The latest case involves six U.S. Marine Corps F-35B fighters delivered without the AN/APG-85 radar. Gen. Gregory Masiello, director of the F-35 program, disclosed the situation during testimony before a U.S. Senate committee while responding to a senator’s question.
The radar problem exists, but it is limited to U.S. aircraft planned for the new sensor. Export aircraft are not affected because foreign customers are not currently being offered the APG-85 radar.
The difference between the two radar types is significant at the technology level. The APG-85 uses gallium nitride technology, while the APG-81 radar used on Polish F-35s relies on gallium arsenide transmit-receive modules.
Gallium nitride offers higher resistance to temperature and better energy efficiency than the older material. This allows the radar to generate more output power while handling heat more effectively, improving detection range and resistance to jamming.
The new radar is also expected to provide better performance against stealth aircraft. That capability is especially important in the strategic competition between the United States and China.
The APG-85 is part of the broader F-35 Block 4 and TR-3 modernization package. Available data cited in the article indicates that the radar requires about 82 kilowatts of power, creating new demands for the aircraft’s front fuselage, cooling and power systems.
Those demands required two major design changes to the aircraft. One involves the F135 Engine Core Upgrade because rising power requirements under Block 4 risked exceeding the margins originally built into the aircraft’s power system.
The second change concerns the aircraft’s nose section. The new radar is larger than the APG-81, requiring redesign of the front avionics bay and mounting system.
As a result, older radars cannot easily be installed in the redesigned space, even as a temporary solution. The first new U.S. aircraft in this configuration have therefore been delivered with ballast weights in place of the radar.
The article identifies this as a consequence of ordering aircraft in a future configuration before the new equipment was ready for operational installation. It says the United States chose to order airframes already configured for the APG-85 and other Block 4/TR-3 elements rather than introduce the radar first on older-configuration aircraft.
Technical problems and certification work have delayed completion of the package. Current expectations suggest the remaining work could take another year, and possibly up to two years, although the article says that forecast should be treated with caution.
Production of the new airframes is already under way, with about 400 aircraft believed to have been ordered in three batches. Only a few have reportedly been delivered so far.
Until the new radar reaches production lines, the affected F-35s will have sharply limited combat utility. They can fly training missions or operate with older F-35s equipped with APG-81 radars and use data-sharing between aircraft, but they are not independently capable of combat missions.
The issue does not affect the operational capability of the large U.S. fleet of older F-35s. Most of those aircraft were delivered in the earlier configuration with the less capable but proven APG-81 radar.
