The F-35B can't carry its most advanced weapon until 2022

Lockheed Martin's F-35B variant has hit yet another snag which could seriously impact the aircraft's overall ability to strike at ground targets.

Now, the fifth-generation aircraft will be unable to carry the military's latest and most advanced munitions for awhile.

Due to a design oversight, the internal weapon's bay of the F-35B is too small to carry the required load of the new Small Diameter Bomb II (SDB II), Inside Defense reports citing the Pentagon's F-35 Joint Program Office. The SDB II is a next-generation precision-strike bomb that was meant to dovetail with the F-35 program.

The F-35B was designed to carry eight SDB IIs inside the internal weapons bay. These bombs would allow the F-35 pilot to target eight points from 40 miles away and with complete precision. The SDB IIs can also change course in-flight to follow moving targets through laser or infrared guidance systems, according to Foxtrot Alpha.

However, the F-35B can only fit four of the required bombs in its weapons bay. The F-35B variant has a significantly smaller internal bay than the F-35A and F-35C due to the aircraft's design as a short-takeoff-vertical-landing aircraft.

Inside Defense reports that the "Navy initially wanted to field the SDB II first on the F-35B/C but is instead bringing forward integration with the F/A-18 Super Hornet. The SDB II is an F-35 Block 4 software capability and the release of that software load has been pushed back to FY-22."

In other words, because the SDB II is included with the weapon Block 4 upgrade for the F-35, the aircraft is now likely to not field the new munitions until 2022.

F-35 spokesman Joe DellaVedova confirmed to Inside Defense that the SDB II problem has been known since 2007 and the more difficult changes to the aircraft have already been made in order to allow it to field the munitions.

"We've been working with the SDB II program office and their contractors since 2007," DellaVedova said. "The fit issues have been known and documented and there were larger and more substantial modifications needed to support SDB II that have already been incorporated into production F-35 aircraft."

The F-35B variant is the Marine Corps model of the plane and 34 aircraft have already been delivered to the branch. The delay in implementing the SDB II will not affect the aircraft's ability to fly but will limit the operations that the F-35B will be able to effectively carry out.