings of 32 carrier-based C-models need to be replaced to carry the Raytheon AIM-9X Sidewinder, the aircraft’s primary dogfighting weapon.

The U.S. Navy variant experienced an undisclosed amount of oscillation or turbulence during flight trials with the AIM-9X in December 2015, and Lt. Gen. Christopher Bogdan says aircraft already delivered need to be retrofitted with strengthened wings.

“It was discovered the outer, folding portion of the wing has inadequate structural strength to support the loads induced by pylons with AIM-9X missiles during maneuvers that cause buffet,” Bogdan says in written testimony to Congress on Feb. 16.

Engineers have already produced an enhanced outer wing design, which is now undergoing flight testing. The issue has impacted the timeline for fielding AIM-9X, which is being rolled out for the Navy in Block 3F. “Once the new design is verified to provide the require strength, the fix will be implemented in production and retrofitted to existing aircraft by swapping existing outer wings with the redesigned ones,” Bogdan writes.

The AIM-9X is the heat-seeking sidekick to the Raytheon AIM-120C advanced medium-range air-to-air missile. Without it, the F-35 would be incapable of high off-boresight shots at close range. Because of a seven-year schedule delay, the fifth-generation fighter will carry air superiority missiles that are one generation behind its legacy counterparts, which are already carrying the newest AIM-9X Block II and AIM-120D.

Various problems discovered during developmental testing of AIM-9X have already delayed the weapon’s expected fleet-wide rollout by one month, shifting from October to November 2017. The missile must be delivered in time to support initial operational test and evaluation and complete the 17-year F-35 system development and demonstration phase by May 2018. The Navy, in particular, must be cleared to fly and shoot the AIM-9X to declare combat-ready status with its first squadron of F-35C Block 3F aircraft in 2018.

Another task for the F-35 team is adding a moving target capability, as reported by Aviation Week on Feb. 15. There are currently no plans to install weapons capable of hitting moving and maneuvering targets, such as an insurgent driving away in a pickup truck. These types of weapons were designed for the wars in Iraq and Afghanistan and can hit targets traveling at speeds of up to at 70 mph. They are now making their mark in the air campaign against the Islamic State group. Because the F-35’s laser designator cannot lead the target, its basic inventory of late-1990s guided bombs will fall short if that target moves briskly.

The JPO is now working with the U.S. Air Force and Marine Corps to integrate Raytheon’s GBU-49 Lot 5 Enhanced Paveway II, which automatically corrects for target speed and direction as well as wind conditions. The Marines have expressed a preference for the Raytheon GBU-53B Small Diameter BombIncrement II, but that is not slated for full integration and flight clearance until Block 4.2, around fiscal 2022 or later. It is not clear if GBU-49 will be automatically selected for F-35 or competed against the latest Boeing Laser Joint Direct Attack Munition and Lockheed Dual Mode Plus. Whatever the decision, it cannot delay F-35 Block 3F.

“I’m working to figure out how we can fit that in sooner rather than later, whether it becomes part of Block 3F or if it gets done at the tail end of 3F,” Bogdan told reporters after the congressional hearing. “The big deal there is to get it done before the middle of Block 4, when we get the moving target capability.”

Bogdan says the F-35 was originally due to be fielded with a cluster bomb that could hit moving targets, the CBU-103 Wind Corrected Munition Dispenser. But the Pentagon has pledged to stop using cluster munitions that leave unexploded ordnance by 2018.

GBU-49 can operate through poor visibility but is not an all-weather weapon. “SDB II is the weapon we all want, and that’s an all-weather moving target [glide bomb],” says Lt. Gen. Jon Davis, deputy commandant for Marine Corps aviation.