The F-35 Lightning II Will Get A New Radar

A U.S. Air Force F-35A of the 493rd Fighter Squadron during the recent Falcon Strike 2022 exercise in Italy. (Photo: Stefano D’Urso/The Aviationist)

Last year, the U.S. Air Force’s unfunded wish list for Fiscal Year 2023 mentioned the procurement of seven F-35A in Block 4 configuration with the APG-85 radar, part of the Lot 17 production contract. This info, first mentioned by Defense News after it appeared on the budget presentation’s slides, was initially dismissed as a typo in place of the APG-81 designation of the radar currently employed by the F-35.

When the same APG-85 designation appeared again in December, doubts started to arise. That’s when The War Zone was able to receive answers from the F-35 Joint Program Office (JPO), which confirmed that there is indeed a new radar in the works for the 5th gen fighter jet in the Block 4 configuration.

“The U.S. Air Force, Navy, and Marine Corps are jointly developing and integrating an advanced radar for the F-35 Lightning II, which is capable of defeating current and projected adversarial air and surface threats,” said the F-35 JPO. “This advanced radar will be compatible with all variants of the F-35 aircraft.”

There are a very few direct radar development/modernization contracts awarded to N. Grumman to support the #F35 as most are rolled into the larger Air-Vehicle modernization efforts. Multi-Ship signal processing is one of the few exceptions. https://t.co/fMu26JdGBJ

— Air Power (@MIL_STD) January 4, 2023

The F-35 is currently equipped with the Northrop Grumman AN/APG-81 active electronically scanned array (AESA) radar, the successor of the F-22’s APG-77 radar and whose development started in 2001. The APG-81 is considered the cornerstone of the F-35’s sensor suite and provides a robust battlespace situational awareness.

Here is how Northrop Grumman describes the radar on its website:

The AN/APG-81 radar has long-range active and passive air-to-air and air-to-ground modes that support a full range of air-to-air and air-to-surface missions complemented by stealth features along with significant electronic warfare and intelligence, surveillance and reconnaissance functions.

In air-to air-combat, The AN/APG-81 provides long range capability allowing the pilot to detect, track, identify and shoot multiple threat aircraft before the adversary detects the F-35. This offers a first look, first shot, and first kill capability.

In air-to-ground combat, this revolutionary, all-weather, precision targeting AESA provides the war fighter with unprecedented situational awareness and detection utilizing its ground and maritime modes. The AN/APG-81 radar can detect, precisely locate, and with aid of its ultra-high-resolution Synthetic Aperture Radar (SAR) mapping mode, can identify and engage military targets with outstanding reliability.

The AN/APG-81 epitomizes the F-35’s multi-role mission requirement showcasing the robust electronic warfare (EW) capabilities and can operate as an EW aperture utilizing the AESA’s multi-function array (MFA). Fully adept at electronic protection (EP), electronic attack (EA) and electronic support measures (ESM) it enables the F-35 the unparalleled capability to suppress and destroy the most advanced enemy air defenses.

Northrop Grumman says the 1,000th APG-81 radar will be delivered this year and more than 3,000 are expected to be built throughout the life of the program. It is not known now how the now radar will change these number, as the available unclassified details are few. It is also unknown if this radar will be available to all F-35 users or if it will be a US-only system.

Without knowing anything else, the APG-85 might be a heavily modified APG-81, to such extent that it required a new designation, or a completely new radar being developed. In fact, if that was just an upgrade, the designation would have been APG-81v1, as done for other radars. Also, it has not been specified who is going to manufacture the new radar.

An F-35A Lightning II fighter jet assigned to the 6th Weapons Squadron, U.S. Air Force Weapons School, takes off for a training mission at Nellis Air Force Base, Nevada, Dec. 13, 2022. (U.S. Air Force photo by William R. Lewis)

The radar is one of the over 75 major upgrades expected to be included in the Block 4. Among the upgrades there are enhancements of the Electronic Warfare capabilities, radar and electro-optical systems, weapons, cockpit and navigation systems. Some of these upgrades will be delivered in increments until the final configuration, for which an engine upgrade might be required in order to provide more power to all the systems.

“Pratt & Whitney submitted a pair of proposals for modernizing the F135 engine to the JPO in March. The plans would improve thrust and range by more than 10 % each and give the F-35B a 5% boost in vertical lift and a 50% improvement in thermal management” https://t.co/3zEfOg36IB pic.twitter.com/Vbv1FbM10W

— Air Power (@MIL_STD) November 6, 2021

Among the unclassified upgrades there are a next generation Distributed Aperture System, a new Integrated Core Processor, cooling systems enhancements, new Electronic Warfare processor and antennas. Unclassified slides from Lockheed Martin also show Auto Ground Collision Avoidance System integration, a new Open System Architecture (part of the Tech Refresh 3), Multi-Domain Operations and Missile Defense capabilities, Manned-Unmanned Teaming and extended range with the use of external fuel tanks.

The program basically had two choices when deciding on modernization. It could either keep upgrades SWP&C neutral, or it could eat into these margins and plan for propulsion enhancements. Block 4 prioritizes capability and modernizes virtually every aspect of the F-35 system. pic.twitter.com/CHvQYFjwQO

— Air Power (@MIL_STD) November 7, 2021

However, the majority of the details about the Block 4 upgrades are classified. Often considered the F-35’s most ambitious upgrade, the Block 4 is meant to help keep the Lightning II’s fighting edge over potential adversaries through 2070. Tech Refresh 3 is considered essential in order to deliver this upgrade and the future ones, as it is described as the IT backbone for all future improvements.

Lots of reactions on this tweet that express shock at them needing engine enhancements. 👇 is a thread going over how extensive the overall F-35 FOM (TR3 & Block 4) is. Also note that the F-16 needed propulsion growth during its modernization in the 90s.https://t.co/l9F31GCKFF

— Air Power (@MIL_STD) November 7, 2021

Forbes reported some more details, saying that TR3 is being installed in all new production aircraft, including the Lot 15 aircraft currently being delivered, and retrofitted on all the F-35s already in service back to Lot 10. The retrofit, which requires 14 days of downtime, will be performed during scheduled maintenance. This way the F-35 will migrate to the open-system architecture and exploit all the advantages we often reported, like adding new or improved capabilities on operational aircraft very quickly and at a reduced cost.

According to Forbes, the Block 4 includes 17 new weapons, the majority of them kinetic, but some also non-kinetic, such Electronic Attack capabilities for an instance. Block 4 also enhances networking capability with other tactical systems to enable integrated, long-range “kill webs”, covering multiple warfighting domains with the fusion of sensor inputs from diverse sources, somewhat confirming the info from the Lockheed Martin slides we mentioned.

Anyway, as we already mentioned, most info about the upcoming F-35 Block 4 configuration are classified, so we will only be allowed to discover just a small part of the highly advanced, next generation technology that goes into the 5th gen fighter. This means that, just as for the current APG-81 radar, it is possible that we will know only very few details about the future APG-85 radar, but we will be sure to report about them when they will be publicly released.